RESEARCH - Long-term outcome following total knee arthroplasty

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Published Online First: 29 July 2008. doi:10.1136/ard.2008.093229

ls of the Rheumatic Diseases 2009;68:642-647

Long-term outcome following total knee arthroplasty: a controlled

longitudinal study

J Cushnaghan1, J 1, I Reading1, P Croft2, P Byng1, K 1, P

Dieppe3,4, D Coggon1 and C 1,4

1 MRC Epidemiology Resource Centre, University of Southampton, Southampton, UK

2 Primary Care Sciences Research Centre, University of Keele, Keele, UK

3 MRC Health Services Research Collaboration, University of Bristol,

Bristol, UK

4 Institute of Musculoskeletal Sciences, University of Oxford, Oxford, UK

Objectives: To assess long-term outcome and predictors of prognosis

following total knee arthroplasty (TKA) for osteoarthritis.

Methods: We followed-up 325 patients from 3 English health districts

approximately 6 years after TKA, along with 363 controls selected from

the general population. Baseline data, collected by interview and

examination, included age, sex, comorbidity, body mass index (BMI),

functional status and preoperative radiographic severity of

osteoarthritis. Functional status at follow-up was assessed by postal

questionnaire. Predictors of change in physical function were analysed

by linear regression.

Results: Between baseline and follow-up, patients reported an

improvement of 6 points in median Short Form 36 Health Survey (SF-36)

physical function score, whereas in controls there was a deterioration

of 14 points (p<0.001). Median SF-36 vitality score declined by 10

points in patients and 5 points in controls (p = 0.005), while their

median SF-36 mental health scores improved by 12 and 13 points,

respectively (p = 0.2). The improvement in physical function was

smaller in patients who were obese than in patients who were

non-obese, but compared favourably with a substantial decline in the

physical function of obese controls. Better baseline physical function

and older age predicted worse changes in physical function in patients

and controls. Improvement in physical function tended to be greater in

patients with more severe radiological disease of the knee, and was

less in those who reported pain at other joint sites at baseline.

Conclusions: Improvements in physical function following TKA for

osteoarthritis are sustained beyond 5 years. The benefits are apparent

in patients who are obese as well as non-obese, and there seems no

justification for withholding TKA from obese patients solely on the

grounds of their body mass index.

http://ard.bmj.com/cgi/content/abstract/68/5/642?etoc

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