Principles and decision making in meniscal surgery.

This article provides a review of the basic science and clinical information available to the orthopedist on which a systematic approach to meniscal surgery can be based. Attitudes toward the meniscus have changed dramatically in the last 50 years. Laboratory investigations show that the menisci participate in many important functions, including tibiofemoral load transmission, shock absorption, lubrication, and passive stabilization of the knee joint. Histologic/structural analyses reveal the menisci to be annular structures, with the ability to transmit and properly distribute load over the tibial plateau, primarily facilitated by the circumferential collagen fibers in the peripheral third of the meniscus, in conjunction with their strong bony attachments at the anterior and posterior horns. Biologic studies demonstrate that meniscal healing can occur through two pathways: an intrinsic ability of the meniscal fibrochondrocyte to migrate, proliferate, and synthesize matrix (provided they are given the proper environment), and extrinsic stimulation through neovascularization (when the meniscal injury occurs in the vascular periphery). This review makes it clear that the menisci are essential components of the normal knee, and that techniques intended to preserve the menisci are both possible and mandatory. As evidence has accumulated from both animal and clinical studies of the frequent development of degenerative changes following meniscectomy, surgeons have become increasingly aggressive in their efforts to conserve as much meniscal tissue as possible. Current approaches to treatment of meniscal tears are based on a thorough understanding of meniscal structure, biology, and function, as well as familiarity with the basic principles of meniscal repair and resection. To synthesize these principles, the article concludes with an algorithm intended to guide surgeons in decision making when faced with a variety of meniscal lesions in different clinical situations.