BILATERAL TEARS OF THE ANTERIOR CRUCIATE LIGAMENT

Abstract

Purpose: Bilateral tears of the ACL are classically described as occurring after a first tear. Few reports have examined the underlying mechanism and the frequency and predisposing morphological factors

Material and methods: We reviewed retrospectively a series of 3722 ACL plasties performed from 1984 to 2001, including 148 patients who underwent bilateral repair. In this group, we detailed the demographic features, the time from tear to repair, the type of sports activity and focused on the radiological measurement of tibial tilt.

Results: The estimated frequency of bilateral tears was 4%. We noted that these bilateral tears were associated with: male predominance (60%), mean age 21 years (±5.5) at first tear, younger age for females, second tear at 24.5±6.5 years, predominant practice of pivot sports without contact (56%), and competition sports. The time between the two tears was 48 months on average. The rate of contralateral tears during the first postoperative year was 16%, it was 60% at three years. The mean tibial tilt was 9.91±2.87° versus 6.8±1.87° in the control population.

Discussion: Our findings were in agreement with the literature for frequency, young age at first tear, particularly for women, short time between the two tears, and type of sports activity. The high rate of contralateral tears during the first year is a significant finding. Hypotheses put forward include loss of confidence in the operated knee leading to more stress on the contralateral knee, but also poorly adapted use of the healthy knee in sports activity. Rehabilitation exercises focusing on bilateral proprioception, respecting sufficient time after the first repair before resuming sports activities, and good control of knee laxity with an ‘anatomic’ plasty appear to be important elements of prevention. The favouring role of a narrow intercondylar notch has been established in the literature. We found that tibial tilt should also be taken into consideration.

Conclusion: Careful search for predisposing factors is important because of the frequency of bilateral tears of the ACL. The rehabilitation program should be well adapted and the patient should be informed of the risk. These measures should help decrease the incidence of this relatively frequent complication.