Review Question - QID 982

Seated leg extensions are open chain exercises that are generally avoided early after ACL surgery. Closed chain exercises are emphasized because it allows for physiologic contraction of the muscles around the knee. Closed chain exercises load an extremity with the most distal segment stabilized, preventing joint shear forces. This is ideal for post-operative rehab for an ACL. For open chain exercises, the foot is unsupported. Quad sets and straight leg raises are generally allowed to help regain quadriceps function. They produce less graft strain because they are isometric about the knee, compared to a seated leg extension in which the quad force is pulling the tibia anteriorly and potentially stressing the graft.

Ross et al reviewed the literature and found support for both closed chain exercises and modified open chain exercises for quadriceps strengthening at different timepoints after ACL reconstruction without causing excessive ACL strain or patellofemoral joint stress.

Beutler et al examined EMG activity of the quad in normal subjects doing single-leg squats and step-ups. They found high sustained quad activity suggesting that these exercises would be effective in muscle rehabilitation and that as functional, closed chain activities, they may also be protective of anterior cruciate ligament grafts.

The study by Wright et al is a systematic review of the recent literature regarding ACL rehabilitation.