Year: 2024
Type: article
Abstract: Anterior cruciate ligament rupture (ACLR) is a prevalent injury among active individuals. Sensorimotor neural plasticity after ACLR manifests along the corticospinal tract and contributes to persistent functional deficits. However, the intricate interplay between supraspinal measures, neuromuscular excitability, and their functional implications remains poorly explored. PURPOSE: 1) determine if individuals with a history of unilateral ACLR display differences in supraspinal measures compared with controls (CON), 2) neuromuscular excitability with and without ACLR, and 3) examine TMS-induced plasticity patterns in supraspinal and neuromuscular excitability between groups. METHODS: Nine women with a history of ACLR (age: 23.2±2.5yr) and 10 otherwise-matched controls (age: 23.5±3.2yr) participated in two laboratory visits and one MRI visit. Quadriceps strength and excitability measures (corticomotor, corticospinal, spinal-reflexive, peripheral excitability) were assessed bilaterally. Paracentral lobule (PCL) thickness was determined from high-resolution three-Tesla structural brain scans. On the final visit, participants received paired associative stimulation (PAS) to examine injury-related plasticity patterns and their impact on motor output. Between-limb and -group PCL thickness and physiological differences were assessed using mixed ANCOVAs. RESULTS: Compared to CON, ACLR reported worse knee function, less psychological readiness for sport, stronger fear-related beliefs during physical activity, and greater between-limb strength asymmetry. In addition, while PCL thickness was symmetrical in CON, ACLR displayed greater PCL thickness and corticomotor volume in the hemisphere contralateral to the injured limb than the healthy limb. CON had symmetrical PCL thickness, but greater corticomotor volume in the dominant limb. Corticospinal excitability did not differ between limbs or groups. However, ACLR had smaller H-reflex responses at rest compared to the active state and resting state in CON. Smaller H-reflex responses were related to worse balance performance. PAS did not change corticospinal, spinal-reflexive, or peripheral excitability, and had no effect on balance performance in either group. DISCUSSION: Years after injury, individuals with unilateral ACLR are less psychologically ready to resume physical activity and continue to perceive themselves as having worse knee function. The asymmetry in leg-specific corticomotor volume and PCL thickness between hemispheres, reduced H-reflex responses, and weaker knee extension strength in the previously injured limb emphasize the interplay between brain morphology and injury-related neuromuscular adaptations.
Author: Canino, Maria
Institution: University of Pittsburgh
Language: English
Subfield: Neurology
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W7039271663