Study on Medial Meniscus Posterior Root Tears

Our study, published in The American Journal of Sports Medicine, used a lab-based simulated-walking model to measure the pressure between the thigh bone and shin bone after creating a tear at the root of the inner (medial) meniscus. As expected, the pressure rose significantly while the contact area dropped. The most clinically interesting finding was the wide variability from knee to knee, which may help explain why some patients tolerate these tears and others don't.

A natural-history study from the Mayo Clinic that we cite reports that, at minimum 10-year follow-up, 53% of patients with untreated posterior root tears had progressed to total knee replacement, and 95% had failed non-surgical treatment. Once the root is detached, the meniscus can no longer convert the load into the hoop-like compression it normally provides, and rapid cartilage wear usually follows.

The variability we observed between knees in the simulated-walking study suggests that not every root tear behaves the same way mechanically. If we can identify which knees will tolerate a tear and which will rapidly wear down, we can offer surgery to those most likely to benefit and avoid it for those who would do well without it. That is the next phase of research.