[Rate of joint space pinching in coxarthrosis]

Accurate measures of cartilage destruction are needed to evaluate the effects of chondroprotective agents in human osteoarthritis. Use of a digitalized image analyzer (HOLOGIC, ICMS software) to measure mean joint space width on roentgenograms of the hip is a simple, reliable method with a coefficient of variation of 3.3%. To determine the rate of joint space loss and to identify factors associated with this parameter, we retrospectively studied 56 hips with osteoarthritis in 39 patients (mean age at baseline 55.5 +/- 12 years; mean roentgenographic follow-up 5.2 +/- 3.6 years, mean number of roentgenograms per patient 3.7 +/- 1.1). Mean annual joint space loss was 13.5 +/- 16.6%, i.e., 0.42 +/- 0.38 mm, and was negatively correlated with the duration of roentgenographic follow-up (r = 0.95 and 0.97, p < 0.01). When only those subjects who were followed up for two to eight years were studied, mean joint space loss was only 6.7% with a considerably smaller standard deviation of 4.2%, i.e., 0.29 +/- 0.21 mm. No influence on the rate of joint space loss was found for age at onset of symptoms, age at the first roentgenographic study, side, gender, or location of the joint space narrowing. The roentgenographic stage or joint space width at baseline were positively correlated with the rate of joint space loss expressed as a percentage but not in mm. These data suggest that the absolute amount of cartilage lost is not influenced by the roentgenographic stage of the osteoarthritis at inclusion of the patient in the study.(ABSTRACT TRUNCATED AT 250 WORDS)