Right and left knee laxity measurements: a prospective study of patients with anterior cruciate ligament injuries and normal control subjects

The purpose of this study was to analyze and compare knee laxity in a group of patients with a unilateral right anterior cruciate ligament (ACL) rupture and a group of patients with a unilateral left ACL rupture. Another goal was to analyze and compare the knee laxity of the right and left knees in a group of persons without any known knee problems. Prospective examination of the same patients preoperatively and 2 years after the reconstruction with examination of the healthy controls at 2 different occasions. Group A was composed of 41 patients with a right-sided chronic ACL rupture, and group B was composed of 44 patients with a left-sided chronic ACL rupture. All patients underwent an arthroscopic ACL reconstruction using patellar tendon autograft. Group C was composed of 35 persons without any known knee problems. One experienced physiotherapist performed all the KT-1000 measurements and the clinical examinations. Group A displayed an increased difference in side-to-side laxity between the injured and non-injured side compared with group B in terms of both anterior and total knee laxity. This difference was found to be statistically significant preoperatively ( P = .01, anterior; P = .001, total) and at follow-up evaluation 2 years after the index surgery ( P = .008, anterior; P = .006, total). In group C, a significant increase was seen in absolute anterior and total laxity in the right knee compared with the left knee when 2 repeated measurements were performed ( P < .0001 and P = .003, anterior; P < .0001 and P = .001, total). The KT-1000 arthrometer revealed a significant increase in laxity measurements in right knees compared with left knees. This difference was found both preoperatively and postoperatively in patients undergoing ACL reconstruction. The same thing was found in a group of persons without any known knee problems. Level II.