Reposition acuity and postural control after exercise in anterior cruciate ligament reconstructed knees

This study aimed to compare the effects of 36 min of continuous exercise on postural control and joint reposition acuity in patients with anterior cruciate ligament reconstruction (ACL-R) and healthy controls.

Twenty patients (10 women and 10 men; mean ± SD; age = 25.5 ± 5.5 yr, height = 1.75 ± 0.10 m, weight = 76.7 ± 14.4 kg) with a history of primary, uncomplicated ACL-R (5.0 ± 4.3 yr postsurgery) were matched to 20 healthy controls (10 women and 10 men, 24.6 ± 5.0 yr, 1.70 ± 0.09 m, 65.2 ± 12.1 kg). The center of pressure (COP) excursions in the medial-lateral (COP(ML-SD)) and anterior-posterior (COP(AP-SD)) directions and the velocity (COP(Vel)) and area (COP(Area)) were calculated during static, unipedal stance. Open-chain knee joint reposition acuity measures (absolute angular error [AAE] and relative angular error [RAE]) at 45° (AAE₄₅ and RAE₄₅) and 15° of knee flexion (AAE₁₅ and RAE₁₅) were recorded. Measures were recorded at baseline and after a 36-min exercise protocol. Exercise consisted of six repeating cycles of inclined treadmill walking (5 min) and jumping exercises (1 min).

At baseline, the ACL-R group exhibited higher magnitude AAE₄₅ compared with controls. AAE₄₅ and COP(ML-SD) significantly increased after exercise in the control group; however, the ACL-R group did not experience a change in these measures.

In a rested state, patients with a history of ACL-R have greater impairment in joint reposition acuity than healthy control. Exercise increased COP measurements and impaired joint reposition acuity. Healthy controls experienced impaired joint reposition acuity after exercise, whereas patients with a history of ACL-R did not.