RESUMO
ABSTRACT Objective: To determine the factors related to quadriceps weakness, to evaluate electromyo-graphic changes in the quadriceps and to attempt to determine the neuromuscular restoration period after anterior cruciate ligament (ACL) repair. Methods: A total of 30 patients (28 males and 2 females) who underwent surgery conducted by two surgeons were reviewed prospectively. All ACLs were reconstructed arthroscopically with anterior tibial tendon allograft, using an anteromedial portal. The patients' quadriceps muscles' neuromuscular activity was determined with electromyography at early and late periods (1-3 months and 6-12 months, respectively). Results: A significant difference was observed (p < 0.01) in the quadriceps circumference between the operated extremities (average, 48.4 cm) and the healthy limbs (average, 50.6 cm), according to measurements obtained on the sixth month after surgery. The tourniquet time was greater than 50 minutes in patients with quadriceps atrophy. A significant elongation was observed in the motor unit potential duration of the operated ipsilateral side, compared to the contralateral side (p < 0.001) at the early-term period. Differences were observed between the ipsilateral MUP amplitude and the durations of early- and late-term patients, but were not significant. Conclusion: Our study demonstrated that atrophies are significantly overcome in the first year after surgery. The electromyographic examinations indicated that tourniquet use not only caused functional harm in the quadriceps muscle but it also caused structural damage. However, these structural injuries did not result in negative effects on the clinical success.