Meniscal tear

Findings

a)      The history may be of slow-onset pain, but usually follows a more acute episode involving twisting in a flexed, weight-bearing, knee position.

b)      The knee may stick, lock, click and have pain on twisting and turning. Episodic catching, with long periods clear, suggests a parrot beak tear.

c)      Joint effusion may or may not be present.

d)     McMurray’s test is usually positive, but a negative test does not exclude a tear. Apley’s grinding test is positive but, again, a negative test does not exclude a tear.

e)      The joint line is tender to palpation.

f)       A unilateral block to extension in a non-osteoarthritic knee is a meniscal tear until proved otherwise.

g)      The duck waddle test is positive.

Cause

Degeneration, and then fimbriation, of the meniscus, which often follows a traumatic twist of the knee, usually from a stumble, blocked twisting movement or other extraneous force that can tear the meniscus. The C-shaped menisci can move, but can become trapped and torn by rapid squatting, as in bunny hops, or an awkward squat with rotation, which the “duck waddle” mimics. There are various types recognized: bucket handle, parrot beak, radial tear, and a horizontal cleavage tear.

Treatment

Small tears that do not lock the joint may well settle over time without treatment. A parrot beak or radial tear may settle with time, but partial meniscectomy is usually required for most meniscal tears and, especially for peripheral tears, meniscal resuturing is undertaken.

The history will give diagnose in most cases, but a block to extension is a most important sign. An unstable knee may lead to meniscal damage. MRI grades of meniscal damage exist, where degeneration may be intrasubstance and mistaken for a tear. Clot implantation may be the way to preserve the meniscus.

"Concise guide to sports injuries, 2^nd edition",Churchill Livingstone, Malcolm T.F. Read,  foreword by Bryan English