Prospective study of changes in impairments and disabilities after anterior cruciate ligament reconstruction.
STUDY DESIGN: Single-group, repeated-measures prospective study. OBJECTIVES: To analyze changes in impairments and disabilities among patients with anterior cruciate ligament (ACL) reconstruction and to assess the relationships between the impairment and disability outcome measures from 3 months to 2 years following ACL reconstruction. BACKGROUND: Outcomes after ACL reconstruction can be categorized as impairments or disabilities. The relationship between impairments and disabilities may be crucial to understanding physical therapy interventions and predicting long-term outcome. METHODS AND MEASURES: Sixty patients who had undergone ACL reconstruction participated in the study. Impairment measures were range of motion, pain, knee-joint laxity, and muscle performance using isokinetic muscle tests. Disability measures were the Cincinnati knee score and lower limb performance using the triple-jump and stair-hop tests. Follow-up times were 3 and 6 months and 1 and 2 years after surgery. RESULTS: The Cincinnati knee score results show significant improvement 1 year after surgery (84.2 +/- 13.6) compared with 6 months (76.8 +/- 13.7) and 3 months (67.4 +/- 16.3) after surgery. Quadriceps total work (percentage of normal leg) significantly improved 2 years after surgery (92.6 +/- 14.1%) compared with 1 year after surgery (81.6 +/- 16.8%). Between 37 and 75% of the variability in the Cincinnati knee score could be explained by variation in the impairment variables, and quadriceps muscle performance and pain were the most significant predictors of disability. Extension deficit and pain at 3 months were significantly related to the Cincinnati knee score at the 2-year follow-up. CONCLUSIONS: Up to 2 years may be needed to regain normal quadriceps muscle performance following ACL reconstruction. Pain and quadriceps muscle performance explained most of the variability in the Cincinnati knee score.