BACKGROUND AND PURPOSE:Patient-reported outcome measures need to reflect true differences rather than measurement artifacts resulting from translations when scores are compared across countries. We evaluated the measurement invariance of the English, Dutch, Danish, and French Oxford Hip Score (OHS) and Oxford Knee Score (OKS) in patients undergoing hip and knee arthroplasty. METHODS:OHS and OKS responses from patients undergoing primary hip or knee arthroplasty for osteoarthritis between 2019 and 2022 were included from national and single-center registries in the United Kingdom, the Netherlands, Denmark, and Switzerland. We evaluated unidimensionality, monotonicity (Hi > 0.3) and local independence (Yen Q3 > 0.20 above the average indicating independence) in each language version separately. Model fit was considered satisfactory when Comparative Fit Index (CFI) and Tucker-Lewis Index (TLI) were ≥ 0.95, root mean square error of approximation (RMSEA) ≤ 0.06, and standardized root mean square residual (SRMR) ≤ 0.08. Measurement invariance across languages was analyzed with multiple group-confirmatory factor analysis on full, random, and matched sample datasets. RESULTS:Across the hip and knee cohorts, unidimensionality was acceptable in the English (n = 21,108 and 28,230), Dutch (n = 36,792 and 29,651), Danish (n = 815 and 1,015), and French (n = 590 and 459) versions. RMSEA ranged from 0.072 to 0.092 for OHS, and from 0.057 to 0.061 for OKS and other fit indices were acceptable. The multiple group-confirmatory factor analysis showed acceptable measurement invariance across languages for both scores, with changes in RMSEA < 0.15 and CFI < 0.1 across gradually more constrained models. CONCLUSION:Measurement invariance of the OHS and OKS was supported across the English, Dutch, Danish, and French versions, with multiple group-confirmatory factor analyses model fit within predefined acceptable limits, supporting cross-comparison of the different language versions of these instruments.

Background and purpose: We aimed to clarify whether preoperative flexion contracture (FC) and limited knee flexion in patients with anteromedial osteoarthritis (OA) were associated with postoperative outcomes in mobile-bearing medial unicompartmental knee arthroplasty (UKA). Methods: We retrospectively evaluated all patients who underwent mobile-bearing medial UKA. Preoperative extension and flexion angles, and the Oxford Knee Score (OKS) and Forgotten Joint Score-12 (FJS) recorded preoperatively and at 3, 12, and 24 months, were assessed. Patients were categorized by preoperative extension (no FC, < 10°, ≥ 10°) and flexion angles (< 120°, ≥ 120°). Changes in OKS and FJS were compared using general linear models with adjustment for age, sex, body mass index, and preoperative scores. Results: 1,199 patients were included. Preoperatively, 85% of patients had full extension, 12% had < 10° FC, and 3.1% had ≥ 10° FC. Regarding flexion, 40% had < 120°, while 60% had ≥ 120°. At 12 months, the < 10° FC group showed greater improvements than the ≥ 10° FC group in OKS (adjusted mean difference, 5.5 points; 95% confidence interval [CI] 0.9–10.2; P = 0.01) and FJS (17.0 points; CI 1.0–33.0; P = 0.03). The < 120° flexion group showed greater FJS improvement than the ≥ 120° flexion group (adjusted mean difference, 4.8 points; CI 0.1–9.6; P = 0.045). At 24 months, the CIs for all between-group differences included no difference. Conclusion: Mild preoperative FC and mild-to-moderately limited knee flexion were not associated with inferior outcomes. Patients with more pronounced FC showed slower recovery but still achieved the same increase in patient-reported outcome measures (PROMs) as those with mild FC.

BACKGROUND AND PURPOSE:Tibial periprosthetic fractures (PPF), periprosthetic joint infections (PJI), and bearing dislocations (BD) are among the most common short-term complications in medial unicompartmental knee arthroplasty (mUKA). We aim to assess whether patients with these complications have patient-reported outcome measures (PROMs) that differ from patients with primary mUKA, primary total knee arthroplasty (TKA), or after revision TKA . METHODS:This observational study included 74 mUKA patients reoperated for PPF (n = 22), PJI (n = 15), or BD (n =3 7) between January 2018 and January 2023. Comparator groups included 1,940 primary mUKA, 3,485 primary TKA, and 350 reoperated TKA patients. The primary endpoint was Oxford Knee Score (OKS) at 12 months. Missing data was imputed, and multilevel Tobit regression was used to analyze differences in PROMs. RESULTS:At 12 months, reoperated mUKAs had lower PROM scores than primary mUKAs (OKS difference -3.3, 95% confidence interval [CI] -5.0 to -1.5) and TKAs (OKS difference -2.7, CI -4.4 to -0.9) but higher than reoperated TKAs (OKS difference: 3.0, CI 1.1 to 5.0). PPF mUKAs had 12-month scores resembling reoperated TKAs (OKS difference -0.7, CI -3.9 to 2.5). PJI mUKAs and BD mUKAs had 12-month scores resembling primary mUKAs (PJI: OKS difference -2.4, CI -6.2 to 1.5, BD: OKS difference -2.2, CI -4.7 to 0.2) and primary TKAs (PJI: OKS difference -1.7, CI -5.6 to 2.1, BD: OKS-difference -1.6, CI -4.1 to 0.8). CONCLUSION:Patients reoperated for PJI and BD achieved outcomes comparable to primary mUKAs and TKAs, while PPF resulted in scores lower than primary mUKAs and TKAs, comparable to reoperated TKAs.

Medial unicompartmental knee arthroplasty is widely used to treat anteromedial osteoarthritis, yet limited data exist on outcomes during its implementation phase. Therefore, this study aimed to evaluate the learning curve and the clinical and radiological outcomes during the early implementation of medial unicompartmental knee arthroplasty. The first 200 medial unicompartmental knee arthroplasty procedures performed by two arthroplasty surgeons were analyzed to assess the relationship between outcomes and the cumulative number of cases. The primary outcome was the learning curve for the duration of surgery, while secondary outcomes included the Oxford Knee Score, the Forgotten Joint Score, and the Activity and Participation Questionnaire, which were assessed at 3, 12, and 24 months postoperatively. Implant survival and positioning were evaluated at the final follow-up. Cumulative summation analysis showed a data-driven reduction in surgical duration after 55 cases. Median Oxford Knee Score was 41 (IQR 34–44) at 12 months and 42 (IQR 35–45) at 24 months. Implant survival at 5 years was 97.4

BACKGROUND:Surgical stress response initiates a complex pathophysiological cascade that alters fluid distribution and intravascular volume. In elective total hip arthroplasty (THA), the perioperative blood loss is potentially substantial, a significant part of the loss being hidden caused by tissue extravasation, residual joint blood, and hemolysis. This far conventional methods to quantify blood loss rely on either visual estimation of bleeding or formulas based on hematological and/or anthropometric parameters, both of which are considered imprecise. Accurate assessment of perioperative blood volume changes may inform more individualized postoperative fluid therapy and improve postoperative outcomes. METHODS:The study design is a single-center prospective observational cohort study with enrollment of 25 patients undergoing elective THA in a standardized fast-track setting. Perioperative blood volume will be assessed using the carbon monoxide (CO)-rebreathing method, enabling quantification of total hemoglobin mass, red cell-, plasma-, and total blood volume. Bioimpedance spectroscopy will be used to evaluate fluid distribution between intra- and extracellular compartments, as well as total body water. Measurements will be performed preoperatively before surgery (baseline), at 6 h postoperatively, and at 24 h postoperatively when feasible. Demographic data, inflammatory markers, and data on perioperative fluid administration will also be collected. The primary outcome is change in total blood volume from baseline to 6 h postoperatively. Secondary outcomes include changes in hemoglobin mass, fluid compartment shifts, and their associations with postoperative orthostatic intolerance. DISCUSSION:By combining CO rebreathing and bioimpedance, our study applies accurate, minimally invasive methods not previously used in surgical patients to characterize blood loss and perioperative fluid shifts. Strengths include the standardized surgical setting, detailed protocol, and transparent statistical plan, whereas limitations include the observational design, minor sample size, and exclusion of patients with major intraoperative bleeding. CONCLUSION:The study will provide detailed information on the changes in perioperative blood volume and its association with orthostatic intolerance following THA. CO rebreathing may offer a precise alternative to conventional estimations of blood loss and contribute to the development of more individualized perioperative fluid management strategies in major orthopedic surgery.

INTRODUCTIONPostoperative complications (PCs) rates are crucial quality metrics in surgery, as they reflect both patient outcomes, perioperative care effectiveness and healthcare resource strain. Despite their importance, efficient, accurate and affordable methods for tracking PCs are lacking. This study aimed to evaluate whether natural language processing (NLP) models could detect 11 PCs from surgical electronic health records at a level comparable to human curation.RESEARCH AND DESIGN METHODSRetrospective study in 18 hospitals across two regions in Denmark. A total of 17 486 surgical cases spanning 6 years were included. The dataset was divided into training, validation and test sets for NLP-model development and evaluation (50.2%/33.6%/16.2%). Model performance was compared against the current method of PC monitoring (International Classification of Diseases, 10th Revision (ICD-10) codes) and manual curation, the latter serving as the gold standard.17 486 surgical cases from spanning 6 years were included. The dataset was divided into training, validation and test sets for NLP-model development and evaluation (50.2%/33.6%/16.2%). Model performance was compared against the current method of PC monitoring (International Classification of Diseases, 10th Revision (ICD-10) codes) and manual curation, the latter serving as the gold standard.RESULTSThe NLP-models had a receiver operating characteristic area under the curve between 0.901 and 0.999 for the test set and significantly outperformed ICD-10 coding in detecting PCs. Sensitivity of the models when compared with manual curation ranged from 0.701 to 1.00, except for myocardial infarction (0.500). Positive predictive value (PPV) ranged from 0.0165 to 0.947, and negative predictive value from 0.995 to 1.00. Using a Human-in-the-Loop approach, only 16.3% of cases required manual review to reach a PPV of 1.00.CONCLUSIONSThe NLP models alone were able to detect PCs at an acceptable level and outperformed ICD-10 codes. While combining NLP with manual review (Human-in-the-Loop) improved overall accuracy and reduced workload, the models still failed to identify some complications. Therefore, NLP algorithms may support (but not replace) manual surveillance and present a potential solution for more scalable PC monitoring.

OBJECTIVE:To test whether an intensive dietary weight loss program (IN) yields non-inferior symptom improvement vs. knee arthroplasty (KA) in people with knee osteoarthritis eligible for knee arthroplasty. DESIGN:A non-inferiority, randomised, comparative effectiveness trial involving participants with obesity (body mass index of ≥30 kg/m2) and knee osteoarthritis eligible for knee arthroplasty. After randomisation a 12 week wait list was installed, after which IN participants were offered a 12-week low-calorie meal replacement program with weekly group sessions focusing on behaviour and education supervised by a dietitian and the KA participants were offered surgical insertion of a knee arthroplasty. We aimed to recruit 200 participants. The primary outcome was knee pain and function assessed by the Oxford Knee Score (0-48 score; higher better) 6 months after treatment start, with a prespecified non-inferiority margin of 4 points. Secondary outcomes included change in body weight. RESULTS:Recruitment target was not reached. 92 participants were randomly assigned to IN (n=45) or KA (n=47). 6 months after treatment start the Oxford Knee Score was 28.2 with IN and 36.5 with KA, with a between-group difference of -8.2 (95%CI, -11.5 to -5.0) favouring KA; the 95% CI did not include the noninferiority margin of 4 points. The mean change in body weight was -11.0 kg (-10.4%) in the IN group and -1.3 kg (-1.2%) in the KA group. The adverse event incidence was similar in the two groups. CONCLUSION:Among people with obesity and severe knee osteoarthritis eligible for knee arthroplasty a 12-week supervised intensive weight loss program was not non-inferior to knee arthroplasty, shown as clinically inferior improvements in patient reported knee pain and function after 6 months. TRIAL REGISTRATION:ClinicalTrials.gov number, NCT05172843.

This study identified the incidence and potential risk factors of tibial component subsidence in cementless unicompartmental knee arthroplasty (UKA) and evaluated its clinical impact. This retrospective cohort study analyzed 123 knees that underwent cementless Oxford mobile-bearing UKA. Anteroposterior and lateral radiographs were obtained preoperatively, immediately postoperatively, and at the first outpatient follow-up (3–6 months). Valgus subsidence was defined as a valgus change of > 2° in the tibial component angle between the immediate postoperative and first follow-up radiographs. The patients were categorized according to the presence or absence of subsidence. The alignment, component angles, and femoral component position relative to the tibial component in the coronal plane were compared between groups. Clinical outcomes were assessed using the Oxford Knee Score (OKS) at 3 months, 1 year, and 2 years. Tibial component subsidence incidence was 4.8

Background and purpose: In the QUADX-1 trial, we randomized 140 patients with severe knee osteoarthritis (OA) eligible for a knee arthroplasty to home-based exercise for 12 weeks. Seventy-nine (68%) of the 117 patients, who completed the exercise intervention, postponed surgery. Here, we report how many patients, who completed the 12-week exercise intervention, had received a knee arthroplasty at 2 years and describe their initial exercise response. Methods: From the QUADX-1 trial, we had the following: isometric knee-extensor strength, Oxford Knee Score (OKS), Knee Osteoarthritis Outcome Score (KOOS), average knee pain last week (0-10 numeric rating scale [NRS]), 6-minute walk test, stair climbing test, and self-reported exercise behaviour. Results: At the 2-year follow-up, 50 (43%) of the 117 patients had received a knee arthroplasty (KA group) and 67 (57%) had not (NO-KA group). Compared with the KA group, the NO-KA group had less severe radiographic OA at baseline (KL grade 4: 38% vs 55%) and showed greater, and often clinically relevant, improvements after the 12-week exercise intervention, including knee pain (-2.1 vs -0.1 NRS points), OKS (+6.9 vs +0.5 points), and KOOS ADL (+13.9 vs +1.3 points). Conclusion: Two years after completing the initial 12-week QUADX-1 exercise intervention, more than half the cohort had not received a knee arthroplasty despite initially being considered eligible. Those who had not received a knee arthroplasty at two years had less severe radiographic OA at baseline and generally responded better to 12-week exercise two years earlier, compared to those who had. ClinicalTrials.gov-ID: [NCT02931058][1]. ### Competing Interest Statement Thomas Bandholm reports: Funding for the present manuscript to include The QUADX-1 trial was supported by grants from The Capital Region's strategic funds (R142-A5363), The Capital Region's foundation for cross-continuum research (P-2015-1-01, P-2018-1-02, P-2019-1-03), The Danish Rheumatism Association (R156-A4923), and Copenhagen University Hospital Amager-Hvidovre's strategic funds (2019-800). He also declares that he is an exercise physiologist and physical therapist and may have a cognitive exercise bias. Anders Troelsen reports: Research support, travel/accommodations/meeting expenses unrelated to activities listed from Zimmer Biomet, research support from Pfizer Denmark, consulting fees from Zimmer Biomet and Pfizer Denmark, payment for lectures including on speakers bureau from Zimmer Biomet, advisory board membership with Pfizer Denmark. Kristian Thorborg declares Deputy editorship with Br J Sports Med. Emma Stenholm Koch, Helle Gybel Juhl-Larsen, Birk Mygind Groenfeldt, and Rasmus Skov Husted declare no competing interests. ### Clinical Trial NCT02931058 ### Clinical Protocols [https://pmc.ncbi.nlm.nih.gov/articles/PMC5774158/pdf/13063\_2017\_Article_2366.pdf][2] ### Funding Statement The QUADX-1 trial was supported by grants from The Capital Regions strategic funds (R142-A5363), The Capital Regions foundation for cross-continuum research (P-2015-1-01, P-2018-1-02, P-2019-1-03), The Danish Rheumatism Association (R156-A4923), and Copenhagen University Hospital Amager-Hvidovres strategic funds (2019-800). The funding sources had no role in this work. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The QUADX-1 trial was pre-registered ([NCT02931058][1]) and approved by the Ethics Committee of the Capital Region, Denmark (H-16025136) as well as the Danish Data Protection Agency (2012-58-0004), including the 2-year follow-up. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Public deposition of raw data points is not possible due to Denmarks national legislation (Data Protection Act Section 10 and Data Disclosure Proclamation Act) which outline that we can only transfer pseudonymized data to a publishing Journal or preprint server after the Data Protection Authorities approval (Data Protection Act Section 10, subsection 3, nr. 3.). Reviewers and others may obtain access to the data by request, and after the Danish Data Protection Agency has approved of the data transfer from the Capital Region to the Journal or repository entity. If others are to gain access to the pseudonymized data, the Journal or repository entity shall ensure that is an adequate legal basis to share the Capital Regions data and ensure that the data is only being processed for scientific research purposes. [1]: /lookup/external-ref?link_type=CLINTRIALGOV&access_num=NCT02931058&atom=%2Fmedrxiv%2Fearly%2F2026%2F05%2F01%2F2026.04.30.26351578.atom [2]: https://pmc.ncbi.nlm.nih.gov/articles/PMC5774158/pdf/13063_2017_Article_2366.pdf

OBJECTIVE:To investigate if treatment with a single injection of autologous micro-fragmented adipose tissue improved patient-reported health compared with a placebo saline injection in patients suffering from pain and functional impairment due to knee osteoarthritis. METHODS:We conducted a randomised controlled trial with patients blinded to the treatment and allocated in a 1:1 ratio to one of two parallel groups. Patients aged 18-70 years with Kellgren-Lawrence grades 2-3 in the tibiofemoral joint and suffering from pain and functional impairment of the knee were eligible for inclusion. Abdominal adipose tissue was harvested by liposuction in all patients. The active treatment group was treated with an intra-articular injection of autologous micro-fragmented adipose tissue, and the placebo group with isotonic saline. The primary outcome was the Knee injury and Osteoarthritis Outcome Score (KOOS4) evaluated at 6 months. RESULTS:238 patients were assessed for eligibility and 120 (mean age 52.2, 58% female) included from January 2019 to February 2022. There were no statistically significant differences between the active treatment and the placebo group at any time point. Both groups showed statistically significant and clinically relevant improvements from baseline to 6, 12 and 24 months. Mean KOOS4 at 6 months was 55.5 (95% CI 51.4 to 59.6) for the active treatment group and 51.5 (95% CI 47.4 to 55.6) for the placebo group. CONCLUSION:This study did not show superiority of micro-fragmented adipose tissue compared with a placebo saline injection for the treatment of knee osteoarthritis. TRIAL REGISTRATION NUMBER:NCT03771989.

Background While evidence-based indications are established for medial UKA, the optimal indications for lateral UKA have not received as much attention. There exists significant anatomical, osteoarthritis phenotype, kinematic, and surgical technique differences between medial and lateral UKA. The indications for the two procedures may therefore not be identical. Hence, this review aims to access the indications and contraindications in published cohort studies on lateral UKA, to assess if consensus exists. Methods In May 2024, a systematic review was carried out following the Preferred Reporting Item for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Cohort studies on lateral UKA with a clear report of indications were included. Data on indications and contraindications were extracted to evaluate consensus. Furthermore, outcomes related to expanding or testing indications for lateral UKA were obtained. Results 38 studies were included. Lateral UKA was mostly performed for primary lateral osteoarthritis. The most reported indications were moderate to severe lateral osteoarthritis, with full-thickness cartilage in the medial compartment, intact ligaments, a correctable valgus deformity, and a flexion contracture < 10–15 degrees. The most reported contraindications were inflammatory arthritis and severe patellofemoral involvement. Eight studies investigated different indications on outcomes after lateral UKA; suggesting better outcomes for primary lateral osteoarthritis, no significant impact from the state of the patellofemoral joint, and conflicting results regarding age and weight. Conclusion While the literature suggests that some agreement does exist regarding indications for lateral UKA, a strong consensus was not found, indicating that well-defined and consensus-based indications for lateral UKA do not yet exist.

PURPOSE:Limited data and experience surround lateral unicompartmental knee arthroplasty (UKA), contributing to uncertainty regarding its broader application in clinical practice. To understand how to optimise lateral UKA outcomes, this study aimed to evaluate the implant survival of lateral UKA and compare it to total knee arthroplasty (TKA) using registry data. METHODS:Data were obtained from the Danish Knee Arthroplasty Registry, the Danish National Patient Registry and the Danish Civil Registration System. Between 1997 and 2022, all primary lateral UKAs (n = 538) and primary TKAs performed on valgus-aligned knees were included. Propensity score matching (1:4) matched patients by age, sex, weight, Charlson comorbidity index, year of surgery and hospital type. Survival analysis used the Fine-Gray subdistribution hazards model to account for competing risks. RESULTS:The 5-year cumulative revision risk was 10.1% for lateral UKA and 5.0% for TKA (1997-2022). For lateral UKA, this decreased from 25.0% (1997-2006) to 7.3% (2017-2022); TKA decreased from 4.6% to 3.7%. Surgery after 2011 and use of the fixed lateral Oxford (FLO) implant significantly reduced the risk of revision. Compared to TKA, the subdistribution hazard ratio for revision was 0.7 (95% confidence interval [CI] = 0.2-2.2) for the FLO implant and 3.4 (95% CI = 1.9-6.1) for other lateral UKAs in the period 2017-2022. No differences were found in 90-day readmissions or complications between lateral UKA and TKA, but the 2-year reoperation rate was significantly lower for lateral UKA in both periods. CONCLUSION:Lateral UKA survival has evolved with improved understanding of knee compartment biomechanics, indications, surgical techniques and implant designs. Lateral UKA with the FLO implant showed lower or similar revision rates compared with TKA. LEVEL OF EVIDENCE:Level III.

Objective: To examine a novel application of exercise-based prehabilitation in severe knee osteoarthritis—termed “pre-evaluation exercise''—focused on supporting surgical decision-making and adherence to clinical guidelines, rather than attempting to enhance post-operative recovery. Design: This narrative review discusses the usage of exercise in the clinical decision process for total knee arthroplasty (TKA). It synthesizes data from studies on exercise-based prehabilitation, covering patient selection, implementation, and its effects on surgical choices. Emphasis is placed on multi-disciplinary coordination within an Enhanced Recovery After Surgery (ERAS) framework. Results: Evidence suggests that pre-evaluation exercise can improve symptom management and may lead to delayed or reduced surgical intervention. This approach shows significant potential in reducing the rate of TKA surgeries among patients with severe knee osteoarthritis by improving physical conditioning, addressing symptom variability, and enhancing informed, patient-centered surgical decisions. Conclusions: Pre-evaluation exercise in knee osteoarthritis is a viable strategy that complements existing ERAS initiatives by facilitating guideline-conformant surgical decision-making. Incorporating this into pre-surgical care pathways can foster improved patient-related outcomes and healthcare resource optimization.

Background and purpose: In contemporary medial unicompartmental knee arthroplasty (mUKA), non-lateral patellofemoral osteoarthritis (PFOA) is not considered a contraindication. However, we still lack knowledge on the association of PFOA severity on patient reported outcome measures (PROMs) after mUKA. We aimed to examine the association between PFOA severity and PROM-score changes after mUKA. Methods: We included 549 mobile-bearing mUKAs. PFOA was graded intraoperatively as 0 = normal cartilage, 1–2 = superficial changes or < 50% of depth, and 3–4 = changes of > 50% of depth or to the bone, using the International Cartilage Repair Society (ICRS) cartilage lesion classification system. All patients completed the Oxford Knee Score (OKS), Activity and Participation Questionnaire (APQ), and Forgotten Joint Score (FJS), preoperatively and 3, 12, and 24 months postoperatively. PROM changes were compared using linear regression models adjusted for sex, age, body mass index, and preoperative PROM score. Results: We found no significant differences in OKS, FJS, and APQ change when comparing group 3–4 with group 0 at any follow-up. When comparing group 1–2 with 0 we found a statistical but not clinical significantly higher change in OKS scores at 24-month follow-up (2.5, 95% confidence interval [CI] 0.36–4.6) and in APQ scores at 24-month follow-up (10.6, CI 1.2–20.0) in favor of group 1–2. Conclusion: Severe PFOA, excluding severe lateral facet PFOA, had no negative association on PROM score development following mobile-bearing mUKA.

Aims: Whether medial unicompartmental knee arthroplasty (mUKA) or total knee arthroplasty (TKA) are more suitable for patients with anteromedial osteoarthritis (AMOA) remains debated. We aimed to compare the development over time in patient-reported outcome measures (PROMs) between patients receiving mUKA and TKA. Methods: We conducted a matched cohort study of patients receiving TKA or mUKA between March 2018 and February 2020. TKA patients were evaluated based on preoperative radiographs and excluded if not deemed eligible for mUKA. The PROMs (Oxford Knee Score (OKS), Forgotten Joint Score (FJS), and Activity and Participation Questionnaire (APQ)) were completed preoperatively, and at three, six, and 12 months postoperatively. Patients were propensity score matched in a variable 1:2 ratio using BMI, sex, age, and preoperative PROM scores. Area under the curve (AUC) was calculated using the trapezium rule to quantify the change from preoperative PROM scores to scores at three, six, and 12 months postoperatively. AUC differences were analyzed using linear regression. Results: A total of 618 patients (242 mUKA, 376 TKA) were included. The AUC was significantly lower for TKA patients compared with mUKA patients across all three PROM scores (OKS: ∆AUC of -19% (95% CI -27% to -9 %); FJS: ∆AUC of -23% (95% CI -32% to -14%); APQ -22% (95% CI -32% to -12%). Median PROM scores at three months were 35 and 30 for OKS, 50 and 43 for FJS, 44 and 31 for APQ, for the mUKA and TKA groups, respectively. At six months, the median PROM scores increased to 39 and 35 for OKS, 62 and 50 for FJS, and 56 and 41 for APQ for the mUKA and TKA groups, respectively. Conclusion: The AUC for PROM scores during the first year was 19% to 23% lower for TKA compared with mUKA. This contrast in development trajectories is present especially in the early recovery three to six months after surgery. Cite this article: Bone Jt Open 2025;6(12):1588–1597.

Aims Diabetes is a known risk factor for periprosthetic joint infection (PJI) following total knee arthroplasty (TKA). However, the diabetes population is characterized by considerable phenotypic heterogeneity. This study aimed to describe the complex clinical risk profile and associated risk of PJI after TKA in patients with and without diabetes. Methods We used Danish National Registry data to identify 75,141 TKA cases, including 9,879 patients with diabetes (both type 1 and type 2), defined by International Classification of Diseases of the World Health Organization diagnosis codes and glucose-lowering drug prescriptions. Patients were classified by diabetes, patient, health, and social factors. We estimated PJI revision incidences five years postoperatively both overall and across various clinical profiles, considering combinations of sex, age, body weight, and the presence of vascular disease, as well as sex and severity of diabetes. Results The five-year PJI incidence was 1.7% (95% CI 1.5 to 2) for diabetes patients and 1.4% (95% CI 1.3 to 1.5) for non-diabetes patients. Diabetes patients were slightly older, more obese, and had poorer health and social status than non-diabetes patients. Among diabetes patients, the five-year PJI incidence ranged from 0.4% (in females, aged > 68 years, with no vascular diseases, and weight < 90 kg) to 3.7% (in males, aged < 68 years, vascular disease, and weight > 100 kg). Non-diabetes patients with the same clinical profiles had five-year PJI incidences of 0.7% and 3.4%, respectively. Females with diabetes and body weight < 90 kg but without vascular diseases had a lower PJI incidence than their non-diabetic counterparts. Conclusion The risk of PJI after TKA varies highly by clinical profile in patients both with and without diabetes. These findings highlight the importance of individualized preoperative risk assessments for patients undergoing TKA.

PURPOSE:To explore content validity, construct validity, and reliability of anchor questions used to determine minimal important change (MIC), patient acceptable symptom state (PASS) and treatment failure (TF) in patients undergoing knee or hip arthroplasty. METHODS:A mixed-methods study from one public hospital. Evaluation of content validity involved applying thematic analysis to data from think-aloud interviews. To ascertain construct validity and reliability, we focused on patients who underwent surgery between 2016 and 2022 and had responded to preoperative and either 3-, 12- or 24-month postoperative questionnaires. Confirmatory factor analysis (CFA) was employed to assess present state bias (PSB), model fit, and reliability of the anchor questions. RESULTS:We conducted 18 interviews with patients aged 52 to 84 (10 female). Based on seven emerging themes from the content validity analysis, MIC and PASS anchor questions were considered relevant and comprehensible, while the TF anchor question had several problems. Data from 1197 to 2207 patients, with 3-, 12-, or 24-month postoperative responses, were used to evaluate construct validity. The median age was 69-70 years (56-59% female). PSB for MIC was between 54 and 73%, and reliability for the anchor questions was between 0.52 and 0.80 for all time points. The CFA models varied between good and poor fit. CONCLUSION:The MIC and PASS anchor questions demonstrated a high degree of content validity, while it was questionable for TF. Construct validity was considered good to poor for PASS, but patients may consider their present state more than their preoperative state when responding to the MIC. Reliability was considered acceptable in both MIC and PASS.