Exploring the brain after ACL reconstruction: examination of neurophysiological and psychological factors during the course of post-operative rehabilitation
Date
2018
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
University of Delaware
Abstract
Rupture of the anterior cruciate ligament (ACL) is a devastating injury affecting approximately 250,000 individuals each year in the United States. Upwards of 130,000 anterior cruciate ligament reconstructions (ACLR) are performed each year. While ACLR restores mechanical stability of the knee, many patients continue to experience functional performance deficits, reduced capacity for physical activity and participation, and second injury. Current rehabilitation strategies may not be sufficiently addressing neurophysiologic alterations and psychological factors related to injury. An improved understanding of these factors may result in more effective post-operative rehabilitation protocols, fewer second injuries and safer return to sports. ☐ The overall goals of this work were: 1) to compare corticospinal, intracortical, and spinal-reflexive excitability in athletes after ACLR and controls, and explore the relationship of these neurophysiologic measures to quadriceps strength, 2) to explore the relationship between psychological readiness to return to sport and gait biomechanics, and 3) to determine if a secondary ACL injury prevention program affects psychological readiness to return to sport and if an improvement in psychological readiness is associated with better outcomes. ☐ This work includes data from two distinct studies. For goal #1, athletes after ACLR underwent neurophysiologic testing via transcranial magnetic stimulation and peripheral electrical stimulation when they achieved 3 important rehabilitation milestones: 1) 2 weeks after surgery, 2) achievement of a “quiet knee” defined as full range of motion and minimal effusion, 3) return to sport (RTS) activities time point defined as achievement of a quadriceps index ≥ 80% and at least 12 weeks post-ACLR. For goals #2 and #3, athletes after ACLR were enrolled after completing impairment resolution defined as: full range of motion, minimal effusion, adequate quadriceps strength and greater than 12 weeks from surgery. Following enrollment, all athletes completed a secondary ACL injury prevention program. Psychological readiness to return to sport and self-reported functional measures were evaluated at enrollment, after the prevention program, and at 1 year after ACLR. ☐ Athletes after ACLR demonstrated alterations in corticospinal, and intracortical excitability early after surgery compared to controls, and these neurophysiologic measures were associated with isometric quadriceps strength during the course of rehabilitation. Changes in these measures did not occur throughout rehabilitation indicating that current rehabilitation may not be addressing cortical alterations associated with chronic quadriceps dysfunction. ☐ For goals #2 and #3 we found that there is a relationship between knee kinematic and kinetic symmetry and psychological readiness to return to sport, prior to return to sport after ACLR. Athletes who scored lower on a psychological readiness to return to sport measure displayed greater asymmetries during gait. Additionally, athletes who demonstrated an improvement in psychological readiness to return to sport had better self-reported function following a secondary injury prevention program and at one year after ACLR. ☐ In conclusion, neurophysiologic pathways from the motor cortex to the
quadriceps muscle and psychological factors are related to common impairments and
outcomes after ACLR. While research is emerging in these two areas, more research
is needed to address the less than optimal outcomes currently related to recovery after
ACLR. Addressing cortical excitability and psychological readiness to return to sport
during rehabilitation have the potential to improve outcomes after ACLR.
Description
Keywords
Biological sciences, ACL reconstruction, Corticospinal excitability, Psychological factors