Comparison of fixed flexion, fluoroscopic semi-flexed and MTP radiographic methods for obtaining the minimum medial joint space width of the knee in longitudinal osteoarthritis trials

SummaryObjectiveTo compare three radiographic techniques (fluoroscopic semi-flexed [Fluoro], fixed flexion [FF], and semi-flexed metatarsophalangeal joint [MTP] views) for measuring medial joint space width (JSW) of the knee in longitudinal osteoarthritis (OA) trials and to identify the percentage of patients with detectable progression.DesignRetrospective summary of the progression and variability of the change in JSW in knee OA.Material and methodsData from the placebo arms of three separate, structure modifying, knee OA trials were compared including gender, age, baseline JSW, change from baseline in JSW, duration of observation, and number and percent of patients with joint space narrowing of various degrees. Computer evaluation of the joint space at its narrowest point in the medial compartment was used in the studies. It is important to note that the narrowest joint space at baseline may not be in the same anatomic location at subsequent evaluations. No statistical tests were performed.ResultsThe average observation times were 0.98, 0.68 and 0.82 years for the Fluoro, FF, and MTP studies, respectively. The amount of progression was different among the three studies. The Fluoro study showed the greatest magnitude of OA structural progression and the lowest variability. The Fluoro study was expected to show the greatest magnitude of structural progression since it was conducted for the longest duration. For all patients, the standard deviation of the change in JSW was 0.42, 0.63, and 0.53 mm for the Fluoro, FF, and MTP studies, respectively. The percent of patients with detectable progression was similar across studies.ConclusionWith these data, information was not sufficient to control for duration of observation and differences in inclusion criteria for the three study populations. Therefore, no definitive conclusions can be made regarding the degree of progression of OA over specific time intervals. However, the data indicate that all three studies contain a cohort of patients that exhibit detectable progression.