title: Quadriceps neural alterations in anterior cruciate ligament reconstructed patients: A 6-month longitudinal investigation.
abstract: The purpose of this investigation was to evaluate differences in quadriceps corticospinal excitability, spinal-reflexive excitability, strength, and voluntary activation before, 2 weeks post and 6 months post-anterior cruciate ligament reconstruction (ACLr). This longitudinal, case-control investigation examined 20 patients scheduled for ACLr (11 females, 9 males; age: 20.9 ± 4.4 years; height:172.4 ± 7.5 cm; weight:76.2 ± 11.8 kg) and 20 healthy controls (11 females, 9 males; age:21.7 ± 3.7 years; height: 173.7 ± 9.9 cm; weight: 76.1 ± 19.7 kg). Maximal voluntary isometric contractions (MVIC), central activation ratio (CAR), normalized Hoffmann spinal reflexes, active motor threshold (AMT), and normalized motor-evoked potential (MEP) amplitudes at 120% of AMT were measured in the quadriceps muscle at the specific time points. ACLr patients demonstrated bilateral reductions in spinal-reflexive excitability compared with controls before surgery (P = 0.02) and 2 weeks post-surgery (P ≤ 0.001). ACLr patients demonstrated higher AMT at 6 months post-surgery (P ≤ 0.001) in both limbs. No MEP differences were detected. Quadriceps MVIC and CAR were lower in both limbs of the ACLr group before surgery and 6 months post-surgery (P ≤ 0.05) compared with controls. Diminished excitability of spinal-reflexive and corticospinal pathways are present at different times following ACLr and occur in combination with clinical deficits in quadriceps strength and activation. Early rehabilitation strategies targeting spinal-reflexive excitability may help improve postoperative outcomes, while later-stage rehabilitation may benefit from therapeutic techniques aimed at improving corticospinal excitability.
authors.affiliation: Department of Kinesiology and Health Promotion, University of Kentucky, Lexington, Kentucky, USA.
authors.forename: A S
authors.initials: AS
authors.lastname: Lepley
authors.affiliation: Department of Rehabilitation Sciences, University of Kentucky, Lexington, Kentucky, USA.
authors.forename: P A
authors.initials: PA
authors.lastname: Gribble
authors.affiliation: Biodynamics Research Laboratory, Department of Kinesiology, University of North Carolina at Charlotte, Charlotte, North Carolina, USA.
authors.forename: A C
authors.initials: AC
authors.lastname: Thomas
authors.affiliation: Department of Rehabilitation Sciences, University of Toledo, Toledo, Ohio, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Tevald
authors.affiliation: Department of Orthopedic Surgery, University of Toledo, Toledo, Ohio, USA.
authors.forename: D H
authors.initials: DH
authors.lastname: Sohn
authors.affiliation: Department of Exercise and Sports Science, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
authors.forename: B G
authors.initials: BG
authors.lastname: Pietrosimone
mesh_terms: D000293:Adolescent; D000328:Adult; D059549:Anterior Cruciate Ligament Reconstruction; D016022:Case-Control Studies; D004576:Electromyography; D019054:Evoked Potentials, Motor; D005260:Female; D006801:Humans; D007537:Isometric Contraction; D008137:Longitudinal Studies; D008297:Male; D053580:Muscle Strength; D011712:Pyramidal Tracts / Q000503:physiopathology; D052097:Quadriceps Muscle / Q000294:innervation* / Q000503:physiopathology*; D012021:Reflex, Abnormal; D050781:Transcranial Magnetic Stimulation; D055815:Young Adult
keywords: Knee injury; muscle inhibition; neuromuscular function; transcranial magnetic stimulation