t_ knee is affected, as most
sudden movements are made from right to left, thus throwing the strain
upon the left knee.

_Clinical Features._--When seen immediately after the accident, the
patient usually gives the history that while making a sudden movement
he was seized with an intense sickening pain in the knee, accompanied,
it may be, by a sensation of something giving way with a distinct
crack, and followed by locking of the joint. He may fall to the
ground and be unable to rise. On examination, the knee is found to be
fixed in a slightly flexed position; and while the surgeon may be able
to carry out movements of flexion to a considerable extent without
increasing the pain, any attempt to extend the joint completely is
extremely painful. Tenderness may be elicited on making pressure to
the medial side of the ligamentum patellae in the groove between the
femur and the tibia, but the meniscus cannot be recognised by
palpation. Considerable effusion rapidly takes place into the synovial
cavity.

The condition is liable to be mistaken for a sprain of the joint,
particularly one implicating the tibial collateral ligament, but
whereas in the lesion of the meniscus the maximum tenderness is in the
interval _between_ the bones, in the sprain of the ligament the
maximum tenderness is over its attachment to the bone, usually the
tuberosity of the tibia.

_Treatment._--To reduce the displacement, the patient is placed on a
couch, and, after the knee is fully flexed, the leg is rotated
laterally and abducted, to separate the medial femoral condyle from
the tibia, and while the rotation and abduction are maintained the leg
is quickly extended. The return of the meniscus to its place is
sometimes attended with a distinct snap, but in other cases reduction
is only recognised to have taken place by the fact that the joint can
be completely extended without causing pain.

Alternate flexion and extension combined with rotatory movements is
sometimes successful. Several attempts are often necessary, and a
general anaesthetic may be called for. After reduction, the limb is
fixed with sand-bags, and massage and movement are employed to get rid
of effusion, care being taken that no rotatory movement at the knee is
permitted. Rest and support are necessary to allow of repair of the
torn ligaments, and when the patient begins to use the limb he must be
careful to avoid movements which throw strain on the damaged
ligaments.

In a