Long-term evaluation of knee stability and function following surgical reconstruction for anterior cruciate ligament insufficiency.

Currently used measures of knee stability and function for ACL reconstructed knees have not gained universal acceptance. Clinical test results often are given more value than the patient's subjective evaluation of the surgical outcome. This study was designed to identify specific knee stability and function variables that were most predictive of the patient's rating of knee function following one of two types of combined (intraarticular and extraarticular) ACL reconstruction procedures. Individual measures of knee stability and function were also evaluated for differences between contralateral operated and nonoperated limbs. Postoperative and healthy contralateral knees of 51 male and female patients aged 18 to 49 years (mean, 23.7 years) were evaluated on a battery of tests at an average of 48.0 months after surgery (range, 24 to 101 months). All subjects possessed a normal contralateral knee for comparative purposes. The results of this retrospective study indicated that the variables selected were not highly correlated with, nor could they effectively predict, the patients' perceptions of postoperative knee status as measured by the Knee Function Rating Form (KFR). Statistically significant differences (P less than 0.001) between operated and nonoperated knees were found for 9 of 11 variables analyzed. The data suggest that patients' perceptions of postoperative knee status were independent of the results of static and dynamic clinical tests commonly used to assess knee stability and function. Postoperative deficits of up to 30% between the surgically reconstructed and normal contralateral knees on specific measures of knee stability and function did not greatly influence the patients' perceptions of knee function. Development of new, more specific dynamic tests may be necessary before stronger relationships between clinical test results and patients' perceptions of knee status in the ACL reconstructed knee can be realized.