Prospective study of kinesthesia after ACL reconstruction

Previous studies used a variety of methods to assess kinesthesia, thus no consensus exists regarding kinesthetic adaptation after anterior cruciate ligament (ACL) reconstruction. This study prospectively examined whether kinesthesia is adapted after ACL reconstruction, and then discussed the actual angular velocity required to properly assess kinesthesia in ACL-reconstructed patients. 31 patients were evaluated using the threshold to detect passive motion (TTDPM) test, which was applied preoperatively, and at 3, 6, and 12 months following surgery. TTDPMs were measured at 15° or 45° of knee flexion toward both extension and flexion with angular velocities of 0.1°/s or 0.2°/s. ACL-reconstructed knees showed significantly impaired TTDPMs compared to healthy knees before the operation at 15° of knee flexion toward extension and at 45° of knee flexion toward both extension and flexion at 0.2°/s (15° of knee flexion toward extension, P=0.036; 45° of knee flexion toward extension, P=0.015; 45° of knee flexion toward flexion, P=0.030). However, there were no significant differences after 3 months of follow-up. On the basis of these results, applying 0.2°/s seems appropriate to assess TTDPM for patients with an ACL reconstruction, and kinesthesia is adapted within 12 months after the operation. Sensory function and biomechanical stability are also adapted following ACL reconstruction.