Alternative treatments for meniscal injuries.

Historical review. “By arterial injection with an opaque medium, one can discern a network of fine vessels from the capsule, entering the convex border of the meniscus but disappearing almost immediately. Because of this, one might expect healing in peripheral meniscus detachments, but none in tears limited to the semilunar cartilage itself”. These were the opening sentences of King’s paper at a meeting of the American Academy of Orthopaedic Surgeons in St Louis, Missouri on 13 January 1936. He performed several experiments to assess the healing capacity of the internal semilunar cartilage of the knee in dogs. Incisions made in and around the semilunar cartilages seemed to heal to a varying degree in relation to contact with the synovium on the outer edge of the meniscus. These findings indicated that (Fig. 1): 1) tears confined to the semilunar cartilage probably never heal; 2) a torn meniscus may heal by connective tissue if the tear communicates with the synovial membrane; 3) a complete transverse or oblique tear results in some separation of the fragments and within three weeks the intervening space fills with firm connective tissue arising from the synovium, indicating the time necessary for complete fixation; and 4) a meniscus partially torn from its peripheral attachment heals readily in a normal anatomical position. Why save the meniscus? On 16 November 1883 Thomas Annandale was the first to suture a medial meniscus, but arthrotomy and meniscectomy have since become common orthopaedic procedures. In the 1950s and the 1960s total meniscectomy was performed for almost any meniscal tear suspected on clinical examination. In the last two decades, arthroscopy has allowed adequate meniscectomy, following the technical rules laid down by authors such as Jackson. Between 1970 and 1980 it was shown that a carefully executed arthroscopic meniscectomy for a torn medial meniscus provided full functional restoration in more than 90% of cases, with short-term results comparable with those of open meniscectomy. In the longer term, factors such as varus malalignment and mechanical overload increase the risk of degeneration of load-bearing cartilage (Fig. 2). The buffer function of the semilunar cartilage between the femoral condyle and medial tibial plateau is lost, and the stabilising factor, the meniscal wall, is also lacking. The result is an increased anteroposterior shift of the femoral condyle in relation to the medial tibial plateau (Fig. 3). Any ligamentous laxity produced by the initial trauma will increase the degenerative changes in the loadbearing area. Even more important, but less controllable, is the magnitude of the mechanical load. This will depend on the weight of the patient and on workand sports-related activity. The same factors also apply to older patients. The shortterm results of accurate arthroscopic meniscectomy are better than those of open total meniscectomy because of the preservation of the meniscal wall. Again, the quality of the load-bearing cartilage will determine the functional outINSTRUCTIONAL COURSE LECTURE