Validity and responsiveness of radiographic joint space width metric measurement in hip osteoarthritis: a systematic review

Aim: To perform a systematic review of the literature on the concurrent validity, predictive validity and responsiveness of radiographic metric measurement of femoro-acetabular joint space width (JSW) in hip osteoarthritis (OA).

Eligibility criteria: studies reporting any data on (1) JSW on X-rays in hip OA patients and (2) concurrent validity (correlations with clinical symptoms), predictive validity (correlations with future symptomatic state, joint space loss or joint replacement), and/or responsiveness (JSW change over time evaluated using the standardized response mean (SRM)).

Search strategy: Medline PUBMED and Embase databases.

Statistical analysis: Random-effects models were constructed to obtain pooled SRMs.

Results: Of 448 articles, 79 met the abstract inclusion criteria and were read for further screening. Of these, 15 reported measures of validity and 11 reported measures of responsiveness. Concurrent validity: Five studies suggested an association between JSW and symptoms in the general population. Two evaluated the correlations between JSW and symptoms in hip OA patients, with conflicting results. Five demonstrated that JSW is predictive of future hip joint replacement. Responsiveness was moderate (SRM=0.66; 95% confidential interval (95%CI): 0.41, 0.91), but tended to be lower in randomized clinical trials than in cohort studies (0.35 vs 0.83), using an intention to treat rather than a completer analysis (0.30 vs 0.80), and using manual rather than computer-based measurement (0.47 vs 1.12).

Conclusion: There is evidence of a weak association between JSW and symptoms, of predictive validity for subsequent joint replacement, and of moderate responsiveness of metric measurement of JSW.