Popliteomeniscal fasciculi and lateral meniscal stability.

In an attempt to understand better the contribution of the anteroinferior and posterosuperior popliteomeniscal fasciculi to lateral meniscus stability, we objectively evaluated the stability of the lateral meniscus before and after sequentially sectioning these fasciculi. In the biomechanical model, we attempted to account for the inherent limitations of arthroscopic evaluation of lateral meniscal stability. When the fasciculi were intact, the average lateral meniscal motion with a 10-N load was 3.6 mm. When the anteroinferior fascicle was disrupted, the average lateral meniscal motion with a 10-N load was 5.4 mm. The mean increase in motion from the intact state was 1.8 mm or 50%, which was significant. When both fasciculi were disrupted, the average lateral meniscal motion with 10-N load was 6.4 mm. The mean increase in motion from the intact state was 2.8 mm or 78% and from the single fascicle disruption state was 1.0 mm or 18%, both differences were significant. The meniscus did not become locked with any of these loading trials, and it spontaneously reduced to the original position when unloaded. Both fasciculi make significant contributions to meniscal stability. Even though the meniscus never became locked in the joint when loaded during this study, with the variable loads seen with normal activities mechanical symptoms might be expected when meniscal motion is almost double. An increase in lateral meniscal motion at the time of surgery may aid in the diagnosis of fasciculi disruption, despite normal meniscal structure on magnetic resonance images and at arthroscopic visualization.