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Abstract Background Indication for mobile-bearing partial knee replacement (PKR) is made on the basis of a radiological decision aid. This study aimed to reveal the inter-rater reproducibility and accuracy of the decision aid when used by experienced surgeons. Patients and methods Anonymised radiographic image sets (anteroposterior, lateral, varus/valgus stress in 20° knee flexion, and skyline views) from 20 consecutive patients who underwent knee replacement were assessed by 12 experienced surgeons. Agreements of each section and accuracy were compared by intra-operative inspection of the status of the anterior cruciate ligament (ACL) and medial and lateral cartilage according to the protocol of Radiographic Assessment for Medial Oxford PKR. Fleiss’ kappa (κ) values were used as a statistical measure. Results Full-thickness medial cartilage had the best agreement between the surgeons (κ = 94.7%) and best accuracy (94.2%). Although functioning ACL (90.8%), intact cartilage (91.7%) and full-thickness lateral cartilage defects (86.1%) were accurately diagnosed, diagnoses of deficient ACL (up to 42.5%) and partial-thickness lateral cartilage defects (11.7%) were poor; they were sometimes misdiagnosed as being intact. Moreover, agreement of lateral and valgus stress radiographs regarding intact MCL function, as well as the overall decision, was considered to be inadequate (κ = 0.47, 0.58 and 0.51, respectively). Conclusions Although the radiological aid is useful for selection of patients who are likely to be suitable for PKR, surgeons should still carefully assess the lateral weight-bearing area for partial-thickness loss and deficiency of the ACL because they were sometimes overlooked by surgeons using radiographs. MRI will be helpful to improve the accuracy of determination of Oxford PKR indication.

Abstract Background To study the biomechanical effects of femoral prostheses at different coronal positions using finite element analysis and provide a clinical reference for unicompartmental knee arthroplasty (UKA). Methods A normal knee joint model was established and verified, establishing 13 working conditions for the femoral prosthesis: the standard position, varus and valgus angles of 3°, 6° and 9° and medial and lateral translations of 1 mm, 3 mm and 5 mm. The stress changes at different positions were analysed, including the polyethylene (PE) insert upper surface, the surface of lateral compartment cartilage and the surface of cancellous bone under tibial prosthesis. Results The stresses on the PE insert upper surface and the cancellous bone surface increased with increasing femoral prosthesis valgus/varus, and the stress increased gradually during medial to lateral translation. The stress change is more significant during valgus and lateral translation. However, the stress on the cartilage surface decreases in the process of varus to valgus and medial translation to lateral translation. Conclusion The fixed-bearing femoral prosthesis of the medial UKA should avoid translation or varus/valgus tilt on the coronal plane as much as possible. The obvious misalignment of the femoral prosthesis will significantly affect the stress on the internal structure of the knee joint, especially the PE insert and cartilage surface. A femoral prosthesis coronal tilt of more than 6° may significantly increase the stress on the PE surface, and varus of more than 6° may significantly increase the stress on the cartilage surface. For the femoral prosthesis position at the distal end of the femoral condyle, it is recommended to be placed in the centre.

Aims Return to sport following undergoing total (TKA) and unicompartmental knee arthroplasty (UKA) has been researched with meta-analyses and systematic reviews of varying quality. The aim of this study is to create an umbrella review to consolidate the data into consensus guidelines for returning to sports following TKA and UKA. Methods Systematic reviews and meta-analyses written between 2010 and 2020 were systematically searched. Studies were independently screened by two reviewers and methodology quality was assessed. Variables for analysis included objective classification of which sports are safe to participate in postoperatively, time to return to sport, prognostic indicators of returning, and reasons patients do not. Results A total of 410 articles were found, including 58 duplicates. Seven articles meeting inclusion criteria reported that 34% to 100% of patients who underwent TKA or UKA were able to return to sports at 13 weeks and 12 weeks respectively, with UKA patients more likely to do so. Prior experience with the sport was the most significant prognostic indicator for return. These patients were likely to participate in low-impact sports, particularly walking, cycling, golf, and swimming. Moderate-impact sport participation, such as doubles tennis and skiing, may be considered on a case-by-case basis considering the patient’s prior experience. There is insufficient long-term data on the risks to return to high-impact sport, such as decreased implant survivorship. Conclusion There is a consensus that patients can return to low-impact sports following TKA or UKA. Return to moderate-impact sport was dependent on a case-by-case basis, with emphasis on the patient’s prior experience in the sport. Return to high-impact sports was not supported. Patients undergoing UKA return to sport one week sooner and with more success than TKA. Future studies are needed to assess long-term outcomes following return to high-impact sports to establish evidence-based recommendations. This review summarizes all available data for the most up-to-date and evidence-based guidelines for returning to sport following TKA and UKA to replace guidelines based on subjective physician survey data. Cite this article: Bone Jt Open 2022;3(3):245–251.

Abstract Background Though unicompartmental knee arthroplasty (UKA) is a useful procedure to treat knee osteoarthritis, it remains a great controversial point as to if navigated systems are able to achieve better accuracy of limb alignment and greater clinic results. Current meta-analysis was conducted to explore if better clinical outcomes and radiographic outcomes could be acquired in the navigated system when compared with conventional procedures. Methods We identified studies in the online databases, including Medline, Embase, the Cochrane Library and Web of Science before May 2021. The PRISMA guidelines in this report were strictly followed. Our research was completed via Review Manager 5.4 software. Results Fourteen articles were included, involving 852 knees. The present meta-analysis displayed that the navigated system had remarkably improved outcomes in inliers of mechanical axis (MA) (P

Abstract Background Although favorable long-term survival of Oxford unicompartmental knee arthroplasty (UKA) has been reported regardless of postoperative varus alignment, the effect of degree of varus alignment on patient-reported outcome measures (PROMs) remains unclear. Furthermore, the Forgotten Joint Score-12 (FJS-12), which has a low ceiling effect, may be useful for such assessment. The objective of this study was to evaluate short-term clinical outcomes after Oxford UKA in knees with a greater degree of preoperative varus alignment focusing on use of the FJS-12. Methods This retrospective study involved 66 knees that had undergone primary Oxford UKA. Based on the hip-knee-ankle angle, the knees were divided into two alignment groups: severe varus group (≥ 185° varus alignment) and a mild varus group (

Objective To evaluate knee scores and clinical efficacies of patients with non‐lateral unicompartmental knee osteoarthritis (OA) who randomly underwent mobile‐bearing (MB) unicompartmental knee arthroplasty (UKA), fixed‐bearing (FB) UKA, and total knee arthroplasty (TKA). Methods From September 2015 to February 2017, a prospective, randomized, parallel, single‐center trial of 180 patients (78 males and 102 females; 63.3 ± 6.9 years) with non‐lateral compartmental knee OA was performed in the first author‐affiliated hospital. The patients were randomly divided into three groups (each group included 60 patients) and received medial cemented Oxford phase 3 MB UKA, medial cemented Link FB UKA, or cemented DePuy Sigma PFC TKA, respectively. A similar perioperative management and fast‐track surgery program was carried out for all patients. The knee scores at 3‐year follow‐up after operation and clinical efficacies of these three groups of patients were recorded, investigated, and compared. Results Primarily, compared to the TKA group, the UKA groups (MB UKA and FB UKA) had shorter operative time (median 63.2 74.5) (P = 0.007), better results in all knee scores (except VAS and KSS function scores) (P 96.0°) (P = 0.001). Secondarily, compared to the TKA group, the MB UKA group showed better results in the Western Ontario and McMaster Universities index (WOMAC) stiffness (83.6 > 79.6), WOMAC total (86.3 > 83.2), Oxford knee score (OKS) (20.0 74.5), and a larger maximum flexion angle of the knee (123.0 > 96.0) (P 88.5), WOMAC stiffness (84.3 > 79.6), WOMAC function (85.2 > 81.7), WOMAC total scores (87.6 > 83.2), and a larger maximum flexion angle of the knee (119.0° > 96.0°) than the TKA group (P 0.05). There was one case with original bearing dislocation in MB UKA group. One patient with displacement of the femoral component caused by a fall injury, and another patient, who lost his life in a car accident, were involved in the FB UKA group. There was an infection case and an intermuscular vein thrombosis case in TKA group. Conclusion UKA showed more advantages than TKA; however, there was no significant difference between the MB UKA and FB UKA groups for treatment of non‐lateral compartmental knee OA.

Abstract Background The goal of this study was to assess short-term outcomes in single compartment osteoarthritis patients associated with the coronal tibiofemoral subluxation (CTFS) of the knee joint after Oxford unicompartmental knee arthroplasty (OUKA), and to establish the potential impact of the degree of CTFS on operative outcomes. Methods Data pertaining to 183 patients with medial compartment osteoarthritis that underwent OUKA treatment between February 2016 and June 2019 were retrospectively analyzed. The presence and degree of severity of CTFS were assessed using preoperative weight-bearing anteroposterior X-ray images of the knee. Patients were stratified into three subgroups based upon the observed degree of subluxation: a normal group, a mild subluxation group (CTFS 0.05). After surgery, OKS and HSS scores declined significantly, but no differences in these scores were observed among groups (P > 0.05). Of these patients, 135 (73.8%) were satisfied with the operation, of whom 80 (43.7%) were very satisfied. There were no significant differences in ROM or VAS scores among groups (P > 0.05). The degree of CTFS for patients in the mild and severe subluxation groups was significantly improved following OUKA relative to preoperative values such that the degree of postoperative CTFS did not differ significantly among these groups (P > 0.05). Postoperative mFTA was also significantly improved in these three patient subgroups (P

Background The objective of this article is to describe for the first time a case of 90° spin out of a mobile bearing unicompartmental knee arthroplasty (UKA) polyethylene insert. In this report, we present a 57-year-old gentleman with a medial compartment UKA for osteoarthritis in 2017 who developed dislodgement and 90° rotation subsequent to traumatic injury when he was involved in a bus crash and impacted the anterolateral knee sustaining a valgus type injury 1 week postoperatively. Following the injury, he reported medial knee pain and a sensation of something moving within the joint. He was initially managed conservatively and progressed to full weight bearing; however, he experienced intermittent symptoms of catching and blocking of the joint, as well as medial knee swelling, that inhibited his ability to perform activities involving walking, kneeling, or pivoting. Imaging taken in 2018 show a 90° rotation of the polyethylene insert. These images showed the longitudinal metallic marker on the insert facing in an anteroposterior direction as opposed to the normal medial-lateral orientation. Failing conservative management, he presented to our clinic in 2019 and proceeded for revision of his UKA. Intraoperatively, his insert was reviewed and seen to easily spin on axis. The liner was therefore removed and upsized from a size 5 medium to a size 7 medium insert which provided excellent stability and stopped any further spinning. He has done tremendously well since the operation and reports full range of motion and no concerns. In patients with a history of pain, swelling, or locking following a UKA, it would be prudent to consider insert spinning, as well as the more common dislocation, through confirming the orientation of the metallic insert marker. Revision surgery to correct the spinning defect has proven effective with good resolution of symptoms and return to full range of motion.

IntroductionPopliteal cysts are secondary to degenerative changes in the knee joint. After total knee arthroplasty (TKA), 56.7% of patients with popliteal cysts at 4.9 years follow-up remained symptomatic in the popliteal area. However, the result of simultaneous arthroscopic cystectomy and unicompartmental knee arthroplasty (UKA) was uncertain.Case presentationA 57-year-old man was admitted to our hospital with severe pain and swelling in his left knee and the popliteal area. He was diagnosed with severe medial unicompartmental knee osteoarthritis (KOA) with a symptomatic popliteal cyst. Subsequently, arthroscopic cystectomy and unicompartmental knee arthroplasty (UKA) were performed simultaneously. A month after the operation, he returned to his normal life. There was no progression in the lateral compartment of the left knee and no recurrence of the popliteal cyst at the 1-year follow-up.ConclusionFor KOA patients with a popliteal cyst seeking UKA, simultaneous arthroscopic cystectomy and UKA are feasible with great success if managed appropriately.

Background: Specific clinical and radiographic risk factors for medial unicompartmental knee arthroplasty (UKA) failure are incompletely understood. The purpose of this study was to perform a midterm survivorship analysis of medial UKA from a single, nondesigner surgeon. Based on observations from clinical practice, we hypothesized that the presence of a lateral trochlear osteophyte on preoperative Merchant radiographs may be predictive of medial UKA failure secondary to progressive osteoarthritis (OA). Methods: Patients who underwent a mobile-bearing medial UKA by a single surgeon with minimum 24 months of clinical follow-up from 2008 to 2019 were retrospectively identified. Radiographic parameters, including the presence of a lateral trochlear osteophyte, were measured. Kaplan-Meier survivorship analyses were performed. Cox proportional hazards models were used to evaluate variables as risk factors for UKA failure, defined as reoperation or component revision. Results: A total of 233 UKAs were included. The mean age was 60 years, mean BMI 32 kg/m2, and 53% of patients were male. The mean follow-up duration was 5.7 years (range, 2.0-13.1 years). Using any reoperation as an endpoint, the 10-year survival was 91%. Using any component revision as an endpoint, the 10-year survival was 93%. Using revision due to progressive OA as an endpoint, the 10-year survival was 95%. The presence of a lateral trochlear osteophyte was associated with an increased risk of any reoperation (hazard ratio 3.6; 95% confidence interval 1.3-9.5) and increased risk of revision due to progressive OA (hazard ratio 9.8; 95% confidence interval 2.9-32.7). Conclusions: The presence of a lateral trochlear osteophyte on preoperative Merchant view radiographs was associated with an increased risk of medial UKA failure.

Abstract Purpose In patients with monocompartmental knee osteoarthritis, unicompartmental knee arthroplasty (UKA) can be performed. This study compared the medial versus lateral UKA in patients with monocompartimental knee arthroplasty. It was hypothesised that both implants achieve a similar outcome in OKS. Methods The UKAs were fixed‐bearing medial PPK (Zimmer‐Biomet, Warsaw, Indiana, USA) and fixed‐bearing lateral Zuk (Lima Corporate, Udine, Italy). An intraarticular drain was placed and removed on the first postoperative day. Enoxaparin sodium 4000 units subcutaneously daily for 45 days was used as thromboembolic prophylaxis. The Italian version of the OKS was used for the clinical assessment. The following complications were also recorded: anterior knee pain, infection and revision surgeries. Results Data from 203 patients were collected. The mean age of the patients was 68.9 ± 6.7 years and the mean BMI was 28.1 ± 4.1 kg/m2. The mean OKS on admission was 22.1 ± 4.5 points. On admission, women, patients older than 70 years, and those with a BMI lower than 28 kg/m2 who underwent lateral UKA evidenced lower OKS. At the last follow‐up, 26.7 and 26.9 months for the lateral and medial UKA, respectively, no between groups difference in OKS was evidenced. No patients experienced complications. Conclusion Medial and lateral UKA achieve similar outcomes in OKS at a minimum of two years of follow‐up.

ObjectiveTo compare the mid-term outcomes of unicompartmental knee arthroplasty (UKA) that was performed in one knee and total knee arthroplasty (TKA) performed in the other knee in the same stage.MethodsThis is a retrospective study. A total of 63 patients (126 knees) scheduled for one-stage knee surgery due to osteoarthritis of both knees were selected, and all patients underwent one-stage mobile platform UKA and TKA of the other knee. Differences in general clinical data, functional recovery, complications, and prosthesis revision rates were assessed after UKA and TKA, respectively. The evaluation indicators for knee joint function recovery included the hospital for special surgery knee score (HSS), Joint Forgotten Score (JFS), Knee Injury and Osteoarthritis Outcome Score (KOOS), and Visual analog scale (VAS). Patient preference between UKA and TKA was also recorded.ResultsDuring a mean follow-up of 76.95 months (range, 65.00 to 87.00 months), there were no significant differences in postoperative complications between the two groups (P = 0.299); however, the prosthesis revision rate was higher in the UKA group than in the TKA group (P = 0.023). The incision length, operation time, blood loss, and postoperative drainage volume in the UKA group were significantly (P

Background: Several strategies have been devised to reduce the length of stay after orthopedic surgery. Telerehabilitation has proved effective in functional outcomes after orthopedic procedures and is appreciated by patients. There is limited information on fast-track surgery and telerehabilitation protocols for unicompartmental knee arthroplasty (UKA). The purpose of this pilot study was to report and compare functional outcomes and satisfaction levels during first 12 months of recovery in patients who underwent UKA according to a fast-track and telerehabilitation protocol (G1) or standard surgery and rehabilitation program (G2). Methods: Data were retrospectively collected and reviewed for all elective UKAs from January 2018 to November 2019. A total of seven patients undergoing UKA according to the fast-track and telerehabilitation protocol were propensity score matched (1:3 ratio) to 21 patients undergoing standard surgery and rehabilitation. Patients were matched for age, sex, body mass index (BMI), and laterality. The Western Ontario and McMaster University (WOMAC) osteoarthritis index and range of motion (ROM) were collected pre- and postoperatively in both groups for 12 months. In addition, patient' satisfaction was collected at 40 days. Results: The G1 group demonstrated significantly better outcomes in WOMAC index scores at 2, 15, and 40 days (p < 0.001, p < 0.001, p < 0.020, respectively) and a significantly greater knee ROM after surgery and at 2, 15, 40, and 12 months (p < 0.001, p < 0.001, p = 0.014, p < 0.001, p = 0.003, respectively). No patients in either group had postoperative complications. One patient was not completely satisfied in the G2, while no one in G1 reported not being completely satisfied (p = 1.000). Conclusions: This fast-track and telerehabilitation protocol after UKA can potentially be applied to patients as it is safe and effective. At 12-months follow-up, both groups reported favorable outcomes after UKA. However, the G1 score was better regarding WOMAC and ROM when compared with the propensity score-matched G2 program. A larger study is warranted to explore the role of fast-track and telerehabilitation in clinical and functional outcomes of UKA. [ABSTRACT FROM AUTHOR]

Background: Heterotopic Ossification (HO) of the knee is most commonly formed anteriorly to the distal femoral shaft in the quadriceps expansion. Although the incidence of severe HO with large dimensions affecting the knee and resulting in severe consequences is extremely rare, these cases are extremely difficult to prevent and have severe clinical limitations for the patient. Aim: The purpose of this study was to present and explore HO formation after Total Knee Arthroplasty (TKA). Conclusions: It is crucial to perform a stratification of patients for the risk of HO formation after TKA and to gain a better understanding of the fundamental role of post-operative treatments. In severe HO, surgery should be considered following appropriate investigations and should only be considered when the HO has fully matured. In comparison to Total Hip Arthroplasty (THA), HO formation after TKA is less frequent and underexplored. Therefore, further studies are required. This case report can represent a protocol for the treatment of clinically relevant HO in the knee after TKA. [ABSTRACT FROM AUTHOR]

Objective: Surgeon handedness has been widely discussed in operative surgery, and could cause clinical discrepancy. However, few studies have reported the effect of handedness on unicompartmental knee arthroplasty (UKA). Based on our clinical observation and case analysis, we aimed to find out the effects of surgeon handedness on UKA. Methods: We retrospectively studied 94 UKA procedures performed by one right‐handed surgeon from January 2017 to December 2018 at a single medical center. The cases were divided into two groups by operation side (49 L‐UKAs and 45 R‐UKAs). Preoperative demographic data were collected. Imaging parameters (femorotibial and hip‐knee‐ankle angles and tibial‐plateau retroversion) and joint function scores (Knee Society Score [KSS] and Oxford Knee Score [OKS]) were recorded. Patients were followed up regularly and Forgotten Joint Score (FJS) was calculated at the last follow‐up. All data were compared between the two groups with independent‐samples t‐test, and paired t‐test was used for intragroup comparisons. Results: The average follow‐up was 26.7 ± 3.2 months. The average patient age was 63.5 ± 9.0 years and the average body mass index was 26.89 ± 3.43 kg/m2. There was no significant group difference in any preoperative characteristic. Both the KSS and OKS improved significantly after surgery (p < 0.05). No significant group difference was found between the KSS or OKS at any follow‐up visit. The varus or valgus of tibial component was 3.57 ± 1.42° on the left side and 3.19 ± 1.56° on the right side (p = 0.45). The varus or valgus of femoral component was 7.81 ± 2.43° in patients undergoing L‐UKA and 7.05 ± 2.90° in those undergoing R‐UKA (p = 0.04). No statistical differences were found in outliers of component orientation on both sides. The femorotibial and hip‐knee‐ankle angles improved significantly in both groups, and there was no significant group difference in either lower limb alignment or tibial‐plateau retroversion. The complication rate was 8.16% (4/49) in the L‐UKA group and 6.67% (3/45) in the R‐UKA group. There was no correlation between prosthesis orientation and early joint function score. Conclusions: Surgeon handedness may cause a worse prosthetic orientation on femoral side during surgeon's non‐dominant UKA, and surgeons should be cautious of bone resection and prosthesis implantation. However, radiographic difference did not bring variations on short‐term clinical outcomes or lower limb alignment. [ABSTRACT FROM AUTHOR]

Background: Although metal-backed tibial component (MB) is biomechanically superior to all-polyethylene (AP) implants in fixed-bearing unicompartmental knee arthroplasty (UKA), recent studies have shown comparable functional outcomes between the two. However, no study has examined this comparison in obese patients (BMI ≥ 30 kg/m2). We investigated whether functional outcomes between the two implants differ among obese patients, and whether the extent of obesity influences these outcomes. Patients and methods: Four hundred twenty-two UKA implants from 347 obese patients were reviewed retrospectively. Patients were assessed using the Knee Society Knee Score (KSKS) and Function Score (KSFS), the original Oxford Knee Score (OKS), and SF-36 Physical Component Summary (PCS) and Mental Component Summary (MCS). Minimal clinically important difference (MCID) attainment was recorded. Patients' fulfillment of expectations and satisfaction with the surgery outcome was also graded. Patients were further divided into lower obesity (BMI 30–34.9 kg/m2) and higher obesity (BMI ≥ 35 kg/m2) to examine effect modification. Results: There were no differences in functional outcomes and quality-of-life scores, MCID attainment of functional scores, as well as satisfaction and expectation fulfillment between AP and MB. Among higher obesity patients, AP was associated with a poorer KSKS (p = 0.031) and lower proportion of satisfaction fulfillment (p = 0.041) 2 years postoperatively compared to MB. Conclusion: We found no differences in functional and quality-of-life outcomes between fixed-bearing AP and MB tibial components among obese patients who underwent UKA. However, among higher obesity patients (BMI ≥ 35 kg/m2), patients with AP tibial component were associated with lower KSKS score and a lower proportion of attaining satisfaction fulfillment 2 years postoperatively. [ABSTRACT FROM AUTHOR]

Introduction: Medial unicompartmental knee arthroplasty (mUKA) requires full-thickness cartilage in the lateral compartment, but slight damage of the cartilage surface can be ignored. However, as this statement lacks literature support, we investigated whether slight cartilage damages in the weight-bearing area of the lateral femoral condyle would affect the outcome of mUKAs. Materials and methods: Outerbridge grading was performed on the cartilage in the weight-bearing area of the lateral femoral condyle intraoperatively. The patients, grouped as normal or as having lateral condyle cartilage of Outerbridge grade 1–2 (slight cartilage damage), underwent mUKA. Full-length lower extremity radiographs were taken and hip–knee–ankle angles (HKAAs) were measured both preoperatively and postoperatively. Using magnetic resonance imaging, the lateral meniscal extrusion distance was also measured. In addition, the Oxford Knee Score (OKS) was assessed preoperatively and at the last follow-up, in addition to the patient satisfaction assessment. Results: We enrolled 152 knees of 142 patients proposed for mUKAs. The mean age of participants was 69.5 years (51–89 years) and they were followed up for a mean of 25.4 months (15–44 months). There was no significant difference in preoperative (p = 0.746) and postoperative (p = 0.202) mean OKS between the normal, Outerbridge grade 1 and Outerbridge grade 2 groups. While the normal group had a higher change in OKS than the group with cartilage damage, this difference was not significant (p = 0.910). The UKA corrected the patients' mean HKAA from 171.1° (preoperatively) to 176.1° (postoperatively). From all patients, only four had slight lateral meniscus extrusion with MEDs of ≤ 0.25 mm. With the exception of one patient with a poor outcome in normal group, the rest were satisfied with the outcome of mUKA. No patients had prosthesis-related complications or revision surgery. Conclusions: Cartilage damage of Outerbridge grade 1 and grade 2 in the weight-bearing area of the lateral femoral condyle will not compromise the short-term outcome of medial mobile-bearing UKA. [ABSTRACT FROM AUTHOR]

Background: Short-acting spinal anesthetics are playing an increasing role in same-day discharge total joint arthroplasty though their direct comparison remains to be studied. Therefore, this study aims to compare two formulations of spinal anesthesia regarding time to discharge following knee arthroplasty surgery.Methods: A retrospective study was performed on 207 patients who underwent unicompartmental knee arthroplasty (UKA, n = 172) and total knee arthroplasty (TKA, n = 35) from May 2018 to December 2020 at a single institution and were discharged the same day. Two formulations of the spinal anesthetic were routinely administered in this population: 1) mepivacaine 1.5% 3-4 mL (n = 184) and 2) ropivacaine 0.5% 2.3-2.7 mL (n = 23). Discharge times were subsequently compared between mepivacaine and ropivacaine spinal anesthesia for each surgical procedure and between surgical procedures.Results: There was no significant difference in discharge times between patients receiving mepivacaine versus ropivacaine for UKA (202 minutes [range = 54-449] versus 218 minutes [range = 175-385], P = .45) or TKA (193 minutes [range = 68-384] versus 196 minutes [range = 68-412], P = .93). Similarly, no difference was found in discharge times between UKA and TKA patients receiving mepivacaine (P = .68) or ropivacaine (P = .51).Conclusion: There was no significant difference in discharge times between anesthetic agents among knee surgery patients. Therefore, either agent may be recommended for same-day discharge. [ABSTRACT FROM AUTHOR]

Background: Indications for unicompartmental knee arthroplasty (UKA) and patello-femoral arthroplasty are expanding. Despite the lower published infection rates for UKA and patello-femoral arthroplasty than total knee arthroplasty, periprosthetic joint infection (PJI) remains a devastating complication and diagnostic thresholds for commonly utilized tests have not been investigated recently. Thus, this study evaluated if diagnostic thresholds for PJI in patients who had a failed partial knee arthroplasty (PKA) align more closely with previously reported thresholds specific to UKA or the 2018 International Consensus Meeting on Musculoskeletal Infection.Methods: We identified 109 knees in 100 patients that underwent PKA with eventual conversion to total knee arthroplasty within a single healthcare system from 2000 to 2021. Synovial fluid nucleated cell count and synovial polymorphonuclear percentage in addition to preoperative serum erythrocyte sedimentation rate, serum C-reactive protein, and serum white blood cell count were compared with Student's t-tests between septic and aseptic cases. Receiver operating characteristic curves and Youden's index were used to assess diagnostic performance and the optimal cutoff point of each test.Results: Synovial nucleated cell count, synovial polymorphonuclear percentage, and serum C-reactive protein demonstrated excellent discrimination for diagnosing PJI with an area under the curve of 0.97 and lower cutoff values than the previously determined UKA specific criteria. Serum erythrocyte sedimentation rateESR demonstrated good ability with an area under the curve of 0.89.Conclusion: Serum and synovial fluid diagnostic thresholds for PJI in PKAs align more closely with the thresholds established by the 2018 International Consensus Meeting as compared to previously proposed thresholds specific to UKA.Level Of Evidence: Level III, retrospective comparative study. [ABSTRACT FROM AUTHOR]

The present study was designed to investigate the role of Taohong Siwu decoction in postoperative recovery from uni- compartmental knee arthroplasty. Eighty gonitis patients undergoing unicompartmental knee arthroplasty were recruited and divided into study and control groups using the random number table method. The control group was treated with analgesics and performed routine functional exercise after the operation as per the recommended standard of care, while those in the study group were additionally treated with Taohong Siwu decoction. The total effectiveness rate for the study group was 95.00% (38/40), which was significantly higher than the control group’s 70.00% (28/40). The study group shows better exercise ability than the control group. While after the operation, the skin temperature in two groups increased and then decreased, the skin temperature in the study group was significantly lower than that in the control group. The Lysholm scores, a measure of knee-specific symptoms, were significantly higher in the study group compared to the control. The adverse reaction rates in the study and control groups were 5.00% and 7.25%, respectively, and the difference was not statistically significant. Taohong Siwu decoction can effectively help relieve pain, reduce the inflammatory cytokine content, elevate the knee joint function, improve the exercise ability, and improve the living ability of gonitis patients undergoing unicompartmental knee arthroplasty. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to determine the changes in patellar heights by comparing standardised pre- and post-operative radiographs in a consecutive series of patients undergoing unicompartmental knee arthroplasty (UKA) with two different approaches and implant designs [fixed bearing (FB) vs mobile bearing (MB)] and to correlate the patellar heights with clinical outcomes. Methods: One hundred and seventy-two UKA patients were prospectively enrolled in the study. 75 patients underwent a minimally invasive FB medial UKA (referred to hereinafter as the 'FB group'); 97 patients were treated with a minimally invasive MB medial UKA. The pre-operative and mid-term (1-year) post-operative patellar heights and clinical scores of these groups of patients were compared using the Insall–Salvati (IS) and Caton–Deschamps (CD) indices and the Oxford Knee Score (OKS). Results: No differences were found between the two groups either with regard to the pre-operative data (p > 0.05) or between pre- and post-operative radiographic scores at the time of each follow-up (p > 0.05). Both the groups reported a significant clinical improvement (p<0.05) as did all the sub-groups (p < 0.05). In the MB group, a higher CD index in females was found at the final follow-up stage (p = 0.043) and a higher pre-operative CD index was found in patients with BMI ≥ 28 (p = 0.040). A statistically negative correlation was found between the pre-operative OKS and pre-operative IS index (rho=− 0.165; p=0.031). Conclusions: Both FB and MB arthroplastys with different surgical approaches did not change the patellar height regardless of the age, gender and BMI at short-medium-term follow-up. The post-operative patellar height seems not to be correlated with the clinical outcomes. A higher pre-operative IS index was correlated with knee pain and function. Level of evidence: Level II—prospective comparative study. Study registration: Researchregistry6433–www.researchregistry.com. [ABSTRACT FROM AUTHOR]

Prosthetic joint infection (PJI) following unicompartmental knee arthroplasty (UKA) is a rare but challenging complication. A paucity of literature exists regarding the management of PJI in UKA. This systematic review aims to assess current treatment patterns in UKA PJI and analyze the failure rates associated with treatment. PubMed, Scopus, and EMBASE were systematically searched for studies that presented cases of PJI following UKA. Data regarding study design, country of publication, index procedure type, diagnosis of PJI, number and incidence of PJI, timing of PJI (acute versus chronic), treatment, and outcomes were recorded. Failure rates in acute and chronic PJI as well as total failure rates were analyzed. Sixteen articles were identified that met inclusion criteria. These included 97 PJI cases (37 acute, 58 chronic, 2 unknown timing); incidence across all studies of 0.80%. The most common treatment for all PJI cases was debridement, antibiotics, and implant retention (DAIR) (40.2%), followed by two-stage conversion to total knee arthroplasty (TKA) (33.0%), one-stage conversion to TKA (23.7%), and one-stage exchange UKA (3.1%). There were no significant differences in failure rates across procedures for acute, chronic or overall PJI management (p > 0.05 for all) This systematic review found relatively few studies reporting on PJI after UKA compared to the available TKA evidence. Further research is warranted to better elucidate the most appropriate treatment of PJI after UKA in both the acute and chronic setting along with risk factors for failure. [ABSTRACT FROM AUTHOR]

This study compares the functional results and survivorship of unicompartmental knee arthroplasty (UKA) and high tibial osteotomy (HTO) with an external fixator for medial compartment osteoarthritis (OA) of the knee. Two cohorts of patients aged less than 60 years who had undergone either a cemented medial mobile-bearing UKA or an HTO with an external fixator were included in the study. The first cohort included patients undergoing a series of 197 consecutive medial UKA procedures (UKA group). The second cohort consisted of 60 consecutive patients undergoing HTO with an external fixator (HTO group). Each patient was assessed based on the Oxford Knee Score (OKS), the Knee Injury and Osteoarthritis Outcome Score (KOOS) and the Subjective International Knee Documentation Committee (IKDC) score/questionnaire. A clinical evaluation was conducted on the day of the surgery (T 0) and at the follow-up visit (T 1) (minimum follow-up time was 60 months). Complications and failures resulting from the surgery were recorded for each patient. Only the age of the patients at the pre-operative time differed significantly between the two groups, with the HTO group being significantly younger (47.7 ± 8.0 versus 55.8 ± 2.2). After the final follow-up visit, all scores improved in both groups (p < 0.05). IKDC and Oxford scores were higher for the UKA group (p < 0.05). In the HTO group, three complications occurred (5%), including two superficial infections and one deep infection. On the other hand, the UKA group reported four complications (2%): three aseptic mobilisations and one infection requiring revision surgery. There was no difference in the complication rate between the two groups (p = 0.208). In young patients (<60 years) with an isolated medial knee OA, both HTO and UKA led to good to excellent clinical results with a low rate of complications at mid-term follow-up; both surgical procedures may be considered in this patient population. Level III. [ABSTRACT FROM AUTHOR]

Background: Mucoid degeneration of the anterior cruciate ligament (ACL) has been shown to cause restricted terminal range of motion and rest pain. If present in a patient undergoing unicompartmental knee arthroplasty, it can deteriorate the final outcome. This study aims to compare functional and clinical outcomes of debulking the mucoid ACL in patients undergoing mobile-bearing unicompartmental knee arthroplasty (UKA). Methods: Patients with mucoid ACL undergoing mobile-bearing UKA at five different centres by five different arthroplasty surgeons were included. They were segregated into two groups matched for all demographic and pre-operative values: group A did not undergo debulking; group B underwent open debulking by a 15-number blade prior to UKA. Patient-related outcome measures, rest pain, clinical outcomes, and subjective patient satisfaction were recorded and compared at 2 years follow-up. Results: A total of 442 patients (226 patients underwent debulking, 216 patients did not undergo debulking) were included. Both groups showed overall improvement after surgery, however, patients who underwent debulking performed better at 2 years follow-up in terms of Knee Society functional score, International Knee Documentation Committee scores, range of motion, rest pain and overall patient satisfaction (p < 0.05) as compared with their counterparts. Conclusions: Debulking of mucoid ACL in patients undergoing unicompartmental knee arthroplasty significantly reduces the rest pain and improves the final range of motion of the knee joint, subsequently improving the overall functional and clinical outcome of the patient and resulting in greater patient satisfaction. [ABSTRACT FROM AUTHOR]

Common complications after unicompartmental knee arthroplasty include infection, aseptic loosening, polyethylene wear, and progression of another compartmental arthritis. Complications caused by extruded cement and loose cement body are very rare, and have not been reported in Korea. This paper reports a case of femoral cartilage injury of the lateral compartment caused by a loose cement body after unicompartmental knee arthroplasty. The loose cement body was removed successfully by arthroscopic surgery. [ABSTRACT FROM AUTHOR]

Purpose: To investigate and compare the survivorship of each surgery in patients with osteoarthritis of knees after performing unicompartmental knee arthroplasty (UKA) on one knee and total knee arthroplasty (TKA) on the other. Materials and Methods: From January 2002 to December 2004, 51 patients with osteoarthritis of knees who underwent UKA on one knee and TKA on the contralateral knee were investigated for the cause of postoperative failure if any, and the survival rate using the Kaplan–Meier method. The Stratified Cox proportional hazard regression for matched-pair analysis was used to verify mutual significance and compare risks. Surgery was performed at intervals of one week during the same hospitalization period. The mean age at surgery was 64.2 years and the mean follow-up period was 12.7 years. Results: Failures following the UKA occurred in 13 cases (25.5%). The causes of the failure included 4 cases of aseptic loosening, 3 cases of dislocation of mobile-bearing, 3 cases of lateral compartment osteoarthritis, 1 case of infection, and 2 cases of unknown cause. Failures following the TKA occurred in 3 cases (5.9%) including 2 cases of polyethylene wear and 1 case of infection. The cumulative survival rate of the UKA was 84.7% at 10 years and 69.6% at 15 years. The cumulative survival rate of the TKA was 97.9% at 10 years and 94.2% at 15 years. As a result of a comparative analysis of the survivorship between the two groups, it was observed that the risk of failure was 3.7 times higher in the UKA than in TKA, and there was a statistically significant difference in the survivorship (p=0.046). Conclusion: When UKA and TKA were performed on both knees in patients with osteoarthritis of knees, the risk of failure of UKA was higher than that of TKA, and the survivorship was also significantly lower. Therefore, it is desirable to select an appropriate surgical method taking into consideration the degree of arthritis, the age of the patient, and other similar factors. [ABSTRACT FROM AUTHOR]

Introduction: The presence of tibiofemoral subluxation (TFS) in patients with unicompartmental arthritis, a potential contraindication to unicompartmental knee arthroplasty (UKA), remains controversial and is not commonly discussed. This study aimed to determine the predictability of postoperative TFS before surgery and the effect of TFS on clinical outcomes after fixed-bearing UKA. Materials and methods: In total, 70 patients with anteromedial osteoarthritis and osteonecrosis of the knee who underwent fixed-bearing UKA from January 2015 to January 2017 were included. The preoperative TFS was assessed using plain anteroposterior and valgus stress radiographs. The patients were classified into three groups as follows: group A (acceptable TFS, n = 36) comprising patients with preoperative TFS less than 5.0 mm; group C (correctable TFS, n = 17) comprising patients with preoperative TFS of more than 5.0 mm but corrected to less than 5.0 mm under valgus stress; and group U (uncorrectable TFS, n = 17) comprising patients with preoperative TFS of more than 5.0 mm under valgus stress. Patient-derived clinical scores were assessed with the 2011 Knee Society Score preoperatively and 2 years postoperatively. The results were compared among the three groups using analysis of variance. Results: Group U showed significantly higher postoperative TFS than groups A and C. Improvements in "symptoms" and "patient satisfaction" scores 2 years after surgery were significantly higher in groups A and C than in group U. Conclusion: Preoperative assessment of TFS under valgus stress could be a predictor of postoperative TFS. Furthermore, preoperative uncorrectable TFS could increase pain and decrease patient satisfaction 2 years after undergoing fixed-bearing UKA. [ABSTRACT FROM AUTHOR]

Background: Five percent to 7% of unicompartmental knee arthroplasties (UKA) require revision for disease progression in untreated compartment(s), most commonly to total knee arthroplasty (TKA). TKA requires removal of bone and usually the anterior cruciate ligament. Preserving the UKA and converting to a bicompartmental arthroplasty (BCA) by performing a second UKA is an alternative.Methods: The results of 73 UKA-BCA patients were compared to 75 patients treated by UKA-TKA revision. Knee Society, Knee Osteoarthritis Outcome Score Joint Replacement, and patient satisfaction scores were collected by a blinded therapist. Patients were asked about their implant preference and recovery. Twenty-two UKA-BCA revision patients had a UKA (6) or TKA (16) in the contralateral knee; thus, a direct comparison of UKA-BCA to both UKA and TKA was possible.Results: Of the UKA-BCA patients, 69 (94%) had excellent or good, 2 (3%) fair, and 2 (3%) poor outcomes with 1 patient requiring revision to TKA. Of patients with a TKA in the contralateral knee, 13 (81%) preferred the UKA-BCA replacement and 3 (19%) preferred the TKA. All patients said the UKA-BCA revision recovery was similar or easier than their initial UKA. Of UKA-TKA revisions, 59 (79%) had excellent or good, 9 (12%) fair, and 7 (9%) poor outcomes. There was 1 wound infection and 1 re-revision in the UKA-BCA group and 1 wound infection and 3 re-revisions in the UKA-TKA group. The Knee Osteoarthritis Outcome Score Joint Replacement and Knee Society Scores were better for UKA-BCA compared to UKA-TKA.Conclusion: UKA-BCA is a successful treatment for disease progression following UKA. [ABSTRACT FROM AUTHOR]

Introduction: Unicompartmental knee arthroplasty (UKA) treats osteoarthritis in one knee compartment, while total knee arthroplasty (TKA) addresses all compartments. The debate focuses on UKA's advantages of quicker recovery and fewer complications versus TKA's lower long-term revision rates, emphasizing the need for thorough outcome evaluations. The aim of the present study is to describe and compare the pain, functional and psychological trajectories during a 6-month postoperative rehabilitation period between total and unicompartmental knee arthroplasties., Materials and Methods: 115 participants who had undergone either TKA or UKA were recruited. Outcome measurements were performed at 1, 4, 12 and 24 weeks post-surgery. Measurements included pain intensity (Visual Analog Scale), range of motion, walking speed (4 m walking test), physical performance (30-s chair stand test), health functioning (Western Ontario and McMaster Universities Osteoarthritis Index), pain catastrophizing (pain catastrophizing scale), fear of movement (Tampa Scale of Kinesiophobia), anxiety and depression (Hospital Anxiety and Depression Scale). A mixed-effects model was used to estimate the influence of type of surgery (either unicompartmental or total knee arthroplasty) to pain, function, and psychological trajectories., Results: Both TKA and UKA groups showed significant improvements across the six-month rehabilitation period except for anxiety symptoms in the TKA group, and fear of movement and depression in the UKA group. Between group analysis revealed that in the acute phase UKA patients showed improved range of motion and TKA patients displayed faster walking speed but higher fear of movement. Overall, the type of surgery does not significantly influence the overall rehabilitation pain, functional and psychological trajectories., Conclusions: Despite differences in the acute phase, there are no differences in pain, functional and psychological trajectories throughout the six-month rehabilitation period. These results should be acknowledged to better inform patients and to improve patient education during the perioperative period., Trial Registration Number: NCT03378440 (2017-12-18), retrospectively registered., Level of Evidence: Level II., Competing Interests: Declarations. Conflict of interest: The authors declare no competing interests., (© 2024. The Author(s).)

Background: Following the implementation of the fast-track protocol in total hip arthroplasty (THA), total knee arthroplasty (TKA), and unicompartmental knee arthroplasty (UKA), the median length of stay (LOS) has been significantly reduced without an increase in readmissions. However, it is unclear if the reduction in LOS is at the expense of an increase in non-home discharge. The aim of this study was to investigate the discharge destination among THA, TKA, and UKA patients., Methods: The prospective multicenter study included 6.856 patients undergoing primary THA, TKA, and UKA in a fast-track setting with an overall median LOS of one day. Outcomes were discharge destination, median LOS in each discharge destination category, and cause of rehabilitation center discharge. Data were gathered using preoperative questionnaires and a review of medical records. Discharge destination and LOS were registered at discharge., Results: We found that 99% of patients had been discharged to their own homes, of which 21% had been discharged to their own homes with home care. There were 1% who were discharged to a rehabilitation facility and 0.1% who were discharged to a nursing home. The THA (1%, 95% confidence interval (CI) 0.7 to 1) and TKA (1%, 95% CI 0.9 to 2) had a significantly higher rate of discharge to a rehabilitation facility compared to UKA (0.1%, 95% CI 0.0 to 0.5)., Conclusion: Despite a short LOS, 99% of patients were discharged to their own homes. Rehabilitation facility discharge was only 1% and was mostly caused by inadequate postoperative mobilization., (Copyright © 2024. Published by Elsevier Inc.)

Background: This study aimed to investigate whether arithmetic hip-knee-ankle angle (aHKA) can be a surrogate for valgus stress radiography (VSR). Furthermore, we investigated the optimal cutoff values for preoperative radiographic parameters, thereby validating the appropriate inclusion criteria for prearthritic/kinematic unicompartmental knee arthroplasty (prearthritic-UKA)., Methods: We retrospectively analyzed 123 patients who underwent medial UKA. We measured the HKA on VSR, termed sHKA. The aHKA was calculated by subtracting the lateral distal femoral angle from the medial proximal tibial angle. Prearthritic-UKA was defined as a postoperative HKA angle within 3° of the aHKA. We divided the patients into the prearthritic-UKA and non-prearthritic-UKA groups. To assess whether the aHKA serves as a surrogate for VSR, Spearman's rank correlations were performed among the radiographic parameters. These radiographic parameters calculated the proper criteria for prearthritic-UKA using receiver operating characteristic (ROC) curve analysis and logistic regression analysis., Results: Overall, 59 patients were classified into the prearthritic-UKA group. The aHKA was larger than the sHKA and exhibited no significant correlation with the sHKA. ROC analysis revealed that the cutoff values of aHKA for detecting overcorrected UKA (i.e., postoperative HKA - aHKA >3°) was -5.0°. Similarly, the cutoff values for detecting undercorrected UKA (i.e., postoperative HKA - aHKA <-3°) were -3°. Logistic regression analysis revealed that the aHKA was significantly associated with prearthritic-UKA., Conclusion: The aHKA was not identified as a surrogate for the sHKA. Comprehensive preoperative radiographic assessment, including both aHKA and VSR, is crucial for optimizing UKA outcomes and minimizing risks of misalignment., 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: This study systematically reviews recent research comparing clinical outcomes and gait function changes in patients undergoing total knee arthroplasty (TKA) versus unicompartmental knee arthroplasty (UKA)., Methods: A systematic search of the Web of Science, PubMed, and Embase databases was conducted, covering publications from January 2013 to September 2024, to identify studies evaluating changes in clinical scores and gait parameters in patients undergoing TKA or UKA. Following stringent selection criteria, data were synthesized from studies involving 171 TKA and 148 UKA patients, focusing on reported gait outcomes and aggregating findings for comprehensive analysis. Direct comparisons between TKA and UKA were performed to assess differences in clinical scores and gait parameters, aiming to elucidate the relative efficacy of each surgical approach and provide robust evidence for clinical decision-making., Results: Ten studies met the inclusion criteria for post-operative gait outcome comparisons between TKA and UKA, with seven studies also addressing clinical scores. One study reported greater improvement in WOMAC scores for the UKA group at 6 months post-operation (P < 0.05), while another found superior EQ-5D scores for UKA patients at 1 year post-surgery (P < 0.05). Conversely, five studies found no significant differences in clinical scores between groups at 1 year (P > 0.05). All ten studies assessed gait parameter recovery, with three studies showing no significant differences at 1 year (P > 0.05). However, seven studies identified superior gait recovery in the UKA group across various parameters, including walking speed, step and stride length, single support time, heel strike force, knee joint range of motion, knee flexion angles during different gait phases, peak knee adduction moment, peak tibial internal rotation moment, gait symmetry, and stride length symmetry (P < 0.05)., Conclusions: The analysis indicates that UKA offers certain advantages in post-operative gait improvements compared to TKA, though these do not translate into significant differences in conventional clinical scoring systems. To enhance the reliability and generalizability of these findings, future studies should involve larger-scale, prospective randomized controlled trials., Competing Interests: Declarations. Ethics approval and consent to participate: Not applicable. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Background: Unicompartmental knee arthroplasty (UKA) is a surgical procedure for managing osteoarthritis of one joint compartment, most commonly the medial side. This systematic review investigates the causes of UKA revision. The outcomes of interest were establishing the revision rate, time to revision, and the most common causes of revision in the long- and midterm follow-up., Methods: This study was conducted according to the 2020 PRISMA statement. In October 2024, the following databases were accessed: PubMed, Web of Science, Google Scholar, and Embase. All the clinical studies investigating the rate and causes of revision in UKA were accessed. Only studies with a minimum of 10 years of follow-up were considered., Results: Data from 56 studies (13,540 patients) were collected. Of them, 65.6% were women. The mean length of the follow-up was 13.1 ± 3.0 years. The mean age of the patients was 65.6 ± 5.6 years, and the mean BMI was 28.5 ± 2.2 kg/m 2 . Revisions were performed in 8.8% (2641 of 30,140) of implanted UKAs. The mean time to revision was 6.5 ± 2.6 (range, 2.5 to 13.0) years., Conclusion: 8.8% (2641 of 30,140) of UKAs were revised at a mean time of 6.5 ± 2.6 years., Level of Evidence: Level IV, systematic review., Competing Interests: Declarations. Ethics approval and consent to participate: This study complies with ethical standards. Consent to publication: Not applicable. Competing interests: The authors declare no competing interests., (© 2024. The Author(s).)

Purpose: To compare the clinical outcomes between opening wedge high tibial osteotomy (OWHTO) and unicompartmental knee arthroplasty (UKA) in patients with Ahlbäck Grade 3 medial compartmental knee osteoarthritis (OA) using a propensity score matching (PSM) analysis., Methods: This retrospective study included all OWHTO and UKA procedures performed between 2016 and 2021 at a single institution. Inclusion criteria were patients diagnosed with medial knee OA, specifically Ahlbäck Grade 3 arthritis. Clinical outcomes were assessed using the Knee Injury and Osteoarthritis Outcome Score (KOOS). Radiographic parameters included hip-knee-ankle (HKA), medial proximal tibial angle (MPTA), lateral distal femoral angle (LDFA) and joint line convergence angle (JLCA). Primary outcomes included improvement in clinical scores at 3, 12 and 24 months post-operatively. Secondary outcomes included radiographic parameters, complication rates and re-intervention rates. One-to-one PSM was conducted based on gender, age and preoperative KOOS pain scores., Results: After evaluating eligibility using PSM, a total of 50 knees in the UKA group and 50 knees in the OWHTO group were included. There was no significant difference between groups in preoperative overall KOOS, but the UKA group had better overall KOOS at 3 months ( p  < 0.001). However, the overall KOOS at 12 and 24 months were superior in the OWHTO group compared to the UKA group (12 months; 84.6 ± 4.9 vs. 86.4 ± 2.9, p  = 0.022, 24 months; 84.9 ± 5.3 vs. 87.0 ± 3.7, p  = 0.022). As for post-operative radiological parameters, HKA, MPTA, LDFA and JLCA were higher in the OWHTO group at 24 months post-operatively. No significant differences were noted in the rates of complication or re-intervention between groups., Conclusions: OWHTO can provide outcomes equal to or better than UKA at 24 months post-operatively in patients with advanced knee OA., Level of Evidence: Level Ⅲ, Prospective designed retrospective comparative study., Competing Interests: Matthieu Ollivier has received consulting fees from Newclip Technics, Arthrex and Stryker. Jean‐Noël Argenson has received consulting fees from Zimmer‐Biomet. The remaining authors declare no conflict of interest., (© 2024 The Author(s). Journal of Experimental Orthopaedics published by John Wiley & Sons Ltd on behalf of European Society of Sports Traumatology, Knee Surgery and Arthroscopy.)

Unicompartmental knee arthroplasty (UKA) offers a more conservative treatment than total knee arthroplasty when osteoarthritis affects only one tibiofemoral knee compartment. Cemented UKA has become the gold standard due to its good functional outcomes and low revision rates. The most common reasons for revision with cemented UKA include aseptic loss, unexplained pain, and radiolucent lines. Cementless UKA, which adds a porous coating of titanium and hydroxyapatite as well as an additional peg on the femoral component, has been shown to reduce the prevalence of radiolucencies compared to cemented UKAs. National registry data have demonstrated comparable functional outcomes and improved revision rates with cementless UKA. This review aims to summarize various advancements in unicompartmental prostheses, and to highlight how the conceptual advantages of the cementless model lead to superior implant survivorship and functional outcomes., 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 The Authors. Published by Elsevier Inc. All rights reserved.)

Unicompartmental knee arthroplasty (UKA) has gained progressive popularity in recent decades, currently comprising approximately 10% of knee arthroplasties in the United States. Nonetheless, UKA has not yet solidified its position as the superior treatment for isolated compartment osteoarthritis, as initially reported implant survivorship was subpar, leading to hesitation in its utilization and stricter patient indications compared to total knee arthroplasty. Patient satisfaction following knee arthroplasty has emerged as a critical metric to gauge patient acceptance and contentment with surgical interventions. Currently, a variety of UKA types exist, differing in bearing design, fixation techniques such as cementless or cemented fixation, and robotic-assisted systems, each with its own merits and drawbacks. Multiple studies have demonstrated the contributions of these innovations to improve clinical outcomes and implant survivorship. However, the abundance of studies has made it challenging to establish a clear overview. This paper provides an overview of the current concepts of UKA, evaluating various aspects of UKA referencing to patient satisfaction and providing a recap of its historical development. Available research demonstrated no significantly universal superior variant of UKA., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Andrew D. Pearle reports a relationship with Smith and Nephew Inc that includes: consulting or advisory. Hendrik A. Zuiderbaan reports a relationship with Smith and Nephew Inc that includes: consulting or advisory. If there are other authors, they 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 The Author(s). Published by Elsevier Inc. All rights reserved.)

The number of outpatient unicompartmental knee arthroplasty (UKA) procedures has increased substantially over the last decade. The ambulatory surgery center (ASC) and hospital outpatient department provide a safe, cost-effective alternative with significant cost savings to the healthcare system. Advancements in technology and perioperative management strategies have expanded the number of eligible patients to optimize outcomes with a focus on safety. Therefore, this review will describe the safety, efficacy, economics, and perioperative protocols for performing UKA in an outpatient setting. Patient selection, risk factors, patient education and expectations, anesthesia, pain management strategies, and outcomes will be discussed., 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 The Author(s). Published by Elsevier Inc. All rights reserved.)

Unicompartmental knee arthroplasty (UKA) continues to increase in popularity as an excellent option for patients with single compartment disease. Robotic-assisted UKA has emerged as an optional tool with hopes for improvement in component placement, limb alignment, and patient outcomes. Furthermore, as patients continue to educate themselves, robotic assistance will become increasingly prevalent. There are now various robotic platforms on the market, each with varying differences, and more published data are emerging on alignment and outcomes. The literature to date largely concludes that robotic-assisted UKA provides more accuracy than manual UKA. Short- to mid-term outcomes may be improved with robotic UKA, but definitive differences in outcomes are uncertain. Survivorship with robotic UKA is non-inferior to reported manual UKA survivorship rates, and more long-term data are needed to fully elucidate this point. Orthopaedic surgeons should weigh these potential advantages against the drawbacks including cost and operative time when making a decision about whether robotic technology is right for their practice., Competing Interests: Declaration of competing interest The author, Rhett MacNeille, declares that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Tsun Law, MD, MBA reports a relationship with Arthrex Inc that includes: consulting or advisory. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Martin Roche, MD reports a relationship with Stryker Orthopaedics that includes: consulting or advisory and speaking and lecture fees. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. The authors declare the following financial interests/personal relationships that may be considered as potential competing interests: James C Chow, MD, reports a relationship with Smith & Nephew Inc. and MicroPort Orthopedics Inc. that includes consulting or advisory, speaking and lecture fees, and travel reimbursement and a relationship with Vomaris Innovations, Inc., Stryker Orthopaedics, and Pfizer Inc. that includes equity or stocks. Martin Roche, MD, reports a relationship with Stryker Orthopaedics that includes consulting or advisory and speaking and lecture fees. Tsun Yee Law, MD, MBA, reports a relationship with Arthrex Inc. that includes consulting or advisory. Rhett MacNeille declares that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this article. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this article., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Unicompartmental knee arthroplasty (UKA) faces significant challenges, including lower survival rates and higher revision rates than total knee arthroplasty (TKA). To address these issues, technological advancements like custom-made implants (CMI), patient-specific alignment (PSA), and computer-assisted systems (CAS) are being explored. These innovations aim to tailor procedures to individual joint morphology, soft tissue balance, and limb alignment, moving away from the traditional "one size fits all" approach. Early studies suggest that CMI may improve survival rates and patient-reported outcomes, though conclusive evidence is lacking. PSA shows potential for restoring pre-surgical alignment; however, its long-term benefits are uncertain. CAS improves implant placement precision and ligament balance; nevertheless, long-term survival data remain inconclusive. Moreover, economic and implementation challenges, such as cost and the need for specialized training, remain underexplored. While promising, further research is needed to fully understand the long-term efficacy and practical application of these technologies in UKA., 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 article., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Lateral unicompartmental knee arthroplasty (LUKA) is a favorable alternative to distal femoral osteotomy and total knee arthroplasty in patients with isolated lateral compartment knee osteoarthritis; however, it only accounts for less than 1 ​% of the total number of knee replacements documented in national joint registries. The anatomy and biomechanics of the lateral knee compartment differ from the medial side, with a greater intrinsic laxity of the lateral collateral ligament complex compared with medial structures. Indications and surgical techniques must be tailored to each unicompartmental replacement to optimize outcomes and mitigate complications. This article will discuss the clinical indications, preoperative evaluation and workup, surgical technique, and outcomes for LUKA., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Gabriel Baron Girgulsky reports administrative support was provided by RedSalud Providencia Clinic. If there are other authors, they 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. Published by Elsevier Inc.)

The anterior cruciate ligament (ACL)-deficient osteoarthritic knee presents a challenging disease entity, which requires careful thought to restore function and enable return to activities. Advancements in technology and surgical techniques have expanded indications for unicompartmental knee arthroplasty (UKA), to inlcude ACL-deficiency in appropriately-selected patients. An improved understanding of the ACL-deficient osteoarthritic knee can aid in clinical and surgeon decision-making to restore knee function. This review will discuss current practice guidelines for the ACL-deficient knee with single-compartment osteoarthritis, including pathoanatomy, indications, contraindications, technical considerations, and clinical outcomes., 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 article., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Medial unicompartmental knee arthroplasty (mUKA) is a highly effective treatment for the management of isolated osteoarthritis in the medial compartment. While favorable long-term survivorship is seen in most series, the long-term rate of revision after mUKAs remains higher than that for total knee arthroplasty. Poor indications and poor surgical technique are often responsible for mUKA failure. Understanding why these complications occur and how to avoid them will optimize clinical outcomes, reduce revision rates, and lead to lower healthcare costs. This review will discuss the five most common causes of mUKA failure including progression of arthritis, aseptic loosening, bearing dislocation, periprosthetic fracture, and polyethylene wear and how to avoid them with proper patient selection and meticulous surgical technique., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Michael Ast reports a relationship with Smith and Nephew Inc that includes: consulting or advisory, speaking and lecture fees, and travel reimbursement. Michael Ast reports a relationship with Stryker that includes: consulting or advisory and speaking and lecture fees. Michael Ast reports a relationship with Ignite Orthomotion that includes: consulting or advisory and travel reimbursement. Daniel Buchalter reports a relationship with Globus Medical that includes: royalties, consulting or advisory, and travel reimbursement. Daniel Buchalter reports a relationship with Alliant Biotech that includes: consulting or advisory and travel reimbursement. Daniel Buchalter reports a relationship with Johnson & Johnson MedTech that includes: consulting or advisory and travel reimbursement. If there are other authors, they 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 The Author(s). Published by Elsevier Inc. All rights reserved.)

Purpose: To evaluate the influence of patellar morphology on functional outcomes and patellofemoral joint alignment after unicompartmental knee arthroplasty (UKA)., Methods: This study retrospectively analyzed the clinical and imaging data of 207 patients with osteoarthritis of the unicompartment of the knee who underwent UKA between September 2020 and April 2023. Patients were divided into three groups according to the Wiberg classification: group W1 (I, n = 47), group W2 (II, n = 117), and group W3 (III, n = 43). Knee function was assessed using the Hospital for Specialty Surgery (HSS) knee score and Feller patellar score, and the incidence of anterior knee pain after surgery was recorded and compared. Imaging parameters such as patellar tilt angle (PTA), lateral patellofemoral angle (LPA) and Insall-Salvati ratio (ISR) were measured to assess patellofemoral joint alignment., Results: The HSS scores of the three groups were not statistically different; the postoperative Feller scores of the group W3 differed significantly from those of the other two groups. The incidence of early postoperative anterior knee pain was higher in the group W3 than in the other two groups. The difference between preoperative PTA, postoperative PTA and preoperative LPA in the group W3 and the other two groups was statistically significant., Conclusion: Patients with Wiberg III patellae exhibited worse patellar scores, as well as more anterior knee pain and patellar tilt postoperatively. This finding highlights the need for individualized treatment to the Wiberg III patella during UKA to enhance surgical outcomes., Competing Interests: Declarations Ethics approval This study was approved by the Ethics Committee of the Affiliated Hospital of Xuzhou Medical University (Ethics Approval Number: XYFY2023-KL350-01). Informed consent All patients signed informed consent to allow further scientific analysis using their anonymised data. Consent for publication All the authors have reviewed and confirmed the accuracy of the whole manuscript. Conflict of interest On behalf of all authors, the corresponding author states that there is no conflict of interest., (© 2024. The Author(s) under exclusive licence to SICOT aisbl.)

Purpose: For younger, more active patients, a cementless unicompartmental knee arthroplasty (UKA) might be more advantageous than cemented fixation. Therefore, this study aimed to compare implant survivorship and patient-reported outcome measures (PROMs) between cementless and hybrid fixation (cemented femur and cementless tibial fixation) in a novel tibial blade-anchored, medial UKA design., Methods: Two surgeon's registries were reviewed for patients who underwent primary cementless or hybrid medial UKA for medial osteoarthritis between 2019 and 2022. Patients were included if implant survivorship and one-year postoperative PROMs (UCLA-activity score, Oxford Knee Score (OKS), Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS-JR), pain (VAS) and satisfaction) were registered. Variables were compared using independent two-sample t-tests or the Chi-square test. Survival rates were determined using the Kaplan-Meier models and compared using the Log-rank test., Results: A total of 132 knees were included (cementless 58.3%; cemented 41.7%; mean follow-up 3.1 ± 0.6 years). Three-year all-cause revision survival rate was significantly superior for the hybrid fixation (hybrid: 100%; cementless 88.5%[84.7%-92.3%], p = 0.026). However, the difference in three-year conversion rate to total knee arthroplasty (TKA) did not reach statistical significance. The one-year postoperative OKS (hybrid: 42.9 ± 4.8; cementless: 39.8 ± 6.4, p = 0.003) and KOOS-JR (hybrid:81.5 ± 13.7; cementless: 74.4 ± 12.1, p = 0.002) were significantly superior for the hybrid fixation. Three-year conversion rate to TKA and two-year postoperative PROMs did not significantly differ., Conclusion: The cementless medial UKA demonstrated a significantly inferior short-term all-cause survival rate and inferior postoperative one-year OKS and KOOS-JR compared to the hybrid medial UKA design with a cemented femoral component., 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.)

Purpose: This retrospective single-center study aimed to investigate incidence and risk factors influencing tibial periprosthetic fractures (TPF) in Oxford unicompartmental knee arthroplasty (UKA), with a specific focus on tibial component positioning and sizing., Methods: A total of 2063 patients with medial UKA using the Oxford® mobile partial knee implant were analyzed between July 2014 and September 2022. Various preoperative and postoperative radiographic parameters determining pre- and postoperative alignment and implant positioning, incidence and characteristics of periprosthetic fractures, and patient demographics were assessed. Statistical analyses, including Mann-Whitney U test and logistic regression, were conducted to identify significant associations and predictors of tibial fractures., Results: Of the 1853 cases that were finally included in the study, 19 (1%) patients experienced TPF. The fracture group presented with a significantly shorter relative mediolateral and posteroanterior distance between the keel and cortex [mediolateral: 23.3% (23.2-24.8%) versus 27.1% (25.7-28.3%), p < 0.001; posteroanterior: 8.4% (6.3-10.3%) versus 10.0% (9.8-10.1%), p = 0.004]. Additionally, an increased posterior tibial slope in pre- and postoperative radiographs [preoperative: 10.4° (8.6-11.1°) versus 7.7° (5.4-10.0°), p < 0.001; postoperative 9.1° ± 3.1° versus 7.5° (5.9-9.0°), p = 0.030] was observed in the fracture group. Furthermore, the use of smaller-sized implants (AA) was associated with higher fracture rates (p < 0.001). Anatomical variants, such as a medial overhanging tibial plateau, were not observed., Conclusions: In UKA, type Oxford TPF are linked to shorter mediolateral and posteroanterior keel-cortex distances, increased pre- and postoperative PTS, and small implant sizes (AA). Fracture lines often extend from the distal keel to the medial tibial cortex. These findings emphasize the importance of precise implant positioning and sizing to minimize fracture risk. Level of evidence Retrospective single-center study, III., Competing Interests: Declarations. Ethics approval and consent to participate: This retrospective, single-center study was approved by the Institutional Review Board and conducted in accordance with the Declaration of Helsinki (no. 22-0990 KB). Consent for publication: The authors affirm that informed consent for publication of all images was given by ethical approval. Competing interests: The authors have no relevant financial or non-financial interests to disclose., (© 2024. The Author(s).)

Background: Periarticular local infiltration analgesia (LIA) has become a widely used method for postoperative pain management after unicompartmental knee arthroplasty (UKA). However, the efficacy of using magnesium sulphate or sodium bicarbonate in LIA cocktails during UKA is not yet clear. The present study aimed to evaluate whether the modified LIA has advantages in pain control and joint function recovery after UKA surgery., Methods: Sixty-one patients who underwent UKA were enrolled and randomly assigned to receive periarticular infiltration of a modified cocktail (comprising ropivacaine, epinephrine, dexamethasone, magnesium sulphate, and sodium bicarbonate) or a conventional cocktail (comprising ropivacaine, epinephrine, dexamethasone, ketorolac, and morphine). The outcomes included the consumption of patient-controlled intravenous analgesia (PCIA) medication used for postoperative analgesia, pain score, early joint functional recovery, discharge time, and complication rates., Results: In the first 12 h after surgery, the conventional cocktail was not superior to the modified cocktail in terms of visual analogue scale (VAS) scores. However, beginning on the second postoperative day, the analgesic effect was significantly prolonged in the modified group, leading to lower VAS scores and better knee functional recovery. Additionally, patients in the modified group required less pain medication via PCIA, both within the first 24 h and cumulatively up to 48 h after surgery. Both groups had similar rates of complications., Conclusions: The present modification of a conventional cocktail significantly prolonged the analgesic effect and reduced pain medication consumption after UKA surgery, which was associated with better functional recovery in the early postoperative days., Trial Registration: Chinese Clinical Trial Registry, ChiCTR2200060500. 21 March 2023., Competing Interests: Declarations Ethics approval and consent to participate Ethics approval was obtained from the ethics committee of our hospital and informed consent was provided by all participants. Approval number: 008-IH01. The study was registered in the Chinese Clinical Trials Registry with the registration number: ChiCTR2200060500. 21 March 2023. Consent for publication Not applicable. Competing interests The authors declare no competing interests., (© 2024. The Author(s).)

Background: Bilateral unicompartmental knee arthroplasty (bUKA) done on the same day (simultaneous) (sbUKA) has been shown to be safe and cost-effective in hospital settings. Given the popularity and increased use of ambulatory surgery centers (ASC), the purpose of this study was to compare safety and patient-reported outcome measures (PROMs) of sbUKA done at the hospital versus ASC., Methods: Consecutive primary sbUKAs over 5 years done by a single surgeon were retrospectively collected. Surgeries were done at a hospital or ASC. Baseline demographics, intraoperative and postoperative results, and Knee injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS-jr) patient-reported outcome scores were collected between the two groups. Groups were compared utilizing Student's unpaired t-tests for continuous variables and χ2 tests for categorical variables., Results: Of 146 patients (292 knees) who underwent sbUKA, 90 were done at a hospital, and 56 were done at an ASC. Length of stay was longer (53 versus five hours, P < 0.001), and operative time was longer (82 versus 68 minutes, P < 0.001) in the hospital group. In the hospital group, 11 (12.2%) were discharged to subacute rehab (SAR) and nine (10%) returned to the emergency department (ED) within 120 days compared to zero patients in the ASC group (P = 0.007 and 0.015, respectively). There was no significant difference in the final range of motion nor KOOS-jr scores postoperatively., Conclusion: Outpatient SbUKA can safely be performed in selected patients. There is no difference in functional outcomes between outpatient and inpatient SbUKA., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Objective: To analyze the accuracy of prosthesis size selection in Naton robot-assisted medial unicondyle knee arthroplasty by comparing the actual prosthesis size used during operation and the preoperative planning., Methods: The clinical data of 100 patients (110 knees) who underwent Naton robot-assisted medial unicondylar knee arthroplasty between June 2023 and July 2024 was retrospectively analyzed, including 47 knees on left side and 63 knees on right side. There were 37 males (40 knees) and 63 females (70 knees) with a mean age of 65.4 years (range, 59-71 years). Body mass index was 22.2-28.6 kg/m 2 (mean, 25.4 kg/m 2 ). The disease duration ranged from 1 to 8 years (mean, 3.4 years). Preoperative planning was performed by Naton robotic surgical system based on lower limb CT data. The final prosthesis size after osteotomy was recorded and compared with the preoperative plan to analyse whether it was consistent with the preoperative plan, as well as the situation of knee flexion and extension gaps (<0.5 mm, >2.0 mm) corresponding to the different models of prostheses., Results: During operation, 5 patients (5 knees) were treated with traditional UKA due to mechanical arm failure, software obstacles, significant bone amputation bias, or loose reference frame, and were excluded from the final analysis. The remaining 95 patients (105 knees) successfully received Naton robot-assisted surgery, and no related complications occurred. The prosthesis size was consistent with the preoperative plan in 101 knees (96.2%) on the femur side, 100 knees (95.2%) on the tibia side, and 97 knees (92.4%) on both femur and tibia sides. The prosthesis size was inconsistent in 3 cases (2.86%) on the femur side alone, 4 cases (3.81%) on the tibial side alone, and 1 case (0.95%) on both femur and tibial sides. Among the prostheses with different models, the flexion and extension gaps were less than 0.5 mm in 3 knees, the flexion gap was less than 0.5 mm and the extension gap was more than 2.0 mm in 3 knees, and the flexion gap was more than 2.0 mm and the extension gap was less than 0.5 mm in 2 knees., Conclusion: The accuracy of prosthesis size selection for Naton robot-assisted medial unicondylar knee arthroplasty is relatively high.