Biomechanical and histological concepts in the rehabilitation of patients with anterior cruciate ligament reconstructions.

The accelerated rehabilitation of patients who have had anterior cruciate ligament reconstructions has resulted in an earlier and more complete return of normal knee function. Although the clinical outcomes of the accelerated program are impressive, they are not entirely consistent with the basic science of graft healing. For example, patients begin stressful sports activities at a time when the surgical graft may be weakest. The purpose of this paper was to provide an understanding of these discrepancies by reviewing the biomechanics and histology of the healing surgical graft. The results indicated that graft isometry, protection of the graft from large anterior drawer forces, and the possible effects of exercise on graft strength and metabolism may explain the absence of deleterious effects during aggressive physical therapy and early return to sports participation.