Changes in the sensorimotor system and semitendinosus muscle morphometry after arthroscopic anterior cruciate ligament reconstruction: a prospective cohort study with 1-year follow-up.

PURPOSE: To evaluate the time course of sensorimotor integration processes involved in balance capability during 1-year follow-up after arthroscopic anterior cruciate ligament (ACL) reconstruction. To evaluate whether an association exists between balance performance and semitendinosus muscle morphometry features.

METHODS: Twenty-seven patients (mean age 29.6 ± 10.8 years) were prospectively followed with stabilometry and ultrasound at 3 months (T0), 6 months (T1), and 1 year (T2) after arthroscopic ACL reconstruction. Body sway and sensorimotor integration processes were evaluated by calculating the percentage difference of sway (PDS) on two surface conditions.

RESULTS: A significant difference in PDS was observed over time (p < 0.001). The interaction "Time × Condition" showed significant differences (p = 0.02), with worse performance on the compliant than the firm surface. There was a significant difference in CSA (p < 0.001), MT (p < 0.001), and %HRD (p < 0.001) over time. The interaction "Time*side" was significant for CSA (p = 0.02) and %HRD (p = 0.01). A negative correlation between PDS on compliant surface and CSA was measured at 3- (r = - 0.71, n = 27, p < 0.001) and 6-month post-surgery (r = - 0.47, n = 27, p = 0.013).

CONCLUSIONS: Balance was regained within the first 6 months after surgery, while morphometry of the semitendinosus muscle improved mostly between 6 and 12 months in patients who returned to sports activities. Balance capabilities paralleled semitendinosus muscle morphometry improvements. The instrumental assessment of sensorimotor integration processes is relevant in clinical practice as screening tests for primary and secondary prevention of ACL injury.

LEVEL OF EVIDENCE: Prospective studies, Level II.