Predictors of functional ambulation and patient perception following total knee replacement and short-term rehabilitation

Abstract

Purpose. To investigate whether measured and patient-perceived function 6 months after total knee replacement (TKR) can be predicted from factors measured during post-operative rehabilitation.

Method. Retrospective analysis of data from a randomised clinical trial involving 100 patients after TKR. High- and low-performing subjects for pain, WOMAC score and 6-min walk test (6MWT) at 2, 8 and 26 weeks post-TKR were partitioned and analysed. Multiple stepwise regression analysis was applied to the contributing factors to determine associations with outcome.

Results. Prediction of outcome was unconvincing based upon variables recorded at 2 weeks; however, status at 8 weeks was a better indicator of functional performance and perception at 26 weeks. 6MWT at 26 weeks could be predicted from VAS pain scores and 6MWT at 8 weeks (r = 0.789; p < 0.001). Prediction of pain and patient perceived function at 26 weeks was also dependent on performance in 6MWT at 8 weeks (r = 0.51; p < 0.05). Males and those with lower body mass index values demonstrated better functional outcomes.

Conclusion. Functional status at 2 weeks post-surgery gives few indicators of ultimate status, possibly because of pain, joint swelling and other immediate post-operative factors. However, measurements taken at 8 weeks, following an outpatient-based exercise programme, provides a reasonable estimate of performance and response 26 weeks after surgery. Patient and clinician expectations for longer-term recovery could be informed by these findings.

Keywords:

• Knee
• osteoarthritis
• arthroplasty
• rehabilitation

Acknowledgements

We wish to recognise the contributions of Dr. Rola Ajjawi, and David Guest in the collection of data for this study. We also wish to acknowledge the contribution of South Western Sydney Area Health Service and the Whitlam Joint Replacement Centre for support of this project. This study was supported by a grant from the Ingham Research Institute (formerly, Health Research Foundation, Sydney South West Health Service).