Inter-Relationships between Static and Dynamic Indicators of Knee Recovery versus Maintenance of Sports Participation 5-10 Years after ACL Reconstruction

Background: A torn Anterior Cruciate Ligament (ACL) is the most common knee injury among athletes. In the United States alone there are 250,000 injuries a year which lead to high financial expenses and the inability of athletes to continue physical/athletic activity. In most cases, and especially in populations interested in resuming physical/athletic activity, treatment of the injury demands surgical intervention while even following reconstructive surgery of the ligament, a great risk of recurring injury exists.

Most injuries do not occur as a result of external physical contact (for example, with a rival player) but from dysfunctional movement patterns, lower limb asymmetry and insufficient technique while performing skills, such as landing after jumping, changes in directions and rotational movements. These causes create an uneven division of weight on the joints of the lower limbs, thus increasing the risk of injury.

Aims: Most of the studies on the topic examined one of the factors influencing limb function within a six-month to one-year time range from the reconstruction of the ligament. The study aims are to examine several factors influencing lower limb functioning after a period of five to ten years from reconstruction by analyzing kinetic variables, kinematic and strength measurements.

Methods: 30 men after isolated autologous hamstring ACL reconstruction at the age 18-35 years with a five-to-ten-year follow-up who didn’t sustain re-injuries underwent dynamic knee evaluation. This included a knee extensors/flexors isokinetic test, time-to-stabilization, lower limb moments during the vertical drop test and the single-legged hop jump distance. Variables were tested by a three-dimensional motion analysis system (Vicon) combined with force plates and isokinetic dynamometer.

A comparison was made between the operated limbs and the healthy limb results.

Results: In this work there were no significant differences between the limbs in the ability to perform functional tasks such as rapid stabilization, landings and bounces.

There were significant differences in the benefit of the healthy limbs in all variables 60 degrees/second at the Isokinetic test.

Discussion and Conclusions: The injured limbs are characterized by a weakness in extensor and flexor muscle groups as opposed to the healthy limbs. In addition, it seems that the motion pattern of the injured limbs is different from that of the healthy limbs. In the injured limbs one can see a dominance of the hip joint in performance of tests as opposed to a dominance of the knee joint in the healthy limbs.