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Stacey J Ackerman,1 Jonathan M Vigdorchik,2 Breana R Siljander,2,3 Jeremy M Gililland,4 Peter K Sculco,2 David W Polly3 1Department of Biomedical Engineering, Johns Hopkins University, San Diego, CA, USA; 2Department of Orthopedic Surgery, Hospital for Special Surgery, New York, NY, USA; 3Department of Orthopedic Surgery, University of Minnesota, Minneapolis, MN, USA; 4Department of Orthopedic Surgery, University of Utah, Salt Lake City, UT, USACorrespondence: Stacey J Ackerman, Email stacey.ackerman.2019@gmail.comPurpose: In the United States (US), total hip arthroplasty (THA) is the most common hospital inpatient operation among Medicare beneficiaries and is ranked fourth when considering all payers. Spinopelvic pathology (SPP) is associated with an increased risk of THA revision (rTHA) due to dislocation. Several strategies have been proposed to mitigate the risk of instability in this population, including use of dual-mobility implants, anterior-based surgical approaches, and technology-assistance (digital 2D/3D pre-surgical planning, computer navigation, and robotic assistance). For primary THA (pTHA) patients with SPP who subsequently undergo rTHA due to dislocation, we aimed to estimate (1) target population size; (2) economic burden; and (3) 10-year projected savings to the US payer of lowering the risk of rTHA due to dislocation among pTHA patients with SPP.Methods: A budget impact analysis from the US payer perspective was undertaken using published literature; American Academy of Orthopaedic Surgeons American Joint Replacement Registry 2021 Annual Report; Centers for Medicare & Medicaid Services MEDPAR 2019; and National (Nationwide) Inpatient Sample (NIS) 2019. Expenditures were inflation-adjusted to 2021 US dollars using the Medical Care component of the Consumer Price Index. Sensitivity analyses were performed.Results: The target population size in 2021 was estimated at 5040 (range, 4830– 6309) for Medicare (fee-for-service plus Medicare Advantage) and 8003 (range, 7669– 10,018) for all-payer. Annual rTHA episode-of-care (through 90 days) expenditures for Medicare and all-payer were $185 million and $314 million, respectively. Using a 4.14% compound annual growth rate from NIS, the estimated number of applicable rTHA procedures that will be performed from 2022– 2031 was 63,419 Medicare and 100,697 all-payer. With each 10% reduction in relative risk of rTHA due to dislocation, Medicare and all-payer could save $233 million and $395 million, respectively, over a 10-year period.Conclusion: Among pTHA patients with spinopelvic pathology, a modest reduction in the risk of rTHA due to dislocation could achieve substantial cumulative savings to payers while improving healthcare quality.Keywords: total hip arthroplasty, revision, spinopelvic pathology, dislocation, economics

Background: Research on hip instability has focused on establishing "safe" ranges of combined component position in supine posture or functional placement of the acetabular component based on the hip-spine relationship. A new angle, the polar axis angle (PAA), of the total hip arthroplasty (THA) components describes the concentricity of both components and can be evaluated in functional positions that confer a greater risk of instability (ie, sitting). The goal of this study was to compare the PAA in functional positions between patients who experienced a postoperative dislocation and a matched control group who did not have a dislocation., Methods: An institutional database was searched for patients experiencing a dislocation after primary THA. Patients who had postoperative full-length standing and lateral-seatedradiographs were included in the dislocator group. A control group of nondislocator patients was matched 2:1 by age, body mass index, sex, and hip-spine classification. Radiographic measurements of the neck angle, acetabular ante-inclination, and PAA were performed by 2 separate blinded, trained reviewers., Results: The lateral-seated neck angle and lateral-seated PAA measurements were significantly lower in the dislocator groups (n = 37) than the control group (n = 74) (23 versus 33 degrees, P < .001; 74 versus 83 degrees, P = .012, respectively). Significant differences were also observed in changes in the polar axes and neck angles between standing and seated positions (P < .001 and P < .001, respectively). When comparing patients who have mobile spines versus stiff spines within the dislocator group, there were no differences in the acetabular, neck, or PAAs. The effect of neck angle on the PAA showed a linear trend across cohorts., Conclusions: Patients who experience postoperative instability have a significantly lower PAA on lateral-seated radiographs when matched for age, sex, body mass index, and hip-spine classification. In addition, the lower seated PAA is driven more strongly by decreased functional femoral anteversion, which emphasizes the role of functional femoral version on stability in THA., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Polyethylene liner exchange and bone grafting is an effective surgical option for the management of periacetabular osteolysis following total hip arthroplasty with well-fixed cups and intact liner locking mechanisms. Purpose: We aimed to evaluate the revision-free survivorship and radiographic lesion progression after polyethylene liner exchange and bone grafting is performed for periacetabular osteolysis. Methods: A systematic review of the literature was performed. We queried Medline, EMBASE, and Cochrane Library for articles published from January 1999 to January 2023 using the following keywords: "osteolysis" AND "well-fixed," "osteolysis" AND "retro-acetabular," "bone graft" AND ("retention" OR "retained" OR "stable") AND "cup," and "uncemented liner" AND "well-fixed." Results: Of 596 articles found, 9 articles were selected for final inclusion (227 cases, mean follow-up time 43.6 months). The overall cup revision rate after liner exchange was 6.6% (15 hips) due to progressive osteolysis (5 hips), aseptic loosening of the acetabular component (5 hips), dislocation (4 hips), and periprosthetic infection (1 hip). There was either radiographic resolution or regression of periacetabular osteolysis in all reported cases that provided measurements (52 hips) except 1 (1.9%) requiring revision. All studies reporting clinical outcomes indicated improved pain and functional scores. Conclusion: This systematic review found that isolated liner exchange with bone grafting for the management of periacetabular osteolysis was associated with a high revision-free survival rate (93.4%) and minimal radiographic progression (1.9%) of osteolytic lesions at short-term to medium-term follow-up. Liner exchange with bone grafting is recommended for the management of large periacetabular osteolytic lesions (> 450 mm 2 ) in well-fixed acetabular cups. We encourage future studies to develop a grading scale for lesions to guide clinical management and risk stratification for patients., Competing Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (© The Author(s) 2023.)

Competing Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: FB reports relationships with Smith & Nephew, OrthoDevelopment, and AccuPredict Inc. GW reports relationships with Stryker, Ethicon, and Exactech. PKS declares relationships with Lima Corporate and Zimmer Biomet. TPS declares a relationship with Exactech. EBG reports relationships with BICMD and Zimmer. BPC reports relationships with Smith & Nephew and Ortho Development. TW reports relationships with Lima Corporate, Zimmer Biomet, and Exactech; he holds a patent (US Patent 8870964) that forms the basis of part of the Exactech knee system. LH declares no potential conflicts of interest.

Understanding spinopelvic mechanics is important for the success of total hip arthroplasty (THA). Despite significant advancements in appreciating spinopelvic balance, numerous challenges remain. It is crucial to recognize the individual variability and postoperative changes in spinopelvic parameters and their consequential impact on prosthetic component positioning to mitigate the risk of dislocation and enhance postoperative outcomes. This review describes the integration of advanced diagnostic approaches, enhanced technology, implant considerations, and surgical planning, all tailored to the unique anatomy and biomechanics of each patient. It underscores the importance of accurately predicting postoperative spinopelvic mechanics, selecting suitable imaging techniques, establishing a consistent nomenclature for spinopelvic stiffness, and considering implant-specific strategies. Furthermore, it highlights the potential of artificial intelligence to personalize care., Competing Interests: A. Fontalis reports that this work was supported by the Onassis Foundation (Scholarship ID: FZR 065-1/2021-2022). A. Fontalis also reports an EFORT Robotic Fellowship supported by Stryker, and a Freemansons' Royal Arch Fellowship with support from Arthritis Research Trust, unrelated to this study. D. Buchalter reports royalties or licenses from Globus Medical, and consulting fees from Globus Medical and Alliant Biotech, unrelated to this study. F. S. Haddad reports multiple research study grants from Stryker, Smith & Nephew, Corin, NIHR, and the International Olympic Committee, royalties from Smith & Nephew, Stryker, Corin, and MatOrtho, consulting fees from Stryker, speaker payments or honoraria from Stryker, Smith & Nephew, Zimmer, AO Recon, and Mathys, support for attending meetings and/or travel from Stryker, Mathys, AO Recon, and The Bone & Joint Journal, all of which are unrelated to this study. F. S. Haddad is also Editor-in-Chief of The Bone & Joint Journal, is President of the International Hip Society, and Vice President of the European Hip Society. P. K. Sculco reports royalties or licenses from Enovis and consulting fees from Zimmer Biomet, unrelated to this study. J. Vigdorchik reports royalties or licenses from Corin and DePuy, consulting fees from Stryker and DePuy, a leadership or fiduciary role on the American Association of Hip and Knee Surgeons and The Bone & Joint Journal, and stock or stock options in Polaris, Ortho AI, Motion Insights, Corin, and Aware, all of which are unrelated to this study., (© 2024 The British Editorial Society of Bone & Joint Surgery.)

Background: Extensor mechanism disruption is a devastating complication following total knee arthroplasty (TKA). Despite its morbidity, there is no consensus regarding the optimal treatment strategy. We aimed to determine the survivorship, clinical outcomes, and improvement in patient-reported outcome measures after primary repair of acute extensor mechanism disruptions following primary or revision TKA., Methods: A retrospective review identified 41 acute extensor mechanism disruptions (33 primary TKAs and eight revision TKAs) from 2015 to 2021. The study group was 56% women, the mean body mass index was 33, the mean age was 66 years, and the mean follow-up was 3 years. Extensor mechanism disruption occurred at the patellar tendon (n = 17), quadriceps tendon (n = 15), and patella (n = 9) at a mean of 10 months following TKA. Surgical management was primary repair (n = 30) or primary repair with augmentation (allograft or autograft) (n = 11). Kaplan-Meier analysis estimated survivorship., Results: The 2-year survivorship free from all-cause reoperation was 72 and 23% following primary and revision TKA, respectively (P = 0.013). The 2-year survivorship free from all-cause reoperation was 66% for primary repair versus 61% for primary repair with augmentation (P = 0.95). There were 17 (41%) patients who underwent reoperation, most commonly for rerupture (n = 4) in two primary repairs and two primary repairs with augmentation (P = 0.288). Revision TKA (P = 0.049) and increased time from disruption to repair (P = 0.039) were risk factors for reoperation. Neither did the mean extensor lag significantly improve nor did patients see improvement in their patient-reported outcome measures., Conclusions: After primary and revision TKA, acute extensor mechanism disruption treated with primary repair with or without augmentation had very poor early survivorship free from all-cause reoperation. Patients should be counseled appropriately, and alternative surgical techniques should be considered., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Patient-specific flanged acetabular components are utilized to treat failed total hip arthroplasties with large acetabular defects. Previous clinical studies from our institution showed that these implants tend to lateralize the acetabular center of rotation. However, the clinical impact of lateralization on implant survivorship is debated. Our goal was to develop a finite element model to quantify how lateralization of the native hip center affects periprosthetic strain and implant-bone micromotion distributions in a static level gait loading condition. To build the model, we computationally created a superomedial acetabular defect in a computed tomography 3D reconstruction of a native pelvis and designed a flanged acetabular implant to address this simulated bone defect. We modeled two implants, one with ~1 cm and a second with ~2 cm of hip center lateralization. We applied the maximum hip contact force and corresponding abductor force observed during level gait. The resulting strains were compared to bone fatigue strength (0.3% strain) and the micromotions were compared to the threshold for bone ingrowth (20 µm). Overall, the model demonstrated that the additional lateralization only slightly increased the area of bone at risk of failure and decreased the areas compatible with bone ingrowth. This computational study of patient-specific acetabular implants establishes the utility of our modeling approach. Further refinement will yield a model that can explore a multitude of variables and could be used to develop a biomechanically-based acetabular bone loss classification system to guide the development of patient-specific implants in the treatment of large acetabular bone defects., (© 2024 Orthopaedic Research Society.)

Background: The impact of a preoperative self-reported nickel allergy in patients undergoing primary total knee arthroplasty (TKA) remains unclear. The aim of this study was to compare the revision rates and outcomes of patients who have a self-reported nickel allergy undergoing primary TKA to patients who do not have a self-reported nickel allergy., Methods: Over 5 years, a total of 284 TKAs in patients who have and 17,735 in patients who do not have a self-reported nickel allergy were performed. Revision rates and differences in preoperative and postoperative patient-reported outcome measures, including Knee Osteoarthritis Outcome Score Joint Replacement (KOOS JR), Visual Analog Scale, Lower Extremity Activity Scale, and the Patient-Reported Outcomes Measurement Information System Mental and Physical Scores, were compared., Results: Survivorship free of all-cause revision at 1 year was similar for patients who have and do not have a self-reported nickel allergy (99.5% [95% CI (confidence interval): 98.6 to 100.0] versus 99.3% [95% CI: 99.1 to 99.4]), P = .49). Patients who have a self-reported nickel allergy undergoing primary TKA had no difference in KOOS JR, Visual Analog Scale, or Lower Extremity Activity Scale scores at 6 weeks and 1 year and slightly worse Patient-Reported Outcomes Measurement Information System mental and physical scores at 6 weeks compared to patients who did not have an allergy. Matched analysis revealed no difference in 6-week or 1-year KOOS, JR scores between patients who did and did not have a self-reported nickel allergy when stratified by implant class (nickel-free versus standard cobalt-chromium) (P = .113 and P = .415, respectively)., Conclusions: Patients who have a self-reported nickel allergy can be advised that, on average, their clinical outcome scores will improve similarly to patients who do not have a self-reported nickel allergy, and revision rates will be similar., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Research has suggested that glucagon-like peptide-1 receptor agonists (GLP-1-RAs) may have therapeutic effects on osteoarthritis of the hip and knee, in addition to managing diabetes and obesity. However, there is a lack of understanding regarding the association between GLP-1-RA use and the diagnosis of osteoarthritis (OA) of the hip and knee., Methods: A collaborative network analytics platform was queried for obese diabetic (n = 1,094,198), obese nondiabetic (n = 916,235), and nonobese diabetic (n = 157,305) patients who had an index visit between 2015 and 2017. Patients who had pre-existing hip and/or knee OA were excluded. A 1:1 propensity score matching was used to balance GLP-1-RA use in stratified cohorts for age, sex, race, body mass index, and hemoglobin A1c. The primary outcomes were rates of progression to hip OA, knee OA, major joint injections, total hip arthroplasty, and total knee arthroplasty. Cox proportional hazards models determined hazard ratios (HRs) between cohorts prescribed and not prescribed GLP-1-RAs., Results: All patients had a five-year follow-up. Rates of progression to hip and knee OA were higher among the GLP-1-RA users in both obese diabetic (hip HR: 1.63, 95% confidence interval [CI]: 1.46 to 1.82; knee HR: 1.52, CI: 1.41 to 1.64) and nonobese diabetic (hip HR: 1.78, CI: 1.50 to 2.10; knee HR: 1.58, CI: 1.39 to 1.80) cohorts. These diabetic cohorts received higher rates of major joint injections, though there was no difference in rates of total hip arthroplasty or total knee arthroplasty. No differences in five-year outcomes were seen when comparing obese, nondiabetic patients who were prescribed GLP-1-RAs with obese, nondiabetic patients not exposed to GLP-1-RAs., Conclusions: This five-year analysis found a greater risk of progression to hip and knee OA among obese and non-obese diabetic GLP-1-RA users. Further studies should explore GLP-1-RA effects upon glucose management, weight loss, and lower extremity arthritis development., Level of Evidence: III, retrospective cohort study., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Interprosthetic femur fractures (IPFFs) are a rare, but devastating complication following total joint arthroplasty. There is limited evidence to help guide their management. The purpose of this study was to describe the features, treatment, and outcomes of surgically managed IPFFs., Methods: We retrospectively identified 75 patients who had 76 IPFFs. The mean age at the time of IPFF was 75 years (range, 29 to 94), and 78% were women. The mean body mass index was 30 (range, 19 to 51), and the mean follow-up was 3 years (range, 0 to 14). There were 16 Vancouver B1 fractures, 28 Vancouver B2 fractures, 2 Vancouver B3 fractures, and 30 Vancouver C fractures. All B1 fractures underwent open reduction internal fixation (ORIF). All Vancouver B2 and B3 fractures underwent revision arthroplasty, including 1 proximal femur replacement and 1 total femur replacement. Vancouver C fractures were treated with ORIF (n = 20), distal femoral replacement (n = 9), and in 1 case, total femur replacement (n = 1). Kaplan-Meier survivorship was used to calculate 2-year survival free from all-cause reoperation and periprosthetic joint infection (PJI)., Results: The 2-year survivorship-free rate from reoperation was 71%. There were 18 reoperations following initial surgical management of the IPFF, including 9 for infection, 3 for refracture, 3 for nonunion, 2 for hardware failure, and 1 for instability. An initial IPFF involving a stemmed femoral total knee arthroplasty component was associated with increased risk for reoperation (P = .007) and PJI (P = .044). There was no difference in survivorship free of reoperation between IPFFs managed with ORIF or revision arthroplasty (P = .72)., Conclusions: An IPFF is a devastating complication following total joint arthroplasty with high reoperation rates, most commonly secondary to PJI. Those IPFFs that occurred between 2 stemmed components were at the highest risk for reoperation., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Initial fixed-bearing hinge designs for primary total knee arthroplasty (TKA) had high rates of aseptic loosening. There are limited data on contemporary rotating-hinge implants. Purpose : We sought to determine survivorship and functional outcomes of contemporary rotating-hinge implants used in primary TKA. Methods : Retrospective review identified 54 primary rotating-hinge TKAs implanted in 49 patients from 2014 to 2018 at a single institution. Patients identified were 76% women, the mean body mass index was 29 kg/m 2 , the mean age was 65 years, and the mean follow-up was 3 years. The primary diagnosis for TKA in all cases was severe instability and ligamentous compromise. Secondary diagnoses included post-traumatic osteoarthritis (11, 20%), neurologic disease (10, 19%), inflammatory arthritis (10, 19%), connective tissue disease (3, 6%), valgus deformity (16, 30%), varus deformity (2, 4%), and recurvatum (2, 4%). Preoperative, postoperative (within 6 weeks), and most recent radiographs were reviewed. In this study, we collected preoperative, 1-year, and 2-year patient-reported outcome measures (PROMs) for patients with primary rotating-hinge TKA. Patient-reported outcome measures were prospectively collected, including the Knee Injury and Osteoarthritis Outcome Survey for Joint Replacement (KOOS JR) scores and the Mental (MCS) and Physical Component Scores (PCS) of the Veterans RAND 12-Item Health Survey (VR-12). Kaplan-Meier analysis was used to determine implant survivorship. Results : Reoperation was required in 6% (3/54); indications included periprosthetic joint infection (1), peripatellar fibrosis (1), and periprosthetic femur fracture (1). At both 2 and 5 years, survivorship free from all-cause reoperation was 95% and from revision for aseptic loosening was 100%. Mean KOOS JR scores increased from 47 preoperatively to 65 at 2 years postoperatively. On radiographic review, there were no progressive radiolucent lines consistent with aseptic loosening at final follow-up. Conclusion : The findings of this single-center, multi-surgeon retrospective case series on the use of rotating-hinge implants for primary TKA suggest excellent 2-year survivorship free from reoperation and no revisions for aseptic loosening. We report modest improvement in a variety of PROMs at 1-year and 2-year follow-up. Despite improvement, clinical outcomes were poor for a primary implant. Longer-term follow-up is required to monitor the durability of primary hinges., Competing Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: AP, MD, reports relationships with AccuJoint Inc, Azra Care, and Elsevier. PKS, MD, reports relationships with DePuy, EOS Imaging, Intellijoint Surgical, Lima Corporate, and Parvizi Surgical Innovation. BPC, MD, reports relationships with Ortho Development, Smith & Nephew, HSS Journal, and The Journal of Arthroplasty. The other authors report no potential conflicts of interest., (© The Author(s) 2024.)

» Perioperative corticosteroids are strongly recommended for reducing the incidence and severity of postoperative nausea and vomiting following elective total hip or total knee arthroplasty.» Corticosteroids may reduce postoperative pain and opioid requirements. Similarly, corticosteroids appear to have a neutral-to-positive effect on length of stay, venous thromboembolism, mobility, delirium, acute kidney injury, and bone cement implantation syndrome (i.e., decreased length of stay).» Perioperative corticosteroids may induce hyperglycemia among both diabetic and nondiabetic patients; however, there is no strong evidence indicating that these transient corticosteroid-induced glycemic derangements may increase the risk of postoperative infectious complications.» The dosage and frequency of perioperative corticosteroid administration play a critical role in optimizing postoperative outcomes, with higher doses showing promise in reducing opioid consumption, postoperative pain, and length of stay.» The optimal dosage and frequency of corticosteroids remain unclear; however, the perioperative administration of 8 to 16 mg dexamethasone, or equivalent steroid, appears reasonable and safe in most cases., Competing Interests: Disclosure: The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article (http://links.lww.com/JBJSREV/B151)., (Copyright © 2024 by The Journal of Bone and Joint Surgery, Incorporated.)

Background: Reliability and validity of the Paprosky classification for acetabular bone loss have been debated. Additionally, the relationship between surgeon training level and Paprosky classification accuracy/treatment selection is poorly defined. This study aimed to: (1) evaluate the validity of preoperative Paprosky classification/treatment selection compared to intraoperative classification/treatment selection and (2) evaluate the relationship between training level and intra-rater and inter-rater reliability of preoperative classification and treatment choice., Methods: Seventy-four patients with intraoperative Paprosky types [I (N = 24), II (N = 27), III (N = 23)] were selected. Six raters (Residents (N = 2), Fellows (N = 2), Attendings (N = 2)) independently provided Paprosky classification and treatment using preoperative radiographs. Graders reviewed images twice, 14 days apart. Cohen's Kappa was calculated for (1) inter-rater agreement of Paprosky classification/treatment by training level (2), intra-rater reliability, (3) preoperative and intraoperative classification agreement, and (4) preoperative treatment selection and actual treatment performed., Results: Inter-rater agreement between raters of the same training level was moderate (K range = 0.42-0.50), and mostly poor for treatment selection (K range = 0.02-0.44). Intra-rater agreement ranged from fair to good (K range = 0.40-0.73). Agreement between preoperative and intraoperative classifications was fair (K range = 0.25-0.36). Agreement between preoperative treatment selections and actual treatments was fair (K range = 0.21-0.39)., Conclusion: Inter-rater reliability of Paprosky classification was poor to moderate for all training levels. Preoperative Paprosky classification showed fair agreement with intraoperative Paprosky grading. Treatment selections based on preoperative radiographs had fair agreement with actual treatments. Further research should investigate the role of advanced imaging and alternative classifications in evaluation of acetabular bone loss., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Modular metaphyseal engaging (MME) femoral components in total hip arthroplasty (THA) allow optimized femoral length, offset, and anteversion and are useful in patients with unusual proximal femoral anatomy. Fretting, corrosion, and stem fractures above the modular sleeve are complications associated with these implants. The purpose of this study was to identify failure mechanisms of retrieved MME femoral components at our institution, identify all broken stem cases, and evaluate how often an extended trochanteric osteotomy (ETO) was required for removal., Methods: All consecutively retrieved MME femoral components from September 2002 to May 2023 were reviewed. Patient demographics, procedure information, component specifications, indications for removal, and requirements for further revision surgery were reviewed. Descriptive statistics were calculated for variables of interest., Results: There were 131 retrieved MME components. The mean age at surgery was 59 years (range, 28 to 75), 49% were women, mean body mass index was 29.4 (range, 20.7 to 33.3), and mean American Society of Anesthesiologists score was 2.4 ± 0.5. There were 102 (78%) stems of 1 design (stem A), and 29 (22%) stems of a different design (stem B). Of 131 components, 10 (7.6%) failed secondary to stem fracture proximal to the modular sleeve. Four of 102 (4%) of stem A and 6 of 29 (21% of stem B) fractured. All broken stems required additional intervention for removal during revision THA, using an ETO (N = 9) or cortical window (N = 1) in which an intraoperative proximal femoral fracture occurred., Conclusions: Broken MME stems present a challenge for orthopaedic surgeons during revision THA. When a stem fracture occurs above the ingrown sleeve, the distal splines may have osseous interdigitation into the clothespin. Thus, when revising a broken MME stem, an ETO should be performed, and the segment should be long enough to allow distal access., (Copyright © 2024. Published by Elsevier Inc.)

Background: Tapered fluted titanium (TFT) stems are the implant design of choice for managing Vancouver B2 periprosthetic femur fractures (PFFs), producing reliable results over the past few decades. The aim of this study was to compare the radiographic and clinical outcomes of Vancouver B2 PFFs treated with contemporary monoblock versus modular TFTs., Methods: A consecutive series of 113 patients (72 women, 64%, mean age 70 years [range, 26 to 96]) who had a B2 PFF were treated with either a monoblock (n = 42) or modular (n = 71) TFT stem between 2008 and 2021. The mean body mass index was 30 ± 7. The mean follow-up was 2.9 years. A radiographic review was performed to assess leg length and offset restoration, endosteal cortical contact length, and stem subsidence. Kaplan-Meier analyses were used to determine survivorship without revision, reoperation, or dislocation., Results: There was no difference in the restoration of leg length (0.3 ± 8.0 mm) or offset (2.8 ± 8.2 mm) between the monoblock and modular cohorts (P > .05). Mean endosteal cortical contact length (47.2 ± 26.6 versus 46.7 ± 2 6.4 mm, P = .89) and stem subsidence (2.7 ± 3.5 versus 2.4 ± 3.2 mm, P = .66) did not differ. No difference in patient-reported outcome measures (Hip Disability and Osteoarthritis Outcome Score-Joint Replacement; Veterans RAND 12 Item Health Survey Physical and Mental; visual analog score; and Lower Extremity Activity Scale) between the groups was observed. Survivorship at 2 years free from reoperation, revision, and dislocation was 90.4, 90.3, and 97.6%, respectively, for the monoblock cohort; and 84.0, 86.9, and 90.0%, respectively, for the modular cohort., Conclusions: No significant differences in radiographic or clinical outcomes were observed between patients treated with monoblock or modular TFTs in this large series of B2 PFFs., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: In revision total knee arthroplasty (TKA), there is little information on the magnitude of potential limb lengthening, risk factors for lengthening, or its impact on patient-reported outcome measures. We aimed to quantify limb length alteration during revision TKA and assess risk factors for lengthening., Methods: We identified 150 patients over a 3-year period who underwent revision TKA and had preoperative and postoperative EOS hip-to-ankle standing radiographs. The average patient age was 64 years, 51% were women; 68% had a preoperative varus deformity and 21% had a preoperative valgus deformity. Outcomes assessed included change in functional and anatomic limb length, risk factors for lengthening, and clinical outcome scores, including the Knee Osteoarthritis Outcome Score Joint Replacement, and the Veterans RAND 12-item Physical and Mental Scores., Results: There were 124 patients (83%) who had functional limb lengthening, and 108 patients (72%) had anatomic limb lengthening. Patients had an average functional limb lengthening of 7 mm (range, -22 to 35) and an average anatomic limb lengthening of 5 mm (range, -16 to 31). Patients undergoing revision for instability experienced significantly greater anatomic lengthening (7.6 versus 4.6, P = .047). Patients who had ≥ 10° of deformity were more likely to be functionally lengthened (91 versus 79%) and had significantly greater average functional lengthening (12 versus 6 mm; P = .003). There was no significant change in clinical outcome scores at 6 weeks and 1 year for patients lengthened ≥ 5 or 10 mm compared to those not lengthened as substantially., Conclusions: There is major potential for functional and anatomic limb lengthening following revision TKA, with greater preoperative deformity and revision for instability being risk factors for lengthening., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Knee instability in midflexion may contribute to patient dissatisfaction following total knee arthroplasty (TKA). Midflexion instability involves abnormal motions and tissue loading in multiple planes. Therefore, we quantified and compared the tensions carried by the medial and lateral collateral ligaments (MCL and LCL) following posterior-stabilized (PS) TKA through knee flexion, and then compared these tensions with those carried by the native knee. Finally, we examined the relationships between collateral ligament tensions and anterior tibial translation (ATT)., Methods: Eight cadaveric knees (from 5 male and 3 female donors with a mean age of 62.6 years and standard deviation of 10.9 years) underwent PS TKA. Each specimen was mounted to a robotic manipulator and flexed to 90°. ATT was quantified by applying 30 N of anterior force to the tibia. Tensions carried by the collateral ligaments were determined via serial sectioning. Robotic testing was also conducted on a cohort of 15 healthy native cadaveric knees (from 9 male and 6 female donors with a mean age of 36 years and standard deviation of 11 years). Relationships between collateral ligament tensions during passive flexion and ATT were assessed via linear and nonlinear regressions., Results: MCL tensions were greater following PS TKA than in the native knee at 15° and 30° of passive flexion, by a median of ≥27 N (p = 0.002), while the LCL tensions did not differ. Median tensions following PS TKA were greater in the MCL than in the LCL at 15°, 30°, and 90° of flexion, by ≥4 N (p ≤ 0.02). Median tensions in the MCL of the native knee were small (≤11 N) and did not exceed those in the LCL (p ≥ 0.25). A logarithmic relationship was identified between MCL tension and ATT following TKA., Conclusions: MCL tensions were greater following PS TKA with this typical nonconforming PS implant than in the native knee. Anterior laxity at 30° of flexion was highly sensitive to MCL tension during passive flexion following PS TKA but not in the native knee., Clinical Relevance: Surgeons face competing objectives when performing PS TKA: they can either impart supraphysiological MCL tension to reduce anterior-posterior laxity or maintain native MCL tensions that lead to heightened anterior-posterior laxity, as shown in this study., Competing Interests: Disclosure: This study was funded by the Clark Foundation and Kirby Foundation. Zimmer Biomet donated the implants used in this study. The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article ( http://links.lww.com/JBJS/I61 )., (Copyright © 2024 by The Journal of Bone and Joint Surgery, Incorporated.)

Background: The purpose of this study was to determine implant survivorship and functional outcomes for revision total knee arthroplasty (rTKA) with contemporary rotating-hinge knee implants., Methods: A retrospective review identified 115 rTKAs using contemporary rotating-hinge implants from 2014 to 2018 for the treatment of instability (34, 30%), reimplantation after periprosthetic joint infection (PJI) (33, 29%), aseptic loosening (25, 22%), arthrofibrosis (14, 12%), periprosthetic fracture (4, 3%), osteolysis (4, 3%), and femoral component fracture (1, 1%). There were 70 women (61%), and the mean age was 67 years (range, 27 to 94). The mean follow-up was 3 years (range, 2 to 6). Kaplan-Meier analysis and Cox proportional hazard models estimated survivorship., Results: The re-revision rate was 20% (23 of 115) at an average of 18 months postoperatively. Re-revision indications included PJI (n = 14), aseptic loosening (n = 4), arthrofibrosis (n = 2), instability/malalignment (n = 1), femoral stem fracture (n = 1), and hinge mechanism disruption (n = 1). At 2 and 5 years, survivorship free from all-cause re-revision was 86 and 64%, and survivorship free from re-revision for aseptic loosening was 100 and 87%, respectively. Use of a rotating-hinge implant in reimplantation after PJI was a risk factor for subsequent re-revision (hazard ratio = 2.4, P = 0.046). On a radiographic review of unrevised rotating-hinges, there were major radiolucent lines around 2 femoral and 5 tibial components. The mean Knee Injury and Osteoarthritis Outcomes Score for Joint Replacement increased from 43 preoperatively to 60 at 1 year (P < 0.001)., Conclusions: In patients treated with a rotating-hinge implant for rTKA, there were relatively poor 2-year (86%) and 5-year (64%) survivorship free from all-cause re-revision, most commonly due to PJI. Midterm survivorship free from re-revision for aseptic loosening was modest (87%). There should be a goal to mitigate complications in complex rTKAs with rotating-hinge implants, namely PJI., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Arthrofibrosis is a common postoperative total knee arthroplasty (TKA) complication that results in limited range of motion (ROM). There is limited literature on outcomes after revision TKA (rTKA) for arthrofibrosis based on preoperative ROM restriction. The aims of this study were to: (1) examine ROM trajectory after rTKA for arthrofibrosis patients who have severe versus nonsevere limitations; (2) compare ROM gains and final arc of motion (AOM) between severe and nonsevere cohorts; (2a) compare ROM gain in a severe cohort treated with a rotating hinge (RH) versus a non-RH (NRH) construct; and (3) assess the impact of arthrofibrosis severity on patient-reported outcome measures., Methods: Patients were divided into 2 groups: group A had preoperative ROM < 70 ° (severe), and group B had preoperative ROM > 70 ° (non-severe). Patients were assessed clinically using AOM gain, absolute ROM, Knee injury and Osteoarthritis Outcomes Score for Joint Replacement, lower extremity activity scale, and pain scores. Postoperative gains in AOM were compared between both groups., Results: A total of 56 rTKAs (group A (severe): n = 36, group B (non-severe): n = 20) were performed for patients who have postoperative fibrosis. Group B had better ROM at the 1-year time point (group B: 95.9 ± 22.5 degrees versus group A: 83.2 ± 25.7 degrees). Group A had significantly better improvement in absolute AOM than group B (31.1 ± 20.9 versus 11.4 ± 25.0 degrees, P < 0.01). The RH group demonstrated significantly better absolute AOM gain than the NRH group (41.3 ± 19.4 versus 18.3 ± 15.2 degrees, P < 0.001). However, there were no significant differences in patient-reported outcome measures between groups A and B or between RH and NRH groups at the final follow-up., Conclusions: Final ROM achieved between severe and nonsevere arthrofibrosis groups was similar, and patients who have severe arthrofibrosis can expect greater absolute ROM gains and similar functional outcomes than nonsevere arthrofibrosis patients. The RH rTKAs provided greater AOM gains for patients who have severe arthrofibrosis, with equivalent functional outcomes to non-RH implants. For severe arthrofibrosis patients, RH designs provided twice the overall ROM gain; however, longer follow-up is necessary to determine whether RH designs have inferior overall implant survivorship., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Extensor mechanism (EM) disruption is a rare but severe complication of total knee arthroplasty (TKA) that can greatly impair function. Treatment options for chronic patella tendon ruptures include primary repair, autograft augmentation, and reconstruction with allograft or synthetic material. Despite various techniques, failures can occur, and options for reconstruction after a failed allograft or mesh are limited, especially if the tibial component is well-fixed and cannot be easily removed, and if there is proximal tibial deficiency from a previous failed EM allograft. This case report presents a novel solution for revision EM reconstruction in a 72y.o. female patient with a history of multiple EM failures using an off-label Trabecular Metal Cone-Mesh-Cone (TM CMC) clamshell construct. The surgical procedure involved the removal of a non-viable allograft from the knee joint and the creation of a custom trabecular metal (TM) clamshell construct with a Marlex mesh graft in between the two TM implants. The customized TM cone was designed to cover the deficient anterior tibia and wrap around the ingrown TM cone. The Marlex mesh was cemented between the existing implant and the customized TM cone, and the construct was secured in place with two cancellous screws. The mesh was tunneled between soft tissue to prevent contact with the implant and rotated scar tissue was interposed to prevent abrasion of the mesh on the implant surfaces. The patient tolerated the procedure well and no complications were noted postoperatively. At a follow-up 12 months after the operation the patient remains satisfied with the result., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background: Chronic extensor mechanism disruption after total knee arthroplasty (TKA) is a rare but challenging condition. There are several surgical approaches for quadriceps tendon repairs. In this report, we present a modified surgical technique for quadriceps tendon repair in chronic extensor mechanism disruption without the use of allografts or mesh augmentation., Methods: We retrospectively reviewed 12 consecutive cases of chronic extensor mechanism with complete quadriceps tendon ruptures after TKA that underwent the advancement and imbrication technique. Patient outcomes were evaluated using the Knee Injury and Osteoarthritis Outcome Score for Joint Replacement, the range of motion and extensor lag measurements, and standardized lateral radiographs were reviewed for Insall-Salvati-Ratio preoperatively and at their most recent follow-up visit., Results: There were 12 knees from patients who had a mean age of 72 years (range, 62 to 81) and were evaluated with a mean follow-up of 15.9 months (range, 11.4 to 50.9). The extensor lag significantly improved from 40.8 ± 31.9° (range, 10 to 90°) to 2.9 ± 6.9° (P = .014), the Insall-Salvati-Ratio significantly changed from 0.87 to 1.07 (P = .010), and the Knee Injury and Osteoarthritis Outcome Score for Joint Replacement showed a significant difference: a raw score of 13.0 ± 5.8 versus 8.7 ± 5.6 (P = .002) and an interval score of 54.1 ± 14.0 versus 66.2 ± 15.6 (P = .001)., Conclusions: Reconstruction of extensor mechanism in chronic quadriceps tendon ruptures after TKA with the advancement and imbrication technique showed excellent functional outcomes with no extensor lag and excellent restoration of motion. This technique can be combined with TKA revision surgery or used on its own. To ensure successful outcomes, the authors favor rigid immobilization for 12 weeks before starting mobilization., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Partial or total release of the posterior cruciate ligament (PCL) is often performed intraoperatively in cruciate-retaining total knee arthroplasty (CR-TKA) to alleviate excessive femoral rollback. However, the effect of the release of selected fibers of the PCL on femoral rollback in CR-TKA is not well understood. Therefore, we used a computational model to quantify the effect of selective PCL fiber releases on femoral rollback in CR-TKA., Methods: Computational models of 9 cadaveric knees (age: 63 years, range 47 to 79) were virtually implanted with a CR-TKA. Passive flexion was simulated with the PCL retained and after serially releasing each individual fiber of the PCL, starting with the one located most anteriorly and laterally on the femoral notch and finishing with the one located most posteriorly on the medial femoral condyle. The experiment was repeated after releasing only the central PCL fiber. The femoral rollback of each condyle was defined as the anterior-posterior distance between tibiofemoral contact points at 0° and 90° of flexion., Results: Release of the central PCL fiber in combination with the anterolateral (AL) fibers, reduced femoral rollback a median of 1.5 [0.8, 2.1] mm (P = .01) medially and by 2.0 [1.2, 2.5] mm (P = .04) laterally. Releasing the central fiber alone reduced the rollback by 0.7 [0.4, 1.1] mm (P < .01) medially and by 1.0 [0.5, 1.1] mm (P < .01) laterally, accounting for 47 and 50% of the reduction when released in combination with the AL fibers., Conclusions: Releasing the central fibers of the PCL had the largest impact on reducing femoral rollback, either alone or in combination with the release of the entire AL bundle. Thus, our findings provide clinical guidance regarding the regions of the PCL that surgeons should target to reduce femoral rollback in CR-TKA., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Manipulation under anesthesia (MUA) occurs in 4% of patients after total knee arthroplasty (TKA). Anti-inflammatory medications may target arthrofibrosis pathogenesis, but the data are limited. This multicenter randomized clinical trial investigated the effect of adjuvant anti-inflammatory medications with MUA and physical therapy on range of motion (ROM) and outcomes., Methods: There were 124 patients (124 TKAs) who developed stiffness after primary TKA for osteoarthritis enrolled across 15 institutions. All received MUA when ROM was < 90° at 4 to 12 weeks postoperatively. Randomization proceeded via a permuted block design. Controls received MUA and physical therapy, while the treatment group also received one dose of pre-MUA intravenous dexamethasone (8 mg) and 14 days of oral celecoxib (200 mg). The ROM and clinical outcomes were assessed at 6 weeks and 1 year. This trial was registered with ClinicalTrials.gov., Results: The ROM significantly improved a mean of 46° from a pre-MUA ROM of 72 to 118° immediately after MUA (P < .001). The ROM was similar between the treatment and control groups at 6 weeks following MUA (101 versus 99°, respectively; P = .35) and at one year following MUA (108 versus 108°, respectively; P = .98). Clinical outcomes were similar at both end points., Conclusions: In this multicenter randomized clinical trial, the addition of intravenous dexamethasone and a short course of oral celecoxib after MUA did not improve ROM or outcomes. However, MUA provided a mean ROM improvement of 46° immediately, 28° at 6 weeks, and 37° at 1 year. Further investigation in regards to dosing, duration, and route of administration of anti-inflammatory medications remains warranted., Level of Evidence: Level 1, RCT., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Cementless total knee arthroplasty (TKA) has regained interest for its potential for long-term biologic fixation. The density of the bone is related to its ability to resist static and cyclic loading and can affect long-term implant fixation; however, little is known about the density distribution of periarticular bone in TKA patients. Thus, we sought to characterize the bone mineral density (BMD) of the proximal tibia in TKA patients., Methods: We included 42 women and 50 men (mean age 63 years, range: 50 to 87; mean body mass index 31.6, range: 20.5 to 49.1) who underwent robotic-assisted TKA and had preoperative computed tomography scans with a BMD calibration phantom. Using the robotic surgical plan, we computed the BMD distribution at 1 mm-spaced cross-sections parallel to the tibial cut from 2 mm above the cut to 10 mm below. The BMD was analyzed with respect to patient sex, age, preoperative alignment, and type of fixation., Results: The BMD decreased from proximal to distal. The greatest changes occurred within ± 2 mm of the tibial cut. Age did not affect BMD for men; however, women between 60 and 70 years had higher BMD than women ≥ 70 years for the total cut (P = .03) and the medial half of the cut (P = .03). Cemented implants were used in 1 86-year-old man and 18 women (seven < 60 years, seven 60 to 70 years, and four ≥ 70 year old). We found only BMD differences between cemented or cementless fixation for women < 60 years., Conclusions: To our knowledge, this is the first study to characterize the preoperative BMD distribution in TKA patients relative to the intraoperative tibial cut. Our results indicate that while sex and age may be useful surrogates of BMD, the clinically relevant thresholds for cementless knees remain unclear, offering an area for future studies., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Robotic-assisted total knee arthroplasty (RA-TKA) allows surgeons to perform intraoperative soft tissue laxity assessments prior to bone resections and is used to alter resections to achieve gap balance. This study compared 2 techniques for flexion gap laxity assessment during RA-TKA., Methods: A prospective study of 50 primary RA-TKAs performed by a single surgeon was conducted between February and October 2023. Following full exposure, anterior tibial dislocation, and osteophyte removal, maximal medial and lateral compartment flexion laxity was quantified to the nearest 0.5 mm by the robotic system using a dynamic, surgeon-applied stress (SURGEON). This data was used to plan a balanced flexion gap by adjusting the femoral component size, rotation, and anterior-posterior translation. Flexion laxity was quantified again after distal femoral and proximal tibial resections using a ligament tensor instrument (TENSOR). These new data were used to plan for the same desired flexion gap using the same variables. Paired-samples t -tests and a simple linear regression were used for analysis., Results: Both methods produced near-identical recommendations for femoral component sizing (mean deviation 0.06 sizes, range -1 to +1 size; P  = .569), rotation (deviation mean 1.0°, range -3.0° to +3.0°; P = .741), and anterior-posterior translation (deviation mean 0.13 mm, range -0.5 to +0.5 mm, P  = .785). SURGEON femoral component rotation predicted TENSOR rotation (R 2  = 0.157; 95% confidence interval = 0.124, 0.633; P  = .004)., Conclusions: Assessing flexion laxity with a surgeon-applied stress vs a ligament tensor produced near-identical laxity data in RA-TKA, suggesting surgeons may comfortably choose either technique as a reliable method., Level of Evidence: Level III., (© 2024 The Authors.)

Background: Perioperative practices have been introduced over the last decade to decrease the risk of periprosthetic joint infection (PJI). We sought to determine whether rates of revision total knee arthroplasty (TKA) for PJI decreased during the period 2006-2016., Methods: This observational cohort study used data from the New York Statewide Planning and Research Cooperative System to identify patients undergoing TKA in 2006-2016. Data through 2017 were used to determine if patients underwent revision TKA for PJI (including debridement, antibiotics and implant retention) within 1 year of the primary surgery. A generalized estimating equation model, clustered by hospital, was used to examine the impact of time on likelihood of revision TKA for PJI., Results: In 2006-2016, 233,165 primary TKAs performed were included. Mean age was 66.1 (standard deviation 10.3) years, and 65% were women. Overall, 0.5% of the patients underwent revision TKA for PJI within 1 year of surgery. The generalized estimating equation model showed that for primary TKA performed in 2006-2013, year of surgery did not impact the likelihood of revision TKA for PJI (odds ratio 1.00, 95% confidence interval 0.97-1.03, P  = .9221), but that for primary TKA performed in 2014-2016, the likelihood decreased by year (odds ratio 0.76, 95% confidence interval 0.66-0.88, P  = .0002)., Conclusions: The likelihood of revision TKA for PJI was stable from 2006 to 2013 but declined during the period 2014-2016 across patient and hospital categories. This decline could be due to infection mitigation strategies or other unmeasured factors., (© 2024 The Authors.)

Background: The outcomes of revision total hip arthroplasty (rTHA) have become increasingly important as their volume increases. Computer navigation, a reliable method to improve component positioning during primary total hip arthroplasty (THA), is not well studied in the rTHA setting. Given that dislocation rates following rTHA are significantly higher than those of primary THA, component positioning becomes paramount in these cases., Methods: Here, we present two case reports and surgical techniques, one of a 77-year-old man undergoing rTHA for recurrent hip instability following primary THA, and one of a 61-year-old woman undergoing rTHA for severe iliopsoas bursitis who was at increased risk for instability and dislocation given her history of large segment spinal fusion., Results: Both patients achieved optimal acetabular component positioning after rTHA with imageless computer navigation., Conclusions: The use of imageless computer navigation in rTHA provides accurate and reproducible component positioning during acetabular rTHA., (© 2024 The Authors.)

Background: Hip dysplasia is considered one of the leading etiologies contributing to hip degeneration and the eventual need for total hip arthroplasty (THA). We validated a deep learning (DL) algorithm to measure angles relevant to hip dysplasia and applied this algorithm to determine the prevalence of dysplasia in a large population based on incremental radiographic cutoffs., Methods: Patients from the Osteoarthritis Initiative with anteroposterior pelvis radiographs and without previous THAs were included. A DL algorithm automated 3 angles associated with hip dysplasia: modified lateral center-edge angle (LCEA), Tönnis angle, and modified Sharp angle. The algorithm was validated against manual measurements, and all angles were measured in a cohort of 3869 patients (61.2 ± 9.2 years, 57.1% female). The percentile distributions and prevalence of dysplastic hips were analyzed using each angle., Results: The algorithm had no significant difference ( P > .05) in measurements (paired difference: 0.3°-0.7°) against readers and had excellent agreement for dysplasia classification (kappa = 0.78-0.88). In 140 minutes, 23,214 measurements were automated for 3869 patients. LCEA and Sharp angles were higher and the Tönnis angle was lower ( P < .01) in females. The dysplastic hip prevalence varied from 2.5% to 20% utilizing the following cutoffs: 17.3°-25.5° (LCEA), 9.4°-15.6° (Tönnis), and 41.3°-45.9° (Sharp)., Conclusions: A DL algorithm was developed to measure and classify hips with mild hip dysplasia. The reported prevalence of dysplasia in a large patient cohort was dependent on both the measurement and threshold, with 12.4% of patients having dysplasia radiographic indices indicative of higher THA risk., (© 2024 The Authors.)

Background: Mid-level constraint polyethylene designs provide additional stability in total knee arthroplasty (TKA). The purposes of this study were to (1) compare the survivorship and reason for revision between mid-level inserts and posterior-stabilized (PS) used in primary TKA and (2) evaluate the biomechanical constraint characteristics of mid-level inserts., Methods: We reviewed all cases of primary TKA performed at our institution from 2016 to 2019 using either PS or mid-level constrained inserts from 1 of 6 manufacturers. Data elements included patient demographics, implants, reasons for revision, and whether a manipulation under anesthesia was performed. We performed finite element analyses to quantify the varus/valgus and axial-rotation constraint of each mid-level constrained insert. A one-to-one propensity score matching was conducted between the patients with mid-level and PS inserts to match for variables, which yielded 2 cohorts of 3,479 patients., Results: For 9,163 PS and 3,511 mid-level TKAs, survivorship free from all-cause revision was estimated up to 5 years and was lower for mid-level than PS inserts (92.7 versus 94.1%, respectively, P = .004). When comparing each company's mid-level insert to the same manufacturer's PS insert, we found no differences in all-cause revision rates (P ≥ .91) or revisions for mechanical problems (P ≥ .97). Using propensity score matching between mid-level and PS groups, no significant differences were found in rates of manipulation under anesthesia (P = .72), all-cause revision (P = .12), revision for aseptic loosening (P = .07), and revision for instability (P = .45). Finite element modeling demonstrated a range in varus/valgus constraint from ±1.1 to >5°, and a range in axial-rotation constraint from ±1.5 to ±11.5° among mid-level inserts., Conclusions: Despite wide biomechanical variations in varus/valgus and axial-rotation constraint, we found minimal differences in early survivorship rates between PS and mid-level constrained knees., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Introduction: Manipulation under anesthesia (MUA) is a first-line treatment for stiffness after total knee arthroplasty (TKA), but predicting outcomes after MUA can be difficult., Purpose: We sought to determine the association between pre-MUA range-of-motion (ROM) and the risk of repeat MUA and revision in patients who underwent primary TKA., Methods: We conducted a retrospective review of 543 MUAs for stiffness at a single institution. Mean age was 62.5 years, and 64% were female. Second MUA or revision TKA were considered failures of treatment. Penalized logistic regression models were used to assess risk factors for failures. The Kaplan-Meier survivorship was used to examine survivorship free from second MUA or revision., Results: Before and after MUA, there was significant improvement in knee flexion (78.0° vs 112.8°, respectively) and extension (4.1° vs 0.8°, respectively); 6.4% of patients required repeat MUA and 5.3% required revision TKA. Survivorship free of second MUA was 90.9%, revision for stiffness was 92.4%, and all-cause revision was 88.2% at 2 years post-MUA. Patients with pre-MUA flexion contracture of ≥5° were more likely to undergo second MUA revision for stiffness and any revision. There were significant improvements in patient-reported outcomes postoperatively., Conclusions: This retrospective chart review suggests that MUA is an effective treatment for post-TKA stiffness, with good early survivorship, and that worse pre-MUA ROM is associated with MUA failure and need for repeat MUA or revision. This information may have implications for patient counseling and management., Competing Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: SC, MD, and ADC, MS, declare no potential conflicts of interest. EMD, MD, PhD, declares relationships with DePuy and Ortho Development. JN, MPH, declares relationships Journal of Women’s Sports Medicine and The American Journal of Sports Medicine. GHW, MD, declares relationships with Ethicon, Exactech, Inc, Stryker, Think Surgical, Eastern Orthopedic Association, and The Knee Society. PKS, MD, declares relationships with DePuy, EOS Imaging, Intellijoint Surgical, Lima Corporate, Parvizi Surgical Innovation, and Zimmer. BPC, MD, declares relationships with Orthodevelopment, Smith & Nephew, HSS Journal, and Journal of Arthroplasty., (© The Author(s) 2024.)

Background: Little is known about patients' postoperative week-by-week progress after undergoing posterior approach total hip arthroplasty (THA) with regard to pain, function, return to work, and driving. Purpose : We sought to evaluate a large cohort of patients undergoing posterior approach THA with modified posterior hip precautions to better understand the trajectory of recovery. Methods : Patients at a single institution undergoing primary posterior approach THA by fellowship-trained arthroplasty surgeons were prospectively enrolled. Patient functional status and early rehabilitation recovery milestones were evaluated preoperatively and each week postoperatively for 6 weeks. Results : Of 312 patients who responded to weekly questionnaires, there were varying response rates per question. At 1 week after surgery, 15% (39/256) of respondents had returned to work, increasing to 57% (129/225) at week 6. At 6 weeks, 77% of patients (174/225) had returned to driving; 25% (56/225) were taking pain medication (including prescription opioids or nonsteroidal anti-inflammatory drugs); and 15% (34/225) were using assistive devices (down from 91%, 78%, 56%, 35%, and 27% at weeks 1, 2, 3, 4, and 5, respectively). Average postoperative Hip dysfunction and Osteoarthritis Outcome Score for Joint Replacement and Lower Extremity Functional Scale scores were significantly higher than preoperative scores. Respondents reported significantly less pain at each week postoperatively than the previous week. Conclusion : These findings suggest that there may be an expected pathway for recovery after posterior THA using perioperative pain protocols, modified postoperative precautions, and physical therapy protocols to improve patient outcomes after THA, with most patients returning to normal at 4 weeks. Defining the expected recovery timeline may help surgeons in counseling patients preoperatively and guiding their recovery., Competing Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Seth A. Jerabek, MD, reports relationships with Stryker and Imagen Technologies. David J. Mayman, MD, reports relationships with Orthalign, Smith and Nephew, Stryker, Imagen, Wishbone, and MiCare Path. Mark P. Figgie, MD, reports relationships with WishBone, Lima, HS2, and the Knee Society nominating committee. Peter K. Sculco, MD, reports relationships with Lima Corporate, Zimmer Biomet, Intellijoint Surgical, Depuy Synthes, ATEC (Eos Imaging), Parvizi Surgical Innovation, and the AAHKS outreach committee and publications committee. The other authors declare no potential conflicts of interest., (© The Author(s) 2023.)

The evaluation, classification, and treatment of significant bone loss after total knee arthroplasty (TKA) continue to be a complex and debated topic in revision TKA (rTKA). Despite the introduction of new evidence and innovative technologies aimed at addressing the approach and care of severe bone loss in rTKA, there is no single document that systematically incorporates these newer surgical approaches. Therefore, a comprehensive review of the treatment of severe bone loss in rTKA is necessary. The Stavros Niarchos Foundation Complex Joint Reconstruction Center Hospital for Special Surgery, dedicated to clinical care and research primarily in revision hip and knee replacement, convened a Management of Bone Loss in Revision TKA symposium on June 24, 2022. At this meeting, the 42 international invited experts were divided into groups; each group was assigned to discuss questions related to 1 of the 4 topics: (1) assessing preoperative workup and imaging, anticipated bone loss, classification system, and implant surveillance; (2) achieving durable fixation in the setting of significant bone loss in revision TKA; (3) managing patellar bone loss and the extensor mechanism in cases of severe bone loss; and (4) considering the use of complex modular replacement systems: hinges, distal femoral, and proximal tibial replacements. Each group came to consensus, when possible, based on an extensive literature review and interactive discussion on their group topic. This document reviews each these 4 areas, the consensus of each group, and directions for future research., Competing Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: PKS, MD, reports relationships with Atec, Depuy Synthesis, Lima Corporate, and Zimmer Biomet. SAJ, MD, reports relationships with Stryker, Imagen Technologies, and Wolters Kluwer Health-Lippincott Williams and Wilkins. WAJ, MD, reports relationships with Biomech, Depuy Orthopedics, The Hip Society, and Moximed. MPB, MD, reports relationships with AAOS, American Austrian Foundation, Hip Society, and Smith & Nephew. FSH, MBBS, MD, reports relationships with Corin, Bone & Joint Journal, Institute of Sport, Exercise and Health, MatOrtho Limited, Smith & Nephew, Stryker, and University College London Hospitals. TKF, MD, reports a relationship with Depuy Synthesis. AGDV, MD, reports relationships with Hip Society, Johnson & Johnson, Link, Naviswiss, and Wishbone. DJB, MD, reports relationships with AO Recon, Bodycad, Current Concepts in Joint Replacement, Depuy, International Hip Society and Wolters Kluwer Health-Lippincott Williams & Wilkins. TPS, MD, reports relationships with Exactech and OREF. The Management of Bone Loss in Revision TKR Work Group declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Matthew S. Austin, MD, declares relationships with Corin, Depuy Synthesis, Link, Zimmer Biomet, AAHKS, AAOS, Knee Society, and American College of Rheumatology. Andrea Baldini, MD, PhD, declares relationships with Convatec, Ethicon, Permedica, Zimmer Biomet, and European Knee Society. Fabio Catani, MD, declares a relationship with Stryker. Antonia F. Chen, MD, declares relationships with Adaptive Phage Therapeutics, BICMD, Convatec, Ethicon, GLG, Guidepoint, Hyalex, Heraeus, IrriMax, IlluminOss Osteal Therapeutics, Peptilogics, Stryker, SLACK, Smith & Nephew, Sonoran, UpToDate, AAOS, AJRR, AAHKS, and European Knee Association. Martin Pietsch, MD, declares a relationship with Zimmer Biomet. Bryan D. Springer, MD, declares relationships with Convatec, Osteoremedies, Stryker, AAHKS, and IOEN. Jonathan Vigdorchik, MD, declares a relationship with Corin, Depuy Synthesis, Intellijoint, and Ortho AI, and Stryker. Geoffrey Westrich, MD, reports relationships with Ethicon, Exactech, Hospital for Special Surgery, Stryker, and Eastern Orthopaedic Association. Friedrich Boettner, MD, reports relationships with OrthoDevelopment and Smith & Nephew. Fernando J Quevedo González, PhD, reports a relationship with Lima Corporate. Erik Hansen, MD, reports relationships with Corin and Medico. Gijs Van Hellemondt, MD, reports relationships with Zimmer Biomet, Smith & Nephew, Materialize, European Knee Society, AO Foundation, MO Journal/JOINTS Journal. Paul F. Lachiewicz, MD, reports relationships with Guidepoint Global Advisors, Gerson Lehrman Group, Innacoll, Heron Therapeutics, AO Foundation, Southern Orthopaedic Association, J Arthroplasty, and JSOA. Arun Mullaji, MD, reports relationships with Depuy, Springer, ISTA, and Indian Society for Hip and Knee Surgery. Neil P. Sheth, MD, declared relationships with Medacta, OrthoInfo, Zimmer Biomet AAOS Now, and Eastern Orthopaedic Association. Mark Taylor, PhD, declares relationships with 360 MedCare, DePuy Synthes, and Synopsys. Matthew P. Abdel, MD, declares relationships with Stryker, OsteoRemedies, Springer, AAHKS, and IOEN. Michael Bolognesi, MD, declares relationships with Smith & Nephew, Total Joint Orthopedics, Zimmer Biomet, EOA, SOA, OREF, and BOS (AAOS). Steven B. Haas, MD, declares relationships with Smith & Nephew, OrthAlign, Health Grades, and Knee Society. Gwo-Chin Lee, MD, declares relationships with Conformis, Corin, and Heron Therapeutics. David G. Lewallen, MD, declares relationships with Accuitive Technologies, Corin USA, Ketai Medical Devices, Zimmer Biomet, Mid-America Orthopaedic Association, and Orthopaedic Research and Education Foundation. Roberto Rossi, MD, declares relationships with Arthrex, Angelini Farmaceutical, Lima Corporate, and Zimmer Biomet. William Walter, MD, declares relationships with Depuy, Johnson & Johnson, Matortho, Microport, Navbit, Smith & Nephew, and Arthroplasty Society of Australia. Derek F. Amanatullah, MD, declares relationships with Exactech, Expert Institute, Knible Designs, Medacta, nSight Surgicak, QT Ultrasound, Recoup Fitness, Stryker, United Orthopedics, OREF, and NCATS. Brian P. Chalmers, MD, declares relationships with Orthodevelopment and DJO. Kevin B. Fricka, MD, declares relationships with Anderson Orthopaedic Research Institute, Operation Walk VA, Orthalign, Smith & Nephew, and Zimmer Biomet. Thorsten Gehrke, MD, PhD declares relationships with Waldeman and Zimmer Biomet. Carlos A. Higuera-Rueda, MD, declares relationships with Stryker, Zimmer Biomet, 3M, Osteal, Microgen Dx, OREF, KCI(3M), AAOS International Committee, AAHKS International Committee. Brett R. Levine, MD, declares relationships with Link, Zimmer Biomet, Smith & Nephew, Exactech, MAOA, AAOS, AAHKS. Joseph D. Lipman, MS, declares relationships with Exactech and John Insall Estate. Giles R. Scuderi, MD, declares relationships with Zimmer Biomet, 3M KCI, Canary, ROM Tech, KAT Robotics, Enhanced Medical Nutrition. Amar S Ranawat, MD, declares relationships with Depuy and India ROC. Ajay Premkumar, MD, declares relationships with Accujoint, Azra Care, and Osgenic. The other authors declare no potential conflicts of interest., (© The Author(s) 2024.)

Aims: Obtaining solid implant fixation is crucial in revision total knee arthroplasty (rTKA) to avoid aseptic loosening, a major reason for re-revision. This study aims to validate a novel grading system that quantifies implant fixation across three anatomical zones (epiphysis, metaphysis, diaphysis)., Methods: Based on pre-, intra-, and postoperative assessments, the novel grading system allocates a quantitative score (0, 0.5, or 1 point) for the quality of fixation achieved in each anatomical zone. The criteria used by the algorithm to assign the score include the bone quality, the size of the bone defect, and the type of fixation used. A consecutive cohort of 245 patients undergoing rTKA from 2012 to 2018 were evaluated using the current novel scoring system and followed prospectively. In addition, 100 first-time revision cases were assessed radiologically from the original cohort and graded by three observers to evaluate the intra- and inter-rater reliability of the novel radiological grading system., Results: At a mean follow-up of 90 months (64 to 130), only two out of 245 cases failed due to aseptic loosening. Intraoperative grading yielded mean scores of 1.87 (95% confidence interval (CI) 1.82 to 1.92) for the femur and 1.96 (95% CI 1.92 to 2.0) for the tibia. Only 3.7% of femoral and 1.7% of tibial reconstructions fell below the 1.5-point threshold, which included the two cases of aseptic loosening. Interobserver reliability for postoperative radiological grading was 0.97 for the femur and 0.85 for the tibia., Conclusion: A minimum score of 1.5 points for each skeletal segment appears to be a reasonable cut-off to define sufficient fixation in rTKA. There were no revisions for aseptic loosening at mid-term follow-up when this fixation threshold was achieved or exceeded. When assessing first-time revisions, this novel grading system has shown excellent intra- and interobserver reliability., Competing Interests: A. Baldini reports royalties or licenses from ZimmerBiomet, consulting fees from Permedica, payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing, or educational events from Convatec, Avanos, Molnlycke, and Ethicon, and a leadership or fiduciary role in the European Knee Society, all of which are unrelated to this study. M. d'Amato reports consulting fees and payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing or educational events from Stryker, unrelated to this study. P. K. Sculco reports royalties or licenses from Lima Corporate, and consulting fees from Lima Corporate and Zimmer Biomet, all of which are unrelated to this study., (© 2024 The British Editorial Society of Bone & Joint Surgery.)

Background: The radiographic assessment of bone morphology impacts implant selection and fixation type in total hip arthroplasty (THA) and is important to minimize the risk of periprosthetic femur fracture (PFF). We utilized a deep-learning algorithm to automate femoral radiographic parameters and determined which automated parameters were associated with early PFF., Methods: Radiographs from a publicly available database and from patients undergoing primary cementless THA at a high-volume institution (2016 to 2020) were obtained. A U-Net algorithm was trained to segment femoral landmarks for bone morphology parameter automation. Automated parameters were compared against that of a fellowship-trained surgeon and compared in an independent cohort of 100 patients who underwent THA (50 with early PFF and 50 controls matched by femoral component, age, sex, body mass index, and surgical approach)., Results: On the independent cohort, the algorithm generated 1,710 unique measurements for 95 images (5% lesser trochanter identification failure) in 22 minutes. Medullary canal width, femoral cortex width, canal flare index, morphological cortical index, canal bone ratio, and canal calcar ratio had good-to-excellent correlation with surgeon measurements (Pearson's correlation coefficient: 0.76 to 0.96). Canal calcar ratios (0.43 ± 0.08 versus 0.40 ± 0.07) and canal bone ratios (0.39 ± 0.06 versus 0.36 ± 0.06) were higher (P < .05) in the PFF cohort when comparing the automated parameters., Conclusions: Deep-learning automated parameters demonstrated differences in patients who had and did not have early PFF after cementless primary THA. This algorithm has the potential to complement and improve patient-specific PFF risk-prediction tools., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Background: Cementless tibial baseplates in total knee arthroplasty include fixation features (eg, pegs, spikes, and keels) to ensure sufficient primary bone-implant stability. While the design of these features plays a fundamental role in biologic fixation, the effectiveness of anterior spikes in reducing bone-implant micromotion remains unclear. Therefore, we asked: Can an anterior spike reduce the bone-implant micromotion of cementless tibial implants?, Methods: We performed computational finite element analyses on 13 tibiae using the computed tomography scans of patients scheduled for primary total knee arthroplasty. The tibiae were virtually implanted with a cementless tibial baseplate with 2 designs of fixation of the baseplate: 2 pegs and 2 pegs with an anterior spike. We compared the bone-implant micromotion under the most demanding loads from stair ascent between both designs., Results: Both fixation designs had peak micromotion at the anterior-lateral edge of the baseplate. The design with 2 pegs and an anterior spike had up to 15% lower peak micromotion and up to 14% more baseplate area with micromotions below the most conservative threshold for ingrowth, 20 μm, than the design with only 2 pegs. The greatest benefit of adding an anterior spike occurred for subjects who had the smallest area of tibial bone below the 20 μm threshold (ie, most at risk for failure to achieve bone ingrowth)., Conclusions: An anteriorly placed spike for cementless tibial baseplates with 2 pegs can help decrease the bone-implant micromotion during stair ascent, especially for subjects with increased bone-implant micromotion and risk for bone ingrowth failure., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Introduction: Options for soft tissue coverage in revision total knee arthroplasty (rTKA) range from primary wound closure to complex muscle flap reconstructions. The purpose of this study was to investigate the institutional experience of wound coverage options for complex soft tissue defects in rTKA., Materials and Methods: 77 patients undergoing rTKA with complex wound closure by a single plastic surgeon were retrospectively reviewed. The average follow-up was 30.1 months. In 18 (23.4%) patients, an intraoperative decision for primary closure was made. Fifty-nine patients (76.6%) received either a local fasciocutaneous (N = 18), a medial gastrocnemius (N = 37), a free latissimus dorsi (N = 3) or a lateral gastrocnemius flap (N = 1). Revision-free survival and complication rates were assessed and risk factors were analyzed with Cox-regression analysis., Results: Medial gastrocnemius flaps had significant lower cumulative revision-free survival rates than local fasciocutaneous flaps (P = 0.021) and primary closures (P < 0.001) (42.5% vs. 71.5% vs. 100%,respectively). Comparing the most common complex closure procedures medial gastrocnemius flaps had the highest rate of prolonged wound healing (29.7%) and infection/reinfection (40.5%). Infection-associated flap procedures had significant lower cumulative revision-free survival rates (30.5%) than non-infection associated flap procedures (62.8%,P = 0.047). A history of more than two prior surgeries (HR = 6.11,P < 0.001) and an age ≥ 65 years (HR = 0.30,P = 0.018) significantly increased the risk of revision., Conclusions: The results of this study indicate that primary closure -if possible- should be preferred to early proactive muscle flap coverage. Even in the hands of an experienced plastic surgeon muscle flaps have high revision and complication rates. The study highlights the need to clarify flap indications and to investigate alternative approaches., (© 2024. The Author(s).)

Robotic assisted (RA) total hip arthroplasty (THA) offers improved acetabular component placement and radiographic outcomes, but inconsistent assessment methods of its learning curves render the evaluation of adopting novel platforms challenging. Therefore, we conducted a systematic review to assess the learning curve associated with RA-THA, both tracking a surgeon's performance across initial cases and comparing their performance to manual THA (M-THA). PubMed, MEDLINE, EBSCOhost, and Google Scholar were searched on June 16, 2023, to identify studies published between January 1, 2000 and June 16, 2023 (PROSPERO registration: CRD42023437339). The query yielded 655 unique articles, which were screened for eligibility. The final analysis included 11 articles, evaluating 1351 THA procedures. Risk of bias was assessed via the Methodological Index for Nonrandomized Studies (MINORS) tool. The mean MINORS score was 21.3 ± 0.9. RA-THA provided immediate improvements in acetabular component placement accuracy and radiographic outcomes compared to M-THA, with little to no experience required to achieve peak proficiency. A modest learning curve (12-17 cases) was associated with operative time, which was elevated compared to M-THA (+ 9-13 min). RA-THA offers immediate advantages to M-THA for component placement accuracy and radiographic outcomes. Surgeons should expect to experience increased operative times, which become less pronounced or equivalent to M-THA after a modest caseload., (© 2024. The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature.)

The John N. Insall Knee Society Traveling Fellowship selects four international arthroplasty or sports fellowship-trained orthopaedic surgeons to spend 1 month traveling to various Knee Society members' joint replacement and knee surgery centers in North America. The fellowship aims to foster research and education and shares ideas among fellows and Knee Society members. The role of such traveling fellowships on surgeon preferences has yet to be investigated. A 59-question survey encompassing patient selection, preoperative planning, intraoperative techniques, and postoperative protocols was completed by the four 2018 Insall Traveling Fellows before and immediately after the completion of traveling fellowship to assess anticipated practice changes (e.g., initial excitement) related to their participation in a traveling fellowship. The same survey was completed 4 years after the completion of the traveling fellowship to assess the implementation of the anticipated practice changes. Survey questions were divided into two groups based on levels of evidence in the literature. Immediately after fellowship, there was a median of 6.5 (range: 3-12) anticipated changes in consensus topics and a median of 14.5 (range: 5-17) anticipated changes in controversial topics. There was no statistical difference in the excitement to change consensus or controversial topics ( p  = 0.921). Four years after completing a traveling fellowship, a median of 2.5 (range: 0-3) consensus topics and 4 (range: 2-6) controversial topics were implemented. There was no statistical difference in the implementation of consensus or controversial topics ( p  = 0.709). There was a statistically significant decline in the implementation of changes in consensus and controversial preferences compared with the initial level of excitement ( p  = 0.038 and 0.031, respectively). After the John N. Insall Knee Society Traveling Fellowship, there is excitement for practice change in consensus and controversial topics related to total knee arthroplasty. However, few practice changes that had initial excitement were implemented after 4-year follow-up. Ultimately, the effects of time, practice inertia, and institutional friction overcome most of the anticipated changes induced by a traveling fellowship., Competing Interests: None declared., (Thieme. All rights reserved.)

Introduction: There are two variants regarding the low location of the patella in relation to the tibio-femoral joint line: patella baja (PB) and pseudo-patella baja (PPB). The purpose of this study is to investigate the incidence of PB and PPB in a cohort of patients that underwent revision total knee arthroplasty (rTKA) for aseptic reasons and describe any differences in each group's ROM., Methods: This retrospective study included 114 patients that underwent aseptic revision TKA surgery between 2017 and 2022. Patients were revised either for stiffness (Group 1) or aseptic loosening/instability (Group 2). The Insall-Salvati ratio (ISR) and Blackburne-Peel ratio (BPR) were used to evaluate the patellar position. ISR < 0.8 defined PB, while cases with ISR ≥ 0.8 and BPI < 0.54 were defined as PPB. ROM was measured and a subanalysis was conducted to investigate the progression of the values of ISR and BPR., Results: 55 patients comprised Group 1, and 59 patients comprised Group 2. Overall, 13 cases (11.4%) had PB before rTKA and 24 (21%) had PB after rTKA. Cases with PPB were 13 (11.4%) before and 34 (29.9%) after rTKA. Group 1 patients presented with more PB before and after rTKA (12.8% vs 10.2% and 27.3% vs 15.2% respectively). However, after rTKA Group 1 patients presented with less PPB (20%) compared to Group 2 (39%) (p = 0.02). In Group 1, patients with PPB after rTKA had less ROM compared to those without PPB [83.2 (± 21.9) vs 102.1 (± 19.9) (p = 0.025)]. The subanalysis (69 patients) showed a statistically significant decrease in ISR before and after rTKA (p = 0.041), and from the native knee to post-rTKA (p = 0.001). There was a statistically significant decrease in BPR before and after rTKA (p = 0.001) and from the native knee to both pre- and post-rTKA (p < 001)., Conclusion: After undergoing rTKA, the incidences of both patella baja (PB) and pseudo-patella baja (PPB) increased. Stiffness in the knee was associated with a higher incidence of PB, while non-stiffness cases showed a significantly higher incidence of PPB. Patients with stiff knees and PPB after rTKA experienced a significant reduction in range of motion (ROM). Additionally, the study revealed a noteworthy decrease in ISR and BPR with each subsequent surgery. This information is crucial for healthcare providers, as it sheds light on potential risks and outcomes of rTKA, allowing for improved patient management and surgical decision-making., Level of Evidence: III., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Background: Periprosthetic femur fracture (PFF) following total hip arthroplasty (THA) is a leading cause of early reoperation. The objective of this study was to compare rates of periprosthetic joint infection (PJI) and reoperation following PFFs occurring early postoperatively to those that occurred late., Methods: We retrospectively identified 173 consecutive surgically managed PFFs following primary THA. Cases were categorized as "early" if they occurred within 90 days of THA (n = 117) or "late" if they occurred following the initial 90 days (n = 56). Mean age at time of PFF was 68 years (range, 26 to 96) and 60% were women. Mean body mass index was 29 (range, 16 to 52). Mean follow-up was 2 years (range, 0 to 13). Kaplan-Meier survival analysis estimated cumulative incidences of PJI and reoperation., Results: Early PFFs had higher 2-year cumulative incidence of PJI (11% versus 0%, P < .001) and reoperation (24% versus 13%, P = .110). Following early PFF, 27 patients required reoperation (ie, 13 for PJI, 5 for instability, 2 for re-fracture, 2 for painful hardware, 2 for non-union, 1 for adverse local tissue reaction, 1 for aseptic loosening, and 1 for leg-length discrepancy). Following late PFF, 5 patients required reoperation (ie, 3 for instability, 1 for re-fracture, and 1 for non-union)., Conclusions: There are greater incidences of PJIs and overall reoperations following early PFFs compared to late PFFs after THA. In addition to focusing efforts on prevention of early PFFs, surgeons should consider antiseptic interventions to mitigate the increased risk of PJI after treatment of early PFF., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Purpose: Computer-navigated (CN) total hip arthroplasty (THA) offers improved acetabular component placement and radiographic outcomes, but inconsistent assessment methods of its learning curves render the evaluation of adopting a novel platform challenging. Therefore, we conducted a systematic review to assess the learning curve associated with CN-THA, both tracking a surgeon's performance across initial cases and comparing their performance to manual THA (M-THA)., Methods: A search was conducted using PubMed, MEDLINE, EBSCOhost, and Google Scholar on June 16, 2023 to find research articles published after January 1, 2000 (PROSPERO registration: CRD4202339403) that investigated the learning curve associated with CN-THA. 655 distinct articles were retrieved and subsequently screened for eligibility. In the final analysis, nine publications totaling 847 THAs were evaluated. The Methodological Index for Nonrandomized Studies (MINORS) tool was utilized to evaluate the potential for bias, with the mean MINORS score of 21.3 ± 1.2., Results: CN-THA showed early advantages to M-THA for component placement accuracy and radiographic outcomes but longer operative times (+ 3- 20 min). There was a learning curve required to achieve peak proficiency in these metrics, though mixed methodologies made the required caseload unclear., Conclusions: CN-THA offers immediate advantages to M-THA for component placement accuracy and radiographic outcomes, though CN-THA's advantages become more pronounced with experience. Surgeons should anticipate longer operative times during the learning curve for CN-THA, which lessen following a modest caseload. A more thorough evaluation of novel computer-navigated technologies would be enhanced by adopting a more uniform method of defining learning curves for outcomes of interest. Registration PROSPERO registration of the study protocol: CRD42023394031, 27 June 2023., (© 2024. The Author(s).)

Aims: Periprosthetic femoral fracture (PPF) is a major complication following total hip arthroplasty (THA). Uncemented femoral components are widely preferred in primary THA, but are associated with higher PPF risk than cemented components. Collared components have reduced PPF rates following uncemented primary THA compared to collarless components, while maintaining similar prosthetic designs. The purpose of this study was to analyze PPF rate between collarless and collared component designs in a consecutive cohort of posterior approach THAs performed by two high-volume surgeons., Methods: This retrospective series included 1,888 uncemented primary THAs using the posterior approach performed by two surgeons (PKS, JMV) from January 2016 to December 2022. Both surgeons switched from collarless to collared components in mid-2020, which was the only change in surgical practice. Data related to component design, PPF rate, and requirement for revision surgery were collected. A total of 1,123 patients (59.5%) received a collarless femoral component and 765 (40.5%) received a collared component. PPFs were identified using medical records and radiological imaging. Fracture rates between collared and collarless components were analyzed. Power analysis confirmed 80% power of the sample to detect a significant difference in PPF rates, and a Fisher's exact test was performed to determine an association between collared and collarless component use on PPF rates., Results: Overall, 17 PPFs occurred (0.9%). There were 16 fractures out of 1,123 collarless femoral components (1.42%) and one fracture out of 765 collared components (0.13%; p = 0.002). The majority of fractures (n = 14; 82.4%) occurred within 90 days of primary THA. There were ten reoperations for PPF with collarless components (0.89%) and one reoperation with a collared component (0.13%; p = 0.034)., Conclusion: Collared femoral components were associated with significant decreases in PPF rate and reoperation rate for PPF compared to collarless components in uncemented primary THA. Future studies should investigate whether new-generation collared components reduce PPF rates with longer-term follow-up., Competing Interests: None declared., (© 2024 The British Editorial Society of Bone & Joint Surgery.)

Aims: Distal femoral resection in conventional total knee arthroplasty (TKA) utilizes an intramedullary guide to determine coronal alignment, commonly planned for 5° of valgus. However, a standard 5° resection angle may contribute to malalignment in patients with variability in the femoral anatomical and mechanical axis angle. The purpose of the study was to leverage deep learning (DL) to measure the femoral mechanical-anatomical axis angle (FMAA) in a heterogeneous cohort., Methods: Patients with full-limb radiographs from the Osteoarthritis Initiative were included. A DL workflow was created to measure the FMAA and validated against human measurements. To reflect potential intramedullary guide placement during manual TKA, two different FMAAs were calculated either using a line approximating the entire diaphyseal shaft, and a line connecting the apex of the femoral intercondylar sulcus to the centre of the diaphysis. The proportion of FMAAs outside a range of 5.0° (SD 2.0°) was calculated for both definitions, and FMAA was compared using univariate analyses across sex, BMI, knee alignment, and femur length., Results: The algorithm measured 1,078 radiographs at a rate of 12.6 s/image (2,156 unique measurements in 3.8 hours). There was no significant difference or bias between reader and algorithm measurements for the FMAA (p = 0.130 to 0.563). The FMAA was 6.3° (SD 1.0°; 25% outside range of 5.0° (SD 2.0°)) using definition one and 4.6° (SD 1.3°; 13% outside range of 5.0° (SD 2.0°)) using definition two. Differences between males and females were observed using definition two (males more valgus; p < 0.001)., Conclusion: We developed a rapid and accurate DL tool to quantify the FMAA. Considerable variation with different measurement approaches for the FMAA supports that patient-specific anatomy and surgeon-dependent technique must be accounted for when correcting for the FMAA using an intramedullary guide. The angle between the mechanical and anatomical axes of the femur fell outside the range of 5.0° (SD 2.0°) for nearly a quarter of patients., Competing Interests: The following authors have disclosures, all of which are unrelated to this work: S. J. Jang declares stock or stock options with Ortho.AI. S. A. Jerabek reports royalties or licenses, consulting fees, and payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing, or educational from Stryker. K. N. Kunze declares being on the editorial board of Arthroscopy. D. J. Mayman discloses royalties or licenses from Smith & Nephew, consulting fees from Stryker, and a leadership or fiduciary role for the Hip Society and the Knee Society; and stock or stock options from Cymedica, Imagen, MiCare, OrthAlign, and Wishbone. P. K. Sculco reports consulting fees for Depuy, EOS, Intellijoint, Lima, and Zimmer Biomet, payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing, or educational events from Depuy, EOS, and Intellijoint, and stock or stock options from Intellijoint and Parvizi Surgical Innovation. J. M. Vigdorchik declares royalties or licenses from Corin and Depuy Synthes, consulting fees from Stryker, Depuy Synthes, Orchard Medical, and Intellijoint, patents (planned, issued, or pending) with Ortho AI, and a leadership or fiduciary role with the American Association of Hip and Knee Surgeons Program Committee., (© 2024 Jang et al.)

Purpose: The primary purpose of the study was to use pre-revision total knee arthroplasty (TKA) computer-tomography (CT)-images to analyse typical tibial bone defects and create a new schematic three-dimensional (3D)-classification system. The secondary purpose was to investigate the association between defect size and implant selection at the time of revision surgery., Methods: Eighty-four patients with preoperative CT-scans underwent revision of a primary TKA. CT-image segmentation with the 3D-Slicer Software was performed retrospectively, and a new three-dimensional classification system was used to grade tibial bone defects. The location of tibial bone defects was recorded for all cases. Volumetric 3D bone defect measurements were used to investigate the association between the bone defect volume, the indication for rTKA, and the use of modular revision components. The t-test, the Mann-Whitney-U test, and the Fisher's exact-test were used for group comparisons, and the Kruskal-Wallis test was used for multiple group comparisons., Results: The most common anatomic regions for both contained and uncontained tibial bone defects were the anteromedial epiphysis (N = 50; mean epiphyseal-defect: 5.9 cm³) and metaphysis (N = 15; mean metaphyseal-defect: 9.6 cm³). A significant association was found between patients with preoperative metaphyseal defects (N = 22) and the use of tibial augments (N = 7) (p = 0.04). The use of cones/sleeves was associated with a significantly increased 3D-CT volume of the preoperative metaphyseal bone defects (p = 0.04). Patients with osteoporosis had significantly larger volumetric defects in the metaphysis (p = 0.01)., Conclusion: Our results emphasise the importance of considering the three-dimensional nature of tibial defects in rTKA. The findings suggest that an understanding of the volume of the defect size through CT imaging can predict the need for augments and cones/sleeves and, especially in patients with osteoporosis can help the surgeon identify larger metaphyseal defects and ensure optimal metaphyseal fixation through appropriate implant selection., Level of Evidence: Level III, retrospective cohort study., (© 2024 European Society of Sports Traumatology, Knee Surgery and Arthroscopy.)

Computational studies of total knee arthroplasty (TKA) often focus on either joint mechanics (kinematics and forces) or implant fixation mechanics. However, such disconnect between joint and fixation mechanics hinders our understanding of overall TKA biomechanical function by preventing identification of key relationships between these two levels of TKA mechanics. We developed a computational workflow to holistically assess TKA biomechanics by integrating musculoskeletal and finite element (FE) models. For our initial study using the workflow, we investigated how tibiofemoral contact mechanics affected the risk of failure due to debonding at the implant-cement interface using the four available subjects from the Grand Challenge Competitions to Predict In Vivo Knee Loads. We used a musculoskeletal model with a 12 degrees-of-freedom knee joint to simulate the stance phase of gait for each subject. The computed tibiofemoral joint forces at each node in contact were direct inputs to FE simulations of the same subjects. We found that the peak risk of failure did not coincide with the peak joint forces or the extreme tibiofemoral contact positions. Moreover, despite the consistency of joint forces across subjects, we observed important variability in the profile of the risk of failure during gait. Thus, by a combined evaluation of the joint and implant fixation mechanics of TKA, we could identify subject-specific effects of joint kinematics and forces on implant fixation that would otherwise have gone unnoticed. We intend to apply our workflow to evaluate the impact of implant alignment and design on TKA biomechanics., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Jonathan D Glenday has nothing to disclose. Jonathan M Vigdorchik is a consultant for DePuy (West Chester, PA), Intellijoint Surgical (Kitchener, Ontario, Canada), and Stryker (Kalamazoo, MI) and receives royalties from Corin USA (Raynham, MA) and DePuy. Peter K Sculco is a consultant for DePuy, EOS Imaging (Paris, France), Intellijoint Surgical, LimaCorporate (Udine, Italy), and Zimmer (Warsaw, IN) and receives research support from Intellijoint Surgical. Cynthia A Kahlenberg has nothing to disclose. Eytan M Debbi is a consultant for DePuy and receives royalties from OrthoDevelopment (Draper, UT). David J Mayman is a consultant for Stryker and receives royalties from OrthoAlign (Aliso Viejo, CA) and Smith & Nephew (London, United Kingdom). Joseph D Lipman receives royalties from Exactech (Gainesville, FL), LimaCorporate, and OrthoDevelopment. Timothy M Wright receives royalties from Exactech and LimaCorporate, and research support from LimaCorporate and Zimmer. Fernando J Quevedo González receives royalties from LimaCorporate and research support from LimaCorporate and Zimmer.., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Background: While robotic-assisted total hip arthroplasty (RA-THA) has been associated with improved accuracy of component placement, the perioperative and early postoperative outcomes of fluoroscopy-based RA-THA systems have yet to be elucidated., Methods: This retrospective cohort analysis included a consecutive series of patients who received manual, fluoroscopy-assisted THA (mTHA) and fluoroscopy-based RA-THA at a single institution. We compared rates of complications within 90 days of surgery, length of hospital stay (LOS), and visual analog scale (VAS) pain scores., Results: No differences existed between groups with respect to demographic data or perioperative recovery protocols. The RA-THA cohort had a significantly greater proportion of outpatient surgeries compared to the mTHA cohort (37.4% vs. 3.8%; p < 0.001) and significantly lower LOS (26.0 vs. 39.5 h; p < 0.001). The RA-THA cohort had a smaller 90-day postoperative complication rate compared to the mTHA cohort (0.9% vs. 6.7%; p = 0.029). The RA-THA cohort had significantly lower patient-reported VAS pain scores at 2-week follow-up visits (2.5 vs. 3.3; p = 0.048), but no difference was seen after 6-week follow visits (2.5 vs. 2.8; p = 0.468)., Conclusion: Fluoroscopy-based RA-THA demonstrates low rates of postoperative complications, improved postoperative pain profiles, and shortened LOS when compared to manual, fluoroscopy-assisted THA., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Robotic-assisted total hip arthroplasty (THA) using a computerized-tomography (CT) based workflow increases surgical time relative to traditional manual technique. The purpose of this investigation was to compare the intra-operative efficiencies of two robotic THA systems: a fluoroscopy-based platform (FL-RTHA) and a contemporary, CT-based (CT-RTHA) platform. A review of 107 consecutive FL-RTHA and 159 CT-RTHA primary, direct anterior approach (DAA) THA procedures was conducted. All cases were performed by one of two surgeons operating at the same institution, for a pre-operative diagnosis of osteoarthritis, avascular necrosis, or rheumatoid arthritis. Primary outcome variables included averages and consistencies (variances) for surgical times and operating room (OR) times. A secondary outcome was to quantify the duration of robot-active phases in the FL-RTHA workflow. The FL-RTHA cohort experienced shorter surgical times (38.71 min ± 7.00 vs. 75.33 min ± 11.38; p < 0.001) and OR times (101.35 min ± 12.22 vs. 156.74 min ± 17.79; p < 0.001) compared to the CT-RTHA cohort. Surgical times and OR times were both more consistent in the FL-RTHA cohort compared to the CT-RTHA cohort (p < 0.001). Patients who underwent DAA THA with the assistance of a fluoroscopy-based robotic system experienced shorter and more consistent surgical times and OR times compared to patients who underwent similar DAA THA procedures with a contemporary, CT-based robotic platform., (© 2023. The Author(s), under exclusive licence to Springer-Verlag London Ltd., part of Springer Nature.)