Journal of Sports Medicine & Doping Studies

Knee Objective Stability and Isokinetic Thigh Muscle Strength after Anterior Cruciate Ligament Reconstruction: A Randomized Six-Month Follow-Up Study

Abstract

Matjaz Sajovic and Simona Pavlic Zaloznik

Purpose: The most frequently used grafts for intra-articular anterior cruciate ligament (ACL) reconstruction are the autologous patellar tendon (PT) or doubled semitendinosus and gracilis tendons (STG) autografts. There are still controversies about graft selection for primary ACL reconstruction.

Methods: A prospective, randomized study was conducted on 57 patients who underwent arthroscopically assisted ACL reconstruction between January 2010 and February 2011. In 29 patients ACL reconstruction was performed with hamstring tendon autograft (STG group), and in 28 patients the ACL reconstruction was performed with patellar tendon autograft (PT group). At 6 months follow-up, all patients have performed the isokinetic extensor and flexor muscles strength and KT-1000 measurements.

Results: At 6 months after surgery, we found significantly lower average isokinetic quadriceps peak torque in the PT group compared to the STG group at angular velocity of 60°/s. However, at the same time we did not find significant difference in flexor muscle power comparing both groups. The manual maximum KT-1000 arthrometer side-to-side difference was 1.7 ± 1.7 mm for the PT group and 1.9 ± 1.6 mm for the STG group (P=0.398). No significant correlation was found between the knee objective stability (KT-1000 measurements) and the isokinetic thigh muscle strength (extensors, Spearman’s rho=0.057, P=0.671; flexors, Spearman’s rho=0.094, P=0.489).

Conclusions: Both hamstring and patellar tendon autografts provided good objective stability at 6 months after surgery In addition, regardless of which graft was used, a considerable percentage of patients continue to have strength deficits. In our opinion, the ACL-reconstructed leg should have 85% or greater return to the strength of the normal leg as one criterion before release to full sports activities. We were particularly intrigued to find only half of the competitive athletes achieved this goal at 6 months after surgery.