Aims

Valgus subsidence of uncemented tibial components following medial unicompartmental knee arthroplasty (UKA) poses a challenge in the early postoperative phase, necessitating a comprehensive understanding of its prevalence, risk factors, and impact on patient outcomes.

Aims

Unicompartmental knee arthroplasty (UKA) is associated with an accelerated recovery, improved functional outcomes, and retention of anatomical knee kinematics when compared to manual total knee arthroplasty (mTKA). UKA is not universally employed by all surgeons as there is a higher revision risk when compared to mTKA. Robotic arm-assisted (ra) UKA enables the surgeon to position the prosthesis more accurately when compared to manual UKA, and is associated with improved functional outcomes and a lower early revision risk. Non-randomized data suggests that, when compared to mTKA, raUKA has a clinically meaningful greater functional benefit. This protocol describes a randomized controlled trial that aims to evaluate the clinical and cost-effectiveness of raUKA compared to mTKA for individuals with isolated medial compartment osteoarthritis (OA).

Aims. Control of acute pain following knee arthroplasty (KA) with a perioperative peripheral nerve block (PNB) may improve functional outcomes and reduce the risk of chronic postoperative knee pain (CPKP). The aims of this study were to assess whether a PNB influences patient-reported outcomes and risk of CPKP at one year following KA. Methods. A retrospective study was conducted over a two-year period and included 3,338 patients who underwent KA, of whom 1,434 (43.0%) had a lower limb PNB. A total of 2,588 patients (77.6%) completed and returned their one-year follow-up questionnaire. The Oxford Knee Score (OKS) and pain component (OKS-PS), EuroQol five-dimension questionnaire (EQ-5D), and EQ-visual analogue scale (VAS) were collected preoperatively and at one year postoperatively. Patient satisfaction was also recorded at one year. The OKS-PS was used to define CPKP at one year. Results. The PNB group were younger (mean difference (MD) 0.7 years, 95% CI 0.0 to 1.3; p = 0.039), had a worse OKS (MD 0.7, 95% CI 0.1 to 1.3; p = 0.027), and were more likely to have had a spinal anaesthesia relative to a general anaesthetic (odds ratio 4.2, 95% CI 3.23 to 5.45; p < 0.001). When adjusting for confounding factors, patients in the PNB group had a significantly reduced improvement in their OKS (MD -0.9, 95% CI -1.6 to -0.1; p = 0.022), which may not be clinically meaningful. There were no significant differences in the OKS-PS (p = 0.068), EQ-5D (p = 0.313), or EQ-VAS (0.855) between the groups when adjusting for confounding factors. When adjusting for confounding factors using binary regression analysis, there were no differences in patient satisfaction (p = 0.132) or in the risk of CPKP (p = 0.794) according to PNB group. Conclusion. PNBs were independently associated with worse knee-specific outcomes, but whether these are clinically meaningful is not clear, as the difference was less than the minimal clinically important difference. Furthermore, PNBs were not independently associated with differences in health-related quality of life, patient satisfaction, or risk of CPKP. Cite this article: Bone Jt Open 2025;6(2):147–154

The February 2025 Hip & Pelvis Roundup. 360. looks at: Postoperative periprosthetic femoral fractures after hip arthroplasty: quantifying the other half of the picture; Hip arthroscopy in patients with borderline dysplasia: how do we know when it will not work?; The morbidly obese patient remains a challenge for arthroplasty surgeons; Unexpected positive cultures in aseptic revision hip and knee arthroplasty: does it make a difference?; Failed spinal anaesthesia in hip and knee arthroplasty surgery; Clinical failure of femoral neck fracture is associated with varus necks; Navigating the angles: how variations in femoral and acetabular versions influence hip pain and treatment; High-tech or hands-on? Similar outcomes in direct anterior total hip arthroplasty

The February 2025 Sports Roundup³⁶⁰ looks at: Long-term outcomes of focal cartilage lesions of the knee; Comparison of early and delayed multiligament knee reconstruction; Platelet-rich plasma does not improve recovery after partial meniscectomy; Patient height and sex predict semitendinosus autograft diameter.

The February 2025 Knee Roundup. 360. looks at: Once-weekly semaglutide in patients with obesity and knee osteoarthritis; How many patients should have a unicompartmental knee arthroplasty?; Staged revision of the infected knee arthroplasty and endoprosthesis; The metal allergy argument and knee arthroplasty; Is kinematic alignment all it’s cracked up to be?; Is bone-patella-bone the gold standard for revision?; Blood flow restriction and the dissatisfied knee arthroplasty

Aims

To evaluate the concurrent use of vancomycin and ε-aminocaproic acid (EACA) in primary total hip arthroplasty (THA).

Aims. Over time, the locking mechanism of Modular Universal Tumour and Revision System (MUTARS) knee arthroplasties changed from polyethylene (PE) to polyether-ether-ketone Optima (PEEK) and metal-on-metal (MoM) in an attempt to reduce the risk of mechanical failure. In this study, we aimed to assess the cumulative incidence of locking mechanism revision for symptomatic instability by type of material, and assess potential associated risk factors. Methods. The MUTARS Orthopaedic Registry Europe was used for a retrospective review of 316 patients (54% male (n = 170), median age 44 years (IQR 23 to 61)) who underwent a MUTARS knee arthroplasty for oncological indications between December 1995 and January 2023. The minimum follow-up was 12 months, and the median follow-up was 7.9 years (IQR 3.3 to 13.0). A competing risk model was used to estimate the cumulative incidence of first locking mechanism revision with death and revision for any other reason as competing events. Possible risk factors were assessed employing a univariate cause-specific hazards regression model. Results. Symptomatic instability of the hinge or locking mechanism due to wear (n = 20) or breakage (n = 14) occurred in 34 patients (11%): 9% of PE (n = 4/45), 20% of PEEK (n = 9/44), and 9% of MoM locking mechanisms (n = 21/227). The cumulative incidences of revision for instability due to wear or locking mechanism breakage at two, five, and ten years were 0%, 5% (95% CI 1 to 15), and 5% (95% CI 1 to 15) for PE, 5% (95% CI 1 to 14), 14% (95% CI 5 to 26), and 16% (95% CI 7 to 29) for PEEK, and 0%, 3% (95% CI 1 to 6), and 10% (95% CI 5 to 16) for MoM. With PE as the reference category, the cause-specific hazard ratio for PEEK and MoM were 3.6 (95% CI 1.1 to 11.9; p = 0.036) and 3.2 (95% CI 1.1 to 9.5; p = 0.043), respectively. Age, BMI, resection length, and extra-articular resections were not associated with the time to locking mechanism revision. Conclusion. Alterations in prosthetic materials have not decreased the revision risk for locking mechanism failure. Besides locking mechanism material, no other patient- or prosthesis-related risk factors for locking mechanism failure were identified. Improvement of the locking mechanism is warranted since revision exposes patients to the risk of serious secondary complications. Cite this article: Bone Joint J 2025;107-B(2):239–245

Aims. This study was performed to investigate the association between the acetabular morphology and the joint space narrowing rate (JSNR) in the non-arthritic hip. Methods. We retrospectively reviewed standing whole-leg radiographs of patients who underwent knee arthroplasty from February 2012 to March 2020 at our institute. Patients with a history of hip surgery, Kellgren-Lawrence grade ≥ II hip osteoarthritis, or rheumatoid arthritis were excluded. The hip JSNR was measured, and the normalized JSNR (nJSNR) was calculated by calibrating the joint space width with the size of the femoral head in 395 patients (790 hips) with a mean age of 73.7 years (SD 8.6). The effects of the lateral centre-edge angle (CEA) and acetabular roof obliquity (ARO) in the standing and supine positions were examined using a multivariate regression model. Results. The mean JSNR and nJSNR were 0.115 mm/year (SD 0.181) and 2.451 mm/year (SD 3.956), respectively. Multivariate regressions showed that older age was associated with a larger nJSNR (p = 0.010, standardized coefficient (SC) 0.096). The quadratic curve approximation showed that the joint space narrowing was smallest when the CEA was approximately 31.9°. This optimal CEA was the same in the standing and supine positions. Multivariate regressions were separately performed for joints with a CEA of < 31.9° and > 31.9°. When the CEA was < 31.9°, a smaller CEA was associated with a larger nJSNR (p < 0.001, SC 0.282). When the CEA was > 31.9°, a larger CEA was associated with a larger nJSNR (p = 0.012, SC 0.152). The ARO was not associated with the nJSNR. Conclusion. Both insufficient coverage and over-coverage of the acetabulum over the femoral head were associated with increased joint space narrowing in hips that were non-arthritic at baseline. The effects of insufficient coverage were stronger than those of overcoverage. Cite this article: Bone Jt Open 2025;6(1):93–102

Aims. We estimated the prevalence of people living with at least one hip, knee, or shoulder arthroplasty in the Netherlands. Methods. We included the first hip (n = 416,333), knee (n = 314,569), or shoulder (n = 23,751) arthroplasty of each patient aged ≥ 40 years between 2007 and 2022 (hip/knee) or 2014 and 2022 (shoulder) from the Dutch Arthroplasty Register (LROI). Data on the size of the Dutch population were obtained from Statistics Netherlands. Annual incidences and deaths from hip and knee arthroplasty since 2010, and shoulder arthroplasty since 2015, were observed from the LROI. Annual incidences and deaths before those years were estimated using Poisson regression analyses and parametric survival models based on a Gompertz distribution. Non-parametric percentile bootstrapping with resampling was used to estimate 95% CIs. Results. Annual incidences per 100,000 Dutch inhabitants aged ≥ 40 years increased for hip arthroplasties from 221 (95% CI 214 to 229) in 1990 to 360 in 2022, for knee arthroplasties from 181 (95% CI 174 to 188) to 272, and for shoulder arthroplasties from 11 (95% CI 8.0 to 16) to 34. In 2022, 791,000 (95% CI 787,000 to 794,000) people in the Netherlands were living with at least one joint replacement, representing 8.4% (95% CI 8.4 to 8.5) of the Dutch population aged ≥ 40 years. For hip, knee, and shoulder arthroplasties, these were 436,000 (95% CI 433,000 to 438,000), 383,000 (95% CI 380,000 to 386,000), and 34,000 (95% CI 33,000 to 36,000) people, corresponding to 4.7% (95% CI 4.6 to 4.7), 4.1% (95% CI 4.1 to 4.1), and 0.4% (95% CI 0.3 to 0.4) of the Dutch population, respectively. The most common age group living with at least one joint replacement was the ≥ 80-year age group, representing 38% (95% CI 37 to 38) of the Dutch population aged ≥ 80 years. Conclusion. Approximately 800,000 people in the Netherlands were living with at least one hip, knee, or shoulder replacement in 2022, representing one in 12 Dutch inhabitants aged ≥ 40 years. Cite this article: Bone Jt Open 2025;6(1):74–81

Aims

Around the world, the emergence of robotic technology has improved surgical precision and accuracy in total knee arthroplasty (TKA). This territory-wide study compares the results of various robotic TKA (R-TKA) systems with those of conventional TKA (C-TKA) and computer-navigated TKA (N-TKA).

Aims. Tibial fixation in revision total knee arthroplasty (rTKA) can present surgical challenges. It has been suggested that appropriate fixation in at least two of the three anatomical zones (epiphysis, metaphysis, and diaphysis) is essential for implant survival. However, supporting clinical data are lacking. In this retrospective case-control study, we investigated the relationship between zonal fixation of hybrid rTKA tibial components and re-revision total knee arthroplasty for aseptic loosening (rrTKA-AL). Methods. All consecutive rTKAs with hybrid tibial components (May 2006 to December 2020) were screened for subsequent rrTKA-AL. A control group was randomly selected from the remaining cohort. Postoperative radiographs of rTKAs were scored in random order by three blinded observers for zonal fixation in the epiphysis (bone resection level below, at, or above fibular head; 0 to 2), metaphysis (number of sufficiently cemented zones; 0 to 4), and diaphysis (canal filling ratio (CFR); %). The intraclass correlation coefficient (ICC) was calculated to quantify the agreement between observers. Multivariate logistic regression analysis was performed to assess the relationship between zonal fixation and rrTKA-AL. Results. Overall, 33 patients underwent a further rrTKA-AL from a total of 1,173 rTKAs where hybrid tibial components (2.8%) were used. Patients requiring rrTKA-AL had a significantly lower epiphyseal bone resection level (OR 0.43; 95% CI 0.23 to 0.76; p = 0.006), lower number of adequately cemented zones (OR 0.50; 95% CI 0.30 to 0.79; p = 0.004), but no difference in CFR (p = 0.858). Furthermore, patients needing rrTKA-AL had more frequently previous revisions (p = 0.047), a higher rate of a prior use of a stemmed tibial component (p = 0.011), and a higher Anderson Orthopaedic Research Institute classification (p < 0.001). Agreement of zonal fixation between observers was good (ICC 0.79 to 0.87). Conclusion. Patients in need of subsequent rrTKA-AL had lower epiphyseal bone resection levels and a lower number of sufficiently metaphyseal cemented zones following rTKA. These results emphasize the importance of appropriate metaphyseal fixation at rTKA. With this information, orthopaedic surgeons can identify patients at greater risk for rrTKA-AL and optimize their surgical technique in revision knee arthroplasty surgery. Cite this article: Bone Joint J 2025;107-B(1):65–71

Aims. Prolonged waits for hip and knee arthroplasty have raised questions about the equity of current approaches to waiting list prioritization for those awaiting surgery. We therefore set out to understand key stakeholder (patient and surgeon) preferences for the prioritization of patients awaiting such surgery, in order to guide future waiting list redesign. Methods. A combined qualitative/quantitative approach was used. This comprised a Delphi study to first inform which factors patients and surgeons designate as important for prioritization of patients on hip and knee arthroplasty waiting lists, followed by a discrete choice experiment (DCE) to determine how the factors should be weighed against each other. Coefficient values for each included DCE attribute were used to construct a ‘priority score’ (weighted benefit score) that could be used to rank individual patients waiting for surgery based on their respective characteristics. Results. In total, 43 people participated in the initial round of the Delphi study (16 patients and 27 surgeons), with a 91% completion rate across all three rounds. Overall, 73 surgeons completed the DCE. Following the final consensus meeting of the Delphi component, the seven final factors designated for inclusion were Pain, Mobility/Function, Activities of Daily Living, Inability to Work/Care, Length of Time Waited, Radiological Severity, and Mental Wellbeing. Output from the adjusted multinomial regression revealed radiological severity to be the most significant factor (coefficient 2.27 (SD 0.31); p < 0.001), followed by pain (coefficient 1.08 (SD 0.13); p < 0.001) and time waited (coefficient for one month additional wait 0.12 (SD 0.02); p < 0.001). Conclusion. These results present a new robust method for determining comparative priority for those on primary hip and knee hip arthroplasty waiting lists. Evaluation of potential implementation in clinical practice is now required. Cite this article: Bone Joint J 2025;107-B(1):89–96

Aims. The Clavien-Dindo (CD) classification and Comprehensive Complication Index (CCI) have been validated primarily among general surgical procedures. To date, the validity of these measures has not been assessed in patients undergoing arthroplasty. Methods. This retrospective cohort study included patients undergoing primary total hip and knee arthroplasty between April 2013 and December 2019. Complications within 90 days of surgery were graded using the CD classification and converted to CCI. Validity was established by assessing the association between both measures and discharge to inpatient rehabilitation, length of stay, and costs. Results. Among 2,884 patients, 414 (14.4%) had an in-hospital complication and 643 (22.3%) had a complication within 90 days. Each increase in CD grade was associated with USD$1,895.48 (95% CI 1,734.77 to 2,056.18) of additional costs, an additional 1.24 days’ length of stay (95% CI 1.15 to 1.33), and 43% (95% CI 26 to 62%) greater odds of discharge to inpatient rehabilitation. Each ten-unit increase in CCI score was associated with USD$1,698.55 (95% CI 1,561.8 to 1,835.3) higher costs, an additional 1.09 days’ length of stay (95% CI 1.02 to 1.17), and 33% (95% CI 19% to 49%) greater odds of discharge to inpatient rehabilitation. Conclusion. Both the CD classification and CCI appear valid and applicable to patients undergoing total joint replacement. Cite this article: Bone Joint J 2025;107-B(1):81–88

Aims

The aim of this study was to perform an incremental cost-utility analysis and assess the impact of differential costs and case volume on the cost-effectiveness of robotic arm-assisted medial unicompartmental knee arthroplasty (rUKA) compared to manual (mUKA).

Aims

Unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA) have both been shown to be effective treatments for osteoarthritis (OA) of the knee. Many studies have compared the outcomes of the two treatments, but less so with the use of robotics, or individualized TKA alignment techniques. Functional alignment (FA) is a novel technique for performing a TKA and shares many principles with UKA. Our aim was to compare outcomes from a case-matched series of robotic-assisted UKAs and robotic-assisted TKAs performed using FA.