Purpose of the study: The purpose of this prospective study was to develop and evaluate a method for measuring the femorotibial joint space and to assess the effect of meniscectomy.
Material and methods: This study was conducted in a consecutive series of 36 patients undergoing arthroscopic meniscectomy for lesions of the medial meniscus on a stable knee. The height of the joint space was measured on x-rays taken in the morning before the operation then ten days later. X-rays were obtained for both knees in complete extension and in the 30 degrees flexion position. The height of the joint space was measured on the digital version of the x-rays midway between the vertical tangents of the posterior limits of the medial condyle.
Results: Readings were not reader dependent and demonstrated no significant difference between the pre and postmeniscectomy height of the medial femorotibial space (30 degrees flexion view, 5.2 +/- 1 and 5.2 +/- 1 before meniscectomy for reader 1 and 5.2 +/- 1 and 5.2 +/- 1 for reader 2 (p=0.05 for Student-Fisher test for paired values). The heights measured by the two readers were correlated (correlation coefficient test).
Discussion: The height of the medial femorotibial joint space can be measured reproductibly on plain x-rays of the knee in the standard flexion position. We were unable to demonstrate any significant difference in joint space between measures taken before and after meniscectomy.