Abstract

Background: The purpose of the study was to determine the changes over time in quadriceps strength and voluntary activation deficits after reconstruction of the anterior cruciate ligament. Methods: Maximal voluntary contraction torque (MVC) and femoral nerve stimulation were used to measure quadriceps strength and voluntary activation deficits (VA) in both legs of 10 subjects with unilateral anterior cruciate ligament reconstruction immediately before and 4, 6, 8, 10, 12, 24, 36 and 48 weeks after surgery. To identify bilateral muscle inhibitions, 23 healthy participants served as controls. Results: The results showed significant changes over time of the involved quadriceps for MVC (F = 31.152; P < 0.001) and VA (F = 4.657; P < 0.05). Preoperatively, the MVC of the injured side showed significantly lower values compared with healthy controls (P > 0.01), whereas no VA deficits were found. Postoperatively, the MVC side-to-side differences lasted up to 12 weeks after surgery and the differences compared with the control group up to the 36 weeks. A unilateral VA deficit (P < 0.01) in the involved quadriceps was detected immediately after surgery (4th week), as well as, significant differences to healthy controls (P < 0.01). Conclusion: The results revealed that MVC and VA fully reflect the functional status of the quadriceps muscle recovery during rehabilitation. In addition to the bilateral VA deficits compared with healthy controls, the operated leg is affected by an extra VA deficit immediately after surgery that should be considered for future rehabilitation programs. Verf.-Referat