Citations

Background: Unicompartmental knee arthroplasty (UKA) is an alternative to total knee arthroplasty for isolated compartment osteoarthritis; however, concerns persist regarding its long-term durability. The purpose of this study was to evaluate revision-free survivorship, risk factors for revision, and clinical outcomes in a large consecutive series of contemporary UKAs. Methods: We retrospectively reviewed consecutive primary UKAs performed from 2000 to 2021 at a single tertiary academic center. Revision-free survivorship was estimated using a Kaplan-Meier analysis, and risk factors for revision were assessed using Cox proportional hazards modeling. Clinical outcomes were assessed using the Knee Society Score (KSS). Results: A total of 2,234 UKAs were included. Fixed-bearing implants were used in 78% of UKAs. Technology assistance was used in 59% of UKAs (fluoroscopy, 43%; robotic assistance, 15%; computer navigation, 1%). The mean patient age was 65 years, the mean body mass index was 31 kg/m 2 , and 49% of UKAs were performed in female patients. Patient race was White in 97% of UKAs, and patient ethnicity was not Hispanic or Latino in 94%. Revision-free survivorship was 92% at 10 years and 85% at 15 years. Overall, 118 UKAs were revised, most commonly through conversion to total knee arthroplasty (97%). The most frequent indications for revision were progression of osteoarthritis in an adjacent compartment (41%), aseptic loosening (23%), unexplained pain (9%), and hardware failure (9%). Factors associated with a lower risk of revision in the univariable analysis included technology assistance (hazard ratio [HR], 0.4; p < 0.01) and high surgeon volume (HR, 0.5; p < 0.01). Mobile-bearing design (HR, 1.9; p < 0.01) was associated with an increased risk of revision in the univariable analysis. The mean KSS improved from 47 preoperatively to 75 at 5 years postoperatively (p < 0.001). Conclusions: In this large consecutive series, UKA demonstrated excellent long-term survivorship, with an approximately 1% annual risk of revision through 15 years. Technology assistance, a fixed-bearing implant design, and high surgeon volume were each associated with a lower risk of revision, underscoring the importance of operative technique and implant selection in achieving durable outcomes. Level of Evidence: Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

Background The management of osteochondral lesions of the talus (OLT) is challenging, with 2 main options being conservative and surgical management. Orthobiologic therapies come to bridge the gap between these 2 options; however, inconsistencies in indication, composition, and heterogeneous evidence limit clinical decision-making. To address these challenges, 3 International Congress Meetings on Cartilage Repair of the Ankle were convened in Pittsburgh, USA (2017), Dublin, Ireland (2019), and New York, USA (2025) to establish agreement on the role of conservative management and injectable orthobiologic strategies in the treatment of OLT. Methods Seventy-five multidisciplinary experts from over 25 countries and 1 territory participated in a structured Delphi-based consensus process. Blinded surveys, structured questionnaires, and in-person discussions were used to develop and refine statements, supported by literature review and graded evidence (A1–E). Consensus strength was defined as consensus (51%-74%), strong consensus (75%-99%), or unanimous (100%) Results In total, 29 consensus statements were achieved across the 3 meetings. Strong agreement was reached regarding indications and expected outcomes of conservative management, including the role of immobilization and appropriate timing for surgical intervention. Orthobiologic injections, including platelet-rich plasma, concentrated bone marrow aspirate, and hyaluronic acid, were considered appropriate in select patients with persistent symptoms, although no superiority was demonstrated among formulations, preparation methods, or injection strategies. When used as adjuncts to surgical procedures, orthobiologics may improve radiological outcomes, with limited evidence for improvement in clinical outcomes. Technical considerations, including preferred harvest sites and a lack of standardized preparation protocols, were identified, along with key principles for patient counseling Conclusion These international consensus statements establish a standardized framework for the conservative management and use of injectable orthobiologic therapies in OLT. By clarifying indications, technical considerations, and current limitations, this work aims to improve consistency in clinical practice, guide treatment decision-making, and inform future research.

Background: Greater trochanteric (GT) fractures after total hip arthroplasty (THA) are typically managed nonoperatively. However, outcome data for patient counseling remain limited. We evaluated the nonoperative results, focusing on fracture union rates and the presence of persistent limp in relation with fracture location, displacement magnitude, and direction. Methods: We retrospectively reviewed 82 postoperative GT fractures not associated with trochanteric osteolysis following primary THA performed between 1984 and 2020. The mean follow-up was 9 years. Fracture location was classified relative to the contralateral lesser trochanter as tip, waist, or base. Initial displacement, migration, final displacement, and bony union were assessed radiographically. Clinical outcomes included the presence of a persistent limp and Harris Hip Score. Multivariable analyses were performed to identify factors associated with nonunion and limp. Results: Fractures were classified as tip (n = 32), waist (n = 29), or base (n = 21). The mean initial displacement was 8.9 mm, with 43% displaced >10 mm. Initial displacement was significantly lower in base fractures (4.8 mm) compared with tip (10.1 mm) or waist (10.8 mm) fractures (p < 0.05). The mean final displacement was 14.6 mm. 45% of fractures achieved complete bony union, and 38% of patients demonstrated a persistent limp. In multivariable analysis, greater final displacement (>12 mm), and tip and waist fractures were independently associated with nonunion. Posterior fracture displacement was significantly associated with persistent limp. Conclusions: Outcomes following nonoperative management of GT fractures after THA depend on fracture morphology and displacement characteristics. Tip and waist fractures and fractures with final displacement >12 mm have a higher risk of nonunion, whereas posterior and superior displacement is associated with persistent limp. Greater than 20 mm of displacement is associated with both limp and nonunion. These findings may assist surgeons in counseling patients and in identifying fracture patterns at higher risk for adverse outcomes of nonoperative management. Level of Evidence: Level III (Prognostic Study). See Instructions for Authors for a complete description of levels of evidence.

Background: Contemporary rotating-hinge total knee arthroplasties (RH-TKAs) have shown reasonable short-term survivorship in smaller series, but concerns remain regarding risks of aseptic and septic failure. The purpose of this study was to assess outcomes of contemporary RH-TKAs in one of the largest series to date. Methods: We retrospectively identified 575 RH-TKAs (60% used for aseptic etiologies and 40% used during reimplantation in 2-stage treatment of periprosthetic joint infection [PJI]) from 2002 to 2021 at a single institution. The mean age was 67 years, 58% were female, and the mean body mass index was 33 kg/m 2 . Sixty-five percent had Anderson Orthopaedic Research Institute (AORI) type-2B or 3 bone loss. Kaplan-Meier survivorship analyses were performed. The mean follow-up was 6 years (range, 2 to 19 years). Results: Survivorship free from any revision was 76% at 5 years and 64% at 10 years. The most common revision indications were PJI (54%) and aseptic loosening (20%). RH-TKA used in the primary setting showed better survivorship compared with RH-TKA used during reimplantation after PJI (79% versus 60% at 10 years). Survivorship free from revision for aseptic loosening was 96% at 5 years and 90% at 10 years. Survivorship free from revision for PJI was 84% at 5 years and 81% at 10 years. Survivorship free from revision for PJI was even lower for RH-TKAs used during reimplantation, 74% at 5 years and 73% at 10 years. RH-TKA used during reimplantation in the treatment of PJI was associated with an increased risk of any revision (HR = 2, p < 0.001). Radiographic analysis of 425 knees that were not revised and had radiographs available for review showed that 6% of femoral components and 8% of tibial components had evidence of loosening at the time of final follow-up. The mean Knee Society Score improved from 33 to 69 at 2 years (p < 0.001). Conclusions: The 10-year survivorship free from aseptic loosening was 90% in this large series of RH-TKAs. This represents one of the best survivorships free from aseptic loosening published to date. Knees with prior PJI had markedly poorer survivorship than knees treated for aseptic etiologies, with double the risk of revision. Level of Evidence: Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

Aims Total knee arthroplasty (TKA) for end-stage osteonecrosis has historically been associated with concerns regarding aseptic loosening, and long-term data are limited. The purpose of this study was to update and expand our previous series with long-term follow-up, with specific emphasis on implant survivorship, risk factors for failure, complications, and clinical outcomes in a consecutive cohort of TKAs performed for primary and secondary osteonecrosis. Methods We retrospectively identified 295 consecutive TKAs in 266 patients for osteonecrosis performed at a single tertiary care academic institution from January 2002 to July 2022. Of these, 207 TKAs (70%) were performed for primary osteonecrosis, and 88 (30%) for secondary osteonecrosis. The predominant cause of secondary osteonecrosis was steroid use (59%; n = 52), followed by post-traumatic (25%; n = 22), radiation-induced (9%; n = 8), and alcohol-induced (7%; n = 6) osteonecrosis. Implant survivorship was analyzed as a time-to-event outcome using Kaplan-Meier estimation. The mean age was 61 years (18 to 93), with 67% being female (n = 197). The mean follow-up was nine years (2 to 20). Results The 15-year survivorship free of any revision for the entire cohort was 92% (95% CI 87 to 97), with similar rates between primary and secondary osteonecrosis (92% (95% CI 87 to 98) vs 93% (95% CI 87 to 100), respectively; p = 0.459). Varus-valgus constraint implant designs (HR 10.8 (95% CI 2.7 to 43.4); p < 0.001) and tibial stem use (HR 12.0 (95% CI 4.1 to 35.1); p < 0.001) were associated with an increased risk of any revision. The 15-year survivorship free of aseptic loosening was 97% (95% CI 93 to 100) for the entire cohort. Age under 65 years (HR 2.7 (95% CI 1.4 to 5.4); p = 0.005) and secondary osteonecrosis (HR 1.9 (95% CI 1.0 to 3.4); p = 0.044) were associated with an increased risk of any reoperation at 15 years. Conclusion TKA is a durable and reliable option for primary osteonecrosis at long-term follow-up. However, TKAs performed for secondary osteonecrosis carry a higher reoperation risk. Cite this article: Bone Joint J 2026;108-B(4):455–462.

Aims Data on revision of unicompartmental knee arthroplasty (UKA) to total knee arthroplasty (TKA) are limited by low patient numbers and short-term follow-up. This study evaluated the mid-term outcomes of revision of UKA to TKA focusing on implant survival, radiological results, and clinical outcomes in a large series. Methods We identified 235 revisions of UKA to TKA performed between 1995 and 2022 utilizing our institutional total joint registry. The mean age was 65 years (SD 10), mean BMI was 32 kg/m 2 (SD 6), and 50% were female (n = 118). The most common indications for revision were aseptic loosening (37%; n = 83), progression of arthritis in adjacent compartments (35%; n = 81), and unexplained pain (20%; n = 47). The mean time from UKA to revision to a TKA was four years (26 days to 15 years). Posterior-stabilized constructs were used in 78% of the revisions (n = 184), varus-valgus constrained implants in 14% (n = 33), and cruciate-retaining implants in 7% (n = 16). Metaphyseal fixation devices were used in 8% of cases (n = 18) and augments in 31% (n = 73). Kaplan-Meier implant survival analyses were performed, radiographs reviewed, and clinical outcomes were measured with Knee Society Scores (KSSs). Mean follow-up was eight years (2 to 25). Results The five-year survival free of any re-revision was 93% (95% CI 89 to 97). There were 17 further re-revisions with femoral and/or tibial aseptic loosening (n = 7), periprosthetic joint infection (n = 4), and stiffness (n = 2) being the most common indications. The five-year survival free of any reoperation was 87% (95% CI 83 to 92). Stiffness (n = 7) and unresurfaced patellar clunk/crepitus (n = 4) were the most common indications for reoperations without implant exchange. There were 25 nonoperative postoperative complications, most commonly stiffness (n = 5), flexion instability (n = 4), and haematoma (n = 4). No unrevised TKAs showed signs of radiological loosening. KSS function score improved from 54 (SD 18) to 69 (SD 26; p = 0.003). Conclusion In this large series of 235 revisions of UKA to TKA, the five-year survival of the TKAs free of re-revision was good. Our data suggest that the implant survival and clinical outcomes were inferior to primary TKA. Tibial component aseptic loosening was the most common reason for re-revision. Cite this article: Bone Joint J 2025;107-B(12):1281–1287.

Aims Arthrofibrosis affects a notable percentage of patients after total knee arthroplasty (TKA). Elevated serum mast cell tryptase (SMCT) levels have been linked to fibrosis, suggesting that SMCT could serve as a biomarker for arthrofibrosis. As such, the aims of this study were to assess SMCT levels in TKA patients, and their possible association with arthrofibrosis and clinical outcomes in a prospective clinical trial. Methods We conducted a prospective study involving 219 patients undergoing primary TKA at a single academic medical centre between January 2018 and December 2022. SMCT levels were measured preoperatively, immediately postoperatively, and at six weeks, three months, and one year postoperatively. Secondary outcomes included revision rates, complications, and Knee Society Scores (KSSs). Allergic and inflammatory conditions were assessed for their influence on SMCT levels. Results At one year postoperatively, eight patients had developed arthrofibrosis (4%), and three (1.5%) had undergone manipulation under anaesthesia. The mean preoperative SMCT level was 5.6 µg/L (SD 3.4), which decreased significantly to 4.1 µg/L (SD 2.7) immediately postoperatively (p < 0.001). At six weeks the mean SMCT level was 6.4 µg/l (SD 4.1), and was 6.1 µg/l at both three months (SD 4.1) and one year (SD 4.0). Elevated preoperative SMCT levels were not significantly associated with the risk of arthrofibrosis development (OR 3; p = 0.370), nor were immediate postoperative levels (OR 2; p = 0.754) or those at six weeks (OR 1; p = 0.989). Of note, elevated SMCT levels at three months (OR 5; 95% CI 0.4 to 64; p = 0.191) and one year (OR 13; 95% CI 1 to 232; p = 0.077) trended toward an increased risk of arthrofibrosis development, without reaching significance. Conclusion In patients undergoing TKA, with the numbers included in this study, there was no significant difference in SMCT levels between patients who did and did not develop arthrofibrosis at any timepoint. However, there was a trend towards elevated SMCT levels at three months and one year in those who developed arthrofibrosis, which merits further study. Cite this article: Bone Joint Res 2025;14(11):1045–1052.

AimsThe aim of this study was to compare the early clinical outcomes of robotically-assisted total knee arthroplasty (RA-TKA) and manual total knee arthroplasty (M-TKA), using daily remote patient monitoring.MethodsWe prospectively enrolled and compared patients who underwent 95 RA-TKAs with those who underwent 114 M-TKAs. All patients used an activity monitor and a patient engagement platform for two weeks preoperatively and 90 days postoperatively to collect daily visual analogue scale (VAS) pain scores, opioid consumption (in morphine milligram equivalents (MMEs)), step counts, weekly Oxford Knee Scores (OKSs), and monthly Forgotten Joint Scores (FJS). There were no significant differences between groups in sex or BMI. Patients in the RA-TKA group were significantly younger (mean age 63 vs 65 years; p = 0.006). Independent-samples t-tests, chi-squared tests, and Fisher’s exact tests were used for statistical analysis.ResultsRA-TKA led to significantly decreased pain (mean VAS 3.6 vs 4.2; p = 0.011) and significantly reduced opioid consumption in the first seven days postoperatively (a mean of 10 less MMEs per day; p < 0.001) compared with M-TKA. The RA-TKA group stopped taking opioids six days sooner (mean 24 days vs 30 days; p = 0.041). There were no significant differences in the number of days before stopping the use of walking aids (mean 31 days vs 35 days; p = 0.091). Patients in the RA-TKA group had significantly increased OKSs for the first five weeks (p = 0.013). There were no significant differences in the FJSs at all times or in OKSs beyond five weeks. There were no significant differences in the operating times (p = 0.405), step counts (p = 0.642), or complications (p = 0.222) between the groups.ConclusionThe use of robotic assistance in TKA led to significant improvements in pain, opioid consumption, and OKSs compared with manual instrumentation in the early recovery after primary TKA.Cite this article: Bone Joint J 2025;107-B(10):1054–1063.

Background: Surgeons often recommend weight loss for patients with obesity before total knee arthroplasty (TKA). However, it is unknown whether preoperative weight loss affects outcomes. The goals of this study were to determine how many patients with obesity lost weight before TKA, to identify weight loss predictors, and to evaluate if preoperative weight loss affected postoperative outcomes. Methods: Among 23,726 primary TKAs performed between 2002 and 2019, we identified 3,665 patients who had a body mass index (BMI) of ≥30 kg/m 2 measured 1 to 24 months before surgery and had a weight measured at surgery. The mean patient age was 68 years, and 59% of patients were female. The mean patient BMI was 36 kg/m 2 . Univariable linear regressions evaluated weight loss predictors. Univariable and multivariable logistic regressions and Cox proportional hazards models evaluated the impact of preoperative weight change on discharge, operative time, periprosthetic joint infections (PJIs), complications, revisions, and reoperations. The mean follow-up was 6 years. Results: Overall, 20% of patients gained ≥5 pounds (1 pound = 0.45 kg), 39% maintained weight, 17% lost 5 to <10 pounds, 15% lost 10 to <20 pounds, and 9% lost ≥20 pounds before TKA. Male patients lost slightly more weight (−4.6 pounds) than female patients (−4.3 pounds) (p = 0.05). In univariable analyses, gaining >5 pounds was associated with increased odds of extended hospital length of stay (odds ratio [OR], 1.4; p = 0.01) and risk of complications (hazard ratio [HR], 1.7; p < 0.01). Losing 10 to <20 pounds was associated with increased risks of revision (HR, 2.0; p = 0.01), PJI (HR, 3.1; p < 0.01), and complications (HR, 1.6; p = 0.03). In multivariable analyses, compared with maintaining weight, losing 10 to <20 pounds was associated with an increased risk of PJI (HR, 2.6; p = 0.01), whereas gaining >5 pounds was associated with an increased risk of complications (HR, 1.5; p = 0.03). Conclusions: Few patients with obesity lost substantial weight before primary TKA, and reaching common preoperative weight loss goals was not associated with improved outcomes. Although a healthy weight is important for general health, weight loss before TKA may not be sufficient to improve postoperative outcomes for most patients with obesity. Level of Evidence: Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Aims The use of jumbo femoral heads, defined as those with a diameter of ≥ 40 mm, in primary total hip arthroplasty (THA) has gained popularity, to mitigate dislocation. The aim of this study was to determine the risk of dislocation, implant survival, and clinical outcomes of a large cohort of primary THAs with jumbo femoral heads. Methods We conducted a retrospective analysis of 1,828 primary THAs with jumbo femoral heads, which were undertaken for osteoarthritis, in 1,578 patients between January 2000 and December 2022, at a single academic medical centre. The femoral head diameter was 40 mm in 1,584 THAs (87%) and 44 mm in 244 THAs (13%). The outer diameter of the acetabular component ranged from 52 mm to 72 mm in those with 40 mm heads, and from 54 mm to 78 mm in those with 44 mm heads. The types of bearing included ceramic-on-highly cross-linked polyethylene (1,229 THAs; 67%) and metal-on-polyethylene (599 THAs; 33%). Elevated liners were used in 472 THAs (26%) and 1,083 (59%) were lateralized. The most common operative approach was posterior (1,388 THAs; 76%). Outcomes of interest included the rate of dislocation, revision for dislocation, any revision, any reoperation, and the Harris Hip Score (HHS). The mean age of the patients at the time of THA was 64 years (8 to 94); 1,477 (81%) were male, and their mean BMI was 28 kg/m² (5 to 55). The mean follow-up was six years (2 to 14). Results The ten-year survival free of dislocation was 97% (95% CI 96 to 98; 97% for 40 mm heads (95% CI 95 to 98) and 99% for 44 mm heads (95% CI 97 to 100) (hazard ratio 3 (95% CI 1 to 14); p = 0.106)). The ten-year survival free of revision for dislocation was 99.6% (95% CI 99 to 100) (99.5% for 40 mm heads (95% CI 98 to 100) and 100% for 44 mm heads (p = 0.546)). The ten-year survival free of any revision and any reoperation was 95% (95% CI 94 to 97) and 93% (95% CI 91 to 95), respectively. There were no significant differences in survival free of any revision (p = 0.746) or any reoperation (p = 0.762) between the two groups. Conclusion In this large single-centre study of the use of jumbo femoral heads in primary THAs, the ten-year survival free of dislocation was 97%, with extremely few revisions for dislocation. These results highlight the potential for jumbo femoral heads to reduce the risk of dislocation and enhance implant longevity without compromising other clinical outcomes. Cite this article: Bone Joint J 2025;107-B(7):698–706.