Long-term assessment of gait biomechanics in patients with total knee arthroplasty

Abstract

s / Osteoarthritis and Cartilage 22 (2014) S57–S489 S90 tibiofemoral BMLs. Longitudinally, baseline higher ISR was associated with greater loss of patellar cartilage volume (b: -2.41%, 95% CI: -4.23%, -0.59%), increases in lateral tibiofemoral cartilage defects (OR: 2.20, 95% CI: 1.01, 4.77), and increases in any BMLs (OR: 2.76, 95% CI: 1.23, 6.19) and medial tibiofemoral BMLs (OR: 2.83, 95% CI: 1.10, 7.34) after adjustment for above covariates. Conclusions: A higher ISR, indicative of patellar alta, is associated with greater loss of patellar cartilage volume and increased cartilage defects and BMLs at tibiofemoral compartments, suggesting that patellar alta can induce patellar cartilage loss locally as well as risk for worsening of structural abnormalities in tibiofemoral compartments. 141 LONG-TERM ASSESSMENT OF GAIT BIOMECHANICS IN PATIENTS WITH TOTAL KNEE ARTHROPLASTY J.A. McClelland y, J.E. Wittwer y, K.E. Webster y, J.A. Feller z. y La Trobe Univ., Bundoora, Australia; zOrthoSport Victoria, Epworth Hlth.care, Melbourne, Australia Purpose: Clinical and radiographic improvements following Total Knee Arthroplasty (TKA) are sustained for up to 15 years following surgery. In contrast, much less is known about the knee biomechanics in the longterm after TKA. Biomechanical characteristics of gait may be associated with functional outcome and longevity of the prosthesis, however it is not clear what may be expected of knee biomechanics greater than 2 years following TKA. It is possible that potentially deleterious biomechanical changes are incremental, and therefore that identification of these changes may create opportunities for intervention that delays further surgery. Therefore, the aim of this study was to assess the knee biomechanics of patients at one and seven years following TKA during level walking. Methods: Forty patients were assessed twelve months following total knee arthroplasty for knee osteoarthritis (age 1⁄4 69.1 8.0 years, height 1⁄4 165.5 11.5 cm, weight 1⁄4 86.4 17.5 kg, 22 males). All participants received the same posterior stabilised prosthesis. Thirty-four of these patients were reassessed 7 years post-TKA. At both assessments, participants’ knee biomechanics were measured during walking at two speeds (self-selected and maximum pace) using an 8 camera Vicon motion analysis system (Vicon Systems, Oxford, UK). The biomechanical variables of interest were the maximum knee flexion during stance, flexion excursion during stance, maximum knee extension during stance, maximum knee flexion during swing, maximum knee flexion moment, maximum knee extension moment and maximum knee adduction moment. These variables were compared between assessments using paired t-test with an adjusted significance level of p<0.01. To establish whether the patients who returned were representative of the entire cohort, an independent t-test was calculated to compare these variables at the one year assessment between the patients who completed the 7 year assessment and those who didn’t. Participants also completed the American Knee Society Knee Score and the Total Knee Function Questionnaire. Results: All patients in the initial cohort achieved good to excellent outcome on the American Knee Society Score (mean 1⁄4 79.7 out of 100), and 78% were ‘more than satisfied’ with their TKA as measured by the Total Knee Function Questionnaire. Eighteen participants of the original sample were able to complete the biomechanical assessment seven years following TKA. Participants who did not complete the assessment had undergone recent orthopaedic surgery (5), developed neurological disease (5), or other illness (6) that affected walking. None of the original cohort had undergone TKA revision. Table 1 Descriptive data for measured biomechanical variables (mean SD)