The effect of medial meniscectomy and meniscal allograft transplantation on knee and anterior cruciate ligament biomechanics.

PURPOSE

Our purpose was to evaluate the effect of meniscectomy and meniscal allograft transplant on anterior cruciate ligament (ACL) and knee biomechanics.

METHODS

A differential variable reluctance transducer was placed in the ACL of 10 human cadaveric knees to record strain. Tibial displacement from a neutral reference was recorded relative to the position of the femur. Testing was performed at 30 degrees, 60 degrees, and 90 degrees of knee flexion. Six cycles of anterior-posterior loads were applied to the limit of 150 N. After a testing cycle, a medial meniscectomy was performed and the testing cycle was repeated. A meniscal allograft transplant was performed, and a final testing cycle was conducted. ACL strain and tibial displacement in the meniscectomy and meniscal allograft states were compared with the intact-knee state.

RESULTS

Tibial displacement after meniscectomy significantly increased at all angles. The meniscal allograft transplant restored tibial displacement to normal values at 30 degrees and 90 degrees. ACL strain increased significantly after meniscectomy at 60 degrees and 90 degrees of flexion, and meniscal allograft transplant returned the strain values to normal at 60 degrees and 90 degrees.

CONCLUSIONS

In most cases medial meniscectomy produced a significant increase in tibial displacement relative to the femur, and meniscal allograft transplantation restored displacement values to normal. Meniscectomy increased ACL strain and meniscal allograft transplant restored strain values to normal in 2 of 3 tested flexion angles.

CLINICAL RELEVANCE

The absence of the medial meniscus exposes the ACL to increased strain, whereas meniscal allograft lowered the strain on the native ACL. This could have implications for those patients undergoing ACL reconstruction who have concomitant removal of the medial meniscus.