[Biomechanical effect of anterior cruciate ligament rupture on posterior horn of lateral meniscus].

OBJECTIVE

Anterior cruciate ligament (ACL) is an important forward stable structure of knees, when its function impaired, the normal mechanical environment of joint will be destroyed. Now, to explore the effect of ACL rupture on the posterior horn of lateral meniscus by measuring biomechanics.

METHODS

Ten specimens of knee joints (5 left and 5 right sides asymmetrically) were donated voluntarily from 10 normal fresh adult male cadavers, aged 26-35 years with an average of 31.4 years. The straining of lateral meniscus posterior horn in 10 knee joint specimens before and after resection of ACL were tested when the knee joints loaded from 0 to 200 N at a velocity of 0.5 mm per second at 0, 30, 60, and 90 degrees of flexion and recorded at the moment when the load was 200 N, the ratio of straining before and after resection of ACL were counted. All the specimens were anatomied and observed in general so as to find injuries such as deformation and tearing in lateral meniscus after test.

RESULTS

The straining of lateral meniscus posterior horn were as follows: intact ACL group, (-11.70 +/- 0.95) microepsilon at 0 degree flexion, (-14.10 +/- 1.95) microepsilon at 30 degrees flexion, (-20.10 +/- 1.20) microepsilon at 60 degrees flexion, and (-26.50 +/- 1.58) microepsilon at 90 degrees flexion; ACL rupture group, (-6.20 +/- 1.55) microepsilon at 0 degree flexion, (-26.30 +/- 1.89) microepsilon at 30 degrees flexion, (-37.70 +/- 1.64) microepsilon at 60 degrees flexion, and (-46.20 +/- 2.78) microepsilon at 90 degrees flexion. There were significant differences between intact ACL group and ACL rupture group (P < 0.05). The straining ratio of the posterior horn of lateral meniscus rupture ACL to intact ACL were 0.53 +/- 0.12, 1.90 +/- 0.31, 1.88 +/- 0.15, and 1.75 +/- 0.16 at 0, 30, 60, and 90 degrees of flexion. The lateral meniscus were intact in general and no injuries such as deformation and tearing were found.

CONCLUSION

ACL has a significant biomechanical effect on posterior horn of lateral meniscus. Consequently, the posterior horn of lateral meniscus is overloaded with ACL rupture at 30, 60, and 90 degrees of flexion, and thereby, it will have the high risk of tear.