Background: The relationship between the biomechanical dose of rehabilitation exercises administered after anterior cruciate ligament (ACL) reconstruction and the healing response of the graft and knee is not well understood.
Hypothesis: After ACL reconstruction, rehabilitation administered with either accelerated or nonaccelerated programs produces the same change in the knees' 6 degrees of freedom, or envelope, laxity values.
Study design: Randomized controlled trial; Level of evidence, 1.
Methods: Patients who underwent ACL reconstruction with a bone-patellar tendon-bone autograft were randomized to rehabilitation with either accelerated (19 week) or nonaccelerated (32 week) programs. At the time of surgery, and then 3, 6, 12, and 24 months later, the 6 degrees of freedom knee laxity values were measured using roentgen stereophotogrammetric analysis and clinical, functional, and patient-oriented outcome measures.
Results: Eighty-five percent of those enrolled were followed through 2 years. Laxity of the reconstructed knee was restored to within the limits of the contralateral, normal side at the time of surgery (baseline) in all participants. Patients in both programs underwent a similar increase in the envelope of knee laxity over the 2-year follow-up interval (anterior-posterior translation 3.2 vs 4.5 mm, and coupled internal-external rotations 2.6° vs 1.9° for participants in the accelerated and nonaccelerated programs, respectively). Those who underwent accelerated rehabilitation experienced a significant improvement in thigh muscle strength at the 3-month follow-up (P < .05) compared with those who participated in nonaccelerated rehabilitation, but no differences between the programs were seen after this time interval. At the 2-year follow-up, the groups were similar in terms of clinical assessment, patient satisfaction, function, proprioception, and isokinetic thigh muscle strength.
Conclusion: Rehabilitation with the accelerated and nonaccelerated programs administered in this study produced the same increase in the envelope of knee laxity. A majority of the increase in the envelope of knee laxity occurred during healing when exercises were advanced and activity level increased. Patients in both programs had the same clinical assessment, functional performance, proprioception, and thigh muscle strength, which returned to normal levels after healing was complete. For participants in both treatment programs, the Knee Injury and Osteoarthritis Outcome Score (KOOS) assessment of quality of life did not return to preinjury levels.