Anteroposterior tibiofemoral displacements during isometric extension efforts

Abstract

Rehabilitation of knee extensors is a major considera tion in patients with cruciate injuries and repairs. Exten sion exercises, however, can produce undesirable loads on the injured or replaced anterior cruciate liga ment (ACL) resulting in permanent stretch of this re straint. Our study measures the tibiofemoral displace ments associated with proximal, middle, and distal lo cations of the external resisting force and knee flexion angles of 30°, 60°, and 90°. Our results show that tibiofemoral displacements are dependent on both location of the external resisting force and knee flexion angle, with anterior displace ments being associated with distal displacement of the resistance pad. The results suggest that patients with ACL injuries or repairs conduct extension exercises with a proximal position of the resistance pad to mini mize loads and prevent stretching of this constraint.