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Background: Total knee arthroplasty (TKA) successfully alleviates pain from knee osteoarthritis, but muscle strength and function are reduced for a long period postoperatively. Postoperative active resistance exercise may play a relevant role., Purpose: To systematically evaluate effects of lower-limb active resistance exercise (ARE) on mobility, physical function, muscle strength and pain intensity in patients with TKA., Methods: A search was conducted in PubMed, EMBASE, and Cochrane Library databases from inception to September 2023. Only randomized controlled trials (RCTs) that compared the effects of ARE and no intervention or other rehabilitation program without PRE were included. The outcome variables were mobility (Maximal walking speed [MWS]/6-Minute Walk Test[6MWT]), physical function (Stair Climb Test [SCT]/Timed Up and Go [TUG]), knee extension/ flexion power(KEP/KFP), joint range of motion (ROM) and pain. Standardized Mean Differences (SMD) or Mean Differences (MD) and 95% confidence intervals (CI) were calculated and combined in meta-analyses. The Cochrane Collaboration's Handbook were used for the methodological quality assessments. GRADE was used to assess the quality of evidence. The meta-analysis was performed using the RevMan 5.4 software., Results: A total of 14 randomized controlled trials, involving 880 patients, were finally included. The lower-limb ARE exhibited significantly greater improvement in MWS (MD 0.13, 95%CI 0.08-0.18, P < 0.00001), TUG(MD -0.92, 95%CI -1.55- -0.28, P = 0.005), KEP (SMD 0.58, 95%CI 0.20-0.96, P = 0.003), KFP (SMD 0.38, 95%CI 0.13-0.63, P = 0.003), ROM-flexion (MD 2.74, 95%CI 1.82-3.67, P < 0.00001) and VAS (MD - 4.65, 95% CI - 7.86- -1.44, p = 0.005) compared to conventional exercise(CE) immediately post-intervention. However, there were no statistically significant differences between both groups in regard to 6MWT (MD 7.98, 95%CI -4.60-20.56, P = 0.21), SCT (MD -0.79, 95%CI -1.69-0.10, P = 0.08) and ROM-extension (MD -0.60, 95%CI -1.23-0.03, P = 0.06)., Conclusions: According to the results of meta-analysis, patients undergoing TKA who receive the lower extremity ARE show better clinical effects in terms of pain relief, strength recovery and knee ROM. Simultaneously, it may be beneficial to improve mobility and physical function of patients after TKA., (© 2024. The Author(s).)

Ganglion cysts (GC) are an uncommon complication following arthroscopic knee surgery. Due to high rates of recurrence following GC resection, many symptomatic patients can experience pain and discomfort for years. The presence of a GC at the site of an arthroscopic knee portal has only been reported once before in the literature. This case report details the history, physical and treatment of an active-duty soldier who had undergone various aspirations and surgical resections with limited improvement until the most recent operative intervention. At 18 months postoperatively, the patient had not experienced recurrence and had returned to all activities. We believe this surgical technique yielded resolution of the GC because following resection, the joint was checked to exclude areas of fluid extravasation, the capsule closure was performed with non-absorbable barbed suture and the operative extremity was immobilised in extension for 2 weeks to promote soft tissue rest and healing., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Aseptic loosening is a feared and not yet fully-understood complication of total knee arthroplasty (TKA). Hypersensitivity reactions may be the underlying cause within some susceptible patients. Metal-free implants have been developed as a possible solution. The aim of this prospective, observational long-term study was the assessment of a completely metal-free ceramic knee replacement system compared to its identical metal counterpart 8 years after implantation, conducted as a follow-up of a previous report. A total of 88 patients (mean age 69 years) were enrolled in this prospective, observational long-term 8-year follow-up study. The "ceramic group" with a completely metal-free total knee replacement system was compared to the "conventional group" with an identical metal TKA system at the final follow-up. Clinical assessment included Knee Society Score (KSS), Oxford Knee Score (OKS), European Quality of Life 5 Dimensions 3 Level Version (EQ-5D-L), European Quality of Life 5 Dimension Visual Analogue Scale (EQ-VAS) and High Activity Arthroplasty Score (HAAS) as well as perioperative or postoperative complications and need for revision. The tibial/femoral positioning, signs of periprosthetic fissures/fractures or radiolucent lines were documented radiographically. All postoperative clinical scores in the ceramic group primarily improved from baseline to 4-year follow-up, but then decreased at the final 8-year follow-up. At the final follow-up, statistically non-significant differences were found in comparison of both groups for the KSS (ceramic: 166 ± 31, conventional: 162 ± 29; p > 0.05), OKS (ceramic: 37, conventional: 39; p > 0.05), EQ-VAS (ceramic: 77 ± 17, conventional: 72 ± 18; p > 0.05), and HAAS (ceramic: 8.29 ± 3.32, conventional: 9.28 ± 4.44; p > 0.05). A significant difference was found for EQ-5D-L (ceramic: 0.819 ± 0.284, conventional: 0.932 ± 0.126; p ≤ 0.05). Progressive radiolucent lines have been found around the uncemented tibial stem (0.8 mm at initial diagnosis (mean 19 months); 1.3 mm at 4-year follow-up; 1.6 mm at 8-year follow-up) without any clinical signs of loosening. One revision surgery was performed after a traumatic polyethylene inlay-breakage. No allergic reactions could be detected. The used ceramic TKA system meets the functional performance standards of an established identical metal TKA system after an 8-year follow-up period, offering a safe option for patients with prior hypersensitivity reactions to metallic materials. Full cementation of ceramic components is recommended., (© 2024. The Author(s).)

The objective of this study was to assess radiolucent lines (RLLs) and to determine their effect on clinical outcomes of the newly introduced cementless mobile-bearing total knee arthroplasty (TKA) system. This was prospective, multicentre study. Seventy-eight patients with knee osteoarthritis who underwent primary TKA were enrolled. Patient-reported outcome measures (PROMs) and radiographic assessments were evaluated at preoperative baseline and at 6 weeks, 1 year, and 2 years after surgery. KOOS, PKIP, 2011KSS, EQ-5D-3L and SKO improved from preoperative baseline to all postoperative timepoints, with no loosening of components. No RLLs were detected at 6 weeks after surgery. However, RLLs ≥ 1 mm developed in 2.8% of the patients for the femur and 9.7% for the tibia at 1 year after surgery, and values were 5.7% and 10.9%, respectively, at 2 years after surgery. RLL incidence was not correlated with PROMs. Age, sex, body mass index, range of motion knee flexion, posterior cruciate ligament treatment and β angle did not impact the occurrence of RLLs. There were no intraoperative complications, revisions or reoperations. This TKA system improved PROMs and showed less incidence of RLLs compared to the previous reported TKA without implant-related complications., (© 2024. The Author(s).)

Background: The prevalence of noncemented total knee arthroplasty (TKA) is increasing as personalized knee alignment strategies deviate from implanting components on a strict mechanical axis. This retrospective study evaluated the outcomes of 74 consecutive noncemented unrestricted kinematic TKA procedures., Methods: This study included 74 consecutive noncemented kinematic TKAs performed by one surgeon at a tertiary academic medical center from 2021 to 2023. The technique used was unrestricted femur-first caliper kinematic TKA. The outcomes included revision, pain scores, and radiographic measurements., Results: Of the 74 procedures performed, there were no revisions or readmissions for problems related to TKA. The mean follow-up was 17.6 months, with 74% of patients being followed up for more than 1 year postoperatively. On the day of surgery, postoperative measurements showed that the average tibial mechanical, distal femoral, and anatomic tibiofemoral angles were 3.3°, 7.7°, and 5.8°, respectively. 5 knees were observed initially with signs of radiolucency, which all resolved by the most recent appointment. None of the knees was radiographically loose. Of the patients, 65%, 19%, and 16% reported no pain, minimal pain, and some pain, respectively, at the 6-week follow-up visit. This improved to 78%, 19%, and 3% at the most recent follow-up., Conclusion: Combining kinematic alignment with noncemented fixation showed excellent clinical and radiographic outcomes with short-term survivorship. Although the use of both kinematic alignment and noncemented TKAs has been controversial, these early data suggest that noncemented kinematic TKA is safe and effective., (Copyright © 2024 The Authors. Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Orthopaedic Surgeons.)

Background: Studies comparing the effectiveness of arthroscopic knee surgery and conservative treatment on knee osteoarthritis (OA) came up with inconsistent results. Systematic review on this topic still is still lacking. This systematic review and meta-analysis aimed to evaluate the effectiveness of arthroscopic knee surgery on knee OA, compared to conservative treatments., Materials and Methods: Literature searches were performed in PubMed, Embase, and Cochrane Library databases for randomized controlled trials (RCTs) published before on 1st July 2024. Studies comparing the effectiveness of arthroscopy and conservative treatments only on knee OA were included. Quality of included studies was evaluated by risk of bias 2 (ROB2). Long-term results in terms of pain relief, functional recovery and patients reported satisfaction were meta-analyzed to evaluate the therapeutic effectiveness., Results: Ten studies were included in this review, among which only 1 was considered as low risk of bias. Five studies were involved in meta-analyses and no difference was found in therapeutic effectiveness of arthroscopic surgery and conservative treatment on knee OA, in the evaluation of VAS (p = 0.63), WOMAC (p = 0.38), SF-36 (p = 0.74) and patient satisfaction (p = 0.07)., Conclusion: The evidence does not support the effectiveness of arthroscopic knee surgery compared to conservative treatments in knee OA., (© 2024. The Author(s).)

Background: Lower limb coronal alignment was thought to be a predictive factor for Unicompartmental Knee Arthroplasty (UKA) result. The tibial bony resection and implant position lead to joint line change postoperatively. Analysis was done to find out the correlation between these factors., Methods: From 2019 to 2021, 90 medial Oxford UKA were implanted by a single surgeon. Hip Knee Ankle Angle (HKAA), Lateral Distal Femoral Angle (LDFA), Medial Proximal Tibial Angle (MPTA), and intraoperative bony resection thickness were measured. The medial joint line change was calculated. The correlation between joint line change and alignment change was evaluated., Results: The mean tibial resection thickness was 4.3 mm. The mean tibial joint line was elevated by 2.3 mm, while the mean femoral joint line proximalized by 0.8 mm. HKAA changed from 8.4° varus preoperatively to 3.6° varus postoperatively. LDFA changed from 89.0° to 86.7°. MPTA changed from 85.6° to 86.6°. Preoperative HKAA showed a strong correlation with postoperative HKAA (p < 0.001), and preoperative MPTA showed a positive correlation with postoperative HKAA (p < 0.001). While preoperative LDFA had a negative correlation with postoperative HKAA (p < 0.001). The femoral joint line change and LDFA change had a significant correlation with HKAA change (p < 0.05)., Conclusion: The change of joint line had no correlation with postoperative HKAA in Oxford UKA. Preoperative HKAA strongly correlated with postoperative HKAA; while preoperative smaller LDFA and larger MPTA had a moderate correlation with postoperative HKAA. The femoral joint line change and LDFA change had a weak to moderate correlation with HKAA change., Competing Interests: Conflicts of interest The authors declare no conflicts of interest., (Copyright © 2024 HCFMUSP. Published by Elsevier España, S.L.U. All rights reserved.)

Background: Matrix-induced autologous chondrocyte implantation (MACI), the third-generation of the technique, is an established procedure for the treatment of focal cartilage defects in the knee. However, the literature lacks long-term results of MACI with good statistical power., Purpose: To determine long-term survival and patient-reported outcomes (PROs) in a representative cohort and to identify patient- and surgery-related parameters that may influence long-term clinical outcomes., Study Design: Case series; Level of evidence, 4., Methods: A total of 103 patients were clinically evaluated at the current follow-up of 8.1 years (range, 5-11.9 years). PRO measures (PROMs) included the Knee injury and Osteoarthritis Outcome Score (KOOS), EQ-5D, visual analog scale for pain, and Tegner Activity Scale. Magnetic resonance imaging results were evaluated by using the AMADEUS (area measurement and depth and underlying structures) and MOCART (magnetic resonance observation of cartilage repair tissue) 2.0 knee score classification systems. Potential factors influencing PROs were first identified univariately and investigated in a multivariate regression model., Results: The defects had a mean size of 4.8 cm 2 (range, 1.2-12 cm 2 ) and were predominantly femorotibial (66%). The mean Kaplan-Meier survival rate of revision for any reason was 97.2% 6 1.6% at 10 years. In comparison to preoperative values, all PROMs were significantly improved at the current follow-up ( P < .05). The MOCART 2.0 score peaked at 12 months (mean, 80.2 6 15.3 months) and showed no significant change at 96 months (mean, 76.1 ± 19.5 months; P = .142). The linear multivariate regression model identified an association of body mass index (BMI), MOCART 2.0 score, and number of previous knee surgeries with KOOS ( R 2 = 0.41; f 2 = 0.69). Further analysis of the individual determinants revealed an optimal BMI range of 20 to 29 for favorable PROs at 96 months. Significant correlations of MOCART subscores with the overall KOOS were found for graft surface and structure, bony reaction, and subchondral detectable changes. Only 30% of patients with 2 previous surgeries and 20% of patients with 3 previous surgeries achieved a Patient Acceptable Symptom State ( χ 2 = 10.93; P = .012)., Conclusion: The present study shows consistently good long-term clinical outcomes after MACI with a low revision rate and high patient satisfaction. BMI and number of previous knee surgeries may influence clinical outcomes and should be considered in patient selection and education. There is a correlation between graft structure, subchondral bone changes on magnetic resonance imaging, and long-term PROMs., Competing Interests: One or more of the authors has declared the following potential conflict of interest or source of funding: T.R. has received research funding at personal disposal from DePuy, Zimmer, Aesculap, German Federal Ministry of Education and Research, Deutsche Arthrose-Hilfe, OttoBock-Stiftung, German Federal Ministry of Economic and Development, Oskar-Helene-Heim Foundation in Berlin, Vielberth Foundation, and Deutsche Forschungsgemeinschaft (DFG); and reimbursement of costs from DePuy, Zimmer, and Aesculap. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.

Background: Data are lacking as to when a meniscal allograft transplant (MAT) may be biomechanically superior to a partially resected lateral meniscus., Hypothesis: Lateral MAT using a bone bridge technique would restore load distribution and contact pressures in the tibiofemoral joint to levels superior to those of a partial lateral meniscectomy., Study Design: Controlled laboratory study., Methods: Eleven fresh-frozen human cadaveric knees were evaluated in 5 lateral meniscal testing conditions (native, one-third posterior horn meniscectomy, two-thirds posterior horn meniscectomy, total meniscectomy, MAT) at 3 flexion angles (0°, 30°, and 60°) under a 1600-N axial load. Pressure sensors were used to acquire contact pressure, contact area, and peak contact pressure within the tibiofemoral joint., Results: Limited (one-third and two-thirds) partial lateral posterior horn meniscectomy showed no significant increase in mean and peak contact pressures as well as no significant decrease in contact area compared with the intact state. Total meniscectomy significantly increased mean contact pressure at 0° and 30° ( P = .008 and P < .001, respectively), increased peak contact pressure at 30° ( P = .04), and decreased mean contact area in all flexion angles compared with the native condition ( P < .01). Lateral MAT significantly improved mean contact pressure compared with total meniscectomy at 0° and 30° ( P = .002 and P = .003, respectively) and increased contact area at 30° and 60° ( P = .003 and P = .009, respectively), although contact area was still significantly smaller (24.1%) after MAT relative to the native meniscus (P = 0.015). However, allograft transplant did not result in better tibiofemoral contact biomechanics compared with limited partial meniscectomy ( P > .05)., Conclusion: The peripheral portion of the lateral meniscus provided the most important contribution to the distribution of contact pressure across the tibiofemoral joint in the cadaveric model. Total meniscectomy significantly increased mean and peak contact pressure in the cadaveric model and decreased contact area. Lateral MAT restored contact biomechanics close to normal but was not superior to the partially meniscectomized status., Clinical Relevance: Surgeons should attempt to preserve a peripheral rim of the posterior lateral meniscus. Meniscal allograft transplant appears to improve but not normalize mean contact pressure and contact area relative to total lateral meniscectomy., Competing Interests: One or more of the authors has declared the following potential conflict of interest or source of funding: A.H.G. has received consulting fees from Zimmer Biomet, Smith & Nephew, Aastrom Biosciences, Aesculap Biologics, Geistlich Pharma, Genzyme Corp, and Sanofi-Aventus; travel payments from Lifenet Health, Fidia Pharmal, and Stryker; and honoraria from Vericel. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.

Background: Bone-patellar tendon-bone (BPTB) and double-looped semitendinosus and gracilis (hamstring) grafts are commonly used for anterior cruciate ligament (ACL) reconstruction. Short-term and midterm studies show little or no differences between the 2 grafts; however, there are only a few long-term studies to compare results between the 2 grafts., Purpose: To compare the results after using either BPTB grafts or hamstring tendon grafts 18 years after ACL reconstruction., Study Design: Randomized controlled trial; Level of evidence 2., Methods: A total of 114 patients with ACL rupture between 2001 and 2004 were randomized to reconstruction with either a BPTB graft or a hamstring tendon graft. Patients were operated on at 4 major hospitals. The 18-year follow-up evaluation included anterior knee laxity measured with a KT-1000 arthrometer, defined as the primary outcome, while clinical examination (Lachman and pivot-shift tests), isokinetic testing of muscle strength, patient-reported outcome measures, and an assessment of radiographic osteoarthritis using the Kellgren-Lawrence classification were defined as secondary outcomes., Results: A total of 96 patients (84%, 47 BPTB and 49 hamstring grafts) were available for follow-up, 71 of these for clinical examination. Seven of 96 patients were excluded for ACL revision (n = 5) or knee replacement (n = 2) surgery. In total, 25 patients (10 BPTB and 15 hamstring grafts) had undergone additional surgery other than ACL revision or total knee arthroplasty. There were no significant differences between the groups in terms of anterior laxity test with KT-1000 arthrometer (primary outcome). In secondary outcomes, no significant differences between groups were reported regarding clinical examination, patient-reported outcome scores, or radiographic osteoarthritis (Kellgren-Lawrence grade 2-4 for patellofemoral joint [18 hamstring and 14 BPTB] or tibiofemoral joint [20 hamstring and 19 BPTB]), while isokinetic testing revealed that the hamstring group had a 10.7% reduction in mean peak flexion torque compared with the BPTB group at 60 deg/s ( df = 59; P = .011). At 60 deg/s the mean total flexion work in the hamstring group was reduced by 17.2% compared with the BPTB group ( df = 59; P = .002)., Conclusion: The flexion strength in the hamstring group was significantly reduced in the operated knee after 18 years. There were no significant differences between the groups regarding subjective outcomes, patient-reported outcomes, range of motion, clinical and instrumented knee laxity, and the development of osteoarthritis., Registration: NCT05876013 (ClinicalTrials.gov identifier)., Competing Interests: The authors declared that they have no conflicts of interest in the authorship and publication of this contribution. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.

Purpose: Functional implant positioning (FIP) for total knee arthroplasty (TKA) is an evolution of kinematic alignment based on preoperative CT scan and robotic-assisted technology. This study aimed to assess the ligament balancing of image-based robotic-assisted TKA in extension, mid-flexion and flexion with an FIP using intraoperative sensor-guided technology. The hypothesis was that image-based robotic-assisted TKA performed by FIP would achieve ligament balancing all along the arc of knee flexion., Methods: This prospective monocentric study included 47 consecutive patients with varus knees undergoing image-based robotic-assisted TKA performed with FIP. After robotic-assisted bone cuts, trial components were inserted, and soft tissue balance was assessed using sensor-guided technology at 10°, 45° and 90° of knee flexion. A mediolateral balanced knee was defined by an intercompartmental pressure difference (ICPD) ≤ 15 lbf and medial and lateral compartment pressure ≤60 lbf. The mean age was 71.6 years old ±6.7, the mean BMI was 29.0 kg/m 2  ± 4.9 and the mean preoperative HKA was 174° ± 5 [159; 183]., Results: The mean postoperative knee alignment was 177.0° ± 2.2° [172; 181]. There were 93.6% of balanced knees (n = 44) at 10 and 90° of knee flexion versus 76.6% (n = 36) at 45° of knee flexion with a significant difference (p = 0.014). Median ICPD at 10, 45 and 90° of knee flexion were, respectively, 7.0 (interquartile range [IQR]: 9), 11.0 (IQR: 9.5) and 8.0 (IQR: 9.0). Pairwise analyses revealed differences for ICPD at 45° versus ICPD at 10° (p = 0.003) and ICPD at 90° versus ICPD at 45° (p = 0.007)., Conclusion: FIP with an image-based robotic-assisted system allowed the restoration of a well-balanced knee at 10° and 90° of flexion in varus knees. Nevertheless, some discrepancies occurred in midflexion, and more work is needed to understand ligament behaviour all along the arc of knee flexion., Level of Evidence: Level II., (© 2024 European Society of Sports Traumatology, Knee Surgery and Arthroscopy.)

Purpose: Resecting the posterior cruciate ligament (PCL) increases posterior laxity and increases the flexion gap more than the extension gap in the native (i.e. healthy) knee. These two effects could lead to significant anterior displacement of the medial femoral condyle in kneeling following total knee arthroplasty even when using a tibial insert with a high degree of medial conformity. Using an insert with ball-in-socket medial conformity and a flat lateral articular surface, the primary purpose was to determine whether the medial femoral condyle remained stable with and without PCL retention during kneeling., Methods: Two groups of patients were studied, one with PCL retention (22 patients) and the other with PCL resection (25 patients), while kneeling at 90º flexion. Following 3D model-to-2D image registration, A-P displacements of both femoral condyles were determined relative to the dwell point of the medial socket., Results: With PCL resection versus PCL retention, the medial femoral condyle was 5.1 ± 3.7 mm versus 0.8 ± 2.1 mm anterior of the dwell point (p < 0.0001). Patient-reported function scores were comparable (p ≥ 0.1610) despite a significantly shorter follow-up of 7.8 ± 0.9 months with PCL retention than 19.6 ± 4.9 months with PCL resection (p < 0.0001). Range of motion was 126 ± 8° versus 122 ± 6° with and without PCL retention, respectively (p = 0.057)., Conclusion: Surgeons that use a highly conforming tibial insert design can stabilize the medial femoral condyle during kneeling by retaining the PCL. In patients with PCL resection, the 9 mm high anterior lip of the insert with ball-in-socket medial conformity was insufficient to prevent significant anterior displacement of the medial femoral condyle when weight-bearing on the anterior tibia., (© 2024. The Author(s) under exclusive licence to SICOT aisbl.)

Background: Arthrofibrosis is a debilitating postoperative complication and a major cause of patient dissatisfaction following total knee arthroplasty (TKA). There is no consensus regarding the optimal treatment for stiffness after TKA. For cases not amenable to manipulation under anesthesia (MUA), one component or full revision are both suitable options. In a value-based healthcare era, maximizing cost-effectiveness with optimized clinical outcomes for patients remains the ultimate goal. As such, we compared (1) Knee Injury and Osteoarthritis Outcome Scores for Joint Replacement (KOOS, JR), (2) range of motion (ROM), as well as (3) complication rates, including MUA and lysis of adhesions (LOA), between polyethylene exchange and full component revision for TKA arthrofibrosis., Methods: Patients were queried from an institutional database who underwent revision TKA for arthrofibrosis between January 1, 2015, and April 31, 2021. There were 33 patients who underwent full revision and 16 patients who underwent polyethylene exchange. Demographics and baseline characteristics between the cohorts were analyzed. Postoperative outcomes included MUA, LOA, and re-revision rates as well as KOOS, JR, and extension and flexion ROM at a mean follow-up of 3.8 years. Baseline comorbidities, including age, body mass index, alcohol use, tobacco use, and diabetes, were comparable between the full revision and polyethylene exchange revision cohorts (P > .05). The one and full component revisions had similar preoperative KOOS, JR (43 versus 42, P = .85), and flexion (81 versus 82 degrees, P = .80) versus extension (11 versus 11 degrees, P = .87) ROM., Results: The full component revision had higher KOOS, JR (65 versus 55, P = .04), and flexion (102 versus 92 degrees, P = .02), but similar extension (3 versus 3 degrees, P = .80) ROM at final follow-up compared to the polyethylene exchange revision, respectively. The MUA (18.2 versus 18.8%, P = .96) and LOA (2.0 versus 0.0%, P = .32) rates were similar between full component and polyethylene exchange revisions. There was one re-revision (3.0%) for the cohort of patients who initially underwent full revision. There were four full re-revisions (25.0%) and two polyethylene exchange re-revisions (12.5%) performed in the cohort of patients who initially underwent a polyethylene exchange revision., Conclusions: The full component revision for stiffness after TKA showed favorable KOOS, JR, ROM, and outcomes in comparison to the polyethylene exchange revision. While the optimal treatment for stiffness after TKA is without consensus, this study supports the use of the full component revision when applied to the institutional population at hand. It is imperative that homogeneity exists in preoperative definitions, preoperative baseline patient demographics, ROM and function levels, outcome measures, and preoperative indications, as well as the inclusion of clinical data that assesses complete exchange, single exchange, and tibial insert exchange., (Copyright © 2024. Published by Elsevier Inc.)

Background: Abnormal angular and torsional alignment of the lower extremities during growth are a common reason for consultation of a paediatrician or orthopaedist. There is often uncertainty about the pathological value of these abnormalities and the need for treatment, even among specialists. In the course of physiological growth and development processes, the axial and torsional alignment of the legs sometimes change considerably and in characteristic patterns., Diagnostics: The ability to assess whether abnormal angular or torsional alignments of the lower limb in the course of growth should still be regarded as normal or already as pathological, depending on age and gender, is essential for the treating physician and requires precise knowledge of the physiological development processes and the tolerable limits in all three spatial dimensions., Treatment: After careful explanation to the frequently concerned parents, a restrictive approach with observation of the spontaneous course of correction on the basis of regular clinical check-ups makes sense in the majority of cases. Pathological deviations from the physiological conditions are rare overall, can be idiopathic or of secondary origin and should be further clarified diagnostically using imaging procedures. As conservative measures are ineffective, pronounced angular and/or torsional deformities of the legs requiring treatment can only be corrected by surgical intervention, even in children and adolescents. The surgical treatment modalities available are varied and differ in terms of their invasiveness and complication profile, depending on the localization, type and severity of the deformity, as well as the age and possible concomitant diseases of the affected child or adolescent., (© 2024. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

Background: Valgus knee deformities pose a unique challenge in total knee arthroplasty (TKA) due to the complexity of achieving ligamentous balance and satisfactory alignment compared to varus or neutral deformities. Robotic-assisted (RA) TKA could aid in achieving improved component alignment and balance., Methods: We retrospectively evaluated a matched cohort of patients to compare image-free RA-TKA (n = 44) versus conventional manual (CM) TKA (n = 30) techniques in patients who have valgus deformity of 5 to 15 degrees, including radiographic and patient-reported outcomes measures (PROMs) over a 3-year period. The patient reported outcome measures (PROMs) studied to determine outcomes were: Western Ontario McMaster University Arthritis Index, Knee Society Score-Function Score, and Short Form 12-item Survey., Results: Overall, the RA-TKA cohort showed faster improvement in PROMs (37.16 ± 1 8.8 versus 25.74 ± 17.7, P = .02), shorter length of stay (1.41 versus 2.29 days, P = .02), and shorter operating room times (120.79 versus 123.67 minutes, P = .02) than CM-TK). Additionally, there was no difference in the use of primary versus varus-valgus constrained polyethylene liners between the cohorts., Conclusions: In this investigation, RA-TKA yielded a slightly faster patient recovery, more objective measurements of ligamentous balance, and proved noninferior PROMs compared to CM-TKA for preoperative valgus knee deformities., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Increasing deformity of the lower extremities, as measured by the hip-knee-ankle angle (HKAA), is associated with poor patient outcomes after total hip and knee arthroplasty (THA, TKA). Automated calculation of HKAA is imperative to reduce the burden on orthopaedic surgeons. We proposed a detection-based deep learning (DL) model to calculate HKAA in THA and TKA patients and assessed the agreement between DL-derived HKAAs and manual measurement., Methods: We retrospectively identified 1,379 long-leg radiographs (LLRs) from patients scheduled for THA or TKA within an academic medical center. There were 1,221 LLRs used to develop the model (randomly split into 70% training, 20% validation, and 10% held-out test sets); 158 LLRs were considered "difficult," as the femoral head was difficult to distinguish from surrounding tissue. There were 2 raters who annotated the HKAA of both lower extremities, and inter-rater reliability was calculated to compare the DL-derived HKAAs with manual measurement within the test set., Results: The DL model achieved a mean average precision of 0.985 on the test set. The average HKAA of the operative leg was 173.05 ± 4.54°; the nonoperative leg was 175.55 ± 3.56°. The inter-rater reliability between manual and DL-derived HKAA measurements on the operative leg and nonoperative leg indicated excellent reliability (intraclass correlation (2,k) = 0.987 [0.96, 0.99], intraclass correlation (2, k) = 0.987 [0.98, 0.99, respectively]). The standard error of measurement for the DL-derived HKAA for the operative and nonoperative legs was 0.515° and 0.403°, respectively., Conclusions: A detection-based DL algorithm can calculate the HKAA in LLRs and is comparable to that calculated by manual measurement. The algorithm can detect the bilateral femoral head, knee, and ankle joints with high precision, even in patients where the femoral head is difficult to visualize., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Printed porous titanium metaphyseal cones have become a mainstay for managing bone loss in revision total knee arthroplasty (rTKA). A short or long stem is routinely used when implanting a cone to augment fixation and offload stresses. This retrospective analysis compared the short-term survivorships and functional outcomes for use of a short or long stem with a metaphyseal cone.A total of 179 cases using metaphyseal cones and stems with median follow-up of 1.95 years (interquartile range, 1.00-2.14) were compared based on stem type. There were 55 cases with long stem(s) and 124 cases with short stem(s). Cases with both long and short stems were excluded. Demographics, Kaplan-Meier survivorships, and preoperative and 1-year postoperative patient-reported outcome measures (PROMs; 2011 Knee Society Score [KSS] objective knee score, function, and satisfaction scores; EuroQol five-dimension scale; and Short Form Survey Physical Component Summary and Mental Component Summary scores) were compared using t -tests with a significance level of α = 0.05. There were no significant differences in body mass index (mean ± standard deviation) or sex (men [%]) between the short and long stem cohorts (32.3 ± 5.3, 36.3% and 31.5 ± 5.5, 38.2%, respectively; p  > 0.05). Patients who had short stems were younger (65.9 ± 8.8 vs. 69.0 ± 9.4, p  = 0.0323).Revision-free survivorship for the femoral or tibial component was 100% for long stems and 98.2% for short stems at 1 and 2 years, respectively (log-rank p  = 0.6330). The two revisions in the short group were for infection, thus the survivorship for aseptic loosening was 100% at 2 years for both cohorts. There were no significant differences in preoperative or postoperative PROMs.This study demonstrated that highly porous printed metaphyseal cones provided rTKA with excellent early survivorship and similar PROMs whether a short or long stem was used. Additional studies will be needed to discern longer term differences., Competing Interests: None declared., (Thieme. All rights reserved.)

Arthrofibrosis following primary total knee arthroplasty (TKA) can result in pain and limit postoperative range of motion (ROM), jeopardizing clinical outcomes and patient satisfaction. This study aims to identify preoperative risk factors associated with necessitating a manipulation under anesthesia (MUA) following primary TKA.We retrospectively reviewed 950 cases of consecutive primary TKAs performed at one institution by three arthroplasty surgeons between May 2017 and May 2019. Recorded preoperative variables included smoking status, race, preoperative ROM, presence of effusion or positive anterior drawer, and medical comorbidities. Demographic characteristics were compared with Student's t -tests or chi-square tests as appropriate. For each preoperative factor, we obtained an odds ratio (OR) for MUA risk using multivariate logistic regression.Twenty (2.3%) patients underwent MUA following their index primary TKA surgery. History of ipsilateral knee surgery (OR: 2.727, p  = 0.047) and diagnosed hypertension (OR: 4.764, p  = 0.016) were identified as risk factors associated with significantly increased risk of MUA. The greater the preoperative ROM, the higher likelihood needed of MUA (OR: 1.031, p  = 0.034).Patients who had diagnosed hypertension or a history of prior ipsilateral knee surgery were associated with increased risk of necessitating an MUA following primary TKA. Additionally, a greater total arc of motion preoperatively increased the odds of needing MUA.Level III of evidence was present., Competing Interests: None declared., (Thieme. All rights reserved.)

Patients with bone sarcomas increasingly choose limb salvage. This can lead to issues with limb length discrepancy (LLD) for the skeletally immature. We synthesize management options into an algorithm and report our results. Patients with bone sarcomas involving any location from the femoral diaphysis to the tibial diaphysis 12 years or younger were reviewed. Our clinical pathway prescribed patients with metadiaphyseal lesions to intercalary allograft reconstruction, epiphyseal lesions and less than 5 cm expected LLD to osteoarticular allograft and patients with more than 5 cm expected LLD to extendable prosthesis. Twenty patients met inclusion criteria: 11 with osteoarticular allografts, 5 with extendable prostheses and 4 with intercalary allografts; median age 11.5 years; median follow-up 8.2 years; and final median LLD 1.6 cm. Five patients had contralateral epiphysiodesis, two patients underwent contralateral femoral shortening and a median of 6 (range 4-8) lengthenings were performed for extendable prostheses. Four patients had residual LLD over 3 cm. There were 13 revisions in 8 patients and 2 amputations. Limb-salvage in paediatric bone sarcoma of the knee can be managed with multiple techniques producing satisfactory results in regards to LLD. Careful pre-operative planning and shared decision making is a requisite given the high rate of secondary procedures for both LLD and reconstructive failures. Level of evidence: Level III Retrospective Comparative Study., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Osteophytes are routinely removed during total knee arthroplasty, yet the preoperative planning currently relies on preoperative computed tomography (CT) scans of the patient's osteoarthritic knee, typically including osteophytic features. This complicates the surgeon's ability to anticipate the exact biomechanical effects of osteophytes and the consequences of their removal before the operation. The aim of this study was to investigate the effect of osteophytes on ligament strains and kinematics, and ascertain whether the osteophyte volume and location determine the extent of this effect. We segmented preoperative CT scans of 21 patients, featuring different osteophyte severity, using image-based active appearance models trained to identify the osteophytic and preosteophytic bone geometries and estimate the cartilage thickness in the segmented surfaces. The patients' morphologies were used to scale a template musculoskeletal knee model. Osteophytes induced clinically relevant changes to the knee's functional behavior, but these were variable and patient-specific. Generally, severe osteophytic knees significantly strained the oblique popliteal ligament (OPL) and posterior capsule (PC) relative to the preosteophytic state. Furthermore, there was a marked effect on the lateral collateral ligament and anterolateral ligament (ALL) strains compared to mild and moderate osteophytic knees, and concurrent alterations in the tibial lateral-medial translation and external-internal rotation. We found a strong correlation between the OPL, PC, and ALL strains and posterolateral condylar and tibial osteophytes, respectively. Our findings may have implications for the preoperative planning in total knee arthroplasty, toward reproducing the physiological knee biomechanics as close as feasibly possible., (© 2024 The Authors. Journal of Orthopaedic Research® published by Wiley Periodicals LLC on behalf of Orthopaedic Research Society.)

Purpose: This study aimed to identify factors influencing persistent muscle weakness in knee flexor strength after anterior cruciate ligament (ACL) reconstruction using the hamstring tendon and establish a clear cut-off value at 3 months postoperatively for the limb symmetry index (LSI) to exceed 90% at 6 months postoperatively., Methods: One hundred forty-eight patients undergoing ACL reconstruction were included and categorised into two groups based on knee flexor strength at 6 months postoperatively: patients with LSI of 90% or greater (achieved group: n = 114) and patients with LSI less than 85% (nonachieved group: n = 34). Items with significant differences between the two groups (preoperative waiting period, LSI to body weight ratio of knee flexor and extensor strength at 3 months postoperatively and peak torque angle of knee flexor muscle) were included in the multiple logistic regression analysis. Additionally, a receiver operating characteristic curve was used to calculate the cut-off value of the LSI at 3 months postoperatively, which was required to achieve the LSI criteria for knee flexor strength 6 months postoperatively., Results: Multiple logistic regression analysis extracted the preoperative waiting period and LSI for knee flexor strength at 3 months postoperatively. The cut-off value at 3 months postoperatively was 76.9% (area under the curve value, 0.82; sensitivity, 0.76; and specificity, 0.81) of the LSI., Conclusion: The LSI of at least 76.9% for knee flexor strength at 3 months after ACL reconstruction was an indicator for achieving the 6 months postoperatively. This is a criterion to aim for, considering the stress on the graft and the regeneration process of the semitendinosus tendon., Level of Evidence: Level III., (© 2024 European Society of Sports Traumatology, Knee Surgery and Arthroscopy.)

Background: Anterior knee pain (AKP) following total knee arthroplasty (TKA) with patellar preservation is a common complication that significantly affects patients' quality of life. This study aimed to develop a machine-learning model to predict the likelihood of developing AKP after TKA using radiological variables., Methods: A cohort of 131 anterior stabilized TKA cases (105 patients) without patellar resurfacing was included. Patients underwent a follow-up evaluation with a minimum 1-year follow-up. The primary outcome was AKP, and radiological measurements were used as predictor variables. There were 2 observers who made the radiological measurement, which included lower limb dysmetria, joint space, and coronal, sagittal, and axial alignment. Machine-learning models were applied to predict AKP. The best-performing model was selected based on accuracy, precision, sensitivity, specificity, and Kappa statistics. Python 3.11 with Pandas and PyCaret libraries were used for analysis., Results: A total of 35 TKA had AKP (26.7%). Patient-reported outcomes were significantly better in the patients who did not have AKP. The Gradient Boosting Classifier performed best for both observers, achieving an area under the curve of 0.9261 and 0.9164, respectively. The mechanical tibial slope was the most important variable for predicting AKP. The Shapley test indicated that high/low mechanical tibial slope, a shorter operated leg, a valgus coronal alignment, and excessive patellar tilt increased AKP risk., Conclusions: The results suggest that global alignment, including sagittal, coronal, and axial alignment, is relevant in predicting AKP after TKA. These findings provide valuable insights for optimizing TKA outcomes and reducing the incidence of AKP., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Knee collateral ligaments play a vital role in providing frontal-plane stability in post-total knee arthroplasty (TKA) knees. Finite element models can utilize computationally efficient one-dimensional springs or more physiologically accurate three-dimensional continuum elements like the Holzapfel-Gasser-Ogden (HGO) formulation. However, there is limited literature defining subject-specific mechanical properties, particularly for the HGO model. In this study, we propose a co-simulation framework to obtain subject-specific material parameters for an HGO-based finite element ligament model integrated into a rigid-body model of the post-TKA knee. Our approach achieves comparable accuracy to spring formulations while significantly reducing coefficient calibration time and demonstrating improved correlation with reference knee kinematics and ligament strains throughout the tested loading range.

Background: The influence of tibial slope on tibial component migration following total knee arthroplasty has not been widely studied, although excessive posterior slope has been implicated in some failures. As implant micromotion measured with radiostereometric analysis can indicate successful fixation, the purpose of this study was to determine the associations between tibial slope, tibial component migration, and inducible displacement., Methods: Radiostereometric analyses at 6 visits over 2 years quantified implant migration for 200 cemented total knee arthroplasties. Longitudinal data analysis examined the influence of postoperative tibial slope on implant migration (overall maximum total point motion (MTPM) migration and anterior-posterior tilt migration), accounting for age, sex, and body mass index. The correlations of tibial slope with 1-year migration, continuous migration, and inducible displacements were also examined. Additionally, the amount of change in slope was compared to migration., Results: The mean posterior tibial slope was 8.0° (standard deviation [SD] 3.8°) preoperatively and 3.8° (SD 3.1°) postoperatively, with a mean reduction in slope of 4.2° (SD 4.7°). Postoperative tibial slope (range 14.0° posterior slope to 3.4° anterior slope) was not associated with longitudinal overall migration (P = .671) or anterior-posterior tilt migration (P = .704). There was no association between postoperative tibial slope and migration at 1 year postoperatively (P = .441 for MTPM migration, P = .570 for tilt migration), change in migration from 1 to 2 years (P = .951), or inducible displacement (P = .970 MTPM, P = .730 tilt). The amount of change in tibial slope was also not associated with migration or inducible displacement., Conclusions: Residual and change in postoperative tibial slope were not associated with implant migration into tilt or overall migration, or inducible displacement for a single implant design. These findings support positioning tibial implants in a range of slopes, which may support patient-specific approaches to implant alignment., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background: Total knee arthroplasty (TKA) is one of the most common procedures in orthopaedics, but there is still debate over the optimal fixation method for long-term durability: cement versus cementless bone ingrowth. Recent improvements in implant materials and technology have offered the possibility of cementless TKA to change clinical practice with durable, stable biological fixation of the implants, improved operative efficiency, and optimal long-term results, particularly in younger and more active patients., Methods: This symposium evaluated the history of cementless TKA, the recent resurgence, and appropriate patient selection, as well as the historical and modern-generation outcomes of each implant (tibia, femur, and patella). Additionally, surgical technique pearls to assist in reliable, reproducible outcomes were detailed., Results: Historically, cemented fixation has been the gold standard for TKA. However, cementless fixation is increasing in prevalence in the United States and globally, with equivalent or improved results demonstrated in appropriately selected patients., Conclusions: Cementless TKA provides durable biologic fixation and successful long-term results with improved operating room efficiency. Cementless TKA may be broadly utilized in appropriately selected patients, with intraoperative care taken to perform meticulous bone cuts to promote appropriate bony contact and biologic fixation., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Identification of femoral component debonding in the work-up of painful total knee arthroplasty (TKA) often poses a diagnostic challenge. The purpose of this study was to compare the sensitivity and specificity of radiographs, computed tomography (CT), and magnetic resonance imaging (MRI) for identifying femoral component loosening with debonding at the time of revision of a primary TKA with a recalled polyethylene insert., Methods: Using an institutional database, we identified all cases of revision TKA performed for this specific implant recall following a primary TKA between 2014 and 2022. Patients who had a preoperative radiograph, CT, and MRI were included (n = 77). Sensitivity, specificity, and positive and negative likelihood ratio (LR) for predicting loosening were compared among the imaging modalities, using the intraoperative evidence of implant loosening as the gold standard., Results: At the time of revision surgery, the femoral component was noted to have aseptic loosening with debonding in 46 of the 77 (60%) of the TKAs. There were no significant differences in demographics in the cohort with femoral debonding compared to those with well-fixed implants. The CT demonstrated a sensitivity of 28% and a specificity of 97%, while the MRI demonstrated a sensitivity of 37% and a specificity of 94% for detecting femoral loosening due to debonding. Both CT and MRI demonstrated poor negative LRs for femoral loosening (LR 0.7)., Conclusions: In this series of revision TKAs for a specific recalled component, neither CT nor MRI accurately diagnosed femoral component debonding. For patients who have this implant, it is imperative to interrogate the implant-cement interface intraoperatively and prepare for full revision surgery as well as marked bone loss secondary to osteolysis., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: There is an increasing number of different brands of robotic total knee arthroplasty (TKA) systems. Most robotic TKA systems share the same coronal alignment, while the definitions of sagittal alignment vary. The purpose of this study was to investigate whether these discrepancies impact the sagittal alignment of the lower extremity., Methods: A total of 72 lower extremity computed tomography scans were included in our study, and 3-dimensional models were obtained using software. A total of 7 brands of robotic TKA systems were included in the study. The lower extremity axes were defined based on the surgical guide for each implant. We also set the intramedullary axis as a reference to evaluate the discrepancies in sagittal alignment of each brand of robotic system., Results: On the femoral side, the axis definition was the same for all 7 robotic TKA systems. The robotic TKA axes showed a 2.41° (1.58°, 3.38°) deviation from the intramedullary axis. On the tibial side, the 7 robots had different axis definitions. The tibial mechanical axis of 6 of the TKA systems was more flexed than that of the intramedullary axis, which means the posterior tibial slope was decreased while the tibial mechanical axis of the remaining system was more extended., Conclusions: The sagittal alignment of the lower extremity for 7 different brands of robotic TKA systems differed from each other and all deviated from the intramedullary axis. Surgeons should be aware of this discrepancy when using different brands of robotic TKA systems to avoid unexpected sagittal alignment and corresponding adverse clinical outcomes., Level of Evidence: Level IV, Therapeutic Study., (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: In patients with a degenerative tear of the medial meniscus, recent meta-analyses and systematic reviews have shown no treatment benefit of arthroscopic partial meniscectomy (APM) over conservative treatment or placebo surgery. Yet, advocates of APM still argue that APM is cost effective. Giving advocates of APM their due, we note that there is evidence from the treatment of other musculoskeletal complaints to suggest that a treatment may prove cost effective even in the absence of improvements in efficacy outcomes, as it may lead to other benefits, such as diminished productivity loss and reduced costs, and so the question of cost effectiveness needs to be answered for APM., Questions/purposes: (1) Does APM result in lower postoperative costs compared with placebo surgery? (2) Is APM cost-effective compared with placebo surgery?, Methods: One hundred forty-six adults aged 35 to 65 years with knee symptoms consistent with a degenerative medial meniscus tear and no knee osteoarthritis according to the American College of Rheumatology clinical criteria were randomized to APM (n = 70) or placebo surgery (n = 76). In the APM and placebo surgery groups, mean age was 52 ± 7 years and 52 ± 7 years, and 60% (42 of 70) and 62% (47 of 76) of participants were men, respectively. There were no between-group differences in baseline characteristics. In both groups, a standard diagnostic arthroscopy was first performed. Thereafter, in the APM group, the torn meniscus was trimmed to solid meniscus tissue, whereas in the placebo surgery group, APM was carefully mimicked but no resection of meniscal tissue was performed; as such, surgical costs were the same in both arms and were not included in the analyses. All patients received identical postoperative care including a graduated home-based exercise program. At the 2-year follow-up, two patients were lost to follow-up, both in the placebo surgery group. Cost effectiveness over the 2-year trial period was computed as incremental net monetary benefit (INMB) for improvements in quality-adjusted life years (QALY), using both the societal (primary) and healthcare system (secondary) perspectives. To be able to consider APM cost effective, the CEA analysis should yield a positive INMB value. Nonparametric bootstrapping was used to assess uncertainty. Several one-way sensitivity analyses were also performed., Results: APM did not deliver lower postoperative costs, nor did it convincingly improve quality of life scores when compared with placebo surgery. From a societal perspective, APM was associated with € 971 (95% CI -2013 to 4017) higher costs and 0.015 (95% CI -0.011 to 0.041) improved QALYs over 2-year follow-up compared with placebo surgery. Both differences were statistically inconclusive (a wide 95% CI that crossed the line of no difference). Using the conventional willingness to pay (WTP) threshold of € 35,000 per QALY, APM resulted in a negative INMB of € -460 (95% CI -3757 to 2698). In our analysis, APM would result in a positive INMB only when the WTP threshold rises to about € 65,000 per QALY. The wide 95% CIs suggests uncertain cost effectiveness irrespective of chosen WTP threshold., Conclusion: The results of this study lend further support to clinical practice guidelines recommending against the use of APM in patients with a degenerative meniscus tear. Given the robustness of existing evidence demonstrating no benefit or cost effectiveness of APM over nonsurgical treatment or placebo surgery, future research is unlikely to alter this conclusion.Level of Evidence Level III, economic analysis., Competing Interests: Each author certifies that there are no funding or commercial associations (consultancies, stock ownership, equity interest, patent/licensing arrangements, etc.) that might pose a conflict of interest in connection with the submitted article related to the author or any immediate family members. All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research ® editors and board members are on file with the publication and can be viewed on request., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the Association of Bone and Joint Surgeons.)

Objective: Supply-demand mismatch of medial femoral condyle (MFC) osteochondral allografts (OCAs) remains a rate-limiting factor in the treatment of osteochondral defects of the femoral condyle. Surface contour mapping was used to determine whether a contralateral lateral femoral condyle (LFC) versus ipsilateral MFC OCA differs in the alignment of donor:native subchondral bone for large osteochondral defects of the MFC., Design: Thirty fresh-frozen human femoral condyles were matched by tibial width into 10 groups of 3 condyles (MFC recipient, MFC donor, and LFC donor) each for 3 cartilage surgeons (90 condyles). The recipient MFC was imaged using nano-computed tomography scan. Donor oval grafts were harvested from each matched condyle and transplanted into a 17 mm × 36 mm defect created in the recipient condyle. Following the first transplant, the recipient condyle was imaged and superimposed on the native condyle nano-CT scan. The donor plug was removed and the process repeated for the other donor. Surface height deviation and circumferential step-off height deviation were compared between native and donor subchondral bone surfaces for each transplant., Results: There was no statistically significant difference in mean subchondral bone surface deviation (LFC = 0.87 mm, MFC = 0.76 mm, P = 0.07) nor circumferential step-off height (LFC = 0.93 mm, MFC = 0.85 mm, P = 0.09) between the LFC and MFC plugs. There were no significant differences in outcomes between surgeons., Conclusions: There were no significant differences in subchondral bone circumferential step-off or surface deviation between ipsilateral MFC and contralateral LFC oval-shaped OCAs for 17 mm × 36 mm defects of the MFC., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Kelly M.R. Taylor: None declared; Conor S. Locke: None declared; Timothy S. Mologne: JRF Ortho, Arthrex; William D. Bugbee: JRF Ortho, Arthrex; John A. Grant: JRF Ortho, Arthrex, Vericel, Aesculap Biologics.

Purpose: To compare the efficacy and safety of MAKO robot-assisted total knee arthroplasty (MA-TKA) with conventional manual total knee arthroplasty (CM-TKA) in patients with end-stage knee osteoarthritis (KOA) during the early postoperative period., Method: A retrospective analysis was conducted on 22 patients with KOA who underwent MA-TKA and 26 patients who underwent CM-TKA from April 2023 to July 2023. Hip-knee-ankle angle (HKA), lateral distal femoral angle (LDFA), medial proximal tibial angle (MPTA), American Knee Society Score (AKSS), Forgotten Joint Score-12 (FJS-12), visual analogue scale (VAS), and postoperative complications were recorded and compared between the two groups., Result: Both groups successfully completed the surgeries. In terms of radiographic parameters, postoperative one month LDFA and HKA in the MA-TKA group were significantly lower than those in the CM-TKA group (P < 0.05). At the one month follow-up, 19 patients (86.4%) in the MA-TKA group had an HKA less than 3°, compared to 20 patients (76.9%) in the CM-TKA group. Clinically, VAS scores at 24 h, 48 h, and 72 h postoperatively were lower in the MA-TKA group both at rest and during activity. At one month and three months postoperatively, AKSS Function Scores and FJS-12 scores in the MA-TKA group were significantly higher than those in the CM-TKA group (P < 0.05). Regarding postoperative complications, no complications occurred in the MA-TKA group, while one patient in the CM-TKA group experienced postoperative knee stiffness, which resolved after physical therapy, with no statistically significant difference (P > 0.05)., Conclusion: Compared with conventional manual total knee arthroplasty, MAKO robot-assisted TKA demonstrates better short-term clinical efficacy, achieves better alignment planning, and maintains good safety., (© 2024. The Author(s).)

Purpose: To compare short-term patient-reported outcomes (PRO) of two contemporary matrix-associated autologous chondrocyte implantation (M-ACI) products for the treatment of large articular cartilage defects of the knee., Methods: A retrospective, registry-based, matched-pair analysis was performed, comparing PRO of patients undergoing isolated M-ACI with either Spherox™, a spheroid-based ACI (Sb-ACI), or NOVOCART™ Inject, a hydrogel-based ACI product (Hb-ACI), for a focal full-thickness cartilage defect of the knee ≥4 cm 2 . Matching parameters included age, sex, body mass index, defect size, defect localization, symptom duration and previous surgeries. The Knee Injury and Osteoarthritis Outcome Score (KOOS) and the International Knee Documentation Committee (IKDC) score were obtained up to the 24-month follow-up. The total KOOS response rate and percentage of patients attaining a substantial clinical benefit (SCB) in KOOS subscores were calculated., Results: A total of 45 patients per group were matched. The response rate after 24 months was not significantly different between the groups (Sb-ACI 64.4% vs. Hb-ACI 82.2%, p = 0.057). The number of patients with a SCB at 24 months was not significantly different in any KOOS subscore, despite significantly higher improvement of the total KOOS (14.8 ± 16.2 vs. 21.5 ± 15.4, p = 0.047) and KOOS pain in the Hb-ACI group (12.2 ± 18.6 vs. 20.6 ± 19.1, p = 0.037). The IKDC score in the Hb-ACI group was significantly higher at the 12- and 24-month follow-up (60.7 ± 20.2 vs. 70.9 ± 18.0, p = 0.013)., Conclusion: The response rate and number of patients achieving an SCB were not significantly different between patients treated with Sb-ACI or Hb-ACI. Both procedures can achieve favourable 2-year PRO. Hb-ACI was associated with better PRO between 1 and 2 years postoperatively; however, the clinical relevance of this benefit is yet to be proven., Level of Evidence: III, Retrospective comparative study., (© 2024 The Authors. Knee Surgery, Sports Traumatology, Arthroscopy published by John Wiley & Sons Ltd on behalf of European Society of Sports Traumatology, Knee Surgery and Arthroscopy.)

Primary bone tumors are rare but more frequently seen during childhood and with predilection for the distal femur and proximal tibia. Therapy of benign tumors-if indicated-includes surgical resection in most cases, whereas malignant bone tumors such as osteo- and Ewing's sarcomas are treated with chemotherapy, wide resection and/or radiation therapy (Ewing's sarcoma). The reconstruction of emerging bone defects is significantly influenced by surgeon-related preferences and tumor-associated factors, respectively. Double-barrel vascularized fibula grafts or extracorporeally irradiated autografts in combination with a free fibula transplant are preferred biological reconstruction techniques around the knee joint. In cases in which the knee joint cannot be preserved, reconstruction is performed using tumor endoprostheses, but potentially emerging leg length discrepancies after resection of a potent physis must be taken into account. In considerably young patients, rotationplasty might represent a viable option with promising functional results., (© 2024. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

Background: Although high tibial osteotomy (HTO) has emerged as a powerful intervention for treating symptomatic medial osteoarthritis and varus malalignment, it can result in an increase in knee joint line obliquity (KJLO) in the frontal plane. Limited current evidence hinders understanding of the effect of increased KJLO on HTO survivorship., Purpose: To investigate the influence of KJLO and other potential risk factors on the survivorship of lateral closing-wedge HTO., Study Design: Cohort study; Level of evidence, 3., Methods: Patients with symptomatic medial knee osteoarthritis and varus malalignment treated with lateral closing-wedge HTO at a single hospital were screened with a minimum follow-up of 5 years. HTO survival rate was assessed using Kaplan-Meier survival analysis. The influence of postoperative increased KJLO (medial proximal tibial angle ≥95°), age (≥55 years), sex (female), preoperative malalignment (hip-knee-ankle angle ≥10° of varus), postoperative untargeted alignment (hip-knee-ankle angle <2° or >6° of valgus), and preoperative osteoarthritis severity (Kellgren-Lawrence grade ≥3) on survivorship of HTO was evaluated using Cox regression analysis. A failure of HTO was defined as a conversion to total knee arthroplasty (TKA)., Results: A total of 410 patients (463 knees) were included, with a mean follow-up of 13.0 years (range, 5.0-18.1 years) and a mean survival time of 11.2 years (range, 1.2-18.1 years) for patients who reached the endpoint of TKA. HTO survival rates at 5, 10, and 15 years postoperatively were 91%, 78%, and 60%, respectively. Multivariate Cox regression analysis showed no significant difference in survivorship between patients with increased KJLO and those with acceptable KJLO (178 vs 285 knees; hazard ratio [HR], 0.8; 95% CI, 0.6-1.1; P = .148), with no significant between-group difference observed in the mean follow-up length (12.9 ± 3.0 years vs 13.1 ± 3.3 years; P = .105). Female sex (HR, 2.0; P < .001) and postoperative untargeted alignment (HR, 1.6; P = .003) were risk factors for a conversion to TKA., Conclusion: Increased postoperative KJLO (medial proximal tibial angle ≥95°) had no significant influence on the survivorship of lateral closing-wedge HTO. Men demonstrated superior survival outcomes compared with women, and it was important to achieve a targeted postoperative alignment (HKA 2°-6° of valgus) to ensure favorable HTO survivorship., Competing Interests: The authors declared that they have no conflicts of interest in the authorship and publication of this contribution. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.

Background: Stiffness remains a common complication after primary total knee arthroplasty (TKA). Manipulation under anesthesia (MUA) is the gold standard treatment for early postoperative stiffness; however, there remains a paucity of data on the risk of MUA after primary TKA if a prior contralateral TKA required MUA., Methods: We performed a retrospective review of 3,102 patients who had staged primary TKAs between 2016 and 2021. The mean body mass index was 33 (range, 18 to 59) and the mean age was 67 years (range, 24 to 91). The mean preoperative range of motion for the first TKA was 2 to 104°, and for the contralateral TKA was 1 to 107°. The primary outcomes were MUA following first and second primary TKAs. Multivariable Poisson regressions were used to evaluate associations between risk factors and outcomes., Results: The rate of MUA after the first TKA was 2.6% (n = 83 of 3,102) and 1.3% (n = 40 of 3,102) after the contralateral TKA. After adjustment, there was a nearly 14-fold higher rate of MUA after the second TKA if the patient had an MUA after the first TKA (relative risk, 13.80; 95% CI [confidence interval], 7.14 to 26.66). For the first TKA, increasing age (adjusted risk ratio [ARR], 0.65; 95% CI, 0.50 to 0.83) and increasing body mass index (ARR, 0.65; 95% CI, 0.47 to 0.90) were associated with lower risk for MUA. For the second TKA, increasing age was associated with a lower risk of MUA (ARR, 0.60; 95% CI, 0.45 to 0.80)., Conclusions: For patients undergoing staged bilateral TKA, patients who undergo MUA following the first primary TKA are nearly 14-fold more likely to undergo an MUA following the contralateral primary TKA than those who did not have an MUA after their first TKA., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Porous tantalum metaphyseal cones may facilitate reconstructions of severe bone defects during revision total knee arthroplasty (TKA), but there remains a paucity of data on their outcomes at mean 5 years of follow-up. This study reports the component survivorship, patient satisfaction, functional outcomes, radiographic osseointegration, and complications of revision TKA with porous tantalum metaphyseal cones at mid-term (mean 5-year) follow-up., Methods: This study included 152 patients who had a mean age of 66 years (range, 33 to 86 years) undergoing revision TKA with porous tantalum metaphyseal cones. Indications for surgery included aseptic loosening (n = 87, 57.3%), second-stage reimplantation for infection (n = 42, 27.6%), osteolysis with well-fixed components (n = 20, 13.2%), and periprosthetic fracture (n = 3, 2.0%). Component survivorship, clinical outcomes, radiographic outcomes, and any complications were recorded. The mean follow-up time was 5.6 years (range, 2.2 to 13.7)., Results: Survivorship was 100% when the end point was revision of the metaphyseal cone (no cones were revised) and 83.8% (95% confidence interval: 77.9 to 90.2%) when the end point was reoperation for any reason at 5-year follow-up. Reoperations were performed for infection (n = 10), instability (n = 4), periprosthetic fracture (n = 2), and quadriceps rupture/dehiscence (n = 3). The mean patient satisfaction score was 78.8 ± 11.3 and the mean Forgotten Joint Score was 62.2 ± 16.7 at the final follow-up. The preoperative median University of California at Los Angeles score improved from 2 (interquartile range 2 to 3) to 6 points (interquartile range 5 to 6) (P < .001), and the preoperative Oxford knee score improved from 15.2 ± 3.8 to 39.4 ± 5.1 points (P < .001) at the final follow-up. All metaphyseal cones showed radiographic evidence of osteointegration without any subsidence or loosening., Conclusions: Porous tantalum metaphyseal cones enabled robust reconstructions of severe femoral and tibial bone defects during revision TKA. These reconstructions were associated with excellent survivorship, improvements in functional outcomes, and reproducible radiographic osseointegration at mean 5-year follow-up. The most common reasons for reoperation were infection and instability., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The number of revision total knee arthroplasties (TKAs) performed annually continues to rise. This article is a summary of a symposium on revision TKAs presented at the 2023 American Association of Hip and Knee Surgeons annual meeting. It will provide an overview of the surgical tips and tricks for exposure and component removal, use of metaphyseal fixation and stems to manage bone loss and optimize fixation, constraint in TKA, as well as how to manage extensor mechanism disruptions with a synthetic mesh reconstruction. LEVEL OF EVIDENCE: V., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Venous thromboembolism (VTE), comprising pulmonary embolism and deep vein thrombosis, is one of the most common complications after knee arthroscopy. Sequelae of VTE include VTE recurrence, postthrombotic syndrome, and potential for loss of limb or life. Given the increasing volume of knee arthroscopy procedures worldwide and the considerable morbidity and mortality associated with VTE, it is important to prevent, diagnose, and treat VTEs efficiently and effectively. Risk factors such as history of VTE, family history of VTE, genetic coagulopathy, oral contraceptive use, cancer history, and old age increase the risk of postoperative VTE and warrant consideration of prophylaxis. Diagnosis and treatment should be initiated rapidly in the setting of concerning symptoms and positive imaging diagnosis, respectively. The purpose of this review was to provide a framework to individualized VTE risk, weigh prophylaxis options, expedite diagnostic pathways, and implement outpatient treatment algorithms., (Copyright © 2024 by the American Academy of Orthopaedic Surgeons.)

Over the past few decades, instrumentation and techniques for total knee arthroplasty have evolved from conventional manual tools to a wide range of technologies, including calibrated guides for accurate bone cuts and alignment, smart tools, dynamic intraoperative sensors for soft tissue balancing, patient-specific guides, computer navigation, and robotics. This review is intended to provide an overview of the latest advancements in total knee arthroplasty technology, address potential challenges and solutions related to the application of these technologies, and explore their limitations., (Copyright © 2024. Published by Elsevier Inc.)

Background: The aim of this study was to compare the clinical results of kinematic alignment (KA) with those of mechanical alignment (MA) in single-stage bilateral total knee arthroplasty., Methods: In this double-blinded randomized controlled trial, 65 patients who had bilateral knee osteoarthritis underwent simultaneous bilateral total knee arthroplasty. One knee was randomly selected to be operated on with the calipered-KA technique and the other with MA. The participants were assessed via the Oxford Knee Score, Western Ontario and McMaster Universities Osteoarthritis Index questionnaire, and visual analog scale before the surgery and the same plus the Forgotten Joint Score at their last follow-up visit, 2 years postoperatively. Maximum knee flexion and the time reaching maximum knee flexion, named the recovery time, were also recorded. Hip-knee-ankle angle, medial proximal tibial angle, and lateral distal femoral angle were measured before and after the surgery using 3-joint-view radiographs., Results: At 2 years, there were significant differences between the KA and MA techniques in terms of duration of surgery, recovery time, and final Western Ontario and McMaster Universities Osteoarthritis Index, Forgotten Joint Score, and maximum flexion range in favor of KA (P < .05), but no significant difference in visual analog scale score or Oxford Knee Score. In patients who have a preferred knee, the KA knee was preferred over the MA knee by most patients. No prosthetic failure or revision was reported in either group., Conclusions: The KA technique yields acceptable functional outcomes compared to the MA technique. The KA technique was associated with a shorter surgery time, a faster recovery time, and higher patient satisfaction in 2-year follow-ups. Larger multicenter studies with longer follow-ups are warranted to confirm these findings., Level of Evidence: I., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Background: Resilience is a psychometric parameter defined as one's ability to recover or bounce back from stressful events and has been shown to correlate with better outcomes following multiple orthopedic procedures. The purpose of this study was to analyze the correlation between resiliency, as measured using the Brief Resiliency Scale (BRS) and various knee outcome scores, including the International Knee Documentation Committee (IKDC), Lysholm, Single Assessment Numeric Evaluation (SANE), and Return to Work, following isolated partial meniscectomy., Methods: One hundred patients who had undergone an isolated partial meniscectomy during a 3-year period at a single institution were successfully recruited to participate in the study. The BRS and knee outcome scores (IKDC, Lysholm, SANE, Return to Work) were obtained via phone. Radiographs for each patient were obtained and graded for arthritis severity using the Kellgren-Lawrence classification system., Results: Brief Resiliency Scale scores ranged 15.0 to 23.0 with a mean of 18.2 ± 1.3. Mean knee outcome scores for IKDC, Lysholm, SANE, and Return to Work were 66.3, 77.1, 70.6, and 41.0, respectively. Outcome scores did not correlate with BRS scores. The severe arthritis group significantly correlated (p < 0.05) with worse IKDC, Lysholm, and Return to Work scores compared to mild arthritis scores. Additionally, analysis of the mild arthritis group revealed that resiliency significantly correlated with higher Return to Work scores compared to low resilience groups., Conclusion: This study suggests that there is no significant relationship between patient resiliency and outcomes following partial meniscectomy. However, those with poorer outcomes had more severe arthritis.

Pathomechanics resulting from rotational deformities of the long bones in an idiopathic population have not been extensively studied, and are chiefly limited to level over ground walking. Thirty-five adolescents with excessive idiopathic outward tibial torsion (TT), femoral rotation, or both (pan genu) were studied both before and after corrective surgery. Data collected included computational motion analysis of a drop jump and patient-reported outcomes consisting of PODCI and Goal Attainment Scores. Results were compared to an age-matched typically developing cohort (n = 25). Subjects with femoral anteversion (FA) exhibited compensatory hip rotations to normalize knee progression angles at landing. Subjects with only TT did not compensate at the hip, landing with typical knee progression but excessive outward foot progression. These strategies resulted in elevated frontal plane knee moments for FA ( P  = 0.008), and elevated lateral knee forces in all groups compared to typical, with the TT group reaching significance ( P  < 0.001). Rotational osteotomies successfully restored elevated kinematics and kinetics to within or below typically developing ranges. Patient-reported outcomes generally improved after surgery across all domains studied. Drop jump testing elucidated compensation strategies employed by these cohorts. Compensation did not fully alleviate elevated forces at the knees. Surgical intervention normalized pathokinematics and pathokinetics, reduced pain, and improved patients' perception of their functional abilities. Greater improvements were found in individuals in the two groups with FA compared to the group with TT only., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Background: We report a rare case of posterior cruciate ligament (PCL) calcification, which has only been reported in two case studies on PubMed., Case Presentation: A 71-year-old man developed left popliteal pain in the morning without any history of trauma and the pain became severe that night. On the following day, he presented to our department. The patient could not flex his left knee at all due to pain and swelling. CT and MRI scans showed calcification behind the PCL with mild osteoarthritic changes and accumulation of synovial fluid in the joint. Synovial fluid analysis did not reveal any crystals. Blood tests at first admission showed inflammation, hyperglycemia, and low blood uric acid levels. Although the patient's knee joint was injected with steroids, his symptoms did not improve. Thus, we performed arthroscopic surgery two days after symptoms had appeared. Intraoperatively, we observed a white, soft tissue in the synovial membrane behind the PCL. Part of this tissue was collected for histological analysis, which revealed sparse fibers with calcium deposits. Immediately after surgery, the patient's symptoms were completely gone. Afterward, the patient remained asymptomatic one month after surgery., Conclusion: This is the first reported case of debridement of PCL calcification and ossification that was performed soon after symptoms appeared. In addition, we demonstrated that early debridement led to complete recovery., (© 2024. The Author(s).)

Background: Around 6,000 revision knee replacement procedures are performed in the United Kingdom each year. Three-quarters of procedures are for aseptic, elective reasons, such as progressive osteoarthritis, prosthesis loosening/wear, or instability. Our understanding of how we can best support these patients undergoing revision knee replacement procedures is limited. This study aimed to explore patients' experiences of having a problematic knee replacement and the impact of undergoing knee revision surgery for aseptic, elective reasons., Methods: Qualitative semi structured interviews with 15 patients (8 women, 7 men; mean age 70 years: range 54-81) who had undergone revision knee surgery for a range of aseptic, elective indications in the last 12 months at an NHS Major Revision Knee Centre. Interviews were audio-recorded, transcribed, de-identified and analysed using reflexive thematic analysis., Results: We developed six themes: Soldiering on; The challenge of navigating the health system; I am the expert in my own knee; Shift in what I expected from surgery; I am not the person I used to be; Lingering uncertainty., Conclusions: Living with a problematic knee replacement and undergoing knee revision surgery has significant impact on all aspects of patients' lives. Our findings highlight the need for patients with problematic knee replacements to be supported to access care and assessment, and for long-term psychological and rehabilitation support before and after revision surgery., (© 2024. The Author(s).)

Case: A 13-year-old adolescent boy with spastic diplegic cerebral palsy (CP) presented with crouch gait and bilateral knee flexion contractures (KFCs). After failure of conservative treatments, the patient was referred to orthopaedics for surgical intervention. Anterior distal femoral hemiepiphysiodesis (ADFH), using a retrograde approach, and Strayer gastrocnemius recession were performed bilaterally. No complications were reported during surgery/follow-up. Full-active knee extension and improved gait were achieved., Conclusion: KFC is prevalent in ambulatory patients with CP, reducing gait function. Retrograde ADFH is an effective surgical intervention to reduce KFC and improve gait, and offers simpler insertion/removal than the traditional antegrade technique., Competing Interests: Disclosure: The Disclosure of Potential Conflicts of Interest forms are provided with the online version of the article (http://links.lww.com/JBJSCC/C425)., (Copyright © 2024 by The Journal of Bone and Joint Surgery, Incorporated.)

This prospective bi-center study aimed to analyze the outcomes of primary total knee arthroplasty using the Stemmable Tibia Attune system. A total of 100 patients who underwent primary total knee arthroplasty with Stemmable Tibia from January 2019 to December 2021 were enrolled in the study. Radiological outcomes (hip-knee-ankle axis and medial proximal tibial angle) were assessed preoperatively and postoperatively. Clinical outcomes (visual analog scale score, Hospital for Special Surgery score, Knee Society function score, Knee Society knee score, flexion contracture, further flexion, and range of motion) were analyzed preoperatively and at 6 weeks, 3 months, 6 months, 1 year, and 2 years postoperatively. Complications (periprosthetic joint infection and aseptic loosening) were examined. The hip-knee-ankle axis decreased (preoperative: 9.5° ± 6.3°, postoperative: 1.1° ± 2.7°), whereas the medial proximal tibial angle increased (preoperative: 84.6° ± 4.1°, postoperative: 89.8° ± 1.9°). The visual analog scale score, Hospital for Special Surgery score, Knee Society knee score, and Knee Society function score increased postoperatively. The Knee Society knee score indicated above good outcomes (100.0% and 99.0% at 1 and 2 years postoperatively, respectively). The Knee Society function score also showed above good results (98.0% and 93.0% at 1 and 2 years postoperatively, respectively). The range of motion significantly improved (p < 0.001): flexion contracture decreased from 9.10° ± 7.23° to 2.15° ± 2.87°, whereas further flexion increased from 136.05° ± 14.78° to 139.80° ± 10.02°. One patient developed periprosthetic joint infection; no early loosening was observed. In conclusion, Attune primary total knee arthroplasty with Stemmable Tibia not only is safe and effective but also leads to radiological and clinical improvements., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Rhee et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Xanthoma typically occurs in the subcutaneous tissues, with rare cases of xanthoma in the joints. However, the case of knee joint osteonecrosis combined with xanthoma is even more uncommon. In this article, we described a 50-year-old female patient who suffered xanthoma in the knee joint on the basis of osteonecrosis of the knee joint. The primary clinical symptoms were knee joint pain and limited mobility. The patient initially received conventional treatment for osteonecrosis. However, there was no significant improvement. Later, we found a synovial xanthoma in the patient's knee. Finally, she underwent arthroscopic excision of the knee joint synovial xanthoma. Following the procedure, her VAS score decreased from 7 to 2, and knee joint mobility increased from 10-103° to 10-140°. Through our follow-up, the patient did not exhibit symptom recurrence. This case is valuable as it provides a feasible therapeutic approach for future clinical applications., (© 2024. The Author(s).)