Functional gait adaptations in patients with anterior cruciate ligament deficiency over time.

Functional adaptations in knee kinematics and kinetics during level walking in 30 patients with unilateral anterior cruciate ligament deficiency and 30 healthy control subjects were studied. To examine the impact of time after injury on the functional adaptations, patients were placed into three time interval groups: early, intermediate, and chronic. The patients with anterior cruciate ligament deficiency had significantly decreased external knee flexion moments (balanced by net quadriceps contraction) and significantly increased external knee extension moments (balanced by net knee flexors contraction) as compared with the control subjects. As time after the injury increased, changes in the sagittal plane knee moments were more pronounced. A significant linear relationship (positive correlation) was found between the midstance knee flexion moment and the corresponding knee flexion angle. The patients with anterior cruciate deficiency had a greater knee flexion angle when generating a comparable midstance knee flexion moment as compared to the control subjects. The identification of gait adaptations over time provides additional information on the natural history of anterior cruciate ligament deficiency and may have implications regarding conservative rehabilitation, evaluation of outcomes, progression of meniscal injury, and the development of degenerative arthritis of the knee.