Ten-year follow-up of stemmed hemiarthroplasty for acute proximal humeral fractures

Aims There is no consensus on the treatment of proximal humeral fractures. Hemiarthroplasty has been widely used in patients when non-surgical treatment is not possible. There is, despite extensive use, limited information about the long-term outcome. Our primary aim was to report ten-year patient-reported outcome after hemiarthroplasty for acute proximal humeral fractures. The secondary aims were to report the cumulative revision rate and risk factors for an inferior patient-reported outcome. Methods We obtained data on 1,371 hemiarthroplasties for acute proximal humeral fractures from the Danish Shoulder Arthroplasty Registry between 2006 and 2010. Of these, 549 patients (40%) were alive and available for follow-up. The Western Ontario Osteoarthritis of the Shoulder (WOOS) questionnaire was sent to all patients at nine to 14 years after primary surgery. Revision rates were calculated using the Kaplan-Meier method. Risk factors for an inferior WOOS score were analyzed using the linear regression model. Results Mean age at surgery was 67 years (24 to 90) and 445 (81%) patients were female. A complete questionnaire was returned by 364 (66%) patients at a mean follow-up of 10.6 years (8.8 to 13.8). Mean WOOS score was 64 (4.3 to 100.0). There was no correlation between WOOS scores and age, sex, arthroplasty brand, or year of surgery. The 14-year cumulative revision rate was 5.7% (confidence interval 4.1 to 7.2). Patients aged younger than 55 years and patients aged between 55 to 74 years had 5.6-times (2.0 to 9.3) and 4.3-times (1.9 to 16.7) higher risk of revision than patients aged older than 75 years, respectively. Conclusion This is the largest long-term follow-up study of acute proximal humeral fractures treated with hemiarthroplasty. We found a low revision rate and an acceptable ten-year patient-reported outcome. The patient-reported outcome should be interpreted with caution as we have no information about the patients who died or did not return a complete WOOS score. The long-term outcome and revision rate suggest that hemiarthroplasty offers a valid alternative when non-surgical treatment is not possible. Cite this article: Bone Joint J 2021;103-B(6):1063–1069.

The effect of body mass index on the outcomes of cementless medial mobile-bearing unicompartmental knee replacements

Purpose Given an increasingly overweight population, unicompartmental knee replacements (UKRs) are being performed in patients with higher body mass indices (BMIs). There are concerns that cemented fixation will not last. Cementless fixation may offer a solution, but the long term results in different BMI groups has not been assessed. We studied the effect of BMI on the outcomes of cementless UKRs. Methods A prospective cohort of 1000 medial cementless mobile-bearing UKR with a mean follow up of 6.6 years (SD 2.7) were analysed. UKRs were categorised into four BMI groups: (1) ≥ 18.5 to < 25 kg/m2 (normal), (2) 25 to < 30 kg/m2 (overweight), (3) 30 to < 35 kg/m2 (obese class 1) and (4) ≥ 35 kg/m2 (obese class 2). Implant survival was assessed using endpoints reoperation and revision. Functional outcomes were assessed. Results Ten-year cumulative revision rate for the normal (n = 186), overweight (n = 434), obese class 1 (n = 213) and obese class 2 (n = 127) groups were 1.8% (CI 0.4–7.4), 2.6% (CI 1.3–5.1), 3.8% (CI 1.5–9.2) and 1.7% (CI 0.4–6.8) with no significant differences between groups (p = 0.79). The 10-year cumulative reoperation rates were 2.7% (CI 0.8–8.2), 3.8% (CI 2.2–6.6), 5.2% (CI 2.5–10.7) and 1.7% (CI 0.4–6.8) with no significant differences between groups (p = 0.44). The 10-year median Oxford Knee Score were 43.0, 46.0, 44.0 and 38.0 respectively. Conclusion Cementless mobile-bearing UKR has low 10-year reoperation and revision rates across in all BMI groups, and there are no significant differences between the groups. Although higher BMI groups had slightly worse functional outcomes, the improvement in function compared to preoperatively tended to be better. This study suggests that BMI should not be considered a contraindication for the cementless mobile-bearing UKR.

The effect of age on the outcomes of cementless mobile bearing unicompartmental knee replacements

Purpose Unicompartmental Knee Replacements (UKR) are being performed in patients with increasing demands and life expectancies with surgical concerns that cemented fixation will not last. Cementless fixation may offer a solution, but the results in different age groups have not been assessed. The effect of age at surgery on the outcomes of cementless UKRs was investigated. Methods A prospective cohort of 1000 medial cementless mobile bearing UKR were analysed. Patients were categorised into four age groups (< 55, 55 to < 65, 65 to < 75 and ≥ 75 years). Implant survival was assessed using endpoints reoperation, revision and major revision requiring revision knee replacement components. Functional outcomes were assessed. Results 10 year cumulative revision rate for the < 55, 55 to < 65, 65 to < 75 and ≥ 75 groups were 2.1% (CI 0.6–6.1), 1.8% (CI 0.6–5.3), 3.2% (CI 1.5–6.5) and 4.1% (1.7–9.6) with no differences between groups (p = 0.52). Two of the 22 revisions were considered major. The 10 year cumulative reoperation rates were 4.5% (CI 2.0–10.0), 3.0% (CI 1.3–6.5), 3.8% (CI 2.0–7.1) and 4.1% (CI 1.7–9.6) with no differences between groups (p = 0.81). The 10 year median Oxford Knee Scores were 42.5, 46.5, 45 and 42.5, respectively. The 10 year median Objective American Knee Society Scores were 95 for all age groups. Conclusion The cementless mobile bearing UKR has low reoperation and revision rates and similar functional outcomes in all age groups. Cementless UKR should be used in all age groups and age should not be considered a contraindication. Level of evidence III.

The three-year survivorship of robotically assisted versus non-robotically assisted unicompartmental knee arthroplasty

Aim There has been a significant reduction in unicompartmental knee arthroplasty (UKA) procedures recorded in Australia. This follows several national joint registry studies documenting high UKA revision rates when compared to total knee arthroplasty (TKA). With the recent introduction of robotically assisted UKA procedures, it is hoped that outcomes improve. This study examines the cumulative revision rate of UKA procedures implanted with a newly introduced robotic system and compares the results to one of the best performing non-robotically assisted UKA prostheses, as well as all other non-robotically assisted UKA procedures. Methods Data from the Australian Orthopaedic Association National Joint Arthroplasty Registry (AOANJRR) for all UKA procedures performed for osteoarthritis (OA) between 2015 and 2018 were analyzed. Procedures using the Restoris MCK UKA prosthesis implanted using the Mako Robotic-Arm Assisted System were compared to non-robotically assisted Zimmer Unicompartmental High Flex Knee System (ZUK) UKA, a commonly used UKA with previously reported good outcomes and to all other non-robotically assisted UKA procedures using Cox proportional hazard ratios (HRs) and Kaplan-Meier estimates of survivorship. Results There was no difference in the rate of revision when the Mako-assisted Restoris UKA was compared to the ZUK UKA (zero to nine months: HR 1.14 (95% CI 0.71 to 1.83; p = 0.596) vs nine months and over: HR 0.66 (95% CI 0.42 to 1.02; p = 0.058)). The Mako-assisted Restoris had a significantly lower overall revision rate compared to the other types of non-robotically assisted procedures (HR 0.58 (95% confidence interval (CI) 0.42 to 0.79); p < 0.001) at three years. Revision for aseptic loosening was lower for the Mako-assisted Restoris compared to all other non-robotically assisted UKA (entire period: HR 0.34 (95% CI 0.17 to 0.65); p = 0.001), but not the ZUK prosthesis. However, revision for infection was significantly higher for the Mako-assisted Restoris compared to the two comparator groups (ZUK: entire period: HR 2.91 (95% CI 1.22 to 6.98; p = 0.016); other non-robotically assisted UKA: zero to three months: HR 5.57 (95% CI 2.17 to 14.31; p < 0.001)). Conclusion This study reports comparable short-term survivorship for the Mako robotically assisted UKA compared to the ZUK UKA and improved survivorship compared to all other non-robotic UKA. These results justify the continued use and investigation of this procedure. However, the higher rate of early revision for infection for robotically assisted UKA requires further investigation. Cite this article: Bone Joint J 2020;102-B(3):319–328

Minimally Invasive Inlay Prosthesis Unicompartmental Knee Arthroplasty for the Treatment of Unicompartmental Osteoarthritis: A Prospective Observational Cohort Study with Minimum 2-Year Outcomes and up to 14-Year Survival

There are limited medium-term outcome data available for the Repicci II device in unicompartmental knee arthroplasty (UKA). The purpose of this study was to report the medium-term (minimum 2 years) patient-reported outcomes and long-term (up to 14 years) procedure survival in a consecutive series of patients undergoing an inlay prosthesis UKA (Repicci II) at an independent orthopaedic clinic. Patients presenting with medially localized unicompartmental knee osteoarthritis and meeting the criteria appropriate for UKA were recruited to a clinical patient registry at the time of presentation. A cemented unicompartmental prosthesis (Repicci II) was implanted using minimally invasive techniques with rapid postoperative mobilization. Patients were asked to complete patient-reported outcomes preoperatively and annually postoperatively. A procedure list was cross-matched with the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR), and an analysis of procedure survival was performed with comparison to the national data for UKA. Data from a cohort of 661 primary medial compartment UKA procedures performed in 551 patients over a 15-year period were extracted from the clinical patient registry. Significant improvements were maintained in general health, disease symptoms, pain, and function at an average follow-up of 9 years compared with preoperative data. Threshold analysis revealed that >65% of patients exceeded Patient Acceptable Symptom State at the latest follow-up, with >80% within or exceeding age-matched norms for general health. Cumulative revision rate was significantly lower than that reported for UKA in the AOANJRR at up to 13 years follow-up. This series represents a lower cumulative revision rate than previously reported, with >65% of patients reporting satisfactory functional outcomes at an average of 9 years from surgery. Surgical options for treating unicompartmental knee osteoarthritis could include UKA as a viable alternative; however, clear definitions of procedure success and its overall cost–benefit ratio in the context of ongoing management of knee osteoarthritis remain to be elucidated.