Instability accounts for approximately 20% of revision total knee arthroplasty (TKA) operations, however, diagnostic tests remain relatively subjective. The aim of this examination was to evaluate the feasibility of using pressure mat analyses during functional tasks to identify abnormal biomechanics associated with TKA instability. Five patients (M = 4; age = 69.80±7.05 years; weight = 79.73±20.12 kg) with suspected TKA instability were examined compared to 10 healthy controls (M = 4; age = 44.6±7.52 years; weight = 70.80±14.65). Peak pressure and time parameters were measured during normal gait and two-minute bilateral stance. Side-to-side pressure distribution was calculated over 10-second intervals during the second minute. Mann-Whitney tests compared loading parameters between groups and side-to-side differences in TKA patients (significance level = p<0.05). Pressure distribution was expressed relative to bodyweight. Notable differences were seen during bilateral stance. Uneven side loading was greater – favouring the non-operated limb – in TKA patients during bilateral stance compared to controls. This was significantly different at 30s (p=0.0336) and 60s (p=0.0336). Gait analyses showed subtle pressure distribution differences in unstable TKA patients. Stance time was indifferent. TKA patients tended to exhibit longer heel contact time (0.76s vs. 0.64s and reduced weight acceptance (50.75% vs. 56.75%) on the operated limb compared to the non-operated limb. Side-to-side differences in peak toe-off forces were significantly more pronounced in TKA patients versus controls (9.25% +/− 1.5% vs. 1.67% +/−5.79%; p=0.0039). Conclusion: This feasibility work demonstrates subtle differences in limb loading mechanics during simple clinical tests in unstable TKA patients that might be invisible to the naked eye. In the long-term, pressure analyses may be a useful diagnostic tool in identifying patients that would benefit from revision surgery for TKA instability.
Instability accounts for approximately 20% of all revision total knee arthroplasty (TKA), however diagnostic tests remain crude and subjective. The aim of this examination was to evaluate the feasibility of pressure mat (SB Mat, TekScan) analyses of functional tasks to differentiate instability in a clinical setting. Five patients (M = 4; age = 69.80±7.05 years; weight = 79.73±20.12 kg) with suspected TKA instability were examined compared to five healthy controls (M = 1; age = 46.80±7.85 years; weight = 71.54±16.17 kg). Peak pressure and time parameters were measured during normal gait and two-minute bilateral stance. Side-to-side pressure distribution was calculated over 10-second intervals during the second minute. Pressure distributions were expressed relative to bodyweight (%BW). T-tests compared loading parameters between groups (significance level = p<0.05). Analyses showed subtle differences in pressure distribution in unstable TKA patients versus healthy controls. Stance time during gait was indifferent. TKA patients tended to exhibit longer heel contact time (0.76 vs. 0.64 sec) and reduced weight acceptance (50.75% vs. 56.75%) on the operated versus non-operated limb. Side-to-side differences in toe-off forces were significantly more pronounced in TKA patients versus controls (9.25% vs. 3.75%;
Patient reported outcomes have become validated objective measures of success in research studies. They take time and effort to develop and administer. However, to remain relevant and universal PROMS should be gathered routinely and used to manage evidence-based change in healthcare systems. To ensure that they are adopted individual clinician involvement is key however a framework for comparison and relevance promotes engagement. Several examples will be presented of system change using PROMS and PREMS as well as using routine data to defend patient selection. How and what we present depends on whom we are expecting to influence.
To investigate the validity of threshold values for the Oxford Hip and Knee Score (OHS and OKS) for treatment success 12 months after total knee or hip replacement. Questionnaires were administered to patients undergoing total hip (THA) or knee (TKA) replacement before and 12 months after surgery alongside questions assessing key accepted aspects of treatment success (satisfaction, pain relief, functional improvement) to form a composite criterion of success and assessed using receiver operator characteristic (ROC) analysis. Thresholds providing maximum sensitivity and specificity for predicting treatment success were determined for the total sample and subgroups defined by pre-surgery scores.Aim
Methods
To evaluate the association of BMI and improvement in patient-reported outcomes after TKA. Knee replacement outcome data for procedures carried out over an eight month period was extracted from a regional arthroplasty register in the UK. Data was available before surgery and 12 months after. We analysed the impact of overweight on post-operative change in the Forgotten Joint Score − 12 (FJS-12) measuring joint awareness and the Oxford Knee Score (OKS) measuring pain and function using five BMI categories (A: <25, B: 25–29.9, C: 30–34.9, D: 35–39.9 and E: >40).Aim
Methods
Obese patients undergoing total knee arthroplasty (TKA) face increased risks of complications such as joint infection and early revision. However, the influence of obesity on measures of patient function following TKA is poorly defined. Knee arthroplasty outcome data for procedures carried out over an eight month period was extracted from a regional database in the UK. We analysed the impact of weight categories (BMI<30, BMI=30–34.9, and BMI≥35) on the Forgotten Joint Score – 12 (FJS-12) and Oxford Knee Score (OKS). Data was available preoperatively and 12 months postoperatively. Physical and mental health was assessed with the SF-12 one year after surgery. Data from 256 patients were available. 49.6% had a BMI<30, 27.4% had a BMI 30–34.9 and 23.1% had a BMI≥35. Mean FJS-12 results at 1-year were 48.7 points for patients with a BMI<30, 40.7 points for patients with a BMI=30–34.9 and 34.0 points for patients with a BMI≥35. Effect sizes for change from baseline to 12-month post-op were 3.0 (Cohen's d) in patients with BMI<30 and d=2.2 in patients with BMI≥35. Mean OKS results at 1 year were 36.9 (BMI<30), 33.7 (BMI=30–34.9) and 32.0 (BMI≥35) respectively. Effect sizes for change from baseline to 12-month was d=2.1 (BMI<30) and d=1.9 (BMI≥35). Differences between BMI groups with regard to post-operative change were statistically significant for the FJS-12 (p=0.038) but not for the OKS (p=0.229). This study highlights that outcome scores may differ in their ability to capture the impact of obesity on patient function following TKA. The FJS-12 showed significant differences in outcome based on patient obesity category, whereas the OKS did not detect between group differences.
Patient function is poorly characterised following revision TKA. Modern semi-constrained implants are suggested to offer high levels of function, however, data is lacking to justify this claim. 52 consecutive aseptic revision TKA procedures performed at a single centre were prospectively evaluated; all were revision of a primary implant to a Triathlon total stabiliser prosthesis. Patients were assessed pre-operatively and at 6, 26, 52 and 104 weeks post-op. Outcome assessments were the Oxford Knee Score (OKS), range of motion, pain rating scale and timed functional assessment battery. Analysis was by repeated measures ANOVA with post-hoc Tukey HSD 95% simultaneous confidence intervals as pairwise comparison. Secondary analysis compared the results of this revision cohort to previously reported primary TKA data, performed by the same surgeons, with identical outcome assessments at equivalent time points. Mean age was 73.23 (SD 10.41) years, 57% were male. Mean time since index surgery was 9.03 (SD 5.6) years. 3 patients were lost to follow-up. All outcome parameters improved significantly over time (p <0.001). Post-hoc analysis demonstrated that all outcomes changed between pre-op, 6 week and 26 weeks post-op assessments. No difference was seen between primary and revision cohorts in OKS (p = 0.2) or pain scores (p=0.19). Range of motion and functional performance was different between groups over the 2 year period (p=0.03), however this was due to differing pre-operative scores, post-hoc analysis showed no difference between groups at any post-operative time point. Patients undergoing aseptic revision TKA with semi-constrained implants made substantial improvements in OKS, pain scores, knee flexion, and timed functional performance, with the outcomes achieved comparable to those of primary TKA. High levels of function can be achieved following revision knee arthroplasty, which may be important considering the changing need for, and demographics of, revision surgery.
Service industry metrics (the net promoter score) are being introduced as a measure of UK healthcare satisfaction. Lower limb arthroplasty, as a ‘service’, scores comparably with the most successful commercial organisations. Satisfaction with care is important to both the patient and the payer. The Net Promoter Score, widely used in the service industry, has been recently introduced to the UK National Health Service as an overarching metric of patient satisfaction and to monitor performance. This questionnaire asks ‘customers’ if they would recommend a service or products to others. Scores range from −100 (everyone is a detractor) to +100 (everyone is a promoter). In industry, a positive score is well regarded, with those over 50 regarded as excellent. Our aims were to assess net promoter scores for joint arthroplasty, to compare these scores with direct measures of patient satisfaction, and to evaluate which factors contributed to net promoter response.Summary Statement
Background
Using current analysis/methodology, new implant technology is unlikely to demonstrate a large enough change in patient function to impact on the cost-effectiveness of the procedure. Cost effectiveness is an increasingly important metric in today's healthcare environment, and decisions surrounding which arthroplasty prosthesis to implant are not exempt from such health economic concerns. Quality adjusted life years (QALYs) are the typical assessment tool for this type of evaluation. Using this methodology, joint arthroplasty has been shown to be cost effective, however studies directly comparing the QALY achieved by differing prostheses are lacking.Summary Statement
Purpose
