Cortico-motor adaptations and proprioceptive acuity in patients with unilateral anterior cruciate ligament deficiency

Abstract

The purpose of this project was to study proprioceptive deficits and corticomotor adaptations in following ACL injuries. Methods. Ten participants with chronic ACL injuries and eight controls participated. Subjective function (KOS-ADLS) and quadriceps strength (MVC) were measured. Proprioceptive acuity was assessed with a weight discrimination task. Transcranial magnetic stimulation was used to assess four indices of cortico-motor excitability and the quadriceps H-reflex was measured. Results. On the injured side in the ACL group, KOS-ADLS, WC (p < 0.018) and proprioceptive acuity (p < 0.01) were reduced. RMT were lower on the injured side ( p = 0.019). H-reflex amplitude was smaller on the injured side (n = 5). The extent of quadriceps motor representation (input-output curve) was correlated (r2 = 0.523) with MVC values on the injured side. Discussion. Reduced proprioception may reflect an impaired capacity to process force signals centrally, whilst increased corticomotor excitability may reflect a greater voluntary control to ensure joint stability.