Damage of a meniscus (semi-lunar cartilage) in the knee. The cartilage is usually detached by a rotatory stress, for example, when the knee is twisted. Meniscal tears may occur as a result of a single traumatic event or they may be the cumulative effect of repeated twisting, turning, and compression forces on the knee over a long period. A tear is characterized by recurrent pain located along the affected joint margins (joint-line tenderness) intermittent catching, locking, or clicking (these can usually be demonstrated by the Apley test and McMurray's test); and weakened or atrophied quadriceps muscles. Radiography, magnetic resonance imaging, CT scanning, and arthroscopy have all been used in the diagnosis of tears. Meniscal tears are named according to their shape, for example, ‘parrot beak’ tear and ‘bucket handle’ tear. As the blood supply to most of the meniscus is very poor, it was once thought that this type of injury could never resolve itself. An athlete with a meniscal tear usually had the choice between retiring from active sport or surgical removal of the whole cartilage. Once removed, the space that was occupied by the meniscus is filled by replacement material ( a meniscal repair implant), but not of the same type or quality as the original meniscus. Consequently, joint mobility becomes marginally worse and the likelihood of arthritis in later life is increased. It is now realized that parts of the meniscus have quite a good blood supply and the formation of blood clots can encourage meniscal healing. Current treatments of meniscal tears depend on the extent and precise location of the tear. They include partial meniscectomy, meniscal repair, and leaving the tear alone. Total meniscectomies are rare. Most athletes return to activity within 4–8 weeks of arthroscopic repair. Experimental work is being done on meniscal transplantations; initial results are encouraging (see tissue engineering). No short-term rejections have been reported. so the meniscus appears to be ‘immunologically privileged’.
Subjects: Sports and Exercise Medicine.