Abstract. Introduction. Total knee replacement (TKR) is a successful operation for many patients, however 15–20% of patients experience chronic post-surgical pain (CPSP). Many will experience neuropathic characteristics. We describe the prevalence and patterns of neuropathic pain in a cohort of patients with CPSP three months after TKR. Methodology. Between 2016–2019, 363 patients with troublesome pain, ≤14 on Oxford Knee score pain subscale, at three months after TKR from eight NHS hospitals were recruited into the Support and Treatment After Replacement (STAR) trial. Self-reported neuropathic pain was assessed at three, nine and fifteen months after surgery using painDETECT and Douleur Neuropathique 4 (DN4). Results. At three months post-operative, 53% reported neuropathic pain on painDETECT and 74% on DN4. Half (56%) remained in neuropathic pain over the twelve-month follow-up period, 26% reported improvement, and 9% reported new neuropathic symtpoms or fluctuated in and out of neuropathic pain (9%). Overall mean neuropathic pain scores improved between three and 15 months after TKR. When the painDETECT cut-off score of ≥13(ambiguous/possible) was used, DN4 and painDETECT measures showed similar prevalence rates at each timepoint. Conclusion. Neuropathic pain is common among patients with CPSP at three months after TKR. Although symptoms improved over time, one quarter to one half of our cohort continued to report symptoms at fifteen months. We propose a painDETECT cutoff score of ≥13 be used to identify neuropathic features in the TKR population. Postoperative care should include identification, assessment, and treatment of neuropathic pain in patients with CPSP after TKR

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

Purpose. The success of total knee replacement (TKR) surgery can be attributed to improvements in TKR design, instrumentation, and surgical technique. Over a decade ago oxidized zirconium (OxZr) femoral components were introduced as an alternative bearing surface to cobalt-chromium (CoCr), based on strong in-vitro evidence, to improve the longevity of TKR implants. Early reports have demonstrated the clinical success of this material however no long-term comparative studies have demonstrated the superiority of OxZr implants compared to a more traditional CoCr implant. This study aims to compare long-term survivorship and outcomes in OxZr and CoCr femoral components in a single total knee design. Methods. We reviewed our institutional database to identify all patients whom underwent a TKA with a posterior stabilized OxZr femoral component with a minimum of 10 years of follow-up. These were then matched to patients whom underwent a TKA with the identical design posterior stabilized CoCr femoral component during the same time period by gender, age and BMI. All patients had their patella resurfaced. All patients were prospectively evaluated preoperatively and postoperatively at 6 weeks, 3 months, 12 months, 2 years and every 1 to 2 years thereafter. Prospectively collected clinical outcome measures included, Western Ontario and McMaster Universities osteoarthritis index (WOMAC), Short-Form 12 (SF-12) and Knee Society clinical rating scores (KSCRS). Charts and radiographs were reviewed to determine the revision rates and survivorship (both all cause and aseptic) at 10 years allowing comparison between the two cohorts. Paired analysis was performed to determine if differences existed in patient reported outcomes. Results. There were 194 OxZr TKAs identified and matched to 194 CoCr TKAs. There was no difference in average age (OxZr, 54.2 years; CoCr, 54.4 years), Gender (OxZr, 61.9% female; CoCr, 61.9% female) and average body mass index (OxZr, 35.9 kg/m2; CoCr, 36.4 kg/m2) between the two cohorts. There were no significant differences preoperatively in any of the outcome scores between the two groups (WOMAC (p=0.361), SF-12 (p=0.771) and KSCRS (p=0.161)). Both the SF12 (p=0.787) and WOMAC (p=0.454) were similar between the two groups, however the OxZr TKA cohort had superior KSCRS compared to the CoCr TKA cohort at a minimum of 10 years (173.5 vs. 159.1, p=0.002). With revision for any reason as the end point, there was no significant difference in 10-year survivorship between the two groups (OxZr and CoCr, 96.4%, p=0.898). Similarly, aseptic revisions demonstrated comparable survivorship rates at 10-year between the OxZr (98.9%) and CoCr groups (97.9%) (p=0.404). Conclusion. In this matched cohort study, both groups demonstrated similar improvements in patient reported outcomes, although the OxZr cohort had greater KSCRS scores compared to the CoCr cohort. The reason for this difference is not clear but may represent selection bias, where OxZr implants were perhaps used in more active patients. Implant survivorship, based on revision rates for all causes and/or aseptic reasons, was excellent and similar for both the OxZr and CoCr femoral components at 10 years. Therefore, with respect to implant longevity at the end of the first decade, there appears to be no clear advantage of OxZr compared to CoCr for patients with similar demographics with this specific posterior stabilized TKA design. Further follow-up into the second and third decade may be required to demonstrate if a difference does exist

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

Abstract. Introduction. Surgery in patients with high body mass index (BMI) is more technically challenging and associated with increased complications post-operatively. Inferior clinical and functional mid-term results for high BMI patients undergoing high tibial osteotomy (HTO) relative to normal weight patients have been reported. This study discusses the clinical, radiological and functional outcomes of HTO surgery in patients with a high BMI. Method. This is a retrospective study on patients undergoing HTO surgery using the Tomofix anatomical MHT plate between 2017 and 2022, with follow-up period of up to 5 years. The cohort was divided: non-obese (BMI <30 kg/m2) and obese (BMI>30 kg/m2). Pre and post operative functional scores were collected: Oxford Knee Score (OKS), EuroQol-5D and Tegner. Complications, plate survivorship and Mikulicz point recorded. Results. 32 HTO procedures; 19 patients BMI <30 (average 27.0) and 14 patients BMI >30 (average 36.1). In BMI<30 cohort, one readmission for investigation of venous thromboembolism, doppler negative; two complications: hinge fracture and stitch abscess. The five year survivorship of the plate was 100%. In BMI>30 cohort, one readmission for pulmonary embolism; one complication: hinge fracture. The 5 year survivorship of the plate was 93%, 1 conversion to unicompartmental knee replacement. The average OKS improvement was 17 and 18 for BMI <30 and >30 respectively. Mikulicz point change was identical. Conclusion. The Tomofix anatomical MHT plate achieves good outcomes and minimal complications irrespective of BMI. Reduced plate survivorship, thus earlier conversion may be required in the obese, however higher cohort numbers are needed to confirm this

Abstract. Aims. Ceramic coatings in total knee arthroplasty have been introduced with the aim of reducing wear and consequently improving implant survivorship. We studied both cobalt-chrome-molybdenum and ceramic-coated components of the same implant design from a single centre to identify if the ceramic coating conferred any benefit at mid-term review. Patients and Methods. We identified 1641 Columbus TKAs (Aesculap AG, Tüttlingen, Germany) from a prospectively collected arthroplasty database. 983 were traditional CoCrMo and 659 had the AS ceramic coating. Patients were followed up until death or revision of the implant. Results. A slightly younger patient population was seen in the AS ceramic cohort which was statistically significant, mean 68.3 (p=<0.0001). There was no significant difference in implant survivorship between the CoCrMo femur and the ceramic coated femur at a mean of 9.2 years follow-up for the CoCrMo group and 5 years for the ceramic coated group (p=0.76). There was no reduction in the proportion of components revised for aseptic loosening or infection in the ceramic coated cohort. Conclusion. The reported benefits of ceramic coatings are note clearly demonstrated within our current cohort. All knee replacements within our cohort were performed by a user of both CoCrMo and AS and therefore implant familiarity does not explain the revision rate within the AS cohort. At mid-term follow-up, there was no benefit in terms of implant survivorship in using a ceramic coating

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

Abstract. Introduction. Anecdotal reports suggest some cementless Oxford Unicompartmental Knee Replacements (OUKRs) have painful early subsidence of the tibial component with valgus rotation and/or posterior tilting. The incidence of subsidence and its association with pain is poorly understood. This radiographic study aimed to evaluate the incidence of tibial subsidence and five-year patient reported outcome measures (PROMs) of a cementless OUKR cohort. Methodology. Cementless OUKRs from a high-volume centre with acceptable post-operative and five-year radiographs were included. Subsidence was determined by measuring the angle of the tibial tray/tibial axis angle and distance between the tibial tray axis and fibula head on anteroposterior and lateral radiographs using a custom MATLAB program. Analysis of 5-year PROMs assessed the relationship between subsidence and pain. Radiographs indicating tibial subsidence were validated by two observers. Results. Radiographs of 94 cementless OUKRs were analysed of which five tibial components had subsided (incidence=5%) with an average of 1.92° varus rotation and 2.97° posterior tilt. Subsidence appeared to occur within the first post-operative year with all tibial components fixed securely at 5 years. Two subsiders had moderate pain (ICOAP=20.5,15.9, AKSS Pain=20,45) and lower Oxford Knee Scores (OKS=26,31) compared to the cohort means (ICOAP=3.91, AKSS Pain=45.9, OKS = 43.6). These two subsiders had BMIs greater than 30. Conclusion. This study found 5% of cementless OUKRs in the cohort underwent tibial subsidence. Subsidence with moderate pain occurred in 2% of cases, and pain may be associated with obesity. A larger study is needed to study subsidence in greater detail

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

Abstract. Introduction. The prevalence of recurrent infection following two-stage exchange arthroplasty following failure of a total knee arthroplasty (TKA) has been reported to be 10% to 25%. There is limited literature available on repeat two stage revisions for TKA infection with only small cohorts and variable success rates. Methodology. A retrospective cohort study investigating the outcome of two stage revision arthroplasty for treatment of TKA infection was conducted with the aim of identifying factors linked to recurrence of infection. A consecutive cohort of all microbiology intra-operative periprosthetic knee samples from a single revision arthroplasty centre between January 2010 and December 2016 was identified. The final cohort consisted of 658 samples taken during 64 patients undergoing two stage revision knee surgery for infection. Patient demographics, medical and orthopaedic history data including post-operative outcomes and subsequent treatment was obtained from the electronic records system and medical notes. Results. 65.6% of the cohort (N=42) had successful eradication of their infection. For the twenty-two patients that had failure of their two stage revision, twenty patients had samples available from further surgical intervention. Sixteen patients (80%) had different organisms isolated when they had repeat surgical samples taken when compared to their first stage samples. Overall, for subsequent treatments there was a success rate of 75% if the same organism was identified and 62.5% if there were new isolated organisms. Conclusion. These findings may have implications for the treatment strategies chosen for re-infection after two stage TKA revisions if new causative organisms are isolated

Abstract. INTRODUCTION. This study investigates whether primary knee arthroplasty (KA) restores health-related quality of life (HRQoL) to levels expected in the general population. METHODOLOGY. This retrospective case-control study utilises two sources: patients undergoing primary KA from a University Teaching hospital; and individual-level data from the Health Survey for England which was used to represent the General Population. Propensity score matching was used to balance covariates (sex, age and body mass index (BMI)) and facilitate group comparisons. Two matched cohorts with 3029 patients each were obtained for the adjusted analyses (median age 70.3 interquartile range (IQR) 64–77; Female sex 3233 (53.4%); median BMI 29.7 IQR 26.5-33.7). HRQoL was measured using the three-level version of the EuroQol 5-Dimensions’ (EQ-5D-3L) Index and EQ-VAS scores. RESULTS. Patients awaiting KA had significantly lower EQ-5D-3L Index scores than the General Population (median 0.620 (IQR 0.16-0.69) vs median 0.796 (IQR 0.69-1.00), p<0.001). By one-year post-operation, the median EQ-5D-3L Index score improved significantly in the KA cohort (mean change 0.32 (Standard deviation 0.33), p<0.001), and demonstrated no significant differences when compared to the General Population (0.796 (IQR 0.69-1.00) vs 0.796 (0.69-1.00), p=1.0). Older age-groups had statistically better Index scores than matched peers in the General Population. Compared to the General Population cohort, the post-operative EQ-VAS was significantly higher in the KA cohort (p<0.001). CONCLUSION. Patients awaiting KA for osteoarthritis have significantly poorer HRQoL than the General Population. However, within one year of surgery, primary KA restored HRQoL to levels expected for patient's age, BMI and sex-matched peers

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

Abstract. Introduction. The number of total knee replacements (TKRs) performed continues to increase and is marked in patients under the age of 60. Increased number of younger patients raises concerns about potentially increased rates of implant failure or revision. Previous studies used small cohorts with only short to medium term follow-up. This study is the largest of its kind reporting long term outcomes and clinical survivorship of patients 50 years or less undergoing TKR. Methods. This is a retrospective cohort study using data from the Scottish Arthroplasty Project. A total of 3727 patients 50 years or less undergoing TKR between 2000 and 2019. Data was also collected for the same time period on patients aged 50–79 years undergoing TKR for comparison. Results. Mean age for under 50 years cohort at initial TKR was 45.4 years. Primary reason for TKR was osteoarthritis (3025 cases) and 321 revisions were performed. The primary reason for revision was aseptic loosening (206 cases), or infection (18 cases). Average time to revision was 5.5 years. In the 50–79 years cohort, average age was 67.5 years. Primary reason for TKR was osteoarthritis (87776 cases) and 2997 revisions were performed. Principle reason for revision was infection (256 cases), or aseptic loosening (2042 cases). Average time to revision was 4 years. Conclusion. This study suggests long-term outcome of patients aged 50 years or less undergoing TKR remain promising. Patients should be aware of relatively higher rates of aseptic loosening requiring revision in patients aged 50 years or less undergoing TKR

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

Abstract. Background. Daycase pathways which aim to discharge patients the same day following Unicompartmental Knee Replacement have been introduced in some centres, though most continue with Standard pathways. While Daycase pathways have cost savings, recovery data comparing pathways is limited. This study aims to compare patient-reported early recovery between Daycase and Standard pathways following UKR. Method. This study was carried out in two centres that originally used the same Standard recovery pathway for UKR. In one centre, the Standard pathway was modified into a Daycase pathway. 26 Daycase-Outpatient, 11 Daycase-Inpatient, and 18 Standard patients were recruited. Patients completed the Oxford Arthroplasty Early Recovery Score (OARS) and SF-36 (Acute) measure between Days 1–42. Results. Standard patients had significantly better Day-1 scores than Daycase patients, but this difference rapidly diminished, and from Day-3 onwards both groups had near-identical scores (OARS Day-1, 59 vs 37, p=0.002, stemming from differences in Pain, Nausea/Feeling-Unwell, Function/Mobility subscores p=0.003,0.014,0.011. OARS Day-3 48 vs 49, p=0.790). Daycase-Outpatients had a higher overall OARS (p=0.002), recovering 1–2 weeks faster than Daycase-Inpatients. OARS subscores demonstrated that Daycase-Outpatients had better Pain, Nausea/Feeling-Unwell, Fatigue/Sleep scores (p=0.020,0.0004,0.019 respectively). SF-36 scores corroborate OARS scores. Conclusion. The Standard cohort had better Day-1 scores than the Daycase cohort, likely due to later mobilisation and stronger inpatient analgesia; these differences diminished by Day-3. Daycase-Outpatients recovered substantially faster than Daycase-Inpatients – likely due to the factors that delayed their discharge. The convergence of scores at 6 weeks demonstrates that both pathways have similar early recovery outcomes

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