Normalized motor function but impaired sensory function after unilateral non-reconstructed ACL injury: patients compared with uninjured controls

Improvement in motor function after anterior cruciate ligament (ACL) injury is achieved by appropriate rehabilitation. However, it has been questioned whether training after injury can lead to sensory improvement. We hypothesized that motor function can be restored after unilateral non-reconstructed ACL injury, whereas the sensory function cannot, i.e., there would be no difference in functional performance or knee muscle strength between subjects with ACL injury and uninjured controls, but the subjects with ACL injury would have poorer kinesthesia than the uninjured controls. This is a Cross-Sectional Study, wherein 56 (20 women and 36 men) individuals with unilateral non-reconstructed ACL injury were assessed at a mean of 15 years (SD 1.4 years) after the initial injury. All patients initially underwent rehabilitation and were advised to modify their activity level, in order to cope with the ACL insufficiency. At 15 years, they had good subjective function and acceptable activity level. Twenty-eight (14 women and 14 men) uninjured subjects served as controls. Patients and controls were assessed with the one-leg hop test for distance, isometric and isokinetic knee muscle strength, and kinesthesia (the threshold to detection of passive motion). The individuals with ACL injury had the same or better functional performance, measured by the one-leg hop test for distance, and knee muscle strength compared with the uninjured controls. Kinesthesia was poorer in the patient group than in the control group. The results indicate that motor function can be restored but that the sensory function is persistently disturbed after ACL injury.