I analyzed insurance claims for injuries sustained in high-school
football over a three-year period in six western states. Nineteen and
one-half per cent of the players sustained at least one injury per season,
of which 12.7 per cent were knee injuries. Follow-up questionnaires
completed by 529 (81 per cent) of the injured players showed that 394 had
been diagnosed as having ligament injuries; eighty-eight, internal
derangement of the knee; and forty-seven, patellar injuries. Twenty-six per
cent of the patients with ligament injuries had further injury to the
involved knee. Fifty-nine per cent of the patients with internal
derangement of the knee had subsequent injury to the same knee.
Eighty-seven per cent of the patients with patellar injuries had a
subsequent injury to the involved knee and an increased incidence (34 per
cent) of injury to the contralateral knee.