Effect of Microfracture on Meniscal Tear Healing in a Goat (Capra hircus) Model

Meniscal injuries are an extremely common cause of knee pain. Meniscal repairs performed with concomitant anterior cruciate ligament reconstruction appear to heal at a higher rate than meniscal repairs performed in isolation. This may be due in part to the release of marrow elements into the knee and the time of meniscal repair. In cases of isolated meniscal repair, some orthopedic surgeons use microfracture to release marrow elements into the joint as an adjunct to enhance meniscal healing. This study evaluated rates of meniscal tear healing with or without the performance of microfracture in a goat (Capra hircus) model. Forty castrated young adult male goats underwent either a horizontal or a longitudinal 1.0-cm meniscal tear with or without microfracture. All procedures were performed open, in a bloodless field. Meniscal tears were created in the peripheral half of the body of the medial meniscus. The goats were euthanized at 6 months, and meniscal tears were analyzed and classified as complete healing, partial healing, or no healing by direct visualization. A probe was used as an aid to evaluate and classify the meniscal tears. Twenty (87%) of 23 goat meniscal tears showed at least partial healing when performed with concomitant microfracture. Only 5 (29%) of 17 menisci showed any healing in goats that did not receive microfracture. This difference in healing rates was statistically significant (P<.001). Fifteen (65%) meniscal tears accomplished with microfracture were completely healed, whereas only 2 (12%) menisci showed complete healing without microfracture (P<.001). The results of this study suggest that the release of bone marrow elements into the knee by microfracture improves meniscal healing rates.