Table 1.
Characteristics and findings of studies investigating neurophysiological changes related to ACL injury
| Study | Participants | Technique, Design | Time Course | Main Findings |
|---|---|---|---|---|
| Diekfuss et al (2018) 14 | ACL: n = 2, female, 16 ± 0 y Control: n = 8, female, 15.9 ± 0.8 y |
fMRI, case-control, prospective | Between testing and injury: 2 wk and 3.5 mo | Poorer connectivity between the left primary sensory cortex and right posterior lobe of cerebellum |
| Diekfuss et al (2019) 13 | ACL: n = 3, male, 16.33 ± 0.58 y Control: n = 12, male, 16.83 ± 0.39 y |
fMRI, case-control, prospective | Between testing and injury: 57, 67, and 243 d | Poorer connectivity between the left secondary somatosensory cortex and left supplementary motor area, left primary somatosensory cortex, and left primary motor cortex |
| Zarzycki et al (2018) 45 | ACL: n = 18, F:M = 10:8, 21.8 ± 3.3 y Control: n = 18, F:M = 10:8, 22.2 ± 2.5 y |
TMS, case-control | 2 weeks after ACLR | Corticospinal excitability is lower and intracortical facilitation is asymmetrical between 2 limbs in ACLR group |
| Zarzycki et al (2020) 46 | ACL: n = 18, F:M = 10:8, 21.6 ± 3.3 y Control: n = 18, F:M = 10:8, 22.3 ± 2.5 y |
TMS, case-control, longitudinal | 3 time points: (1) 2 wk after ACLR, (2) quiet knee, (iii) return to running | ICF is asymmetrical for the injured limb in ACL regardless of time point. Positive relationship between SICI and quadriceps strength at quite knee |
| Tang et al (2020) 39 | ACL: n = 20, F:M = 5:15, 24.1 ± 3.55 y Control: n = 20, F:M = 5:15, 22.3 ± 2.62 y |
TMS, case-control | Between testing and injury: 31 mo, between testing and ACLR: 27 mo | SICI was lower and ICF was higher in the injured limbs |
| Criss et al (2020) 9 | ACL: n = 15, F:M = 8:7, 20.9 ± 2.7 y Control: n = 15, F:M = 8:7, 22.5 ± 2.5 y |
fMRI, case-control | 43.3 ± 33.1 mo after surgery | Increased activity and connectivity in brain regions associated with visuospatial cognition and attention |
| Grooms et al (2015) 22 | ACL: n = 1, male, 25 y Control: n = 1, male, 26 y |
fMRI, case-control, prospective | 10 mo after initial, 26 d before secondary injury | Increased activity of motor planning, sensory, and visuomotor areas after the initial, before the second injury |
| Lepley et al (2020) 26 | ACL: n = 10, F:M = 6:4, 22.6 ± 1.9 y | MRI, TMS cross-sectional | 70.0 ± 23.6 mo after surgery | Reduced white matter volume and excitability in contralateral hemisphere |
| Lepley et al (2019) 25 | ACL: n = 11, F:M = 6:5, 22.6 ± 1.8 y Control: n = 11, F:M = 6:5, 23.2 ± 1.6 years |
fMRI, TMS, case-control | 69.4 ± 22.4 mo after surgery | Increased activation in frontal and cingulate cortex, increased active motor threshold and decreased motor-evoked potentials |
| Scheurer et al (2020) 33 | ACL: n = 16, F:M = 8:8, 20.4 ± 1.8 y Control: n = 16, F:M = 8:8, 21.0 ± 1.7 |
TMS, case-control | 33.9 ± 26.1 mo after surgery | Decreased corticospinal excitability and increased intracortical inhibition associate with reduced torque development |
ACL, anterior cruciate ligament; ACLR, anterior cruciate ligament reconstruction; F, female; fMRI, functional magnetic resonance imaging; ICF, intracortical facilitation; M, male; MRI, magnetic resonance imaging; SICI, short-interval intracortical inhibition; TMS, transcranial magnetic stimulation.