Joint-space width in the weight-bearing radiogram of the tibiofemoral joint. Should the patient stand on one leg or two?

Purpose: The aim of the study was to compare the minimal joint-space (MJS) width of the tibiofemoral joint (TFJ) in weight-bearing radiograms with the patient in two different positions. Material and Methods: From a study of 54 patients with chronic knee pain (aged 42-59 years, mean 52 years), we selected 21 consecutive patients for this study. In these 21 patients, both knees were examined by means of p.a. weight-bearing radiograms in semiflexion with fluoroscopic guidance. The patient stood with the weight: (1) almost entirely on the examined leg; and (2) equally distributed on both legs. The MJS was measured with a scale loupe in tenths of a millimeter in the medial and lateral compartments of the TFJ. Results: With the patient standing on one leg, the MJS was 0.18 mm wider (p<0.006) in the medial compartment and 0.18 mm narrower (p<0.029) in the lateral compartment as compared to standing on both legs. Conclusion: With the technique used, the assessment of the MJS width in the p.a. view of the TFJ in weight-bearing examinations should be performed with equal weight on both legs. Standing on only the examined leg might be an option in cases of suspected narrowing in the lateral compartment. (orig.)