Introduction

Meniscal roots detachment has deleterious consequences for knee biomechanics causing chondral injuries or osteonecrosis. Anterior roots can also produce chondral injuries after anterior root avulsions, probable because of similar biomechanical alterations. Our hypothesis was that the tear of the anterior root of lateral meniscus (ARLM) alters knee biomechanics, increasing the pressure on the cartilage and altering its kinematics; the repair of the tear restores the preinjury levels.
Study Design: Controlled Laboratory Study.

Methods

Nine cadaveric knees underwent 1000N of compression at 0º, 30°, 60° and 90° flexion in 4 lateral meniscus conditions: intact, ARLM tears, in-situ root repair and total meniscectomy. Contact area, mean and peak pressures and position of pressure centers at each articular compartment were determined with the aids pressure sensors at meniscotibial interface.

Results

ARLM avulsions produced contact area decreases in the affected side of 45% at 0º(p=0.012), 40% at 30º(p=0.017), 40% at 60º(p=0.017), 24% at 90º(p=0.025); mean pressure increases of 108% at 0º(p=0.018), 113% at 30º(p=0.012), 85% at 60º(p=0.012), 35% at 90º(p=0.036); and peak pressure increases of 141% at 0º(p=0.012), 153% at 30º(p=0.017), 99% at 60º(p=0.017), all alterations greater at low flexion. Compared to the lesion, in-situ repair partially recovered contact area, increasing a 40% at 0º(p=0.024) and 17% at 60º(p=0.05); mean pressure, decreasing a 51% at 0º(p=0.036), 43% at 30º(p=0.036), 33% at 60º(p=0.036) and peak pressure, decreasing 51% at 0º(p=0.024), 48% at 30º(p=0.034). The injury induced a displacement of the centers of pressures (COP) of both compartments that was always partially reversed by repair and worsened by meniscectomy.

Conclusion

The avulsion of the ARLM produces significant alterations in the knee contact biomechanics, increasing pressures and reducing contact area on the lateral articular cartilage, being greater at low knee flexion angles where they resemble a total meniscectomy. Additionally, the lesion modifies COP positions in both articular compartments, indicating kinematical alterations. In-situ repair partially restores these biomechanical alterations to the preinjury condition.