Location-specific hip joint space width for progression of hip osteoarthritis--data from the osteoarthritis initiative

Abstract

Objective: To establish the performance of a location-specific computer-assisted quantitative measure of hip joint space width (JSW), by measuring responsiveness in those with hip osteoarthritis (OA) and pain and those without. Secondary purposes included investigating the most responsive location and comparison to minimum joint space width (mJSW).

Design: nested case-control.

Data: from the Osteoarthritis Initiative (OAI), a longitudinal cohort study of knee OA. All participants had standardized standing anterior-posterior (AP) pelvis radiographs at baseline and 48 months. Case definition (1): subjects with a total hip replacement (THR) after the 48 month visit (n = 27) were selected and matched (1:1) on sex and age to subjects without a THR. Case definition (2): subjects with a THR at any point after baseline (n = 79) were selected and the contralateral (CL) hip was designated the case hip, and subjects were matched (1:1) as above. Pain: the CL hip group were examined for the presence/absence of pain. Measurements of superior hip JSW were made at three fixed locations relative to a landmark-based line, facilitated by software. The standardized response mean (SRM) was used to examine sensitivity to change from baseline to 48 months. Paired t-tests were used to compare cases and controls.

Results: Significant differences were observed between cases and controls and those with and without pain. The location-specific measure outperformed mJSW in all analyses, with SRM ranging from 0.53 (contralateral hip) to 1.06 (THR hip). The superior-medial location was most responsive.

Conclusion: A new computer-assisted location-specific measure of hip JSW may provide a superior method to mJSW for radiographic OA progression. The superior-medial location was the most responsive.

Keywords: Computer measurement; Hip osteoarthritis; Joint space width; Radiography.