Early versus late start of isokinetic hamstring-strengthening exercise after anterior cruciate ligament reconstruction with patellar tendon graft.

Background: Hamstring strengthening after anterior cruciate ligament reconstruction is a vital component of the rehabilitation program.

Purpose: The objective of this trial was to investigate the effects of hamstring isokinetic training used in the early phase of the rehabilitation program on the stability, strength, symptoms, and functional outcomes of patients throughout 12 months after anterior cruciate ligament surgery.

Study Design: Randomized controlled clinical trial; Level of evidence, 2.

Methods: Forty-eight men underwent anterior cruciate ligament reconstruction with an ipsilateral bone-patellar tendon-bone autograft. The patients were randomly assigned to perform daily isokinetic hamstring exercises at postoperative 3 weeks (group I) or to perform daily isokinetic hamstring exercises at postoperative 9 weeks (group II). The patients were evaluated monthly for the first 4 months and at the 12th month for postoperative hamstring and quadriceps strength, as well as for knee function via the Cincinnati Knee Rating Scale and International Knee Documentation Committee form.

Results: Hamstring isometric strength at 30 degrees of knee flexion (at the first and second months) and concentric isokinetic strength (at 2, 3, 4, and 12 months) at the angular velocity of 60 deg/s were significantly (P <.05-.01) greater in group I compared with group II. Average scores of the Cincinnati Knee Rating Scale for symptoms were significantly (P <.05-.001) higher in group I compared with group II at all evaluation periods. Walking and stair-climbing scores at 1, 2, 3, and 4 months and squatting score at all evaluation periods were also better (P <.05-.01) in group I compared with group II. In addition, group I exhibited better (P <.01-.001) Lachman test results compared with group II for all postoperative evaluation periods. The International Knee Documentation Committee final rating scores were significantly (P <.01) greater at 2, 3, and 4 months in group I compared with group II.

Conclusion: The results of this study suggest that hamstring as well as quadriceps strength can be increased via early hamstring strengthening after anterior cruciate ligament reconstruction with no negative impact on knee function.