Rationale: joint space assessment on roentgenograms is considered reliable for evaluating the anatomic severity of hip osteoarthritis. Methods for measuring this parameter include the scoring system developed by Kellgren and Lawrence, joint space width measurement, and joint space surface area measurement after digitalization of roentgenograms.
Objective: to compare the sensitivity to change of the three above-listed methods.
Patients and methods: the study included patients with hip osteoarthritis meeting ACR criteria for whom two roentgenograms showing evidence of hip osteoarthritis taken 10 to 15 months apart were available. Roentgenograms were read by a single investigator who was unaware of the chronological order of films. Sensitivity to change of the three measurement techniques was determined by calculating standardized response mean (mean change/standard deviation of change).
Results: the study evaluated 34 hips (68 roentgenograms) in 22 patients (12 females and ten males, mean age 63 +/- 10 years) with osteoarthritis of one (n = 10) or both (n = 12) hips. Standardized response mean were 0.37, 0.33, and 0.16 for joint space width, joint space surface area, and the Kellgren-Lawrence score, respectively.
Conclusion: this study suggests that joint space width or surface area may be more sensitive than the Kellgren-Lawrence score for monitoring the course of hip osteoarthritis.