Abstract
Introduction
Patients with knee osteoarthritis frequently complain that they develop pain in other joints due to over-loading during gait. However, there have been no previous studies examining the effect of knee arthritis on the other weight bearing joints. The aim of this study was to examine the loading of the hips and contra-lateral knee during gait in a cohort of patients pre- and post knee replacement.
Methods
Twenty patients with single joint osteoarthritis awaiting knee replacement and 20 healthy volunteers were recruited. Gait analysis during level gait and at self selected speed was performed using a 12 camera Vicon motion analysis system. The ground reaction force was collected using EMG electrodes attached to the medial and lateral hamstrings and quadriceps bilaterally. Patients were invited to return 12 months post-operatively. Data was analysed using the Vicon plug-in-gait model and statistical testing was performed with SPSS v16.0 using ANCOVA to account for gait speed.
Results
The mean age of the patients was 69 (range 53-82) and the controls was 70 (range 60-83). Mid-stance moments and knee adduction impulses were elevated at both hips and both knees in patients compared to normal individuals (Impulses: OA Knee=1.87Nms; opposite knee=1.46Nms; controls=0.86Nms; p<0.01) whilst peak moments were not significantly different. Muscular co-contraction was elevated in both knees compared to normal (p<0.01).
Ten patients returned for follow up. Correction of varus resulted in improvements in moments at the replaced knee however recovery of moments in the other joints was variable and dependant on alignment, gait speed and their ability to mobilise their centre of mass.
Conclusion
Patients with single joint knee osteoarthritis have abnormal loading of both knees and both hips, potentially leading to further disease and disability. Recovery following knee replacement is variable and dependant on limb alignment and the patient's functional recovery.
