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Background The aim of this study was to determine if radiographic severity, extent or pattern of knee osteoarthritis was associated with pain and function before total knee arthroplasty (TKA) or improvement therein one year after TKA. Methods A prospective study of 259 patients undergoing unilateral TKA for Kellgren-Lawrence (KL) grade ≥ 3 knee osteoarthritis was conducted: mean age 69.8 ± 9.7 (44–91); mean BMI 31.0 ± 5.8 (17–52); 152/259 (58.7%) female. Preoperative radiographs were assessed using the KL and Ahlback systems. Preoperatively and 1 year postoperatively patients completed Oxford Knee Scores, VAS-Pain and EQ-5D scores. Full thickness cartilage loss was recorded intraoperatively. Results Median radiographic severity was Ahlback 2, KL 4: 51/259 (19.7%) hypertrophic; 23/259 (8.8%) atrophic. Neither Ahlback nor Kellgren-Lawrence OA grade was associated with OKS, VAS Pain or EQ-5D prior to TKA (p > 0.05). The extent and pattern of cartilage loss did not affect preoperative PROMs. Radiographic OA severity, compartment involvement, and pattern of cartilage loss were not significantly associated with PROMs or improvements therein following TKA (p > 0.05). Hypertrophic OA was associated with less pain before TKA (difference 6.8, 0.23–13.9 95%CI, p = 0.044), and worse improvement in OKS following TKA (difference −3.41, −6.8 to −0.05 95%CI, p = 0.047). Better preoperative OKS and hypertrophic OA were independently associated with poorer improvement in OKS 1 year following TKA (R2 = 0.208). Conclusion Provided at least one compartment has KL grade ≥ 3 changes, further radiographic severity, pattern or extent of cartilage loss did not affect PROMs before or after TKA: multicompartmental was no worse than unicompartmental disease.

Background The aim of this study was to assess the reliability of the Oxford Knee Score (OKS) collected verbally compared with the validated written score, using a population of patients who underwent total knee arthroplasty (TKR). Methods Ninety patients (mean age 70.6; (43–92), 56.7% female) undergoing TKR were prospectively assessed. One group (n = 45) completed written (standard) and verbal (over the telephone) OKS preoperatively, half (n = 23) performed the written questionnaire first followed by the verbal questionnaire, and the other half (n = 22) performed this in reverse. A separate group (n = 45) completed the same regime one year postoperatively. Results A mean difference of 0.63 (95% CI − 0.985–2.23) points between verbal and written OKS was observed preoperatively, and of 1.36 (95% CI − 0.942–3.65) points was observed at one year postoperatively. Excellent reliability was observed using ‘average measures’ intra-class coefficient for the OKS preoperatively (r = 0.848) and at one year postoperatively (r = 0.970) in both groups who had written scores performed first, and those who had verbal scores performed first (preoperative r = 0.780, one year r = 892). Bland and Altman plots demonstrated consistent correlation between patients reporting their preoperative score and one-year postoperative score verbally and written. There was no significant variation between groups who had written scores performed prior to verbal, compared with those who reported verbal scores prior to written. Conclusions Prospective written collection of OKS remains the benchmark. However, verbal recording of OKS is not clinically different to written score, and may be a useful alternative to OKS in patients who are unable to attend or complete written questionnaires.

Background The aim of this study was to identify minimal clinically important difference (MCID), minimal important change (MIC) and minimal detectable change (MDC) for the Short Form (SF-) 12 physical and mental component summary (PCS, MCS) scores after total knee arthroplasty (TKA) using an anchor based methodology. Methods During a 10-year period, 2589 TKA were performed. SF-12 PCS and MCS scores were recorded preoperatively and at one year postoperatively. At one year, patients were asked “How much did the knee replacement surgery improve the quality of your life?” Their response was recorded as: a great improvement, moderate improvement, little improvement, no improvement at all, or the quality of my life is worse. Patients recording a little (n = 211) and no (n = 115) were used to calculate the MCID and the MIC. The MDC90 was calculated using distribution based methods for the whole cohort. Results The MCID was 1.8 (p = 0.04) for the PCS and 1.5 (p = 0.33) for the MCS score. The MIC was 2.7 (p = 0.04) for the PCS and − 1.4 (p = 0.17) for the MCS score. The MDC90 was 8.9 for the PCS and 13.8 for the MCS score. Conclusion The MCID for the PCS can be used to compare the outcomes between groups, and the MIC can be used to ensure that a clinical difference has been observed for a cohort of patients. The values for the MDC90 can be used to assess whether or not an individual patient has experienced a change.

Background The primary aim was to assess survival of opening wedge high tibial osteotomy (HTO) for medial compartment osteoarthritis. The secondary aim was to identify independent predictors of early conversion to total knee arthroplasty (TKA). Methods During the 18-year period (1994–2011) 111 opening wedge HTO were performed at the study centre. Mean age was 45 years (range 18–68) and the majority male (84%). Mean follow-up was 12 (range six to 21) years. Failure was defined as conversion to TKA. Kaplan–Meier, Cox regression and receiver operating curve (ROC) analyses were performed. Results Forty (36.0%) HTO failed at a mean of 6.3 years (range one to 15). By Kaplan–Meier analysis, the five-year survival rate was 84% (95% confidence interval (CI) 82.6–85.4), 10-year rate 65% (95% CI 63.5–66.5) and 15-year rate 55% (95% CI 53.3–56.7). Cox regression analysis identified older age (hazard ratio (HR) 1.07 for each additional year, 95% CI 1.03–1.11, p b 0.001) and female gender (HR 2.37, 95% CI 1.06–5.33, p = 0.04) as independent predictors of failure. ROC analysis identified a threshold age of 47 years above which the risk of failure increased significantly (area under curve 0.72, 95% CI 0.62–0.81, p b 0.001). Cox regression analysis, adjusting for covariates, identified a significantly greater (HR 2.49, 95% CI 1.26–4.91, p = 0.01) risk of failure in patients aged 47 years old or more. Conclusion The risk of early conversion to TKA is significantly increased in females and those older than 47. These risk factors should be considered pre-operatively when planning intervention for isolated medial compartment osteoarthritis.

Background The aim of this study was to compare the outcomes and cost economics of TKA without patella resurfacing in patients with and without patellar cartilage loss. Methods Prospective case control study of 209 consecutive patients undergoing TKA without patella resurfacing. Patella cartilage status was documented intra-operatively: 108 patients had patella cartilage loss (mean age 70 ± 9.7, mean BMI 31 ± 6.2, 72 (67%) female) and 101 control patients did not (age 68 ± 9.2, BMI 31 ± 5.6, 52 (51%) female). The primary outcome measure was Oxford Knee Score (OKS) improvement at one year. Secondary outcomes included OKS, EQ-5D, anterior knee pain (AKP), Kujala scores and reoperation at 2–4 years. The cost to prevent secondary patella resurfacing was calculated. Results There were more women in the patella cartilage loss group (67% Vs 51%, p = 0.037), but no other preoperative characteristics differed. There was no difference in OKS improvement between those with and without patella cartilage loss at 1 year (mean difference −1.03, −3.68 to 1.62 95%CI, p = 0.446) or 2–4 years (mean difference 1.52, −1.43 to 4.45 95%CI, p = 0.310). At 2–4 years there was no difference in AKP (14/87 with vs 17/80 without, p = 0.430) nor Kujala score (mean difference 2.66, −3.82 to 9.13 95%CI, p = 0.418). Routine patella resurfacing would have cost £58,311 to prevent one secondary resurfacing. Conclusion There was no difference in OKS, anterior knee pain, reoperation or Kujala scores up to 2–4 years between patients with and without patellar cartilage loss following TKA without patella resurfacing. Resurfacing for this indication would not have been a cost effective intervention.

The aim was to assess the whether there was a clinically important change in the Oxford knee score (OKS) between one and two years after total knee arthroplasty (TKA), and to identify predictors associated with a clinically important change.A retrospective cohort study was undertaken using an established arthroplasty database of 5857 primary TKA. Patient demographics, body mass index, social deprivation, OKS and EuroQoL five-domain (EQ-5D) score were collected preoperatively and at one and two years postoperatively. A clinically important change in the OKS was defined as ≥5 points.There was a 0.2 point increase in the OKS between one and two years, which was statistically significant (95% confidence interval (CI) 0.1 to 0.4, p .0001), but not clinically important. A better preoperative OKS (p .001) and in contrast a worse one year OKS (p .001) were independently associated with a greater improvement from one to two years. There were 1006 (17.3%) patients that had a clinically important improvement in the OKS between one and two years. Receiver operating characteristic curve analysis showed that a one year OKS of less than 35 was a reliable predictor of a clinically important improvement between one and two years (area under the curve 0.77, 95% CI 0.76 to 0.78, p .001).There was not a clinically important change in the OKS from one to two years after TKA when assessed as a group. However, individual patients with a one year OKS of less than 35 may demonstrate a clinically important improvement at two years.Retrospective diagnostic study, Level III.

Background The position of the femoral component can influence knee kinematics by altering the posterior (PCO) and anterior condylar offset (ACO). The primary aim of this study was to assess whether the length of the cemented stem influences the sagittal position of the femoral component after revision total knee arthroplasty (rTKA). The secondary aim was to determine the influence of the sagittal position on PCO and ACO. Methods There were 172 consecutive patients over a seven-year period that underwent rTKA with a cemented semi-constrained prosthesis. The 172 patients were separated into two groups: 115 with short stems (50 mm) and 57 with longer stems (100 or 150 mm). Using rotationally acceptable lateral radiographs, the degree of flexion(+)/extension(−) of the femoral components, PCO, and ACO were measured. Results There was no significant difference (p > 0.25) between the two groups for sagittal position, PCO, or ACO. The average flexion of the femoral component with short stems was 2.2 ± 4.1° and 2.2 ± 3.4° for long stems (difference = 0.0, 95% confidence intervals (CI) − 1.3 to 1.2). The average PCO ratio was 1.02 ± 0.15 for short stems and 0.99 ± 0.17 for long stems (difference = 0.03, 95% CI − 0.02 to 0.08). The average ACO ratio was at 0.07 ± 0.08 for short stems and 0.08 ± 0.08 for long stems (difference = 0.01, 95% CI − 0.01 to 0.04). There was a significant correlation between sagittal alignment of the femoral component and PCO (flexion increased PCO, r = 0.39, p Conclusions Cemented stem length does not influence the position of femoral component in the sagittal axis, PCO, or ACO. Surgical technique and sizing of the femoral component may be more predictive.

The primary aim of this study was to assess whether patients dissatisfied with both recreational activities and overall outcome were different to those dissatisfied with recreational activities but satisfied with their overall outcome one year after total knee arthroplasty (TKA).A retrospective cohort consisting of 3324 primary TKA were identified from an established arthroplasty database. Patient demographics, comorbidities, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and Short Form (SF) 12 scores were collected pre-operatively and one year post-operatively. Overall patient satisfaction and satisfaction with recreational activities were assessed at one year.The rate of patient satisfaction with recreational activities (n = 2672, 80.4%) was significantly (odds ratio (OR) 0.47, 95% confidence intervals (CI) 0.41 to 0.54, p 0.001) lower than satisfaction with the overall outcome (n = 2982, 89.7%). When adjusting for confounding variables older age (OR 1.03, p = 0.008), increasing BMI (OR 1.05, p = 0.01) and absence of hypertension (OR 0.66, p = 0.02) were independent predictors of being dissatisfied with recreational activities in isolation. The one-year components and total WOMAC scores were significant (p 0.001) predictors of satisfaction with recreational activities and were reliable with an area under the curve of ≥0.82 CONCLUSION: Patients of older age, higher BMI and without hypertension are more likely to be dissatisfied with recreational activities despite being satisfied with their overall outcome.

Background The low contact stress (LCS) mobile-bearing total knee replacement (TKR) was designed to minimise polyethylene wear, aseptic loosening and osteolysis. However, registry data suggests there is a significantly greater revision rate associated. The primary aim of this study was to assess long-term survivorship of the LCS TKR performed at a single high-volume centre. Secondary aims were to assess survival by mechanism of failure and identify predictors of revision. Methods During a 13-year period (1993–2006) 1091 LCS TKRs were performed by two senior surgeons. Thirty-three with incomplete data were excluded. The patients were retrospectively identified from an arthroplasty register. Mean age was 69 (range 30–96) years. Five hundred seventy-seven TKRs were performed in females, 481 in males. Mean follow-up was 14 years (SD 4.3). Results There were 59 revisions during the study period: 14 (23.7%) for infection, 18 (30.5%) for instability, and 27 (45.8%) for polyethylene wear. Three hundred ninety-two patients died. All-cause survival at 10 years was 95% (95%CI 91.7–98.3) and at 15 years was 93% (95%CI 88.6–97.8). Survival at 10 years according to mechanism of failure was: infection 99% (95%CI 94–100%), instability 98% (95%CI 94–100%), and polyethylene wear 98% (95%CI 92–100). Of the 27 with polyethylene wear, only 19 (70.4%) had osteolysis requiring component revision, the other eight (29.6%) had polyethylene exchanges. Cox regression analysis identified younger age as the only predictor of revision (HR 0.96, 95%CI 0.94–0.99, p = 0.003), with a four percent decreased risk of revision for each increase in year of age. Conclusions The LCS TKR demonstrates excellent long-term survivorship with a low rate of revision for osteolysis, however this risk is increased in younger patients.

There is conflicting evidence as to whether diabetes mellitus influences the functional outcome and patient satisfaction after a total knee replacement (TKR). The aim of this study was to assess the effect of diabetes upon the Oxford knee score (OKS), short form (SF)-12, and patient satisfaction after TKR.Prospective pre- and post-operative (one year) OKS and SF-12 scores for 2389 patients undergoing primary TKR were compiled, of which 275 (12%) patients suffered with diabetes. Patient satisfaction was assessed at one year.Patients with diabetes were more likely to have a greater level of comorbidity (p0.001), and a worse pre-operative OKS and SF-12 score (p0.02), compared to those patients without diabetes. Diabetes was not a significant (p0.41) independent predictor of post-operative OKS or the SF-12 physical score on multivariable analysis. Although, factors more prevalent within the diabetic cohort (heart disease, vascular disease, liver disease, anaemia, depression, back pain, worse pre-operative OKS and SF-12 score) were found to be independent predictors of post-operative OKS and SF-12 physical score. Interestingly, diabetes was associated with a significantly greater improvement in mental wellbeing (SF-12 mental component), which was confirmed on multivariable analysis. Patient satisfaction was not influenced by a concomitant diagnosis of diabetes (p=0.57).The outcome of TKR as assessed by the OKS, SF-12, and overall patient satisfaction rates are not influenced by diabetes per se, although factors more prevalent within this population result in a worse post-operative outcome.prospective cohort study, level III.

Patient reported outcome measures are widely used in the evaluation of outcomes after Total Knee Replacement (TKR) in joint registries and large studies. The aim of this study was to assess the relationship between the Oxford knee score (OKS) and range of motion (ROM) after TKR, and to construct and validate prediction models of ROM from the measured OKS.Eight hundred sixty patients reviewed five years postoperatively and 273 patients reviewed nine to 10 years postoperatively completed an OKS. Of these, 808 (94%) and 226 (83%) patients, respectively, had a complete dataset (knee extension and ROM) and formed the study cohort.Regression analysis demonstrated a significant correlation between the OKS and ROM (r=0.38, p0.001) after adjusting for other confounding variables (age, sex, body mass index, and knee extension). A prediction model was constructed and validated using a second cohort of 226 patients at nine to 10 years after their TKR. Intraclass correlation demonstrated good reliability (r=0.60, 95% CI 0.47 to 0.69) between predicted and actual measured ROM for this group. However, when the OKS is used in isolation the reliability of the predicted ROM is diminished (intraclass correlation r=0.41, 95% CI 0.24 to 0.55).The OKS is an independent predictor of ROM after TKR. It is also possible to predict ROM from the OKS, but the reliability of this is improved when other independent predictors such as age, gender, body mass index (BMI) and degree of knee extension are also acknowledged.

There is a high rate of knee deformity in patients with hereditary multiple exostoses (HME), and a quarter of patients have a limb length discrepancy.A prospective database of 172 patients with HME was compiled. Patient demographics, knee deformity and range of movement, leg length and height, and number of exostoses around the knee were recorded.Nine out of 10 patients with HME were affected by exostoses around the knee, of which the distal femur was the most common site to be involved. Approximately 20% of patients had a valgus deformity and 16% had a fixed flexion deformity of the knee, with 25% having a diminished range of movement. Height was directly proportional to leg length and a quarter of patients were below the 10th centile for height. The presence of a distal femoral exostosis was an independent predictor of knee deformity (p=0.002), diminished range of movement (ROM) (p0.001), and smaller stature (p0.001) on multivariate analysis. In addition increasing age, prior surgery, genotype, and gender were also intendant predictors of ROM and height.Future studies analysing if surgical excision improves knee function and limits deformity would need to assess whether this is dependent upon anatomical site, as our results suggest that distal femoral exostoses may have the greatest affect upon these outcomes.Level II.