Abstract
Functional studies have shown the importance of preserving damaged menisci. Consequently, injuries of the peripheral actively performed to treat meniscus are usually sutured if blood flow has been preserved. However, it is still not clear whether a repaired meniscus can function properly or whether menisci are innervated. Therefore, we developed a neuro-vascular double staining method (NVDS) that can simultaneously show the distributions of microvasculature and peripheral nerves on single sections. After peripheral injuries of the medial meniscus were prepared in 18 dogs, the NVDS method was used to observe the healing process of blood vessels and nerve fibers 2, 4, 6, 8, 12, and 24 weeks after surgical repair of the meniscus. Histologic examination revealed that blood vessels were distributed 1/2 to 1/3 of the distance from the edge to the center of the menisci. However, only a small number of nerve fibers were distributed only about 1/5 of the distance. Only free nerve endings were observed. No mechanoreceptors were present. Although regenerated blood vessels could be observed about 6 weeks after surgery, nerve fibers has not regenerated by 24 weeks. This study demonstrates in detail how nerve fibers and blood vessels of the meniscus are distributed and interrelated. Furthermore, we found that peripherally torn and sutured menisci do not regenerate quickly.
