Longitudinal effects of anterior cruciate ligament injury and patellar tendon autograft reconstruction on neuromuscular performance

We examined persons after anterior cruciate ligament injury and for 1.5 yea rs after anterior cruciate ligament reconstruction to analyze changes in an terior knee laxity, lower extremity muscle strength, endurance, and several parameters of neuromuscular function. Sixteen men and nine women (average age, 23.8 years) were evaluated preoperatively, then underwent intraarticul ar autogenous patellar tendon anterior cruciate ligament reconstruction by the same surgeon and were evaluated at 6, 12, and 18 months postoperatively . Muscle strength was measured isokinetically and neuromuscular function wa s quantified with simultaneous anterior tibial translation and surface elec tromyography tests. Forty subjects (26 men and 14 women; average age, 23.5 years) with no known knee abnormalities served as the control group, Subjec tive questionnaire results showed that by 18 months postoperatively, 20 sub jects (80%) believed they had regained their preoperative levels of functio n. Unfortunately, muscle function in most subjects had not returned to norm al. At 12 to 18 months postoperatively, when knee rehabilitation was termin ated, significant deficiencies in muscle performance persisted in most pati ents. Interestingly, in this group of stable knees, quadriceps and hamstrin g muscle reaction times appeared to be the best objective indicators of sub jective knee function.