The importance of the meniscus in unstable knees

Abstract

This study analyzes differences in knee function in ACL deficient knees with different meniscus status. Eighty patients, 12 women and 68 men, were matched in four groups according to sex, age, knee injuries, and follow up time. Group I had two intact menisci; Group II, one meniscus successfully repaired; Group III, one menis cus removed; and Group IV, both menisci removed. The ACL was repaired acutely or reconstructed later in most cases and other significant ligament injuries were treated. All patients were reexamined clinically 6 to 8 years after injury. Knee function was recorded using the Lysholm knee function score. Activity level before injury and at followup was rated with the Tegner scale. Stability was tested and weightbearing roentgen ograms were taken. There was a higher frequency of ACL reconstructions in Groups I and II, but instability was the same in all groups. No difference was found in Lysholm score (range, 86 to 92). The activity level was higher in Group IV at followup. A lower frequency of motion impairment was found in Group III, (20% versus 50%). Subjective evaluation was similar and positive in all groups. Group I had six meniscus ruptures during the follow-up period. In Group II three of the repaired menisci were removed, as were two of the contralateral menisci in Group III. Roentgenograms, available in 55 of 80 cases, showed osteoarthritis in 65%. There were no differences in the frequency of osteoarthritis among the first three groups, but Group IV had a higher incidence of osteoar thritic changes. Osteoarthritis did not result in lower knee function, poorer subjective evaluation, or in creased impairment of motion. Of the patients with osteoarthritis, more maintained their preinjury activities. In terms of function and osteoarthritis, instability and chosen activity level seemed to be of prognostic impor tance.