Association of Preoperative Tibial Varus Deformity With Joint Line Orientation and Clinical Outcome After Open-Wedge High Tibial Osteotomy for Medial Compartment Osteoarthritis: A Propensity Score–Matched Analysis

Background: The correction of lower limb deformity should be performed at the site of deformity to maintain knee joint orientation. However, the effectiveness of open-wedge high tibial osteotomy (OWHTO) for treatment of medial osteoarthritis in varus malalignment without definite tibial varus deformity has not been confirmed. Purpose/Hypothesis: This study aimed to compare the clinical and radiologic outcomes after OWHTO in patients without tibial varus deformity versus patients with tibial varus deformity after matching for confounding factors. We hypothesized that these outcomes would be inferior in patients without tibial varus deformity. Study Design: Cohort study; Level of evidence, 3. Methods: The outcomes of 133 OWHTO operations for medial osteoarthritis in 107 patients were retrospectively reviewed after follow-up for >2 years. The patients were divided into group 1 (tibia with varus deformity, preoperative medial proximal tibial angle [MPTA] <85°) and group 2 (tibia without varus deformity, preoperative MPTA ≥85°). The confounding factors, including patient characteristics, preoperative limb alignment, degree of osteoarthritis, and correction angle, were matched using propensity score matching. The radiologic parameters, including MPTA and joint line obliquity, were evaluated preoperatively, between 6 and 12 months postoperatively, and at the last follow-up. The radiologic outcomes were assessed using the medial joint space width and mechanical hip-knee-ankle angle. The clinical outcomes were evaluated by the Hospital for Special Surgery knee score, Knee Society Score (KSS), and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score. The clinical and radiologic outcomes were compared between the groups. The proportions of patients achieving improvement in the clinical outcome beyond the minimal clinically important difference (MCID) or minimally important change were compared between the groups. Results: After propensity score matching, 32 patients were selected for each group. The mechanical hip-knee-ankle angle was corrected without significant difference from a mean ± SD varus angle of 8.0°± 3.3° to valgus angle of −3.2°± 2.5° in group 1 and from varus 8.0°± 3.6° to valgus −3.9°± 1.7° in group 2. The preoperative joint line obliquity was greater in group 2 as compared with group 1 (2.2°± 2.2° vs −0.4°± 1.8°, P < .001). With a similar 10° correction angle, the postoperative MPTA and joint line obliquity were 96.6°± 2.5° and 5.3°± 2.3°, respectively, in group 2, which were greater than 94.0°± 2.6° and 3.5°± 1.8°, respectively, in group 1 (both P < .001). The changes in joint space width and mechanical hip-knee-ankle angle were not significantly different between the groups over the follow-up period. At the last follow-up, the postoperative KSS objective score and WOMAC pain score in terms of symptom improvement were not significantly different between groups ( P = .092 and .068). However, the postoperative KSS and WOMAC functional scores were significantly worse in group 2 than in group 1 (77.3 ± 14.1 vs 84.4 ± 11.6, P = .044; 10.3 ± 9.2 vs 5.6 ± 7.2, P = .001). In group 1, 96.9% and 100% of patients showed improvements of >10 points in the KSS functional score and 15 points in the WOMAC functional score based on MCID or minimally important change. Meanwhile, 65.6% and 81.3% of patients in group 2, which were significantly lower than those of group 1, were improved beyond the MCID or minimally important change ( P = .001 and .024, respectively). Conclusion: In varus malalignment, the knee joint line was more oblique in patients without tibial varus deformity after OWHTO pre- and postoperatively. The clinical outcomes in terms of functional scores were inferior in patients without tibial varus deformity. However, the radiologic outcomes and symptomatic improvement after OWHTO were comparable regardless of the preoperative tibial varus deformity on midterm follow-up.

OP0154-HPR FEASIBILITY OF A WEB-BASED, PEER-SUPPORTED EXERCISE PROGRAM FOR PEOPLE WITH HIP OR KNEE OSTEOARTHRITIS

Background:Long-term physical activity (PA) and exercise is recommended as a cornerstone in the treatment of people with osteoarthritis (OA) (1), yet adherence to exercise is challenging (2). The treatment needs for this large group of patients cannot be fully managed within the health-care system, thus developing innovative and effective follow-up strategies is urgently needed.Objectives:To explore the feasibility and preliminary efficacy of a web-based, peer-supported exercise program for people with hip or knee OA.Methods:This study was a single-group, pre-post feasibility study. Patients aged 40-80 years with hip or knee OA who were not candidates for surgery were eligible. The 12-week intervention was delivered through a patient-organizations (The Norwegian Association for Rheumatic Diseases) web-based platforms, and included weekly exercise programs, weekly motivational messages, an OA and exercise website and assigned peer-supporters. Feasibility was evaluated by calculating the proportion of eligible patients who were enrolled and retained at follow-up, as well as time resources used on delivery of the intervention. Acceptability was evaluated by calculating proportion of patients who had valid baseline accelerometer data and completed the maximal cardiorespiratory exercise test according to protocol. Primary efficacy measures were change in PA assessed by accelerometers and change in exercise capacity (VO2peak) assessed by indirect maximal cardiorespiratory exercise test. Secondary efficacy measures were change in patient reported outcomes assessed by HOOS and KOOS (www.koos.nu) (a 10-point change in normalized scores was considered a minimally important change). Data was analysed using paired sample t-test, given as mean change (95% confidence interval) and p-values.Results:We identified 49 eligible patients of which 35 (71%) consented and were enrolled. Among those who consented, 22 (63%) were retained. Time resources used on delivery of the exercise programs and motivational messages were mean (SD) 7.3±1.1 min per week/patient. Compliance with wearing the accelerometer was mean (SD) 6.1±1.0 valid days (mean (SD) 13.8±1.3 hours/day). Twenty (67%) out of 30 patients who attended baseline testing performed the maximal cardiorespiratory exercise test, of which 18 completed according to protocol. Due to Covid-19 restrictions, follow-up testing of primary efficacy measures included only eight patients. For these patients there was a significant increase from baseline to follow-up on moderate-to-vigorous PA (mean change 16.4 minutes/day; 95% CI 6.9, 25.9, p=0.005) and VO2peak (mean change 1.83 ml/kg/min; 95% CI 0.29, 3.36, p=0.026). Across all secondary efficacy measures 30-52% of the patients (n=21) improved from baseline to follow-up (Figure 1).Figure 1.Proportion (%) of patients with Minimally Important Change (from baseline to follow-up) in normalized scores in subdomains of Hip disability and Osteoarthritis Outcome Score (HOOS) / Knee injury and Osteoarthritis Outcome Score (KOOS).Conclusion:Overall, the examined study processes were considered to be feasible and acceptable. Some minor amendments should be applied to improve the recruitment and retention rate before it can be carried out in a larger trial. The efficacy results should be interpreted with caution due the small sample size. However, if the positive results in this study are confirmed in a power-calculated randomised controlled trial, our novel follow-up strategy may be implemented and recommended for long-term management of hip and knee OA.References:[1]Kolasinski SL, Neogi T, Hochberg MC, Oatis C, Guyatt G, Block J, et al. 2019 American College of Rheumatology/Arthritis Foundation Guideline for the Management of Osteoarthritis of the Hand, Hip, and Knee. Arthritis Rheumatol. 2020;72(2):220-33.[2]Williamson W, Kluzek S, Roberts N, Richards J, Arden N, Leeson P, et al. Behavioural physical activity interventions in participants with lower-limb osteoarthritis: a systematic review with meta-analysis. BMJ Open. 2015;5(8):e007642.Acknowledgements:The authors wish to acknowledge all patients for participating, the patient representative who gave invaluable input on interventional components and the peer-supporters for volunteering to provide interventional support.Disclosure of Interests:None declared

Between Group-Level Minimally Important Change and Individual Treatment Responders

Purpose Estimates of the minimally important change (MIC) can be used to evaluate whether group-level differences are large enough to be important. But responders to treatment have been based upon group-level MIC thresholds, resulting in inaccurate classification of change over time. This article reviews options and provides suggestions about individual-level statistics to assess whether individuals have improved, stayed the same, or declined. Methods Review of MIC estimation and an example of misapplication of MIC group-level estimates to assess individual change. Secondary data analyses to show how perceptions about meaningful change can be used along with significance of individual change. Results MIC thresholds yield over-optimistic conclusions (i.e., classify those who have not changed as responders to treatment). Individual change statistics can be used along with individual retrospective ratings of change. Conclusions Future studies need to evaluate the significance of individual change using appropriate individual-level statistics such as the reliable change index or the equivalent coefficient of repeatability.

The Achilles tendon Total Rupture Score is a responsive primary outcome measure: an evaluation of the Dutch version including minimally important change

Purpose Aim of this study was to evaluate the responsiveness of the Dutch version of the Achilles tendon Total Rupture Score (ATRS-NL). Methods Patients (N = 47) completed the ATRS-NL at 3 and 6 months after Achilles tendon rupture (ATR). Additionally, they filled out the Euroqol-5D-5L (EQ-5D-5L) and Global Rating of Change Score (GRoC). Effect sizes (ES) and standardized response means (SRM) were calculated. The anchor-based method for determining the minimally important change (MIC) was used. GRoC and improvement on the items mobility and usual activities on the EQ-5D-5L served as external criteria. The scores on these anchors were used to categorize patients’ physical functioning as improved or unchanged between 3 and 6 months after ATR. Receiver operating curve (ROC) analysis was performed, with the calculation of the area under the ROC curve (AUC) and the estimation of MIC values using the optimal cut-off points. Results There was a large change (ES: 1.58) and good responsiveness (SRM: 1.19) of the ATRS-NL between 3 and 6 months after ATR. Using ROC analysis, the MIC values ranged from 13.5 to 28.5 for reporting improvement on EQ-5D-5L mobility and GRoC, respectively. The AUC of improvement on mobility and improvement on GRoC were > 0.70. Conclusion The ATRS-NL showed good responsiveness in ATR patients between 3 and 6 months after injury. Use of this questionnaire is recommended in clinical follow-up and longitudinal research of ATR patients. MIC values of 13.5 and 28.5 are recommended to consider ATR patients as improved and greatly improved between 3 and 6 months after ATR. Level of evidence II.

Psychometric Properties of the Hip–Return to Sport After Injury Scale (Short Form) for Evaluating Psychological Readiness to Return to Sports After Arthroscopic Hip Surgery

Background: Successful return to sports activity after surgery requires both physical and psychological readiness. The Hip–Return to Sport After Injury (Short Form) has been developed to assess psychological readiness to return to sports after hip injury and hip surgery, including hip arthroscopy. Purpose: To evaluate the reliability, validity, responsiveness, and interpretability of the scale for a cohort of patients after hip arthroscopy with a range of sports participation levels. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: Invitations to participate were sent to 145 patients from 3 specialist surgeons. The study included 77 participants 1 to 24 months after hip arthroscopy (mean ± SD age, 35 ± 9 years; 62% women) and 33 healthy age-matched controls (age, 37 ± 7 years; 52% women). The scale was administered electronically on 3 occasions to patients: baseline (≥1 month postarthroscopy), 1 week later, and 6 months later. In addition to the scale, participants were asked about sports participation status and their global rating of postsurgical change. The scale was administered to healthy controls on 1 occasion. The minimal detectable difference, discriminant validity, floor and ceiling effects, responsiveness, and interpretability (minimally important change) were determined for the scale. Results: Among the postarthroscopy group, excellent test-retest reliability was found (intraclass correlation coefficient = 0.869; 95% CI, 0.756-0.932) with a minimal detectable difference of 26 points out of 100 at the individual level and 4 points out of 100 at the group level. At baseline discriminant validity was evident between those who had returned to sports (median = 69, n = 35) and those who had not returned to sports (median = 30, n = 42; Mann-Whitney U score = 232.5, z = −5.141, P < .001) and between the returned-to-sports postarthroscopy group and healthy controls (median = 96, n = 33; Mann-Whitney U score = 165.500, z = 5.666, P < .001). No floor or ceiling effects were evident. Responsiveness was demonstrated for the scale in relation to sports status. With sports status as an anchor, a minimally important change of 26 points was identified. Conclusion: Assessment of the Hip–Return to Sport After Injury (Short Form) supports its use as a reliable and valid measure of psychological readiness to return to sports in patients after hip arthroscopy.