AN ELECTROMYOGRAPHIC ANALYSIS OF THE KNEE DURING FUNCTIONAL ACTIVITIES .2. THE ANTERIOR CRUCIATE LIGAMENT-DEFICIENT AND LIGAMENT-RECONSTRUCTED PROFILES

This study compared the electromyographic activity of normal (N = 22), rehabilitated anterior cruciate ligament-deficient (N = 8), and -reco nstructed knees (N = 10) while subjects performed activities. Each sub ject had evaluation of 8 muscles during 7 functional activities. Sixty -seven percent of the differences in the quadriceps muscle reflected i ncreased activity in the vastus lateralis muscle of the rehabilitated group; 75% of the differences in the hamstrings muscles noted increase d biceps femoris muscle activity in the rehabilitated group; 56% of th e differences in the lower leg musculature showed increased tibialis a nterior muscle activity in the rehabilitated group. Eighty-six percent of the statistically different intervals involved rehabilitated subje cts demonstrating increased activity over reconstructed or normal subj ects or both. The presence of a quadriceps-hamstrings muscles coordina ted response was identified consistently in all 3 groups in each activ ity. This study supports surgical reconstruction for the anterior cruc iate ligament-deficient knee. It also demonstrates the importance of t he vastus lateralis, biceps femoris, and tibialis anterior musculature in the rehabilitation of the anterior cruciate ligament-deficient pat ient. The presence of a quadriceps-hamstrings muscles coordinated resp onse this reflex are exist in structures other than the cruciate ligam ent.