Aims. The aim of this study was to determine the long-term risk of undergoing knee arthroplasty in a cohort of patients with meniscal tears who had undergone arthroscopic partial meniscectomy (APM). Patients and Methods. A retrospective national cohort of patients with a history of isolated APM was identified over a 20-year period. Patients with prior surgery to the same knee were excluded. The primary outcome was knee arthroplasty. Hazard ratios (HRs) were adjusted by patient age, sex, year of APM, Charlson comorbidity index, regional deprivation, rurality, and ethnicity. Risk of arthroplasty in the index knee was compared with the patient’s contralateral knee (with vs without a history of APM). A total of 834 393 patients were included (mean age 50 years; 37% female). Results. Of those with at least 15 years of follow-up, 13.49% (16 256/120 493; 95% confidence interval (CI) 13.30 to 13.69) underwent subsequent arthroplasty within this time. In women, 22.07% (95% CI 21.64 to 22.51) underwent arthroplasty within 15 years compared with 9.91% of men (95% CI 9.71 to 10.12), corresponding to a risk ratio (RR) of 2.23 (95% CI 2.16 to 2.29). Relative to the general population, patients with a history of APM were over ten times more likely (RR 10.27; 95% CI 10.07 to 10.47) to undergo arthroplasty rising to almost 40 times more likely (RR 39.62; 95% CI 27.68 to 56.70) at a younger age (30 to 39 years). In patients with a history of APM in only one knee, the risk of arthroplasty in that knee was greatly elevated in comparison with the contralateral knee (no APM; HR 2.99; 95% CI 2.95 to 3.02). Conclusion. Patients developing a meniscal tear undergoing APM are at greater risk of knee arthroplasty than the general population. This risk is three-times greater in the patient’s affected knee than in the contralateral knee. Women in the cohort were at double the risk of progressing to knee arthroplasty compared with men. These important new reference data will inform shared decision making and enhance approaches to treatment, prevention, and clinical surveillance. Cite this article: Bone Joint J 2019;101-B:1071–1080

Aims. This study investigates whether primary knee arthroplasty (KA) restores health-related quality of life (HRQoL) to levels expected in the general population. Methods. This retrospective case-control study compared HRQoL data from two sources: patients undergoing primary KA in a university-teaching hospital (2013 to 2019), and the Health Survey for England (HSE; 2010 to 2012). Patient-level data from the HSE were used to represent the general population. Propensity score matching was used to balance covariates and facilitate group comparisons. A propensity score was estimated using logistic regression based upon the covariates sex, age, and BMI. Two matched cohorts with 3,029 patients each were obtained for the adjusted analyses (median age 70.3 (interquartile range (IQR) 64 to 77); number of female patients 3,233 (53.4%); median BMI 29.7 kg/m. 2. (IQR 26.5 to 33.7)). HRQoL was measured using the three-level version of the EuroQol five-dimension questionnaire (EQ-5D-3L), and summarized using the Index and EuroQol visual analogue scale (EQ-VAS) scores. Results. Patients awaiting KA had significantly lower EQ-5D-3L Index scores than the general population (median 0.620 (IQR 0.16 to 0.69) vs median 0.796 (IQR 0.69 to 1.00); p < 0.001). By one year postoperatively, the median EQ-5D-3L Index score improved significantly in the KA cohort (mean change 0.32 (SD 0.33); p < 0.001), and demonstrated no clinically relevant differences when compared to the general population (median 0.796 (IQR 0.69 to 1.00) vs median 0.796 (IQR 0.69 to 1.00)). Compared to the general population cohort, the postoperative EQ-VAS was significantly higher in the KA cohort (p < 0.001). Subgroup comparisons demonstrated that older age groups had statistically better EQ-VAS scores than matched peers in the general population. Conclusion. Patients awaiting KA for osteoarthritis had significantly poorer HRQoL than the general population. However, within one year of surgery, primary KA restored HRQoL to levels expected for the patient’s age-, BMI-, and sex-matched peers. Cite this article: Bone Joint J 2023;105-B(4):365–372

Aims. The aims of this study were to assess mapping models to predict the three-level version of EuroQoL five-dimension utility index (EQ-5D-3L) from the Oxford Knee Score (OKS) and validate these before and after total knee arthroplasty (TKA). Methods. A retrospective cohort of 5,857 patients was used to create the prediction models, and a second cohort of 721 patients from a different centre was used to validate the models, all of whom underwent TKA. Patient characteristics, BMI, OKS, and EQ-5D-3L were collected preoperatively and one year postoperatively. Generalized linear regression was used to formulate the prediction models. Results. There were significant correlations between the OKS and EQ-5D-3L preoperatively (r = 0.68; p < 0.001) and postoperatively (r = 0.77; p < 0.001) and for the change in the scores (r = 0.61; p < 0.001). Three different models (preoperative, postoperative, and change) were created. There were no significant differences between the actual and predicted mean EQ-5D-3L utilities at any timepoint or for change in the scores (p > 0.090) in the validation cohort. There was a significant correlation between the actual and predicted EQ-5D-3L utilities preoperatively (r = 0.63; p < 0.001) and postoperatively (r = 0.77; p < 0.001) and for the change in the scores (r = 0.56; p < 0.001). Bland-Altman plots demonstrated that a lower utility was overestimated, and higher utility was underestimated. The individual predicted EQ-5D-3L that was within ± 0.05 and ± 0.010 (minimal clinically important difference (MCID)) of the actual EQ-5D-3L varied between 13% to 35% and 26% to 64%, respectively, according to timepoint assessed and change in the scores, but was not significantly different between the modelling and validation cohorts (p ≥ 0.148). Conclusion. The OKS can be used to estimate EQ-5D-3L. Predicted individual patient utility error beyond the MCID varied from one-third to two-thirds depending on timepoint assessed, but the mean for a cohort did not differ and could be employed for this purpose. Cite this article: Bone Jt Open 2022;3(7):573–581

Aims. Achievement of accurate microbiological diagnosis prior to revision is key to reducing the high rates of persistent infection after revision knee surgery. The effect of change in the microorganism between the first- and second-stage revision of total knee arthroplasty for periprosthetic joint infection (PJI) on the success of management is not clear. Methods. A two-centre retrospective cohort study was conducted to review the outcome of patients who have undergone two-stage revision for treatment of knee arthroplasty PJI, focusing specifically on isolated micro-organisms at both the first- and second-stage procedure. Patient demographics, medical, and orthopaedic history data, including postoperative outcomes and subsequent treatment, were obtained from the electronic records and medical notes. Results. The study cohort consisted of 84 patients, of whom 59.5% (n = 50) had successful eradication of their infection at a mean follow-up of 4.7 years. For the 34 patients who had recurrence of infection, 58.8% (n = 20) had a change in isolated organism, compared to 18% (n = 9) in the infection eradication group (p < 0.001). When adjusting for confound, there was no association when the growth on the second stage was the same as the first (odd ratio (OR) 2.50, 95% confidence interval (CI) 0.49 to 12.50; p = 0.269); however, when a different organism was identified at the second stage, this was independently associated with failure of treatment (OR 8.40, 95% CI 2.91 to 24.39; p < 0.001). There were no other significant differences between the two cohorts with regard to patient demographics or type of organisms isolated. Conclusion. Change in the identified microorganism between first- and second-stage revision for PJI was associated with failure of management. Identification of this change in the microorganism prior to commencement of the second stage may help target antibiotic management and could improve the success of surgery in these patients. Cite this article: Bone Jt Open 2023;4(9):720–727

Aims. This study aimed to explore the biological and clinical importance of dysregulated key genes in osteoarthritis (OA) patients at the cartilage level to find potential biomarkers and targets for diagnosing and treating OA. Methods. Six sets of gene expression profiles were obtained from the Gene Expression Omnibus database. Differential expression analysis, weighted gene coexpression network analysis (WGCNA), and multiple machine-learning algorithms were used to screen crucial genes in osteoarthritic cartilage, and genome enrichment and functional annotation analyses were used to decipher the related categories of gene function. Single-sample gene set enrichment analysis was performed to analyze immune cell infiltration. Correlation analysis was used to explore the relationship among the hub genes and immune cells, as well as markers related to articular cartilage degradation and bone mineralization. Results. A total of 46 genes were obtained from the intersection of significantly upregulated genes in osteoarthritic cartilage and the key module genes screened by WGCNA. Functional annotation analysis revealed that these genes were closely related to pathological responses associated with OA, such as inflammation and immunity. Four key dysregulated genes (cartilage acidic protein 1 (CRTAC1), iodothyronine deiodinase 2 (DIO2), angiopoietin-related protein 2 (ANGPTL2), and MAGE family member D1 (MAGED1)) were identified after using machine-learning algorithms. These genes had high diagnostic value in both the training cohort and external validation cohort (receiver operating characteristic > 0.8). The upregulated expression of these hub genes in osteoarthritic cartilage signified higher levels of immune infiltration as well as the expression of metalloproteinases and mineralization markers, suggesting harmful biological alterations and indicating that these hub genes play an important role in the pathogenesis of OA. A competing endogenous RNA network was constructed to reveal the underlying post-transcriptional regulatory mechanisms. Conclusion. The current study explores and validates a dysregulated key gene set in osteoarthritic cartilage that is capable of accurately diagnosing OA and characterizing the biological alterations in osteoarthritic cartilage; this may become a promising indicator in clinical decision-making. This study indicates that dysregulated key genes play an important role in the development and progression of OA, and may be potential therapeutic targets. Cite this article: Bone Joint Res 2024;13(2):66–82

Aims. Unicompartmental knee arthroplasty (UKA) has higher revision rates than total knee arthroplasty (TKA). As revision of UKA may be less technically demanding than revision TKA, UKA patients with poor functional outcomes may be more likely to be offered revision than TKA patients with similar outcomes. The aim of this study was to compare clinical thresholds for revisions between TKA and UKA using revision incidence and patient-reported outcomes, in a large, matched cohort at early, mid-, and late-term follow-up. Methods. Analyses were performed on propensity score-matched patient cohorts of TKAs and UKAs (2:1) registered in the New Zealand Joint Registry between 1 January 1999 and 31 December 2019 with an Oxford Knee Score (OKS) response at six months (n, TKA: 16,774; UKA: 8,387), five years (TKA: 6,718; UKA: 3,359), or ten years (TKA: 3,486; UKA: 1,743). Associations between OKS and revision within two years following the score were examined. Thresholds were compared using receiver operating characteristic analysis. Reasons for aseptic revision were compared using cumulative incidence with competing risk. Results. Fewer TKA patients with ‘poor’ outcomes (≤ 25) subsequently underwent revision compared with UKA at six months (5.1% vs 19.6%; p < 0.001), five years (4.3% vs 12.5%; p < 0.001), and ten years (6.4% vs 15.0%; p = 0.024). Compared with TKA, the relative risk for UKA was 2.5-times higher for ‘unknown’ reasons, bearing dislocations, and disease progression. Conclusion. Compared with TKA, more UKA patients with poor outcomes underwent revision from early to long-term follow-up, and were more likely to undergo revision for ‘unknown’ reasons, which suggest a lower clinical threshold for UKA. For UKA, revision risk was higher for bearing dislocations and disease progression. There is supporting evidence that the higher revision UKA rates are associated with lower clinical thresholds for revision and additional modes of failure. Cite this article: Bone Joint J 2023;105-B(3):269–276

Aims. Obtaining solid implant fixation is crucial in revision total knee arthroplasty (rTKA) to avoid aseptic loosening, a major reason for re-revision. This study aims to validate a novel grading system that quantifies implant fixation across three anatomical zones (epiphysis, metaphysis, diaphysis). Methods. Based on pre-, intra-, and postoperative assessments, the novel grading system allocates a quantitative score (0, 0.5, or 1 point) for the quality of fixation achieved in each anatomical zone. The criteria used by the algorithm to assign the score include the bone quality, the size of the bone defect, and the type of fixation used. A consecutive cohort of 245 patients undergoing rTKA from 2012 to 2018 were evaluated using the current novel scoring system and followed prospectively. In addition, 100 first-time revision cases were assessed radiologically from the original cohort and graded by three observers to evaluate the intra- and inter-rater reliability of the novel radiological grading system. Results. At a mean follow-up of 90 months (64 to 130), only two out of 245 cases failed due to aseptic loosening. Intraoperative grading yielded mean scores of 1.87 (95% confidence interval (CI) 1.82 to 1.92) for the femur and 1.96 (95% CI 1.92 to 2.0) for the tibia. Only 3.7% of femoral and 1.7% of tibial reconstructions fell below the 1.5-point threshold, which included the two cases of aseptic loosening. Interobserver reliability for postoperative radiological grading was 0.97 for the femur and 0.85 for the tibia. Conclusion. A minimum score of 1.5 points for each skeletal segment appears to be a reasonable cut-off to define sufficient fixation in rTKA. There were no revisions for aseptic loosening at mid-term follow-up when this fixation threshold was achieved or exceeded. When assessing first-time revisions, this novel grading system has shown excellent intra- and interobserver reliability. Cite this article: Bone Joint J 2024;106-B(5):468–474

Aims. To identify the responsiveness, minimal clinically important difference (MCID), minimal clinical important change (MIC), and patient-acceptable symptom state (PASS) thresholds in the 36-item Short Form Health Survey questionnaire (SF-36) (v2) for each of the eight dimensions and the total score following total knee arthroplasty (TKA). Methods. There were 3,321 patients undergoing primary TKA with preoperative and one-year postoperative SF-36 scores. At one-year patients were asked how satisfied they were and “How much did the knee arthroplasty surgery improve the quality of your life?”, which was graded as: great, moderate, little (n = 277), none (n = 98), or worse. Results. Physical function, role limitations due to physical problems (‘role physical’), bodily pain, and the total score SF-36 scores demonstrated the greatest effect sizes (> 0.9). The MCID for each of SF-36 dimensions ranged from 1.7 for role emotional to 6.4 for bodily pain. The MICs for a cohort of patients ranged from -1.0 for general health to 11.1 for bodily pain. The MICs for an individual patient were marginally greater (one to two points) compared to those for a cohort, and ranging from 0.0 for general and mental health to 13.5 for physical function. The lowest PASS score threshold was associated with physical function (> 34 points) whereas the greatest threshold (> 69 points) was associated with mental health. Conclusion. The SF-36 is a responsive tool, and the estimates for MCID, MIC, and PASS thresholds that can be used to power studies, assess whether there has been a meaningful change in patients’ health-related quality of life, and can be used as a marker of achieving patient satisfaction following TKA. Cite this article: Bone Joint Res 2022;11(7):477–483

Aims. Hereditary haemochromatosis is a genetic disorder that is caused by several known mutations in the human homeostatic iron regulator protein (HFE) gene. Abnormal accumulation of iron causes a joint disease that resembles osteoarthritis (OA), but appears at a relatively younger age and is accompanied by cirrhosis, diabetes, and injury to other organs. Increased serum transferrin saturation and ferritin levels are known markers of haemochromatosis with high positive predictive values. Methods. We have retrospectively analyzed the iron studies of a cohort of 2,035 patients undergoing knee joint arthroplasty due to OA. Results. No patients had HFE gene C282Y, S65C, or H63D mutations testing. In total, 18 patients (2.96%) of the male cohort and 51 (3.58%) of the female cohort had pathologically increased ferritin levels that may be indicative of haemochromatosis. Seven patients (0.34%) had serum transferrin saturation above 45%. Conclusion. The awareness for the diagnosis of this disorder in Orthopaedics is low and needs improvement. Osteoarthritic patients undergoing knee arthroplasty should be routinely screened for haemochromatosis by iron studies and referred to genetic testing when needed. Level of evidence: Level III - Retrospective cohort study. Cite this article: Bone Jt Open 2021;2(12):1062–1066

Aims. To establish our early clinical results of a new total knee arthroplasty (TKA) tibial component introduced in 2013 and compare it to other designs in use at our hospital during the same period. Methods. This is a retrospective study of 166 (154 patients) consecutive cemented, fixed bearing, posterior-stabilized (PS) TKAs (ATTUNE) at one hospital performed by five surgeons. These were compared with a reference cohort of 511 knees (470 patients) of other designs (seven manufacturers) performed at the same hospital by the same surgeons. There were no significant differences in age, sex, BMI, or follow-up times between the two cohorts. The primary outcome was revision performed or pending. Results. In total, 19 (11.5%) ATTUNE study TKAs have been revised at a mean 30.3 months (SD 15), and loosening of the tibial component was seen in 17 of these (90%). Revision is pending in 12 (7%) knees. There was no difference between the 31 knees revised or with revision pending and the remaining 135 study knees in terms of patient characteristics, type of bone cement (p = 0.988), or individual surgeon (p = 0.550). In the reference cohort, there were significantly fewer knees revised (n = 13, 2.6%) and with revision pending (n = 8, 1.5%) (both p < 0.001), and only two had loosening of the tibial component as the reason for revision. Conclusion. This new TKA design had an unexpectedly high early rate of revision compared with our reference cohort of TKAs. Debonding of the tibial component was the most common reason for failure. Additional longer-term follow-up studies of this specific component and techniques for implantation are warranted. The version of the ATTUNE tibial component implanted in this study has undergone modifications by the manufacturer. Cite this article: Bone Joint J 2021;103-B(6 Supple A):137–144

Aims. To compare rates of serious adverse events in patients undergoing revision knee arthroplasty with consideration of the indication for revision (urgent versus elective indications), and compare these with primary arthroplasty and re-revision arthroplasty. Methods. Patients undergoing primary knee arthroplasty were identified in the national Hospital Episode Statistics (HES) between 1 April 1997 to 31 March 2017. Subsequent revision and re-revision arthroplasty procedures in the same patients and same knee were identified. The primary outcome was 90-day mortality and a logistic regression model was used to investigate factors associated with 90-day mortality and secondary adverse outcomes, including infection (undergoing surgery), pulmonary embolism, myocardial infarction, and stroke. Urgent indications for revision arthroplasty were defined as infection or fracture, and all other indications (e.g. loosening, instability, wear) were included in the elective indications cohort. Results. A total of 939,021 primary knee arthroplasty procedures were included (939,021 patients), of which 40,854 underwent subsequent revision arthroplasty, and 9,100 underwent re-revision arthroplasty. Revision surgery for elective indications was associated with a 90-day rate of mortality of 0.44% (135/30,826; 95% confidence interval (CI) 0.37 to 0.52) which was comparable to primary knee arthroplasty (0.46%; 4,292/939,021; 95% CI 0.44 to 0.47). Revision arthroplasty for infection was associated with a much higher mortality of 2.04% (184/9037; 95% CI 1.75 to 2.35; odds ratio (OR) 3.54; 95% CI 2.81 to 4.46), as was revision for periprosthetic fracture at 5.25% (52/991; 95% CI 3.94 to 6.82; OR 6.23; 95% CI 4.39 to 8.85). Higher rates of pulmonary embolism, myocardial infarction, and stroke were also observed in the infection and fracture cohort. Conclusion. Patients undergoing revision arthroplasty for urgent indications (infection or fracture) are at higher risk of mortality and serious adverse events in comparison to primary knee arthroplasty and revision arthroplasty for elective indications. These findings will be important for patient consent and shared decision-making and should inform service design for this patient cohort. Cite this article: Bone Joint J 2021;103-B(10):1578–1585

Aims. The aim of this study was to describe and compare joint-specific and generic health-related quality of life outcomes of the first versus second knee in patients undergoing staged bilateral total knee arthroplasty (BTKA) for osteoarthritis. Methods. This retrospective cohort study used Australian national arthroplasty registry data from January 2013 to January 2021 to identify participants who underwent elective staged BTKA with six to 24 months between procedures. The primary outcome was Oxford Knee Score (OKS) at six months postoperatively for the first TKA compared to the second TKA, adjusted for age and sex. Secondary outcomes compared six-month EuroQol five-dimension five-level (EQ-5D-5L) domain scores, EQ-5D index scores, and the EQ visual analogue scale (EQ-VAS) between knees at six months postoperatively. Results. The cohort included 635 participants (1,270 primary procedures). Preoperative scores were worse in the first knee compared to the second for all instruments; however, comparing the first knee at six months postoperatively with the second knee at six months postoperatively, the mean between-knee difference was minimal for OKS (-0.8 points; 95% confidence interval (CI) -1.4 to -0.2), EQ-VAS (3.3; 95% CI 1.9 to 4.7), and EQ-5D index (0.09 points; 95% CI 0.07 to 0.12). Outcomes for the EQ-5D-5L domains ‘mobility’, ‘usual activities’, and ‘pain/discomfort’ were better following the second TKA. Conclusion. At six months postoperatively, there were no clinically meaningful differences between the first and second TKA in either the joint-specific or overall generic health-related quality of life outcomes. However, individual domain scores assessing mobility, pain, and usual activities were notably higher after the second TKA, likely reflecting the cumulative improvement in quality of life after both knees have been replaced. Cite this article: Bone Jt Open 2024;5(3):202–209

Aims. Blood transfusion and postoperative anaemia are complications of total knee arthroplasty (TKA) that are associated with substantial healthcare costs, morbidity, and mortality. There are few data from large datasets on the risk factors for these complications. Methods. We retrospectively reviewed the records of TKA patients from a single tertiary care institution from February 2016 to December 2020. There were a total of 14,901 patients in this cohort with a mean age of 67.9 years (SD 9.2), and 5,575 patients (37.4%) were male. Outcomes included perioperative blood transfusion and postoperative anaemia, defined a priori as haemoglobin level < 10 g/dl measured on the first day postoperatively. In order to establish a preoperative haemoglobin cutoff, we investigated a preoperative haemoglobin level that would limit transfusion likelihood to ≤ 1% (13 g/dl) and postoperative anaemia likelihood to 4.1%. Risk factors were assessed through multivariable Poisson regression modelling with robust error variance. Results. In multivariable analyses, each gram of tranexamic acid reduced transfusion likelihood by 39% (adjusted risk ratio (ARR) 0.61 (95% confidence interval (CI) 0.47 to 0.78)). Risk factors associated with an increased risk of transfusion included operating time (ARR 2.07 (95% CI 1.54 to 2.77)) and drain use (ARR 1.73 (95% CI 1.34 to 2.24)). Conclusion. In this study, we found that increased tranexamic acid dosing, decreased operating time, and decreased drain use may reduce transfusions following TKA. We also established a single preoperative haemoglobin cutoff of 13 g/dl that could help minimize transfusions and reduce postoperative complete blood counts. Cite this article: Bone Joint J 2023;105-B(10):1086–1093

Aims. The purpose of this study was to assess mid-term survivorship following primary total knee arthroplasty (TKA) with Optetrak Logic components and identify the most common revision indications at a single institution. Methods. We identified a retrospective cohort of 7,941 Optetrak primary TKAs performed from January 2010 to December 2018. We reviewed the intraoperative findings of 369 TKAs that required revision TKA from January 2010 to December 2021 and the details of the revision implants used. Kaplan-Meier analysis was used to determine survivorship. Cox regression analysis was used to examine the impact of patient variables and year of implantation on survival time. Results. The estimated survivorship free of all-cause revision was 98% (95% confidence interval (CI) 97% to 98%), 95% (95% CI 95% to 96%), and 86% (95% CI 83% to 88%) at two, five, and ten years, respectively. In 209/369 revisions there was a consistent constellation of findings with varying severity that included polyethylene wear and associated synovitis, osteolysis, and component loosening. This failure mode, which we refer to as aseptic mechanical failure, was the most common revision indication. The mean time from primary TKA to revision for aseptic mechanical failure was five years (5 months to 11 years). Conclusion. In this series of nearly 8,000 primary TKAs performed with a specific implant, we identified a lower-than-expected mid-term survivorship and a high number of revisions with a unique presentation. This study, along with the recent recall of the implant, confirms the need for frequent monitoring of patients with Optetrak TKAs given the incidence of polyethylene failure, osteolysis, and component loosening. Cite this article: Bone Joint J 2023;105-B(3):277–283

Aims. Access to total knee arthroplasty (TKA) is sometimes restricted for patients with severe obesity (BMI ≥ 40 kg/m. 2. ). This study compares the cost per quality-adjusted life year (QALY) associated with TKA in patients with a BMI above and below 40 kg/m. 2. to examine whether this is supported. Methods. This single-centre study compared 169 consecutive patients with severe obesity (BMI ≥ 40 kg/m. 2. ) (mean age 65.2 years (40 to 87); mean BMI 44.2 kg/m. 2. (40 to 66); 129/169 female) undergoing unilateral TKA to a propensity score matched (age, sex, preoperative Oxford Knee Score (OKS)) cohort with a BMI < 40 kg/m. 2. in a 1:1 ratio. Demographic data, comorbidities, and complications to one year were recorded. Preoperative and one-year patient-reported outcome measures (PROMs) were completed: EuroQol five-dimension three-level questionnaire (EQ-5D-3L), OKS, pain, and satisfaction. Using national life expectancy data with obesity correction and the 2020 NHS National Tariff, QALYs (discounted at 3.5%), and direct medical costs accrued over a patient’s lifetime, were calculated. Probabilistic sensitivity analysis (PSA) was used to model variation in cost/QALY for each cohort across 1,000 simulations. Results. All PROMs improved significantly (p < 0.05) in both groups without differences between groups. Early complications were higher in BMI ≥ 40 kg/m. 2. : 34/169 versus 52/169 (p = 0.050). A total of 16 (9.5%) patients with a BMI ≥ 40 kg/m. 2. were readmitted within one year with six reoperations (3.6%) including three (1.2%) revisions for infection. Assuming reduced life expectancy in severe obesity and revision costs, TKA in patients with a BMI ≥ 40 kg/m. 2. costs a mean of £1,013/QALY (95% confidence interval £678 to 1,409) more over a lifetime than TKA in patients with BMI < 40 kg/m. 2. In PSA replicates, the maximum cost/QALY was £3,921 in patients with a BMI < 40 kg/m. 2. and £5,275 in patients with a BMI ≥ 40 kg/m. 2. . Conclusion. Higher complication rates following TKA in severely obese patients result in a lifetime cost/QALY that is £1,013 greater than that for patients with BMI < 40 kg/m. 2. , suggesting that TKA remains a cost-effective use of healthcare resources in severely obese patients where the surgeon considers it appropriate. Cite this article: Bone Joint J 2022;104-B(4):452–463

Aims. The aim of this study was to describe the prevalence and patterns of neuropathic pain over one year in a cohort of patients with chronic post-surgical pain at three months following total knee arthroplasty (TKA). Methods. Between 2016 and 2019, 363 patients with troublesome pain, defined as a score of ≤ 14 on the Oxford Knee Score pain subscale, three months after TKA from eight UK NHS hospitals, were recruited into the Support and Treatment After Replacement (STAR) clinical trial. Self-reported neuropathic pain and postoperative pain was assessed at three, nine, and 15 months after surgery using the painDETECT and Douleur Neuropathique 4 (DN4) questionnaires collected by postal survey. Results. Symptoms of neuropathic pain were common among patients reporting chronic pain at three months post-TKA, with half reporting neuropathic pain on painDETECT (191/363; 53%) and 74% (267/359) on DN4. Of those with neuropathic pain at three months, half continued to have symptoms over the next 12 months (148/262; 56%), one-quarter had improved (67/262; 26%), and for one-tenth their neuropathic symptoms fluctuated over time (24/262; 9%). However, a subgroup of participants reported new, late onset neuropathic symptoms (23/262; 9%). Prevalence of neuropathic symptoms was similar between the screening tools when the lower cut-off painDETECT score (≥ 13) was applied. Overall, mean neuropathic pain scores improved between three and 15 months after TKA. Conclusion. Neuropathic pain is common in patients with chronic pain at three months after TKA. Although neuropathic symptoms improved over time, up to half continued to report painful neuropathic symptoms at 15 months after TKA. Postoperative care should include screening, assessment, and treatment of neuropathic pain in patients with early chronic postoperative pain after TKA. Cite this article: Bone Joint J 2024;106-B(6):582–588

Aims. The impact of a diaphyseal femoral deformity on knee alignment varies according to its severity and localization. The aims of this study were to determine a method of assessing the impact of diaphyseal femoral deformities on knee alignment for the varus knee, and to evaluate the reliability and the reproducibility of this method in a large cohort of osteoarthritic patients. Methods. All patients who underwent a knee arthroplasty from 2019 to 2021 were included. Exclusion criteria were genu valgus, flexion contracture (> 5°), previous femoral osteotomy or fracture, total hip arthroplasty, and femoral rotational disorder. A total of 205 patients met the inclusion criteria. The mean age was 62.2 years (SD 8.4). The mean BMI was 33.1 kg/m. 2. (SD 5.5). The radiological measurements were performed twice by two independent reviewers, and included hip knee ankle (HKA) angle, mechanical medial distal femoral angle (mMDFA), anatomical medial distal femoral angle (aMDFA), femoral neck shaft angle (NSA), femoral bowing angle (FBow), the distance between the knee centre and the top of the FBow (DK), and the angle representing the FBow impact on the knee (C’KS angle). Results. The FBow impact on the mMDFA can be measured by the C’KS angle. The C’KS angle took the localization (length DK) and the importance (FBow angle) of the FBow into consideration. The mean FBow angle was 4.4° (SD 2.4; 0 to 12.5). The mean C’KS angle was 1.8° (SD 1.1; 0 to 5.8). Overall, 84 knees (41%) had a severe FBow (> 5°). The radiological measurements showed very good to excellent intraobserver and interobserver agreements. The C’KS increased significantly when the length DK decreased and the FBow angle increased (p < 0.001). Conclusion. The impact of the diaphyseal femoral deformity on the mechanical femoral axis is measured by the C’KS angle, a reliable and reproducible measurement. Cite this article: Bone Jt Open 2023;4(4):262–272

Aims. Distal femoral resection in conventional total knee arthroplasty (TKA) utilizes an intramedullary guide to determine coronal alignment, commonly planned for 5° of valgus. However, a standard 5° resection angle may contribute to malalignment in patients with variability in the femoral anatomical and mechanical axis angle. The purpose of the study was to leverage deep learning (DL) to measure the femoral mechanical-anatomical axis angle (FMAA) in a heterogeneous cohort. Methods. Patients with full-limb radiographs from the Osteoarthritis Initiative were included. A DL workflow was created to measure the FMAA and validated against human measurements. To reflect potential intramedullary guide placement during manual TKA, two different FMAAs were calculated either using a line approximating the entire diaphyseal shaft, and a line connecting the apex of the femoral intercondylar sulcus to the centre of the diaphysis. The proportion of FMAAs outside a range of 5.0° (SD 2.0°) was calculated for both definitions, and FMAA was compared using univariate analyses across sex, BMI, knee alignment, and femur length. Results. The algorithm measured 1,078 radiographs at a rate of 12.6 s/image (2,156 unique measurements in 3.8 hours). There was no significant difference or bias between reader and algorithm measurements for the FMAA (p = 0.130 to 0.563). The FMAA was 6.3° (SD 1.0°; 25% outside range of 5.0° (SD 2.0°)) using definition one and 4.6° (SD 1.3°; 13% outside range of 5.0° (SD 2.0°)) using definition two. Differences between males and females were observed using definition two (males more valgus; p < 0.001). Conclusion. We developed a rapid and accurate DL tool to quantify the FMAA. Considerable variation with different measurement approaches for the FMAA supports that patient-specific anatomy and surgeon-dependent technique must be accounted for when correcting for the FMAA using an intramedullary guide. The angle between the mechanical and anatomical axes of the femur fell outside the range of 5.0° (SD 2.0°) for nearly a quarter of patients. Cite this article: Bone Jt Open 2024;5(2):101–108

Aims. The purpose of this study is to determine an individual’s age-specific prevalence of total knee arthroplasty (TKA) after cruciate ligament surgery, and to identify clinical and genetic risk factors associated with undergoing TKA. Methods. This study was a retrospective case-control study using the UK Biobank to identify individuals reporting a history of cruciate ligament surgery. Data from verbal history and procedural codes recorded through the NHS were used to identify instances of TKA. Patient clinical and genetic data were used to identify risk factors for progression from cruciate ligament surgery to TKA. Individuals without a history of cruciate ligament reconstruction were used for comparison. Results. A total of 2,576 individuals with a history of cruciate ligament surgery were identified, with 290 (11.25%) undergoing TKA. In patients with prior cruciate ligament surgery, prevalence of TKA was 0.75% at age 45 years, 9.10% at age 65 years, and 20.43% at age 80 years. Patients with prior cruciate ligament surgery were 4.6 times more likely to have undergone TKA by age 55 years than individuals without prior cruciate ligament surgery. In the cruciate ligament surgery cohort, BMI > 30 kg/m. 2. (odds ratio (OR) 4.01 (95% confidence interval (CI) 2.74 to 5.87)), a job that always involved heavy manual or physical labour (OR 2.72 (95% CI 1.57 to 4.71)), or a job that always involved walking and standing (OR 2.58 (95% CI 1.58 to 4.20)) were associated with greater TKA odds. No single-nucleotide polymorphism (SNP) was associated with risk of TKA following cruciate ligament surgery. Conclusion. Patients with a history of prior cruciate ligament surgery have substantially higher risk of TKA and undergo arthroplasty at a relatively younger age than individuals without a history of prior cruciate ligament surgery. Physically demanding work and obesity were associated with higher odds of TKA after cruciate ligament surgery, but no SNP was associated with risk of TKA. Cite this article: Bone Joint J 2024;106-B(3):249–255

Aims. This prospective study reports longitudinal, within-patient, patient-reported outcome measures (PROMs) over a 15-year period following cemented single radius total knee arthroplasty (TKA). Secondary aims included reporting PROMs trajectory, 15-year implant survival, and patient attrition from follow-up. Methods. From 2006 to 2007, 462 consecutive cemented cruciate-retaining Triathlon TKAs were implanted in 426 patients (mean age 69 years (21 to 89); 290 (62.7%) female). PROMs (12-item Short Form Survey (SF-12), Oxford Knee Score (OKS), and satisfaction) were assessed preoperatively and at one, five, ten, and 15 years. Kaplan-Meier survival and univariate analysis were performed. Results. At 15 years, 28 patients were lost to follow-up (6.1%) and 221 patients (51.9%) had died, with the mean age of the remaining cohort reducing by four years. PROMs response rates among surviving patients were: one-year 63%; five-year 72%; ten-year 94%; and 15-year 59%. OKS and SF-12 scores changed significantly over 15 years (p < 0.001). The mean improvement in OKS was 18.8 (95% confidence (CI) 16.7 to 19.0) at one year. OKS peaked at five years (median 43 years) declining thereafter (p < 0.001), though at 15 years it remained 17.5 better than preoperatively. Age and sex did not alter this trajectory. A quarter of patients experienced a clinically significant decline (≥ 7) in OKS from five to ten years and from ten to 15 years. The SF-12 physical component score displayed a similar trajectory, peaking at one year (p < 0.001). Patient satisfaction was 88% at one, five, and ten years, and 94% at 15 years. In all, 15-year Kaplan-Meier survival was 97.6% (95% CI 96.0% to 99.2%) for any revision, and 98.9% (95% CI 97.9% to 99.9%) for aseptic revision. Conclusion. Improvements in PROMs were significant and maintained following single radius TKA, with OKS peaking at five years, and generic physical health peaking at one year. Patient satisfaction remained high at 15 years, at which point 2.4% had been revised. Cite this article: Bone Jt Open 2023;4(10):808–816

Aims. This systematic review and meta-analysis aimed to compare the influence of patellar resurfacing following cruciate-retaining (CR) and posterior-stabilized (PS) total knee arthroplasty (TKA) on the incidence of anterior knee pain, knee-specific patient-reported outcome measures, complication rates, and reoperation rates. Methods. A systematic review of MEDLINE, PubMed, and Google Scholar was performed to identify randomized controlled trials (RCTs) according to search criteria. Search terms used included: arthroplasty, replacement, knee (Mesh), TKA, prosthesis, patella, patellar resurfacing, and patellar retaining. RCTs that compared patellar resurfacing versus unresurfaced in primary TKA were included for further analysis. Studies were evaluated using the Scottish Intercollegiate Guidelines Network assessment tool for quality and minimization of bias. Data were synthesized and meta-analysis performed. Results. There were 4,135 TKAs (2,068 resurfaced and 2,027 unresurfaced) identified in 35 separate cohorts from 33 peer-reviewed studies. Anterior knee pain rates were significantly higher in unresurfaced knees overall (odds ratio (OR) 1.84; 95% confidence interval (CI) 1.20 to 2.83; p = 0.006) but more specifically associated with CR implants (OR 1.95; 95% CI 1.0 to 3.52; p = 0.030). There was a significantly better Knee Society function score (mean difference (MD) -1.98; 95% CI -1.1 to -2.84; p < 0.001) and Oxford Knee Score (MD -2.24; 95% CI -0.07 to -4.41; p = 0.040) for PS implants when patellar resurfacing was performed, but these differences did not exceed the minimal clinically important difference for these scores. There were no significant differences in complication rates or infection rates according to implant design. There was an overall significantly higher reoperation rate for unresurfaced TKA (OR 1.46 (95% CI 1.04 to 2.06); p = 0.030) but there was no difference between PS or CR TKA. Conclusion. Patellar resurfacing, when performed with CR implants, resulted in lower rates of anterior knee pain and, when used with a PS implant, yielded better knee-specific functional outcomes. Patellar resurfacing was associated with a lower risk of reoperation overall, but implant type did not influence this. Cite this article: Bone Joint J 2023;105-B(6):622–634

Aims. This study examined windswept deformity (WSD) of the knee, comparing prevalence and contributing factors in healthy and osteoarthritic (OA) cohorts. Methods. A case-control radiological study was undertaken comparing 500 healthy knees (250 adults) with a consecutive sample of 710 OA knees (355 adults) undergoing bilateral total knee arthroplasty. The mechanical hip-knee-ankle angle (mHKA), medial proximal tibial angle (MPTA), and lateral distal femoral angle (LDFA) were determined for each knee, and the arithmetic hip-knee-ankle angle (aHKA), joint line obliquity, and Coronal Plane Alignment of the Knee (CPAK) types were calculated. WSD was defined as a varus mHKA of < -2° in one limb and a valgus mHKA of > 2° in the contralateral limb. The primary outcome was the proportional difference in WSD prevalence between healthy and OA groups. Secondary outcomes were the proportional difference in WSD prevalence between constitutional varus and valgus CPAK types, and to explore associations between predefined variables and WSD within the OA group. Results. WSD was more prevalent in the OA group compared to the healthy group (7.9% vs 0.4%; p < 0.001, relative risk (RR) 19.8). There was a significant difference in means and variance between the mHKA of the healthy and OA groups (mean -1.3° (SD 2.3°) vs mean -3.8°(SD 6.6°) respectively; p < 0.001). No significant differences existed in MPTA and LDFA between the groups, with a minimal difference in aHKA (mean -0.9° healthy vs -0.5° OA; p < 0.001). Backwards logistic regression identified meniscectomy, rheumatoid arthritis, and osteotomy as predictors of WSD (odds ratio (OR) 4.1 (95% CI 1.7 to 10.0), p = 0.002; OR 11.9 (95% CI 1.3 to 89.3); p = 0.016; OR 41.6 (95% CI 5.4 to 432.9), p ≤ 0.001, respectively). Conclusion. This study found a 20-fold greater prevalence of WSD in OA populations. The development of WSD is associated with meniscectomy, rheumatoid arthritis, and osteotomy. These findings support WSD being mostly an acquired condition following skeletal maturity. Cite this article: Bone Jt Open 2024;5(10):879–885

Aims. The aims were to assess whether joint-specific outcome after total knee arthroplasty (TKA) was influenced by implant design over a 12-year follow-up period, and whether patient-related factors were associated with loss to follow-up and mortality risk. Methods. Long-term follow-up of a randomized controlled trial was undertaken. A total of 212 patients were allocated a Triathlon or a Kinemax TKA. Patients were assessed preoperatively, and one, three, eight, and 12 years postoperatively using the Oxford Knee Score (OKS). Reasons for patient lost to follow-up, mortality, and revision were recorded. Results. A total of 94 patients completed 12-year functional follow-up (62 females, mean age 66 years (43 to 82) at index surgery). There was a clinically significantly greater improvement in the OKS at one year (mean difference (MD) 3.0 (95% CI 0.4 to 5.7); p = 0.027) and three years (MD 4.7 (95% CI 1.9 to 7.5); p = 0.001) for the Triathlon group, but no differences were observed at eight (p = 0.331) or 12 years’ (p = 0.181) follow-up. When assessing the OKS in the patients surviving to 12 years, the Triathlon group had a clinically significantly greater improvement in the OKS (marginal mean 3.8 (95% CI 0.2 to 7.4); p = 0.040). Loss to functional follow-up (53%, n = 109/204) was independently associated with older age (p = 0.001). Patient mortality was the major reason (56.4%, n = 62/110) for loss to follow-up. Older age (p < 0.001) and worse preoperative OKS (p = 0.043) were independently associated with increased mortality risk. An age at time of surgery of ≥ 72 years was 75% sensitive and 74% specific for predicting mortality with an area under the curve of 78.1% (95% CI 70.9 to 85.3; p < 0.001). Conclusion. The Triathlon TKA was associated with clinically meaningful greater improvement in knee-specific outcome when compared to the Kinemax TKA. Loss to follow-up at 12 years was a limitation, and studies planning longer-term functional assessment could limit their cohort to patients aged under 72 years. Cite this article: Bone Jt Open 2024;5(10):911–919

Aims. Despite recent literature questioning their use, vancomycin and clindamycin often substitute cefazolin as the preoperative antibiotic prophylaxis in primary total knee arthroplasty (TKA), especially in the setting of documented allergy to penicillin. Topical povidone-iodine lavage and vancomycin powder (VIP) are adjuncts that may further broaden antimicrobial coverage, and have shown some promise in recent investigations. The purpose of this study, therefore, is to compare the risk of acute periprosthetic joint infection (PJI) in primary TKA patients who received cefazolin and VIP to those who received a non-cephalosporin alternative and VIP. Methods. This was a retrospective cohort study of 11,550 primary TKAs performed at an orthopaedic hospital between 2013 and 2019. The primary outcome was PJI occurring within 90 days of surgery. Patients were stratified into two groups (cefazolin vs non-cephalosporin) based on their preoperative antibiotic. All patients also received the VIP protocol at wound closure. Bivariate and multiple logistic regression analyses were performed to control for potential confounders and identify the odds ratio of PJI. Results. In all, 10,484 knees (90.8%) received cefazolin, while 1,066 knees (9.2%) received a non-cephalosporin agent (either vancomycin or clindamycin) as preoperative prophylaxis. The rate of PJI in the cefazolin group (0.5%; 48/10,484) was significantly lower than the rate of PJI in the non-cephalosporin group (1.0%; 11/1,066) (p = 0.012). After controlling for confounding variables, the odds ratio (OR) of developing a PJI was increased in the non-cephalosporin cohort compared to the cefazolin cohort (OR 2.389; 1.2 to 4.6); p = 0.01). Conclusion. Despite the use of topical irrigant solutions and addition of local antimicrobial agents, the use of a non-cephalosporin perioperative antibiotic continues to be associated with a greater risk of TKA PJI compared to cefazolin. Strategies that increase the proportion of patients receiving cefazolin rather than non-cephalosporin alternatives must be emphasized. Cite this article: Bone Jt Open 2022;3(1):35–41

Aims. Spinal anaesthesia has seen increased use in contemporary primary total knee arthroplasties (TKAs). However, controversy exists about the benefits of spinal in comparison to general anaesthesia in primary TKAs. This study aimed to investigate the pain control, length of stay (LOS), and complications associated with spinal versus general anaesthesia in primary TKAs from a single, high-volume academic centre. Methods. We retrospectively identified 17,690 primary TKAs (13,297 patients) from 2001 to 2016 using our institutional total joint registry, where 52% had general anaesthesia and 48% had spinal anaesthesia. Baseline characteristics were similar between cohorts with a mean age of 68 years (SD 10), 58% female (n = 7,669), and mean BMI of 32 kg/m. 2. (SD 7). Pain was evaluated using oral morphine equivalents (OMEs) and numerical pain rating scale (NPRS) data. Complications including 30- and 90-day readmissions were studied. Data were analyzed using an inverse probability of treatment weighted model based on propensity score that included many patient and surgical factors. Mean follow-up was seven years (2 to 18). Results. Patients treated with spinal anaesthesia required fewer postoperative OMEs (p < 0.001) and had lower NPRS scores (p < 0.001). Spinal anaesthesia also had fewer cases of altered mental status (AMS; odds ratio (OR) 1.3; p = 0.044), as well as 30-day (OR 1.4; p < 0.001) and 90-day readmissions (OR 1.5; p < 0.001). General anaesthesia was associated with increased risk of any revision (OR 1.2; p = 0.021) and any reoperation (1.3; p < 0.001). Conclusion. In the largest single institutional report to date, we found that spinal anaesthesia was associated with significantly lower OME use, lower risk of AMS, and lower overall 30- and 90-day readmissions following primary TKAs. Additionally, spinal anaesthesia was associated with reduced risk of any revision and any reoperation after accounting for numerous patient and operative factors. When possible and safe, spinal anaesthesia should be considered in primary TKAs. Cite this article: Bone Joint J 2022;104-B(11):1209–1214

Aims. While residual fixed flexion deformity (FFD) in unicompartmental knee arthroplasty (UKA) has been associated with worse functional outcomes, limited evidence exists regarding FFD changes. The objective of this study was to quantify FFD changes in patients with medial unicompartmental knee arthritis undergoing UKA, and investigate any correlation with clinical outcomes. Methods. This study included 136 patients undergoing robotic arm-assisted medial UKA between January 2018 and December 2022. The study included 75 males (55.1%) and 61 (44.9%) females, with a mean age of 67.1 years (45 to 90). Patients were divided into three study groups based on the degree of preoperative FFD: ≤ 5°, 5° to ≤ 10°, and > 10°. Intraoperative optical motion capture technology was used to assess pre- and postoperative FFD. Clinical FFD was measured pre- and postoperatively at six weeks and one year following surgery. Preoperative and one-year postoperative Oxford Knee Scores (OKS) were collected. Results. Overall, the median preoperative navigated (NAV) FFD measured 6.0° (IQR 3.1 to 8), while the median postoperative NAV FFD was 3.0° (IQR 1° to 4.4°), representing a mean correction of 49.2%. The median preoperative clinical FFD was 5° (IQR 0° to 9.75°) for the entire cohort, which decreased to 3.0° (IQR 0° to 5°) and 2° (IQR 0° to 3°) at six weeks and one year postoperatively, respectively. A statistically significant improvement in PROMs compared with baseline was evident in all groups (p < 0.001). Regression analyses showed that participants who experienced a larger FFD correction, showed greater improvement in PROMs (β = 0.609, p = 0.049; 95% CI 0.002 to 1.216). Conclusion. This study found that UKA was associated with an approximately 50% improvement in preoperative FFD across all three examined groups. Participants with greater correction of FFD also demonstrated larger OKS gains. These findings could prove a useful augment to clinical decision-making regarding candidacy for UKA and anticipated improvements in FFD

Aims. The optimal management of an infrapopliteal deep venous thrombosis (IDVT) following total knee arthroplasty (TKA) remains unknown. The risk of DVT propagation and symptom progression must be balanced against potential haemorrhagic complications associated with administration of anticoagulation therapy. The current study reports on a cohort of patients diagnosed with IDVT following TKA who were treated with aspirin, followed closely for development of symptoms, and scanned with ultrasound to determine resolution of IDVT. Methods. Among a cohort of 5,078 patients undergoing TKA, 532 patients (695 TKAs, 12.6%) developed an IDVT between 1 January 2014 to 31 December 2019 at a single institution, as diagnosed using Doppler ultrasound at the first postoperative visit. Of the entire cohort of 532 patients with IDVT, 91.4% (486/532) were treated with aspirin (325 mg twice daily) and followed closely. Repeat lower limb ultrasound was performed four weeks later to evaluate the status of IDVT. Results. Follow-up Doppler ultrasound was performed on 459/486 (94.4%) patients and demonstrated resolution of IDVT in 445/459 cases (96.9%). Doppler diagnosed propagation of IDVT to the popliteal vein had occurred in 10/459 (2.2%) cases. One patient with an IDVT developed a pulmonary embolus six weeks postoperatively. Conclusion. The results of this study demonstrate a low rate of IDVT propagation in patients managed with aspirin. Additionally, no significant bleeding episodes, wound-related complications, or other adverse events were noted from aspirin therapy. Cite this article: Bone Joint J 2021;103-B(6 Supple A):18–22

Aims. The aim of this study was to report the meaningful values of the EuroQol five-dimension three-level questionnaire (EQ-5D-3L) and EuroQol visual analogue scale (EQ-VAS) in patients undergoing primary knee arthroplasty (KA). Methods. This is a retrospective study of patients undergoing primary KA for osteoarthritis in a university teaching hospital (Royal Infirmary of Edinburgh) (1 January 2013 to 31 December 2019). Pre- and postoperative (one-year) data were prospectively collected for 3,181 patients (median age 69.9 years (interquartile range (IQR) 64.2 to 76.1); females, n = 1,745 (54.9%); median BMI 30.1 kg/m. 2. (IQR 26.6 to 34.2)). The reliability of the EQ-5D-3L was measured using Cronbach’s alpha. Responsiveness was determined by calculating the anchor-based minimal clinically important difference (MCID), the minimal important change (MIC) (cohort and individual), the patient-acceptable symptom state (PASS) predictive of satisfaction, and the minimal detectable change at 90% confidence intervals (MDC-90). Results. The EQ-5D-3L demonstrated good internal consistency with an overall Cronbach alpha of 0.75 (preoperative) and 0.88 (postoperative), respectively. The MCID for the Index score was 0.085 (95% confidence interval (CI) 0.042 to 0.127) and EQ-VAS was 6.41 (95% CI 3.497 to 9.323). The MIC. COHORT. was 0.289 for the EQ-5D and 5.27 for the EQ-VAS. However, the MIC. INDIVIDUAL. for both the EQ-5D-3L Index (0.105) and EQ-VAS (-1) demonstrated poor-to-acceptable reliability. The MDC-90 was 0.023 for the EQ-5D-3L Index and 1.0 for the EQ-VAS. The PASS for the postoperative EQ-5D-3L Index and EQ-VAS scores predictive of patient satisfaction were 0.708 and 77.0, respectively. Conclusion. The meaningful values of the EQ-5D-3L Index and EQ-VAS scores can be used to measure clinically relevant changes in health-related quality of life in patients undergoing primary KA. Cite this article: Bone Joint Res 2022;11(9):619–628

Aims. The aim of this study was to evaluate the association between chondral injury and interval from anterior cruciate ligament (ACL) tear to surgical reconstruction (ACLr). Methods. Between January 2012 and January 2022, 1,840 consecutive ACLrs were performed and included in a single-centre retrospective cohort. Exclusion criteria were partial tears, multiligament knee injuries, prior ipsilateral knee surgery, concomitant unicompartmental knee arthroplasty or high tibial osteotomy, ACL agenesis, and unknown date of tear. A total of 1,317 patients were included in the final analysis, with a median age of 29 years (interquartile range (IQR) 23 to 38). The median preoperative Tegner Activity Score (TAS) was 6 (IQR 6 to 7). Patients were categorized into four groups according to the delay to ACLr: < three months (427; 32%), three to six months (388; 29%), > six to 12 months (248; 19%), and > 12 months (254; 19%). Chondral injury was assessed during arthroscopy using the International Cartilage Regeneration and Joint Preservation Society classification, and its association with delay to ACLr was analyzed using multivariable analysis. Results. In the medial compartment, delaying ACLr for more than 12 months was associated with an increased rate (odds ratio (OR) 1.93 (95% confidence interval (CI) 1.27 to 2.95); p = 0.002) and severity (OR 1.23 (95% CI 1.08 to 1.40); p = 0.002) of chondral injuries, compared with < three months, with no association in patients aged > 50 years old. No association was found for shorter delays, but the overall dose-effect analysis was significant for the rate (p = 0.015) and severity (p = 0.026) of medial chondral injuries. Increased TAS was associated with a significantly reduced rate (OR 0.88 (95% CI 0.78 to 0.99); p = 0.036) and severity (OR 0.96 (95% CI 0.92 to 0.99); p = 0.017) of medial chondral injuries. In the lateral compartment, no association was found between delay and chondral injuries. Conclusion. Delay was associated with an increased rate and severity of medial chondral injuries in a dose-effect fashion, in particular for delays > 12 months. Younger patients seem to be at higher risk of chondral injury when delaying surgery. The timing of ACLr should be optimally reduced in this population. Cite this article: Bone Joint J 2023;105-B(9):953–960

Aims. A novel enhanced cement fixation (EF) tibial implant with deeper cement pockets and a more roughened bonding surface was released to market for an existing total knee arthroplasty (TKA) system.This randomized controlled trial assessed fixation of the both the EF (ATTUNE S+) and standard (Std; ATTUNE S) using radiostereometric analysis. Methods. Overall, 50 subjects were randomized (21 EF-TKA and 23 Std-TKA in the final analysis), and had follow-up visits at six weeks, and six, 12, and 24 months to assess migration of the tibial component. Low viscosity bone cement with tobramycin was used in a standardized fashion for all subjects. Patient-reported outcome measure data was captured at preoperative and all postoperative visits. Results. The patient cohort mean age was 66 years (SD seven years), 59% were female, and the mean BMI was 32 kg/m. 2. (SD 6 kg/m. 2. ). Mean two-year subsidence of the EF-TKA was 0.056 mm (95% confidence interval (CI) 0.025 to 0.086) versus 0.006 mm (95% CI -0.029 to 0.040) for the Std-TKA, and the two-year maximum total point motion (MTPM) was 0.285 mm (95% upper confidence limit (UCL) ≤ 0.363) versus 0.346 mm (95% UCL ≤ 0.432), respectively, for a mean difference of -0.061 mm (95% CI -0.196 to 0.074). Inducible displacement also did not differ between groups. The MTPMs between 12 and 24 months for each group was below the published threshold of 0.2 mm for predicting early aseptic loosening (p < 0.001 and p = 0.001, respectively). Conclusion. Both the enhanced fixation and the standard tibial implant design showed fixation with a predicted low risk of long-term aseptic loosening. Cite this article: Bone Jt Open 2024;5(1):20–27

Aims. The surgical target for optimal implant positioning in robotic-assisted total knee arthroplasty remains the subject of ongoing discussion. One of the proposed targets is to recreate the knee’s functional behaviour as per its pre-diseased state. The aim of this study was to optimize implant positioning, starting from mechanical alignment (MA), toward restoring the pre-diseased status, including ligament strain and kinematic patterns, in a patient population. Methods. We used an active appearance model-based approach to segment the preoperative CT of 21 osteoarthritic patients, which identified the osteophyte-free surfaces and estimated cartilage from the segmented bones; these geometries were used to construct patient-specific musculoskeletal models of the pre-diseased knee. Subsequently, implantations were simulated using the MA method, and a previously developed optimization technique was employed to find the optimal implant position that minimized the root mean square deviation between pre-diseased and postoperative ligament strains and kinematics. Results. There were evident biomechanical differences between the simulated patient models, but also trends that appeared reproducible at the population level. Optimizing the implant position significantly reduced the maximum observed strain root mean square deviations within the cohort from 36.5% to below 5.3% for all but the anterolateral ligament; and concomitantly reduced the kinematic deviations from 3.8 mm (SD 1.7) and 4.7° (SD 1.9°) with MA to 2.7 mm (SD 1.4) and 3.7° (SD 1.9°) relative to the pre-diseased state. To achieve this, the femoral component consistently required translational adjustments in the anterior, lateral, and proximal directions, while the tibial component required a more posterior slope and varus rotation in most cases. Conclusion. These findings confirm that MA-induced biomechanical alterations relative to the pre-diseased state can be reduced by optimizing the implant position, and may have implications to further advance pre-planning in robotic-assisted surgery in order to restore pre-diseased knee function. Cite this article: Bone Joint J 2024;106-B(11):1231–1239

Aims. Outcomes of current operative treatments for arthrofibrosis after total knee arthroplasty (TKA) are not consistently positive or predictable. Pharmacological in vivo studies have focused mostly on prevention of arthrofibrosis. This study used a rabbit model to evaluate intra-articular (IA) effects of celecoxib in treating contracted knees alone, or in combination with capsular release. Methods. A total of 24 rabbits underwent contracture-forming surgery with knee immobilization followed by remobilization surgery at eight weeks. At remobilization, one cohort underwent capsular release (n = 12), while the other cohort did not (n = 12). Both groups were divided into two subcohorts (n = 6 each) – one receiving IA injections of celecoxib, and the other receiving injections of vehicle solution (injections every day for two weeks after remobilization). Passive extension angle (PEA) was assessed in live rabbits at 10, 16, and 24 weeks, and disarticulated limbs were analyzed for capsular stiffness at 24 weeks. Results. IA celecoxib resulted in greater mean PEA at ten weeks (69.6° (SD 4.6) vs 45.2° (SD 9.6), p = 0.004), 16 weeks (109.8° (SD 24.2) vs 60.9° (SD10.9), p = 0.004), and 24 weeks (101.0° (SD 8.0) vs 66.3° (SD 5.8), p = 0.004). Capsular stiffness was significantly reduced with IA celecoxib (2.72 Newton per cm (N·cm)/° (SD 1.04), p = 0.008), capsular release (2.41 N·cm/° (SD 0.80), p = 0.008), and capsular release combined with IA celecoxib (3.56 N·cm/° (SD 0.99), p = 0.018) relative to IA vehicle (6.09 N·cm/° (SD 1.64)). Conclusion. IA injections of a celecoxib led to significant improvements in passive extension angles, with reduced capsular stiffness, when administered to rabbit knees with established experimental contracture. Celecoxib was superior to surgical release, and the combination of celecoxib and a surgical release did not provide any additional value. Cite this article: Bone Joint Res 2022;11(1):32–39

Aims. The aim of this study was to determine the long-term mortality rate, and to identify factors associated with this, following primary and revision knee arthroplasty (KA). Methods. Data from the Scottish Arthroplasty Project (1998 to 2019) were retrospectively analyzed. Patient mortality data were linked from the National Records of Scotland. Analyses were performed separately for the primary and revised KA cohorts. The standardized mortality ratio (SMR) with 95% confidence intervals (CIs) was calculated for the population at risk. Multivariable Cox proportional hazards were used to identify predictors and estimate relative mortality risks. Results. At a median 7.4 years (interquartile range (IQR) 4.0 to 11.6) follow-up, 27.8% of primary (n = 27,474/98,778) and 31.3% of revision (n = 2,611/8,343) KA patients had died. Both primary and revision cohorts had lower mortality rates than the general population (SMR 0.74 (95% CI 0.73 to 0.74); p < 0.001; SMR 0.83 (95% CI 0.80 to 0.86); p < 0.001, respectively), which persisted for 12 and eighteight years after surgery, respectively. Factors associated with increased risk of mortality after primary KA included male sex (hazard ratio (HR) 1.40 (95% CI 1.36 to 1.45)), increasing socioeconomic deprivation (HR 1.43 (95% CI 1.36 to 1.50)), inflammatory polyarthropathy (HR 1.79 (95% CI 1.68 to 1.90)), greater number of comorbidities (HR 1.59 (95% CI 1.51 to 1.68)), and periprosthetic joint infection (PJI) requiring revision (HR 1.92 (95% CI 1.57 to 2.36)) when adjusting for age. Similarly, male sex (HR 1.36 (95% CI 1.24 to 1.49)), increasing socioeconomic deprivation (HR 1.31 (95% CI 1.12 to 1.52)), inflammatory polyarthropathy (HR 1.24 (95% CI 1.12 to 1.37)), greater number of comorbidities (HR 1.64 (95% CI 1.33 to 2.01)), and revision for PJI (HR 1.35 (95% 1.18 to 1.55)) were independently associated with an increased risk of mortality following revision KA when adjusting for age. Conclusion. The SMR of patients undergoing primary and revision KA was lower than that of the general population and remained so for several years post-surgery. However, approximately one in four patients undergoing primary and one in three patients undergoing revision KA died within tenten years of surgery. Several patient and surgical factors, including PJI, were associated with the risk of mortality within ten years of primary and revision surgery. Cite this article: Bone Joint J 2022;104-B(1):45–52

Aims. We have previously reported the mid-term outcomes of revision total knee arthroplasty (TKA) for flexion instability. At a mean of four years, there were no re-revisions for instability. The aim of this study was to report the implant survivorship and clinical and radiological outcomes of the same cohort of of patients at a mean follow-up of ten years. Methods. The original publication included 60 revision TKAs in 60 patients which were undertaken between 2000 and 2010. The mean age of the patients at the time of revision TKA was 65 years, and 33 (55%) were female. Since that time, 21 patients died, leaving 39 patients (65%) available for analysis. The cumulative incidence of any re-revision with death as a competing risk was calculated. Knee Society Scores (KSSs) were also recorded, and updated radiographs were reviewed. Results. The cumulative incidence of any re-revision was 13% at a mean of ten years. At the most recent-follow-up, eight TKAs had been re-revised: three for recurrent flexion instability (two fully revised to varus-valgus constrained implants (VVCs), and one posterior-stabilized (PS) implant converted to VVC, one for global instability (PS to VVC), two for aseptic loosening of the femoral component, and two for periprosthetic joint infection). The ten-year cumulative incidence of any re-revision for instability was 7%. The median KSS improved significantly from 45 (interquartile range (IQR) 40 to 50) preoperatively to 70 (IQR 45 to 80) at a mean follow-up of ten years (p = 0.031). Radiologically, two patients, who had not undergone revision, had evidence of loosening (one tibial and one patellar). The remaining components were well fixed. Conclusion. We found fair functional outcomes and implant survivorship at a mean of ten years after revision TKA for flexion instability with a PS implant. Recurrent instability and aseptic loosening were the most common indications for re-revision. Components with increased constraint, such as a VVC or hinged, should be used in these patients in order to reduce the risk of recurrent instability. Cite this article: Bone Joint J 2022;104-B(10):1126–1131

Aims. Aseptic loosening of the tibial component is a frequent cause of failure in primary total knee arthroplasty (TKA). Management options include an isolated tibial revision or full component revision. A full component revision is frequently selected by surgeons unfamiliar with the existing implant or who simply wish to “start again”. This option adds morbidity compared with an isolated tibial revision. While isolated tibial revision has a lower morbidity, it is technically more challenging due to difficulties with exposure and maintaining prosthetic stability. This study was designed to compare these two reconstructive options. Methods. Patients undergoing revision TKA for isolated aseptic tibial loosening between 2012 and 2017 were identified. Those with revision implants or revised for infection, instability, osteolysis, or femoral component loosening were excluded. A total of 164 patients were included; 88 had an isolated tibial revision and 76 had revision of both components despite only having a loose tibial component. The demographics and clinical and radiological outcomes were recorded. Results. The patient demographics were statistically similar in the two cohorts. The median follow-up was 3.5 years (interquartile range (IQR) 1 to 12.5). Supplementary femoral metaphyseal fixation was required in five patients in the full revision cohort. There was a higher incidence of radiological tibial loosening in the full component revision cohort at the final follow-up (8 (10.5%) vs 5 (5.7%); p = 0.269). Three patients in the full component revision cohort developed instability while only one in the isolated tibial cohort did. Three patients in the full revision cohort developed a flexion contracture greater than 5° while none in the isolated tibial cohort did. Conclusion. Isolated tibial revision for aseptic tibial loosening has statistically similar clinical and radiological outcomes at a median follow-up of 3.5 years, when compared with full component revision. Substantial bone loss can occur when removing a well-fixed femoral component necessitating a cone or sleeve. Femoral component revision for isolated tibial loosening can frequently be avoided provided adequate ligamentous stability can be obtained. Cite this article: Bone Joint J 2020;102-B(6 Supple A):123–128

Aims. The aim of this study was to identify the minimal clinically important difference (MCID), minimal important change (MIC), minimal detectable change (MDC), and patient-acceptable symptom state (PASS) threshold in the Forgotten Joint Score (FJS) according to patient satisfaction six months following total knee arthroplasty (TKA). Methods. During a one-year period 484 patients underwent a primary TKA and completed preoperative and six-month FJS and OKS. At six months patients were asked, “How satisfied are you with your operated knee?” Their response was recorded as: very satisfied, satisfied, neutral, dissatisfied, or very dissatisfied. The difference between patients recording neutral (n = 44) and satisfied (n = 153) was used to define the MCID. MIC for a cohort was defined as the change in the FJS for those patients declaring their outcome as satisfied, whereas receiver operating characteristic curve analysis was used to determine the MIC for an individual and the PASS threshold. Distribution-based methodology was used to calculate the MDC. Results. Using satisfaction as the anchor question, the MCID for the FJS was 16.6 (95% confidence interval (CIs) 8.9 to 24.3; p < 0.001) and when adjusting for confounding this decreased to 13.7 points (95% CI 4.8 to 22.5; p < 0.001). The MIC for the FJS for a cohort of patients was 17.7 points and for an individual patient was 10 points. The MDC90 for the FGS was 12 points; where 90% of patients scoring more than this will have experienced a real change that is beyond measurement error. The PASS was defined as 22 points or more in the postoperative FJS. Conclusion. The estimates for MCID and MIC can be used to assess whether there is clinical difference between two groups and whether a cohort/patient has had a meaningful change in their FJS, respectively. The MDC90 of 12 points suggests a value lower than this may fall within measurement error. A postoperative FJS of 22 or more was predictive of achieving PASS. Cite this article: Bone Joint J 2021;103-B(5):846–854

Aims. The purpose of this investigation was to determine the relationship between height, weight, and sex with implant size in total knee arthroplasty (TKA) using a multivariate linear regression model and a Bayesian model. Methods. A retrospective review of an institutional registry was performed of primary TKAs performed between January 2005 and December 2016. Patient demographics including patient age, sex, height, weight, and body mass index (BMI) were obtained from registry and medical record review. In total, 8,100 primary TKAs were included. The mean age was 67.3 years (SD 9.5) with a mean BMI of 30.4 kg/m. 2. (SD 6.3). The TKAs were randomly split into a training cohort (n = 4,022) and a testing cohort (n = 4,078). A multivariate linear regression model was created on the training cohort and then applied to the testing cohort . A Bayesian model was created based on the frequencies of implant sizes in the training cohort. The model was then applied to the testing cohort to determine the accuracy of the model at 1%, 5%, and 10% tolerance of inaccuracy. Results. Height had a relatively strong correlation with implant size (femoral component anteroposterior (AP) Pearson correlation coefficient (ρ) = 0.73, p < 0.001; tibial component mediolateral (ML) ρ = 0.77, p < 0.001). Weight had a moderately strong correlation with implant size, (femoral component AP ρ = 0.46, p < 0.001; tibial ML ρ = 0.48, p < 0.001). There was a significant linear correlation with height, weight, and sex with implant size (femoral component R. 2. = 0.607, p < 0.001; tibial R. 2. = 0.695, p < 0.001). The Bayesian model showed high accuracy in predicting the range of required implant sizes (94.4% for the femur and 96.6% for the tibia) accepting a 5% risk of inaccuracy. Conclusion. Implant size was correlated with basic demographic variables including height, weight, and sex. The linear regression and Bayesian models accurately predicted required implant sizes across multiple manufacturers based on height, weight, and sex alone. These types of predictive models may help improve operating room and implant supply chain efficiency. Level of Evidence: Level IV. Cite this article: Bone Joint J 2020;102-B(6 Supple A):85–90

Aims. The aim of this study was to screen the entire genome for genetic markers associated with risk for anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) injury. Methods. Genome-wide association (GWA) analyses were performed using data from the Kaiser Permanente Research Board (KPRB) and the UK Biobank. ACL and PCL injury cases were identified based on electronic health records from KPRB and the UK Biobank. GWA analyses from both cohorts were tested for ACL and PCL injury using a logistic regression model adjusting for sex, height, weight, age at enrolment, and race/ethnicity using allele counts for single nucleotide polymorphisms (SNPs). The data from the two GWA studies were combined in a meta-analysis. Candidate genes previously reported to show an association with ACL injury in athletes were also tested for association from the meta-analysis data from the KPRB and the UK Biobank GWA studies. Results. There was a total of 2,214 cases of ACL and PCL injury and 519,869 controls within the two cohorts, with three loci demonstrating a genome-wide significant association in the meta-analysis: INHBA, AEBP2, and LOC101927869. Of the eight candidate genes previously studied in the literature, six were present in the current dataset, and only COL3A1 (rs1800255) showed a significant association (p = 0.006). Conclusion. Genetic markers in three novel loci in this study and one previously-studied candidate gene were identified as potential risk factors for ACL and PCL injury and deserve further validation and investigation of molecular mechanisms. Cite this article: Bone Jt Open 2021;2(6):414–421

Aims. Meniscal allograft transplantation (MAT) for patients with symptomatic meniscal loss has demonstrated good clinical results and survivorship. Factors that affect both functional outcome and survivorship have been reported in the literature. These are typically single-centre case series with relatively small numbers and conflicting results. Our aim was to describe an international, two-centre case series, and identify factors that affect both functional outcome and survival. Methods. We report factors that affect outcome on 526 patients undergoing MAT across two sites (one in the UK and one in Italy). Outcomes of interest were the Knee injury and Osteoarthritis Outcome Score four (KOOS4) at two years and failure rates. We performed multiple regression analysis to examine for factors affecting KOOS, and Cox proportional hazards models for survivorship. Results. Our results indicate that baseline KOOS4 score affects functional outcome at two years, but no other included factors were significantly related to functional outcome. The only factor that affected failure rate was the presence of cartilage lesions down to bone on both the femur and tibia, decreasing the five-year survivorship from 95% (95% confidence interval (CI) 91 to 99) to 84% (95% CI 74 to 94). Conclusion. To our knowledge, this is the largest international cohort reporting on MAT. Our results indicate that factors such as age, BMI, and cartilage lesions down to bone on both the femur and tibia of the affected compartment should not present barriers to offering MAT. Baseline KOOS4 score and the presence of bone-on-bone arthritis can be used to help counsel patients regarding the expected risks and rewards of surgery. Cite this article: Bone Joint J 2022;104-B(6):657–662

Aims. Treatment of end-stage anteromedial osteoarthritis (AMOA) of the knee is commonly approached using one of two surgical strategies: medial unicompartmental knee arthroplasty (UKA) or total knee arthroplasty (TKA). In this study we aim to investigate if there is any difference in outcome for patients undergoing UKA or TKA, when treated by high-volume surgeons, in high-volume centres, using two different clinical guidelines. The two strategies are ‘UKA whenever possible’ vs TKA for all patients with AMOA. Methods. A total of 501 consecutive AMOA patients (301 UKA) operated on between 2013 to 2016 in two high-volume centres were included. Centre One employed clinical guidelines for the treatment of AMOA allowing either UKA or TKA, but encouraged UKA wherever possible. Centre Two used clinical guidelines that treated all patients with a TKA, regardless of wear pattern. TKA patients were included if they had isolated AMOA on preoperative radiographs. Data were collected from both centres’ local databases. The primary outcome measure was change in Oxford Knee Score (OKS), and the proportion of patients achieving the patient-acceptable symptom state (PASS) at one-year follow-up. The data were 1:1 propensity score matched before regression models were used to investigate potential differences. Results. The matched cohort included 400 patients (mean age 67 years (SD 9.55), 213 (53%) female, mean BMI 30.2 kg/m. 2. , 337 (84%) American Society of Anesthesiologists grade ≤ 2). We found a mean adjusted difference in change score of 3.02 points (95% confidence interval (CI) 1.41 to 4.63; p < 0.001) and a significantly larger likeliness of achieving PASS (odds ratio 3.67 (95% CI 1.73 to 8.45); p = 0.001) both in favour of the UKA strategy. Conclusion. UKA and TKA are both good strategies for treating end-stage AMOA. However, when compared as a strategy, UKA achieved larger improvements in OKS, and were more likely to reach the PASS value at one-year follow-up. Cite this article: Bone Jt Open 2022;3(5):441–447

Aims. Tibial cones are often utilized in revision total knee arthroplasty (TKA) with metaphyseal defects. Because there are few studies evaluating mid-term outcomes with a sufficient cohort, the purpose of this study was to evaluate tibial cone survival and complications in revision TKAs with tibial cones at minimum follow-up of five years. Methods. A retrospective review was completed from September 2006 to March 2015, evaluating 67 revision TKAs (64 patients) that received one specific porous tibial cone during revision TKA. The final cohort was composed of 62 knees (59 patients) with five years of clinical follow-up or reoperation. The mean clinical follow-up of the TKAs with minimum five-year clinical follow-up was 7.6 years (5.0 to 13.3). Survivorship analysis was performed with the endpoints of tibial cone revision for aseptic loosening, tibial cone revision for any reason, and reoperation. We also evaluated periprosthetic joint infection (PJI), risk factors for failure, and performed a radiological review. Results. The rate of cone revision for aseptic loosening was 6.5%, with an eight-year survival of 95%. Significant bone loss (Anderson Orthopaedic Research Institute grade 3) was associated with cone revision for aseptic loosening (p = 0.002). The rate of cone revision for any reason was 17.7%, with an eight-year survival of 84%. Sixteen percent of knees developed PJI following revision. A pre-revision diagnosis of reimplantation as part of a two-stage exchange protocol for infection was associated with both PJI (p < 0.001) and tibial cone revision (p = 0.001). Conclusion. Mid-term results of tibial cones showed a survivorship free of cone revision for aseptic loosening of 95%. Patients with significant bone loss were more likely to have re-revision for tibial cone failure. Infection was common, and patients receiving cones at reimplantation were more likely to develop PJI and undergo cone revision. Cite this article: Bone Joint J 2021;103-B(6 Supple A):158–164

Aims. The aim of this study was to compare ten-year longitudinal healthcare costs and revision rates for patients undergoing unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA). Methods. The Humana database was used to compare 2,383 patients undergoing UKA between 2007 and 2009, who were matched 1:1 from a cohort of 63,036 patients undergoing primary TKA based on age, sex, and Elixhauser Comorbidity Index. Medical and surgical complications were tracked longitudinally for one year following surgery. Rates of revision surgery and cumulative mean healthcare costs were recorded for this period of time and compared between the cohorts. Results. Patients undergoing TKA had significantly higher rates of manipulation under anaesthesia (3.9% vs 0.9%; p < 0.001), deep vein thrombosis (5.0% vs 3.1%; p < 0.001), pulmonary embolism (1.5% vs 0.8%; p = 0.001), and renal failure (4.2% vs 2.2%; p < 0.001). Revision rates, however, were significantly higher for UKA at five years (6.0% vs 4.2%; p = 0.007) and ten years postoperatively (6.5% vs 4.4%; p = 0.002). Longitudinal-related healthcare costs for patients undergoing TKA were greater than for those undergoing UKA at one year ($24,771 vs $22,071; p < 0.001) and five years following surgery ($26,549 vs $25,730; p < 0.001); however, the mean costs of TKA were comparable to UKA at ten years ($26,877 vs $26,891; p = 0.425). Conclusion. Despite higher revision rates, patients undergoing UKA had lower mean healthcare costs than those undergoing TKA up to ten years following the procedure, at which time costs were comparable. In the era of value-based care, surgeons and policymakers should be aware of the costs involved with these procedures. UKA was associated with fewer complications at one year postoperatively but higher revision rates at five and ten years. While UKA was significantly less costly than TKA at one and five years, costs at ten years were comparable with a mean difference of only $14. Lowering the risk of revision surgery should be targeted as a source of cost savings for both UKA and TKA as the mean related healthcare costs were 2.5-fold higher in patients requiring revision surgery. Cite this article: Bone Joint J 2021;103-B(6 Supple A):23–31

Aims. Alternative alignment concepts, including kinematic and restricted kinematic, have been introduced to help improve clinical outcomes following total knee arthroplasty (TKA). The purpose of this study was to evaluate the clinical results, along with patient satisfaction, following TKA using the concept of restricted kinematic alignment. Methods. A total of 121 consecutive TKAs performed between 11 February 2018 to 11 June 2019 with preoperative varus deformity were reviewed at minimum one-year follow-up. Three knees were excluded due to severe preoperative varus deformity greater than 15°, and a further three due to requiring revision surgery, leaving 109 patients and 115 knees to undergo primary TKA using the concept of restricted kinematic alignment with advanced technology. Patients were stratified into three groups based on the preoperative limb varus deformity: Group A with 1° to 5° varus (43 knees); Group B between 6° and 10° varus (56 knees); and Group C with varus greater than 10° (16 knees). This study group was compared with a matched cohort of 115 TKAs and 115 patients using a neutral mechanical alignment target with manual instruments performed from 24 October 2016 to 14 January 2019. Results. Mean overall patient satisfaction for the entire cohort was 4.7 (SE 0.1) on a 5-point Likert scale, with 93% being either very satisfied or satisfied compared with a Likert of 4.3 and patient satisfaction of 81% in the mechanical alignment group (p < 0.001 and p < 0.006 respectively). At mean follow-up of 17 months (11 to 27), the mean overall Likert, Knee Injury and Osteoarthritis Outcome Score for Joint Replacement, Western Ontario and McMaster Universities Osteoarthritis Index, Forgotten Joint Score, and Knee Society Knee and Function Scores were significantly better in the kinematic group than in the neutral mechanical alignment group. The most common complication in both groups was contracture requiring manipulation under anaesthesia, involving seven knees (6.1%) in the kinematic group and nine knees (7.8%) in the mechanical alignment group. Conclusion. With the advent of advanced technology, and the ability to obtain accurate bone cuts, the target limb alignment, and soft-tissue balance within millimetres, using a restricted kinematic alignment concept demonstrated excellent patient satisfaction following primary TKA. Longer-term analysis is required as to the durability of this method. Cite this article: Bone Joint J 2021;103-B(6 Supple A):59–66

Aims. The aim of this study was to compare any differences in the primary outcome (biphasic flexion knee moment during gait) of robotic arm-assisted bi-unicompartmental knee arthroplasty (bi-UKA) with conventional mechanically aligned total knee arthroplasty (TKA) at one year post-surgery. Methods. A total of 76 patients (34 bi-UKA and 42 TKA patients) were analyzed in a prospective, single-centre, randomized controlled trial. Flat ground shod gait analysis was performed preoperatively and one year postoperatively. Knee flexion moment was calculated from motion capture markers and force plates. The same setup determined proprioception outcomes during a joint position sense test and one-leg standing. Surgery allocation, surgeon, and secondary outcomes were analyzed for prediction of the primary outcome from a binary regression model. Results. Both interventions were shown to be effective treatment options, with no significant differences shown between interventions for the primary outcome of this study (18/35 (51.4%) biphasic TKA patients vs 20/31 (64.5%) biphasic bi-UKA patients; p = 0.558). All outcomes were compared to an age-matched, healthy cohort that outperformed both groups, indicating residual deficits exists following surgery. Logistic regression analysis of primary outcome with secondary outcomes indicated that the most significant predictor of postoperative biphasic knee moments was preoperative knee moment profile and trochlear degradation (Outerbridge) (R. 2. = 0.381; p = 0.002, p = 0.046). A separate regression of alignment against primary outcome indicated significant bi-UKA femoral and tibial axial alignment (R. 2. = 0.352; p = 0.029), and TKA femoral sagittal alignment (R. 2. = 0.252; p = 0.016). The bi-UKA group showed a significant increased ability in the proprioceptive joint position test, but no difference was found in more dynamic testing of proprioception. Conclusion. Robotic arm-assisted bi-UKA demonstrated equivalence to TKA in achieving a biphasic gait pattern after surgery for osteoarthritis of the knee. Both treatments are successful at improving gait, but both leave the patients with a functional limitation that is not present in healthy age-matched controls. Cite this article: Bone Joint J 2022;103-B(4):433–443

Aims. The Coronal Plane Alignment of the Knee (CPAK) classification is a simple and comprehensive system for predicting pre-arthritic knee alignment. However, when the CPAK classification is applied in the Asian population, which is characterized by more varus and wider distribution in lower limb alignment, modifications in the boundaries of arithmetic hip-knee-ankle angle (aHKA) and joint line obliquity (JLO) should be considered. The purposes of this study were as follows: first, to propose a modified CPAK classification based on the actual joint line obliquity (aJLO) and wider range of aHKA in the Asian population; second, to test this classification in a cohort of Asians with healthy knees; third, to propose individualized alignment targets for different CPAK types in kinematically aligned (KA) total knee arthroplasty (TKA). Methods. The CPAK classification was modified by changing the neutral boundaries of aHKA to 0° ± 3° and using aJLO as a new variable. Radiological analysis of 214 healthy knees in 214 Asian individuals was used to assess the distribution and mean value of alignment angles of each phenotype among different classifications based on the coronal plane. Individualized alignment targets were set according to the mean lateral distal femoral angle (LDFA) and medial proximal tibial angle (MPTA) of different knee types. Results. A very high concentration, 191 from 214 individuals (89.3%), were found in knee types with apex distal JLO when the CPAK classification was applied in the Asian population. By using aJLO as a new variable, the high distribution percentage in knee types with apex distal JLO decreased to 125 from 214 individuals (58.4%). The most common types in order were Type II (n = 70; 32.7%), Type V (n = 55; 25.7%), and Type I (n = 46; 21.5%) in the modified CPAK classification. Conclusion. The modified CPAK classification corrected the uneven distribution when applying the CPAK classification in the Asian population. Setting individualized TKA alignment targets according to CPAK type may be a practical method to recreate optimal LDFA and MPTA in KA-TKA. Cite this article: Bone Jt Open 2022;3(3):211–217

Aims. The aim of this study was to assess the effects of transferring patients to a specialized arthroplasty centre between the first and second stages (interstage) of prosthetic joint infection (PJI) of the knee. Patients and Methods. A search of our institutional database was performed to identify patients having undergone two-stage revision total knee arthroplasty (TKA) for PJI. Two cohorts were created: continuous care (CC) and transferred care (TC). Baseline characteristics and outcomes were collected and compared between cohorts. Results. A total of 137 patients were identified: 105 in the CC cohort (56 men, 49 women; mean age 67.9) and 32 in the TC cohort (17 men, 15 women; mean age 67.8 years). PJI organism virulence was greater in the CC cohort (36.2% vs 15.6%; p = 0.030). TC patients had a higher rate of persisting or recurrent infection (53.6% vs 13.4%; p < 0.001), soft-tissue complications (31.3 vs 14.3%; p = 0.030), and reduced requirement for porous metal augments (78.1% vs 94.3%; p = 0.006). Repeat first stage debridement after transfer led to greater need for plastic surgical procedures (58.3% vs 0.0%; p < 0.001). Conclusion. Patient transfer during the interstage of treatment for infected TKA leads to poorer outcomes compared with patients receiving all their treatment at a specialized arthroplasty centre. Cite this article: Bone Joint J 2019;101-B:1087–1092

Aims. There is limited information on outcomes of revision ACL reconstruction (rACLR) in soccer (association football) athletes, particularly on return to sport and the rate of additional knee surgery. The purpose of this study was to report return to soccer after rACLR, and to test the hypothesis that patient sex and graft choice are associated with return to play and the likelihood of future knee surgery in soccer players undergoing rACLR. Methods. Soccer athletes enrolled in a prospective multicentre cohort were contacted to collect ancillary data on their participation in soccer and their return to play following rACLR. Information regarding if and when they returned to play and their current playing status was recorded. If they were not currently playing soccer, they were asked the primary reason they stopped playing. Information on any subsequent knee surgery following their index rACLR was also collected. Player demographic data and graft choice were collected from their baseline enrolment data at rACLR. Results. Soccer-specific follow-up was collected on 76% (33 male, 39 female) of 95 soccer athletes. Subsequent surgery information was collected on 95% (44 male, 46 female). Overall, 63% of athletes returned to soccer a mean 9.6 months (SD 5.8) after index revision surgery but participation in soccer decreased to 19% at a mean of 6.4 years (SD 1.3) after surgery. There was no significant association of patient sex or graft choice with return to play, time of return to play, or long-term return to play. Females were more likely than males to have subsequent knee surgery following rACLR (20% (9/46) vs 5% (2/44); p = 0.050). The rate of recurrent graft tear (5.6%; 5/90) was similar between males and females. Conclusion. Approximately two-thirds of soccer players return to sport after rACLR, but the rate of participation drops significantly over time. Neither patient sex nor graft choice at the time of rACLR were associated with return to play. Female soccer players face a higher risk for additional knee surgery after rACLR than male soccer players. Cite this article: Bone Jt Open 2021;2(12):1043–1048

Aims. There are comparatively few randomized studies evaluating knee arthroplasty prostheses, and fewer still that report longer-term functional outcomes. The aim of this study was to evaluate mid-term outcomes of an existing implant trial cohort to document changing patient function over time following total knee arthroplasty using longitudinal analytical techniques and to determine whether implant design chosen at time of surgery influenced these outcomes. Methods. A mid-term follow-up of the remaining 125 patients from a randomized cohort of total knee arthroplasty patients (initially comprising 212 recruited patients), comparing modern (Triathlon) and traditional (Kinemax) prostheses was undertaken. Functional outcomes were assessed with the Oxford Knee Score (OKS), knee range of movement, pain numerical rating scales, lower limb power output, timed functional assessment battery, and satisfaction survey. Data were linked to earlier assessment timepoints, and analyzed by repeated measures analysis of variance (ANOVA) mixed models, incorporating longitudinal change over all assessment timepoints. Results. The mean follow-up of the 125 patients was 8.12 years (7.3 to 9.4). There was a reduction in all assessment parameters relative to earlier assessments. Longitudinal models highlight changes over time in all parameters and demonstrate large effect sizes. Significant between-group differences were seen in measures of knee flexion (medium-effect size), lower limb power output (large-effect size), and report of worst daily pain experienced (large-effect size) favouring the Triathlon group. No longitudinal between-group differences were observed in mean OKS, average daily pain report, or timed performance test. Satisfaction with outcome in surviving patients at eight years was 90.5% (57/63) in the Triathlon group and 82.8% (48/58) in the Kinemax group, with no statistical difference between groups (p = 0.321). Conclusion. At a mean 8.12 years, this mid-term follow-up of a randomized controlled trial cohort highlights a general reduction in measures of patient function with patient age and follow-up duration, and a comparative preservation of function based on implant received at time of surgery. Cite this article: Bone Joint J 2020;102-B(4):434–441

Introduction. The primary aim of this study was to describe a baseline comparison of early knee-specific functional outcomes following revision total knee arthroplasty (TKA) using metaphyseal sleeves with a matched cohort of patients undergoing primary TKA. The secondary aim was to compare incidence of complications and length of stay (LOS) between the two groups. Methods. Patients undergoing revision TKA for all diagnoses between 2009 and 2016 had patient-reported outcome measures (PROMs) collected prospectively. PROMs consisted of the American Knee Society Score (AKSS) and Short-Form 12 (SF-12). The study cohort was identified retrospectively and demographics were collected. The cohort was matched to a control group of patients undergoing primary TKA. Results. Overall, 72 patients underwent revision TKA and were matched with 72 primary TKAs with a mean follow-up of 57 months (standard deviation (SD) 20 months). The only significant difference in postoperative PROMs was a worse AKSS pain score in the revision group (36 vs 44, p = 0.002); however, these patients still produced an improvement in the pain score. There was no significant difference in improvement of AKSS or SF-12 between the two groups. LOS (9.3 days vs 4.6 days) and operation time (1 hour 56 minutes vs 1 hour 7 minutes) were significantly higher in the revision group (p < 0.001). Patients undergoing revision were significantly more likely to require intraoperative lateral release and postoperative urinary catheterisation (p < 0.001). Conclusion. This matched-cohort study provides results of revision TKA using modern techniques and implants and outlines what results patients can expect to achieve using primary TKA as a control. This should be useful to clinicians counselling patients for revision TKA

Aims. The purpose of this study was to develop a personalized outcome prediction tool, to be used with knee arthroplasty patients, that predicts outcomes (lengths of stay (LOS), 90 day readmission, and one-year patient-reported outcome measures (PROMs) on an individual basis and allows for dynamic modifiable risk factors. Methods. Data were prospectively collected on all patients who underwent total or unicompartmental knee arthroplasty at a between July 2015 and June 2018. Cohort 1 (n = 5,958) was utilized to develop models for LOS and 90 day readmission. Cohort 2 (n = 2,391, surgery date 2015 to 2017) was utilized to develop models for one-year improvements in Knee Injury and Osteoarthritis Outcome Score (KOOS) pain score, KOOS function score, and KOOS quality of life (QOL) score. Model accuracies within the imputed data set were assessed through cross-validation with root mean square errors (RMSEs) and mean absolute errors (MAEs) for the LOS and PROMs models, and the index of prediction accuracy (IPA), and area under the curve (AUC) for the readmission models. Model accuracies in new patient data sets were assessed with AUC. Results. Within the imputed datasets, the LOS (RMSE 1.161) and PROMs models (RMSE 15.775, 11.056, 21.680 for KOOS pain, function, and QOL, respectively) demonstrated good accuracy. For all models, the accuracy of predicting outcomes in a new set of patients were consistent with the cross-validation accuracy overall. Upon validation with a new patient dataset, the LOS and readmission models demonstrated high accuracy (71.5% and 65.0%, respectively). Similarly, the one-year PROMs improvement models demonstrated high accuracy in predicting ten-point improvements in KOOS pain (72.1%), function (72.9%), and QOL (70.8%) scores. Conclusion. The data-driven models developed in this study offer scalable predictive tools that can accurately estimate the likelihood of improved pain, function, and quality of life one year after knee arthroplasty as well as LOS and 90 day readmission. Cite this article: Bone Joint J 2020;102-B(9):1183–1193

Aims. A limited number of investigations with conflicting results have described perivascular lymphocytic infiltration (PVLI) in the setting of total knee arthroplasty (TKA). The purpose of this study was to determine if PVLI found in TKAs at the time of aseptic revision surgery was associated with worse clinical outcomes and survivorship. Methods. A retrospective review was conducted on 617 patients who underwent aseptic TKA revision who had histological analysis for PVLI at the time of surgery. Clinical and radiological data were obtained pre- and postoperatively, six weeks postoperatively, and then every year thereafter. Results. Within this cohort, 118 patients (19.1%) were found to have PVLI on histological analysis. Re-revision was performed on 83 patients (13.4%) with no significant differences in all-cause or aseptic revisions between groups. A higher incidence of PVLI was noted in female patients (p = 0.037). There was no significant difference in improvement in the range of motion (p = 0.536), or improvement of KSC (p = 0.66), KSP (p = 0.61), or KSF (p = 0.3) clinical outcome scores between PVLI and no PVLI sub-groups. There was a higher incidence of a preoperative diagnosis of pain in the PVLI group compared with patients without PVLI (p = 0.002) present. Conclusion. PVLI found on large-scale histological analysis in TKAs at aseptic revision surgery was not associated with worse clinical outcomes or rates of re-revision. Cite this article: Bone Joint J 2021;103-B(6 Supple A):145–149

Aims. Stemmed tibial components are frequently used in revision total knee arthroplasty (TKA). The purpose of this study was to evaluate patient satisfaction, overall pain, and diaphyseal tibial pain in patients who underwent revision TKA with cemented or uncemented stemmed tibial components. Methods. This is a retrospective cohort study involving 110 patients with revision TKA with cemented versus uncemented stemmed tibial components. Patients who underwent revision TKA with stemmed tibial components over a 15-year period at a single institution with at least two-year follow-up were assessed. Pain was evaluated through postal surveys. There were 63 patients with cemented tibial stems and 47 with uncemented stems. Radiographs and Knee Society Scores were used to evaluate for objective findings associated with pain or patient dissatisfaction. Postal surveys were analyzed using Fisher’s exact test and the independent-samples t-test. Logistic regression was used to adjust for age, sex, and preoperative bone loss. Results. No statistically significant differences in stem length, operative side, or indications for revision were found between the two cohorts. Tibial pain at the end of the stem was present in 25.3% (16/63) of cemented stems and 25.5% (12/47) of uncemented stems (p = 1.000); 74.6% (47/63) of cemented patients and 78.7% (37/47) of uncemented patients were satisfied following revision TKA (p = 0.657). Conclusion. There were no differences in patient satisfaction, overall pain, and diaphyseal tibial pain in cemented and uncemented stemmed tibial components in revision TKA. Patient factors, rather than implant selection and surgical technique, likely play a large role in the presence of postoperative pain. Stemmed tibial components have been shown to be a possible source of pain in revision TKA. There is no difference in patient satisfaction or postoperative pain with cemented or uncemented stemmed tibial components in revision TKA. Cite this article: Bone Joint J 2021;103-B(6 Supple A):165–170

Aims. MRI has been suggested as an objective method of assessing anterior crucate ligament (ACL) graft “ligamentization” after reconstruction. It has been proposed that the MRI appearances could be used as an indicator of graft maturity and used as part of a return-to-sport assessment. The aim of this study was to evaluate the correlation between MRI graft signal and postoperative functional scores, anterior knee laxity, and patient age at operation. Methods. A consecutive cohort of 149 patients who had undergone semitendinosus autograft ACL reconstruction, using femoral and tibial adjustable loop fixations, were evaluated retrospectively postoperatively at two years. All underwent MRI analysis of the ACL graft, performed using signal-to-noise quotient (SNQ) and the Howell score. Functional outcome scores (Lysholm, Tegner, International Knee Documentation Committee (IKDC) subjective, and IKDC objective) were obtained and all patients underwent instrumented side-to-side anterior laxity differential laxity testing. Results. Two-year postoperative mean outcome scores were: Tegner 6.5 (2 to 10); Lysholm 89.8 (SD 10.4; 52 to 100); and IKDC subjective 86.8 (SD 11.8; 51 to 100). The objective IKDC score was 86% A (128 patients), 13% B (19 patients), and 1% C (two patients). Mean side-to-side anterior laxity difference (134 N force) was 0.6 mm (SD 1.8; -4.1 to 5.6). Mean graft SNQ was 2.0 (SD 3.5; -14 to 17). Graft Howell scores were I (61%, 91 patients), II (25%, 37 patients), III (13%, 19 patients), and IV (1%, two patients). There was no correlation between either Howell score or SNQ with instrumented anterior or Lysholm, Tegner, and IKDC scores, nor was any correlation found between patient age and ACL graft SNQ or Howell score. Conclusion. The two-year postoperative MRI appearances of four-strand, semitendinosus ACL autografts (as measured by SNQ and Howell score) do not appear to have a relationship with postoperative functional scores, instrumented anterior laxity, or patient age at surgery. Other tools for analysis of graft maturity should be developed. Cite this article: Bone Jt Open 2021;2(8):569–575

Aims. There is little information regarding the risk of a patient developing prosthetic joint infection (PJI) after primary total knee arthroplasty (TKA) when the patient has previously experienced PJI of a TKA or total hip arthroplasty (THA) in another joint. The goal of this study was to compare the risk of PJI of primary TKA in this patient population against matched controls. Patients and Methods. We retrospectively reviewed 95 patients (102 primary TKAs) treated between 2000 and 2014 with a history of PJI in another TKA or THA. A total of 50 patients (53%) were female. Mean age was 69 years (45 to 88) with a mean body mass index (BMI) of 36 kg/m. 2. (22 to 59). In total, 27% of patients were on chronic antibiotic suppression. Mean follow-up was six years (2 to 16). We 1:3 matched these (for age, sex, BMI, and surgical year) to 306 primary TKAs performed in 306 patients with a THA or TKA of another joint without a subsequent PJI. Competing risk with death was used for statistical analysis. Multivariate analysis was followed to evaluate risk factors for PJI in the study cohort. Results. The cumulative incidence of PJI in the study cohort (6.1%) was significantly higher than the matched cohort (2.6%) at ten years (hazard ratio (HR) 3.3; 95% confidence interval 1.18 to 8.97; p = 0.02). Host grade in the study group was not a significant risk factor for PJI. Patients on chronic suppression had a higher rate of PJI (HR 15; p = 0.002), with six of the seven patients developing PJI in the study group being on chronic suppression. The new infecting microorganism was the same as the previous in only two of seven patients. Conclusion. In this matched cohort study, patients undergoing a clean primary TKA with a history of TKA or THA PJI in another joint had a three-fold higher risk of PJI compared with matched controls with ten-year cumulative incidence of 6.1%. The risk of PJI was 15-fold higher in patients on chronic antibiotic suppression; further investigation into reasons for this and mitigation strategies are recommended. Cite this article: Bone Joint J 2019;101-B(7 Supple C):91–97

Aims. Manipulation under anaesthesia (MUA) remains an effective intervention to address restricted range of motion (ROM) after total knee arthroplasty (TKA) and occurs in 2% to 3% of primary TKAs at our institution. Since there are few data on the outcomes of MUA with different anaesthetic methods, we sought to compare the outcomes of patients undergoing MUA with intravenous (IV) sedation and neuraxial anaesthesia. Methods. We identified 548 MUAs after primary TKA (136 IV sedation, 412 neuraxial anaesthesia plus IV sedation) from March 2016 to July 2019. The mean age of this cohort was 62 years (35 to 88) with a mean body mass index of 31 kg/m. 2. (18 to 49). The mean time from primary TKA to MUA was 10.2 weeks (6.2 to 24.3). Pre-MUA ROM was similar between groups; overall mean pre-MUA extension was 4.2° (p = 0.452) and mean pre-MUA flexion was 77° (p = 0.372). We compared orthopaedic complications, visual analogue scale (VAS) pain scores, length of stay (LOS), and immediate and three-month follow-up knee ROM between these groups. Results. Following MUA, patients with IV sedation had higher mean VAS pain scores of 5.2 (SD 1.8) compared to 4.1 (SD = 1.5) in the neuraxial group (p < 0.001). The mean LOS was shorter in patients that received IV sedation (9.5 hours (4 to 31)) compared to neuraxial anaesthesia (11.9 hours (4 to 51)) (p = 0.009), but an unexpected overnight stay was similar in each group (8.6%). Immediate-post MUA ROM was 1° to 121° in the IV sedation group and 0.9° to 123° in the neuraxial group (p = 0.313). Three-month follow-up ROM was 2° to 108° in the IV sedation group and 1.9° to 110° in the neuraxial anaesthesia group (p = 0.325) with a mean loss of 13° (ranging from 5° gain to 60° loss), in both groups by three months. No patients in either group sustained a complication. Conclusion. IV sedation alone and neuraxial anaesthesia are both effective anaesthetic methods for MUA after primary TKA. Surgeons and anaesthetists should offer these anaesthetic techniques to match patient-specific needs as the orthopaedic outcomes are similar. Also, patients should be counselled that ROM following MUA may decrease over time. Cite this article: Bone Joint J 2021;103-B(6 Supple A):126–130

Aims. Anterior cruciate ligament (ACL) and multiligament knee (MLK) injuries increase the risk of development of knee osteoarthritis and eventual need for total knee arthroplasty (TKA). There are limited data regarding implant use and outcomes in these patients. The aim of this study was to compare the use of constrained implants and outcomes among patients undergoing TKA with a history of prior knee ligament reconstruction (PKLR) versus a matched cohort of patients undergoing TKA with no history of PKLR. Patients and Methods. Patients with a history of ACL or MLK reconstruction who underwent TKA between 2007 and 2017 were identified in a single-institution registry. There were 223 patients who met inclusion criteria (188 ACL reconstruction patients, 35 MLK reconstruction patients). A matched cohort, also of 223 patients, was identified based on patient age, body mass index (BMI), sex, and year of surgery. There were 144 male patients and 79 female patients in both cohorts. Mean age at the time of TKA was 57.2 years (31 to 88). Mean BMI was 29.7 kg/m. 2. (19.5 to 55.7). Results. There was a significantly higher use of constrained implants among patients with PKLR (76 of 223, 34.1%) compared with the control group (40 of 223, 17.9%; p < 0.001). Subgroup analysis showed a higher use of constrained implants among patients with prior MLK reconstruction (21 of 35, 60.0%) compared with ACL reconstruction (55 of 188, 29.3%; p < 0.001). Removal of hardware was performed in 69.5% of patients with PKLR. Mean operative time (p < 0.001) and tourniquet time (p < 0.001) were longer in patients with PKLR compared with controls. There were no significant differences in rates of deep vein thrombosis, pulmonary embolism, infection, transfusion, postoperative knee range of movement (ROM), or need for revision surgery. There was no significant difference in preoperative or postoperative Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS, JR) scores between groups. Conclusion. Results of this study suggest a history of PKLR results in increased use of constrained implants but no difference in postoperative knee ROM, patient-reported outcomes, or incidence of revision surgery. Cite this article: Bone Joint J 2019;101-B(7 Supple C):77–83

Aims. The purpose of this study was to assess total knee arthroplasty (TKA) volume and rates of early complications in morbidly obese patients over the last decade, where the introduction of quality models influencing perioperative care pathways occurred. Methods. Patients undergoing TKA between 2011 to 2018 were identified in the American College of Surgeons National Surgical Quality Improvement Program database. Patients were stratified by BMI < 40 kg/m. 2. and ≥ 40 kg/m. 2. and evaluated by the number of cases per year. The 30-day rates of any complication, wound complications, readmissions, and reoperation were assessed. Trends in these endpoints over the study period were compared between groups using odds ratios (ORs) and multivariate analyses. Results. In total, 314,695 patients underwent TKA and 46,362 (15%) had BMI ≥ 40 kg/m. 2. The prevalence of morbid obesity among TKA patients did not change greatly, ranging between 14% and 16%. Reoperation rate decreased from 1.16% to 0.96% (odds ratio (OR) 0.81 (95% confidence interval (CI) 0.66 to 0.99)) for patients with BMI < 40 kg/m. 2. , as did rates of readmission (4.46% to 2.87%; OR 0.61 (0.55 to 0.69)). Patients with BMI ≥ 40 kg/m. 2. also had fewer readmissions over the study period (4.87% to 3.34%; OR 0.64 (0.49 to 0.83)); however, the rate of reoperation did not change (1.37% to 1.41%; OR 0.99 (0.62 to 1.56)). Significant improvements were not observed for infective complications over time for either group; patients with BMI ≥ 40 kg/m. 2. had increased risk of both deep infection and wound complications compared to non-morbidly obese patients. Rate of any complication decreased for all patients. Conclusion. The proportion of TKAs in morbidly obese patients has not significantly changed over the past decade. Although readmission rates improved for all patients, reductions in reoperation in non-morbidly obese patients were not experienced by the morbidly obese, resulting in a widening of the complication gap between these cohorts. Care improvements have not lowered the differential risk of infective complications in the morbidly obese. Cite this article: Bone Joint J 2021;103-B(6 Supple A):38–44

Aims. A comprehensive classification for coronal lower limb alignment with predictive capabilities for knee balance would be beneficial in total knee arthroplasty (TKA). This paper describes the Coronal Plane Alignment of the Knee (CPAK) classification and examines its utility in preoperative soft tissue balance prediction, comparing kinematic alignment (KA) to mechanical alignment (MA). Methods. A radiological analysis of 500 healthy and 500 osteoarthritic (OA) knees was used to assess the applicability of the CPAK classification. CPAK comprises nine phenotypes based on the arithmetic HKA (aHKA) that estimates constitutional limb alignment and joint line obliquity (JLO). Intraoperative balance was compared within each phenotype in a cohort of 138 computer-assisted TKAs randomized to KA or MA. Primary outcomes included descriptive analyses of healthy and OA groups per CPAK type, and comparison of balance at 10° of flexion within each type. Secondary outcomes assessed balance at 45° and 90° and bone recuts required to achieve final knee balance within each CPAK type. Results. There was similar frequency distribution between healthy and arthritic groups across all CPAK types. The most common categories were Type II (39.2% healthy vs 32.2% OA), Type I (26.4% healthy vs 19.4% OA) and Type V (15.4% healthy vs 14.6% OA). CPAK Types VII, VIII, and IX were rare in both populations. Across all CPAK types, a greater proportion of KA TKAs achieved optimal balance compared to MA. This effect was largest, and statistically significant, in CPAK Types I (100% KA vs 15% MA; p < 0.001), Type II (78% KA vs 46% MA; p = 0.018). and Type IV (89% KA vs 0% MA; p < 0.001). Conclusion. CPAK is a pragmatic, comprehensive classification for coronal knee alignment, based on constitutional alignment and JLO, that can be used in healthy and arthritic knees. CPAK identifies which knee phenotypes may benefit most from KA when optimization of soft tissue balance is prioritized. Further, it will allow for consistency of reporting in future studies. Cite this article: Bone Joint J 2021;103-B(2):329–337

Aims. This study aimed to identify the tibial component and femoral component coronal angles (TCCAs and FCCAs), which concomitantly are associated with the best outcomes and survivorship in a cohort of fixed-bearing, cemented, medial unicompartmental knee arthroplasties (UKAs). We also investigated the potential two-way interactions between the TCCA and FCCA. Methods. Prospectively collected registry data involving 264 UKAs from a single institution were analyzed. The TCCAs and FCCAs were measured on postoperative radiographs and absolute angles were analyzed. Clinical assessment at six months, two years, and ten years was undertaken using the Knee Society Knee score (KSKS) and Knee Society Function score (KSFS), the Oxford Knee Score (OKS), the 36-Item Short-Form Health Survey questionnaire (SF-36), and range of motion (ROM). Fulfilment of expectations and satisfaction was also recorded. Implant survivorship was reviewed at a mean follow-up of 14 years (12 to 16). Multivariate regression models included covariates, TCCA, FCCA, and two-way interactions between them. Partial residual graphs were generated to identify angles associated with the best outcomes. Kaplan-Meier analysis was used to compare implant survivorship between groups. Results. Significant two-way interaction effects between TCCA and FCCA were identified. Adjusted for each other and their interaction, a TCCA of between 2° and 4° and a FCCA of between 0° and 2° were found to be associated with the greatest improvements in knee scores and the probability of fulfilling expectations and satisfaction at ten years. Patients in the optimal group whose TCCA and FCCA were between 2° and 4°, and 0° and 2°, respectively, had a significant survival benefit at 15 years compared with the non-optimal group (optimal: survival = 100% vs non-optimal: survival = 92%, 95% confidence interval (CI) 88% to 96%). Conclusion. Significant two-way interactions between the TCCA and FCCA demonstrate the importance of evaluating the alignment of the components concomitantly in future studies. By doing so, we found that patients who concomitantly had both a TCCA of between 2° and 4° and a FCCA of between 0° and 2° had the best patient-reported outcome measures at ten years and better survivorship at 15 years. Cite this article: Bone Joint J 2021;103-B(2):338–346

Aims. The primary aim of this study was to assess whether the postoperative Oxford Knee Score (OKS) demonstrated a ceiling effect at one and/or two years after total knee arthroplasty (TKA). The secondary aim was to identify preoperative independent predictors for patients that achieved a ceiling score after TKA. Methods. A retrospective cohort of 5,857 patients undergoing a primary TKA were identified from an established arthroplasty database. Patient demographics, body mass index (BMI), OKS, and EuroQoL five-dimension (EQ-5D) general health scores were collected preoperatively and at one and two years postoperatively. Logistic regression analysis was used to identify independent preoperative predictors of patients achieving postoperative ceiling scores. Receiver operating characteristic curve was used to identify a preoperative OKS that predicted a postoperative ceiling score. Results. The ceiling effect was 4.6% (n = 272) at one year which increased significantly (odds ratio (OR) 40.3, 95% confidence interval (CI) 30.4 to 53.3; p < 0.001) to 6.2% (n = 363) at two years, when defined as those with a maximal score of 48 points. However, when the ceiling effect was defined as an OKS of 44 points or more, this increased to 26.3% (n = 1,540) at one year and further to 29.8% (n = 1,748) at two years (OR 21.6, 95% CI 18.7 to 25.1; p < 0.001). A preoperative OKS of 23 or more and 22 or more were predictive of achieving a postoperative ceiling OKS at one and two years when defined as a maximal score or a score of 44 or more, respectively. Conclusion. The postoperative OKS demonstrated a small ceiling effect when defined by a maximal score, but when defined by a postoperative OKS of 44 or more the ceiling effect was moderate and failed to meet standards. The preoperative OKS was an independent predictor of achieving a ceiling score. Cite this article: Bone Joint J 2020;102-B(11):1519–1526

Aims

In the last decade, perioperative advancements have expanded the use of outpatient primary total knee arthroplasty (TKA). Despite this, there remains limited data on expedited discharge after revision TKA. This study compared 30-day readmissions and reoperations in patients undergoing revision TKA with a hospital stay greater or less than 24 hours. The authors hypothesized that expedited discharge in select patients would not be associated with increased 30-day readmissions and reoperations.

Aims

The aim of this study was to describe the pattern of revision indications for unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA) and any change to this pattern for UKA patients over the last 20 years, and to investigate potential associations to changes in surgical practice over time.

Aims

Loosening of components after total knee arthroplasty (TKA) can be associated with the development of radiolucent lines (RLLs). The aim of this study was to assess the rate of formation of RLLs in the cemented original design of the ATTUNE TKA and their relationship to loosening.

Aims

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 unicompartmental knee arthroplasty (rUKA) compared to manual (mUKA).

Aims

The aim of this study was to identify variables associated with time to revision, demographic details associated with revision indication, and type of prosthesis employed, and to describe the survival of hinge knee arthroplasty (HKA) when used for first-time knee revision surgery and factors that were associated with re-revision.

Aims

Total knee arthroplasty (TKA) may provoke ankle symptoms. The aim of this study was to validate the impact of the preoperative mechanical tibiofemoral angle (mTFA), the talar tilt (TT) on ankle symptoms after TKA, and assess changes in the range of motion (ROM) of the subtalar joint, foot posture, and ankle laxity.

Aims

The rate of day-case total knee arthroplasty (TKA) in the UK is currently approximately 0.5%. Reducing length of stay allows orthopaedic providers to improve efficiency, increase operative throughput, and tackle the rising demand for joint arthroplasty surgery and the COVID-19-related backlog. Here, we report safe delivery of day-case TKA in an NHS trust via inpatient wards with no additional resources.

Aims

The metabolic equivalent of task (MET) score examines patient performance in relation to energy expenditure before and after knee arthroplasty. This study assesses its use in a knee arthroplasty population in comparison with the widely used Oxford Knee Score (OKS) and EuroQol five-dimension index (EQ-5D), which are reported to be limited by ceiling effects.

Aims

Periprosthetic joint infection (PJI) is a challenging complication of any arthroplasty procedure. We reviewed our use of static antibiotic-loaded cement spacers (ABLCSs) for staged management of PJI where segmental bone loss, ligamentous instability, or soft-tissue defects necessitate a static construct. We reviewed factors contributing to their failure and techniques to avoid these complications when using ABLCSs in this context.

Aims

The aim of this study was to assess factors associated with the estimated lifetime risk of revision surgery after primary knee arthroplasty (KA).

Aims

Tibial tubercle osteotomy (TTO) facilitates surgical exposure and protects the extensor mechanism during revision total knee arthroplasty (rTKA). The purpose of this study was to determine the rates of bony union, complications, and reoperations following TTO during rTKA, to assess the functional outcomes of rTKA with TTO at two years’ minimum follow-up, and to identify the risk factors of failure.

Aims

The primary aim was to assess whether robotic total knee arthroplasty (rTKA) had a greater early knee-specific outcome when compared to manual TKA (mTKA). Secondary aims were to assess whether rTKA was associated with improved expectation fulfilment, health-related quality of life (HRQoL), and patient satisfaction when compared to mTKA.

Aims

Patient dissatisfaction following primary total knee arthroplasty (TKA) with manual jig-based instruments has been reported to be as high as 30%. Robotic-assisted total knee arthroplasty (RA-TKA) has been increasingly used in an effort to improve patient outcomes, however there is a paucity of literature examining patient satisfaction after RA-TKA. This study aims to identify the incidence of patients who were not satisfied following RA-TKA and to determine factors associated with higher levels of dissatisfaction.

Aims

The diagnosis of periprosthetic joint infection (PJI) can be challenging as the symptoms are similar to other conditions, and the markers used for diagnosis have limited sensitivity and specificity. Recent research has suggested using blood cell ratios, such as platelet-to-volume ratio (PVR) and platelet-to-lymphocyte ratio (PLR), to improve diagnostic accuracy. The aim of the study was to further validate the effectiveness of PVR and PLR in diagnosing PJI.

Aims

The use of high tibial osteotomy (HTO) to delay total knee arthroplasty (TKA) in young patients with osteoarthritis (OA) and constitutional deformity remains debated. The aim of this study was to compare the long-term outcomes of TKA after HTO compared to TKA without HTO, using the time from the index OA surgery as reference (HTO for the study group, TKA for the control group).

Aims

The aim of this study was to compare the preinjury functional scores with the postinjury preoperative score and postoperative outcome scores following anterior cruciate ligament (ACL) reconstruction surgery (ACLR).

Aims

The mean age of patients undergoing total knee arthroplasty (TKA) has reduced with time. Younger patients have increased expectations following TKA. Aseptic loosening of the tibial component is the most common cause of failure of TKA in the UK. Interest in cementless TKA has re-emerged due to its encouraging results in the younger patient population. We review a large series of tantalum trabecular metal cementless implants in patients who are at the highest risk of revision surgery.

Aims

Total knee arthroplasty (TKA) with a highly congruent condylar-stabilized (CS) articulation may be advantageous due to increased stability versus cruciate-retaining (CR) designs, while mitigating the limitations of a posterior-stabilized construct. The aim was to assess ten-year implant survival and functional outcomes of a cemented single-radius TKA with a CS insert, performed without posterior cruciate ligament sacrifice.

Aims

In cases of severe periprosthetic joint infection (PJI) of the knee, salvage procedures such as knee arthrodesis (KA) or above-knee amputation (AKA) must be considered. As both treatments result in limitations in quality of life (QoL), we aimed to compare outcomes and factors influencing complication rates, mortality, and mobility.

Aims

Knowledge on total knee arthroplasties (TKAs) in patients with a history of poliomyelitis is limited. This study compared implant survivorship and clinical outcomes among affected and unaffected limbs in patients with sequelae of poliomyelitis undergoing TKAs.

Aims

The aim was to assess whether robotic-assisted total knee arthroplasty (rTKA) had greater knee-specific outcomes, improved fulfilment of expectations, health-related quality of life (HRQoL), and patient satisfaction when compared with manual TKA (mTKA).

Aims

Medial unicompartmental knee arthroplasty (mUKA) is an advised treatment for anteromedial knee osteoarthritis. While long-term survival after mUKA is well described, reported incidences of short-term surgical complications vary and the effect of surgical usage on complications is less established. We aimed to describe the overall occurrence and treatment of surgical complications within 90 days of mUKA, as well as occurrence in high-usage centres compared to low-usage centres.

Aims

This multicentre retrospective observational study’s aims were to investigate whether there are differences in the occurrence of radiolucent lines (RLLs) following total knee arthroplasty (TKA) between the conventional Attune baseplate and its successor, the novel Attune S+, independent from other potentially influencing factors; and whether tibial baseplate design and presence of RLLs are associated with differing risk of revision.

Aims

This study aimed to analyze kinematics and kinetics of the tibiofemoral joint in healthy subjects with valgus, neutral, and varus limb alignment throughout multiple gait activities using dynamic videofluoroscopy.

Aims

As has been shown in larger animal models, knee immobilization can lead to arthrofibrotic phenotypes. Our study included 168 C57BL/6J female mice, with 24 serving as controls, and 144 undergoing a knee procedure to induce a contracture without osteoarthritis (OA).

Aims

The tibial component of total knee arthroplasty can either be an all-polyethylene (AP) implant or a metal-backed (MB) implant. This study aims to compare the five-year functional outcomes of AP tibial components to MB components in patients aged over 70 years. Secondary aims are to compare quality of life, implant survivorship, and cost-effectiveness.

Aims

Metal particles detached from metal-on-metal hip prostheses (MoM-THA) have been shown to cause inflammation and destruction of tissues. To further explore this, we investigated the histopathology (aseptic lymphocyte-dominated vasculitis-associated lesions (ALVAL) score) and metal concentrations of the periprosthetic tissues obtained from patients who underwent revision knee arthroplasty. We also aimed to investigate whether accumulated metal debris was associated with ALVAL-type reactions in the synovium.

Aims

Robotic arm-assisted surgery offers accurate and reproducible guidance in component positioning and assessment of soft-tissue tensioning during knee arthroplasty, but the feasibility and early outcomes when using this technology for revision surgery remain unknown. The objective of this study was to compare the outcomes of robotic arm-assisted revision of unicompartmental knee arthroplasty (UKA) to total knee arthroplasty (TKA) versus primary robotic arm-assisted TKA at short-term follow-up.

Aims

The aim of this study was to compare patient-reported outcomes (PROMs) following isolated anterior cruciate ligament reconstruction (ACLR), with those following ACLR and concomitant meniscal resection or repair.

Aims

This Delphi study assessed the challenges of diagnosing soft-tissue knee injuries (STKIs) in acute settings among orthopaedic healthcare stakeholders.

Aims

Distal femoral osteotomies (DFOs) are commonly used for the correction of valgus deformities and lateral compartment osteoarthritis. However, the impact of a DFO on subsequent total knee arthroplasty (TKA) function remains a subject of debate. Therefore, the purpose of this study was to determine the effect of a unilateral DFO on subsequent TKA function in patients with bilateral TKAs, using the contralateral knee as a self-matched control group.

Aims. In patients with a “dry” aspiration during the investigation of prosthetic joint infection (PJI), saline lavage is commonly used to obtain a sample for analysis. The aim of this study was to investigate prospectively the impact of saline lavage on synovial fluid analysis in revision arthroplasty. Methods. Patients undergoing revision hip (THA) or knee arthroplasty (TKA) for any septic or aseptic indication were enrolled. Intraoperatively, prior to arthrotomy, the maximum amount of fluid possible was aspirated to simulate a dry tap (pre-lavage) followed by the injection with 20 ml of normal saline and re-aspiration (post-lavage). Pre- and post-lavage synovial white blood cell (WBC) count, percent polymorphonuclear cells (%PMN), and cultures were compared. Results. A total of 78 patients had data available for analysis; 17 underwent revision THA and 61 underwent revision TKA. A total of 16 patients met modified Musculoskeletal Infection Society (MSIS) criteria for PJI. Pre- and post-lavage %PMNs were similar in septic patients (87% vs 85%) and aseptic patients (35% vs 39%). Pre- and post-lavage synovial fluid WBC count were far more disparate in septic (53,553 vs 8,275 WBCs) and aseptic (1,103 vs 268 WBCs) cohorts. At a cutoff of 80% PMN, the post-lavage aspirate had a sensitivity of 75% and specificity of 95%. At a cutoff of 3,000 WBCs, the post-lavage aspirate had a sensitivity of 63% and specificity of 98%. As the post-lavage synovial WBC count increased, the difference between pre- and post-lavage %PMN decreased (mean difference of 5% PMN in WBC < 3,000 vs mean difference 2% PMN in WBC > 3,000, p = 0.013). Of ten positive pre-lavage fluid cultures, only six remained positive post-lavage. Conclusion. While saline lavage aspiration significantly lowered the synovial WBC count, the %PMN remained similar, particularly at WBC counts of > 3,000. These findings suggest that in patients with a dry-tap, the %PMN of a saline lavage aspiration has reasonable sensitivity (75%) for the detection of PJI. Cite this article: Bone Joint J 2020;102-B(6 Supple A):138–144

Aims

Revision total knee arthroplasty (rTKA) is a technically challenging and costly procedure. It is well-documented that primary TKA (pTKA) have better survivorship than rTKA; however, we were unable to identify any studies explicitly investigating previous rTKA as a risk factor for failure following rTKA. The purpose of this study is to compare the outcomes following rTKA between patients undergoing index rTKA and those who had been previously revised.

Aims

To assess the incidence of radiological lateral osteoarthritis (OA) at 15 years after medial unicompartmental knee arthroplasty (UKA) and assess the relationship of lateral OA with symptoms and patient characteristics.

Aims. The aim of this study was to investigate the incidence, risk factors, and outcome of venous thromboembolism (VTE) following anterior cruciate ligament (ACL) reconstruction in a nationwide cohort. Patients and Methods. All ACL reconstructions, primary and revision, that were recorded in the Swedish Knee Ligament Register (SKLR) between 2006 and 2013 were linked with data from the Swedish National Board of Health and Welfare. The incidence of VTE was determined by entries between the day of surgery until 90 days postoperatively based on diagnosis codes and the prescription of anticoagulants. Risk factors, outcome, and the use of thromboprophylaxis were analyzed. Descriptive statistics with multivariate analysis were used to describe the findings. Results. The cohort consisted of 26 014 primary and revision ACL reconstructions. There were 89 deep venous thromboses (DVTs) and 12 pulmonary emboli (PEs) with a total of 95 VTEs (0.4 %). Six patients with a PE had a simultaneous DVT. The only independent risk factor for VTE was age greater than or equal to 40 years (odds ratio 2.31, 95% confidence interval 1.45 to 3.70; p < 0.001). Thromboprophylaxis was prescribed to 9461 patients (36%) and was equally distributed between those with and those without a VTE (37.9% vs 36.4%). All patient-reported outcome measures (PROMs) one and two years postoperatively were significantly lower in those with VTE. Conclusion. The incidence of VTE following ACL reconstruction is 0.4%, and the only significant risk factor is age. Patients with VTE had worse postoperative clinical outcome than patients without VTE. We recommend against the routine use of thromboprophylaxis, but it should be considered in older patients

Aims. While patients with psychological distress have poorer short-term outcomes after total knee arthroplasty (TKA), their longer-term function is unknown. We aimed to 1) assess the influence of preoperative mental health status on long-term functional outcomes, quality of life, and patient satisfaction; and 2) analyze the change in mental health after TKA, in a cohort of patients with no history of mental health disorder, with a minimum of ten years’ follow-up. Methods. Prospectively collected data of 122 patients undergoing primary unilateral TKA in 2006 were reviewed. Patients were assessed pre- and postoperatively at two and ten years using the Knee Society Knee Score (KSKS) and Function Score (KSFS); Oxford Knee Score (OKS); and the Mental (MCS) and Physical Component Summary (PCS) which were derived from the 36-Item Short-Form Health Survey questionnaire (SF-36). Patients were stratified into those with psychological distress (MCS < 50, n = 51) and those without (MCS ≥ 50, n = 71). Multiple regression was used to control for age, sex, BMI, Charlson Comorbidity Index (CCI), and baseline scores. The rate of expectation fulfilment and satisfaction was compared between patients with low and high MCS. Results. There was no difference in the mean KSKS, KSFS, OKS, and SF-36 PCS at two years or ten years after TKA. Equal proportions of patients in each group attained the minimal clinically important difference for each score. Psychologically distressed patients had a comparable rate of satisfaction (91.8% (47/51) vs 97.1% (69/71); p = 0.193) and fulfilment of expectations (89.8% vs 97.1%; p = 0.094). The proportion of distressed patients declined from 41.8% preoperatively to 29.8% at final follow-up (p = 0.021), and their mean SF-36 MCS improved by 10.4 points (p < 0.001). Conclusion. Patients with poor mental health undergoing TKA may experience long-term improvements in function and quality of life that are comparable to those experienced by their non-distressed counterparts. These patients also achieved a similar rate of satisfaction and expectation fulfilment. Undergoing TKA was associated with improvements in mental health in distressed patients, although this effect may be due to residual confounding. Cite this article: Bone Joint J 2020;102-B(7):845–851

Aims

Accurate identification of the ankle joint centre is critical for estimating tibial coronal alignment in total knee arthroplasty (TKA). The purpose of the current study was to leverage artificial intelligence (AI) to determine the accuracy and effect of using different radiological anatomical landmarks to quantify mechanical alignment in relation to a traditionally defined radiological ankle centre.

Aims. Recent studies have suggested that corticosteroid injections into the knee may harm the joint resulting in cartilage loss and possibly accelerating the progression of osteoarthritis (OA). The aim of this study was to assess whether patients with, or at risk of developing, symptomatic osteoarthritis of the knee who receive intra-articular corticosteroid injections have an increased risk of requiring arthroplasty. Methods. We used data from the Osteoarthritis Initiative (OAI), a multicentre observational cohort study that followed 4,796 patients with, or at risk of developing, osteoarthritis of the knee on an annual basis with follow-up available up to nine years. Increased risk for symptomatic OA was defined as frequent knee symptoms (pain, aching, or stiffness) without radiological evidence of OA and two or more risk factors, while OA was defined by the presence of both femoral osteophytes and frequent symptoms in one or both knees. Missing data were imputed with multiple imputations using chained equations. Time-dependent propensity score matching was performed to match patients at the time of receving their first injection with controls. The effect of corticosteroid injections on the rate of subsequent (total and partial) knee arthroplasty was estimated using Cox proportional-hazards survival analyses. Results. After removing patients lost to follow-up, 3,822 patients remained in the study. A total of 249 (31.3%) of the 796 patients who received corticosteroid injections, and 152 (5.0%) of the 3,026 who did not, had knee arthroplasty. In the matched cohort, Cox proportional-hazards regression resulted in a hazard ratio of 1.57 (95% confidence interval (CI) 1.37 to 1.81; p < 0.001) and each injection increased the absolute risk of arthroplasty by 9.4% at nine years’ follow-up compared with those who did not receive injections. Conclusion. Corticosteroid injections seem to be associated with an increased risk of knee arthroplasty in patients with, or at risk of developing, symptomatic OA of the knee. These findings suggest that a conservative approach regarding the treatment of these patients with corticosteroid injections should be recommended. Cite this article: Bone Joint J 2020;102-B(5):586–592

Aims

Despite new technologies for total knee arthroplasty (TKA), approximately 20% of patients are dissatisfied. A major reason for dissatisfaction and revision surgery after TKA is persistent pain. The radiological grade of osteoarthritis (OA) preoperatively has been investigated as a predictor of the outcome after TKA, with conflicting results. The aim of this study was to determine if there is a difference in the intensity of pain 12 months after TKA in relation to the preoperative radiological grade of OA alone, and the combination of the intensity of preoperative pain and radiological grade of OA.

Aims

The aim of this study was to compare the migration of the femoral component, five years postoperatively, between patients with a highly cross-linked polyethylene (HXLPE) insert and those with a conventional polyethylene (PE) insert in an uncemented Triathlon fixed insert cruciate-retaining total knee arthroplasty (TKA). Secondary aims included clinical outcomes and patient-reported outcome measures (PROMs). We have previously reported the migration and outcome of the tibial components in these patients.