RESEARCH - Long-term outcome following total knee arthroplasty: a controlled longitudinal study

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

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Extended Report

Long-term outcome following total knee arthroplasty: a controlled

longitudinal study

Janet Cushnaghan 1, 1, Isabel Reading 1, Croft 2,

Byng 1, Ken 1, Dieppe 3, Coggon 1 and Cyrus

1*

1 University of Southampton, United Kingdom

2 School of Postgraduate Medicine, United Kingdom

3 University of Bristol, United Kingdom

Abstract

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

following total knee arthroplasty (TKA) for osteoarthritis.

Methods: We followed-up 325 patients from three English health

districts approximately six 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 pre-operative 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 SF-36 physical function score

whereas in controls there was a deterioration of 14 points (p<0.0001).

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 obese than in

non-obese patients, 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

both 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 five years. The benefits are

apparent in obese as well as non-obese patients, 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/ard.2008.093229v2?papetoc

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