Comparison of Knee Muscle Strength of Non-injured and Injured Sides following Anterior and Posterior Cruciate Ligament Reconstruction

Abstract

SangWook Hyun, Tae-Ho Kim.

Purpose: The purpose of this study was to compare knee muscle strength of non-injured and injured legs after reconstruction of the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL).
Methods: Thirteen volunteers (males) with anterior ligament injury and 10 volunteers (males) with posterior ligament injury participated in this study. Post reconstruction, the peak torque, total work, and hamstrings to quadriceps (H/Q) ratio were calculated at angular velocities of 60°/sec and 180°/sec in both groups using an isokinetic dynamometer. A t-test was used to compare the mean difference within-group and between-group comparisons. The data were analyzed using SPSS version 18.0 for Windows.
Results: In the within-group comparison of muscle strength and muscle endurance in the affected side and unaffected side at angular velocities of 60°/sec and 180°/sec, there was a significant difference in extensor strength in the ACL injury group and a significant difference in flexors and extensor strength in the PCL injury group (p<0.05). In the between-group comparison of the muscle strength and endurance of the affected side, flexors in the PCL injury group showed significantly higher muscle strength and endurance than those in the ACL injury group (p<0.05). No significant between-group difference in extensor strength was observed (p>0.05). In within-group comparisons, there was a significant difference in the H/Q ratio in the ACL injury group when the angular velocity was 60°/sec (p<0.05). At an angular velocity of 180°/sec, the H/Q ratio of the affected side in the ACL injury group was higher than that of the unaffected side, and the H/Q ratio in the PCL injury group was higher for the affected side than unaffected side, with a significant difference (p<0.05). In the between-group comparison of the H/Q ratio of the affected side, the value in the PCL injury group was higher than that in the ACL injury group when the angular velocity was 60°/sec, and the result was statistically significant (p<0.05). The H/Q ratio in the ACL injury group was significantly higher than that in the PCL injury group when the angular velocity was 180°/sec (p<0.05). Loss of extensor muscle strength was greater in the ACL group than in the PCL group. The PCL injury group showed loss of both extensor strength and flexor strength, with greater loss of flexor muscle strength than extensor strength.
Conclusion: These results suggest that individuals with ACL injury should focus on exercises for muscle strength and endurance in knee extensors and that those with PCL injury should concentrate on exercises for muscle strength and endurance in both knee flexors and extensors, especially knee flexors.