QUANTITATIVE-EVALUATION OF JOINT SPACE WIDTH IN FEMOROTIBIAL OSTEOARTHRITIS - COMPARISON OF 3 RADIOGRAPHIC VIEWS

Objective: Quantitative evaluation of radiographic methods proposed to improve the detection of joint space narrowing (JSN) in femorotibial osteoarthritis (OA). Methods: Thirty-two consecutive patients with kne e OA and five normal controls had three different weight-bearing radio graphs of the knee: (1) anteroposterior film of both knees in full ext ension (extended knees), (2) anteroposterior film of one knee in exten sion while the patient was standing on the homolateral foot (standing on homolateral foot), (3) posteroanterior film of both knees flexed at 30 degrees (schuss view). Joint space was analyzed blind using both a n evaluation of JSN with a six-grade scale (JSN score) and an image an alyser computer measurement; of the mean joint space width (mean JSW). The medial compartments of medial femorotibial OA knees, the lateral compartment of lateral femorotibial OA knees, as well as both compartm ents of control knees, were measured. Extended knee and schuss views w ere made 1 year later in 10 patients for the evaluation of sensitivity to change. Results: The JSN scores +/- S.D. in schuss, standing on th e homolateral foot and extended knee views were 2.75 +/- 1.31, 1.95 +/ - 1.3 and 1.66 +/- 1.27, respectively. The mean JSW +/- s.D. in schuss , standing on the homolateral foot, and extended knee views were 2.9 /- 1.9 mm, 3.5 +/- 1.6 mm and 3.8 +/- 1.5 mm, respectively. Changes in JSN scores and mean JSW with schuss view increased with OA severity. In controls, JSW of the medial compartment: did not vary in the three views. JSW of the lateral compartment of controls was significantly la rger in the schuss view. The change in JSW after 1 year was -0.41 mm ( P=0.02) in the schuss view and -0.17 mm (P > 0.05) in the extended kne e view. Conclusion: The schuss view is suggested as the most accurate method for the evaluation of JSW in femorotibial OA.