Knee osteoarthritis (OA) is common in older adults. Determination of risk factors for onset of knee OA may help in its prevention. The objective of this systematic review, and meta-analysis, was to determine the current evidence on risk factors for knee OA.
A systematic literature search was carried out for cohort and case-control studies evaluating the association of demographic, comorbid, and other patient-determined factors with onset of knee OA. A scoring tool was developed to assess the quality of studies. Heterogeneity of studies was examined. Where possible studies were pooled to give an overall estimate of the association of factors with onset of knee OA.
Of the 2233 studies screened, 85 were eventually included in the review. Study quality tended to be moderate. The main factors consistently associated with knee OA were obesity (pooled OR 2.63, 95% CI 2.28-3.05), previous knee trauma (pooled OR 3.86, 95% CI 2.61-5.70), hand OA (pooled OR 1.49, 95% CI 1.05-2.10), female gender (pooled OR 1.84 95% CI 1.32-2.55) and older age. Smoking appeared to have a moderate protective effect, however this was not evident once the analysis was restricted to cohort studies only.
Whilst certain factors have been extensively reviewed (for example, body mass index), more longitudinal studies are needed to investigate the association of physical occupational and other patient-determined factors with future knee OA. The quality of such studies also needs to be improved. However, there are identifiable factors which can be targeted for prevention of disabling knee pain.