SENSORIMOTOR PERFORMANCE AND NEUROMUSCULAR ACTIVITY DURING EARLY REHABILITATION AFTER ACL RECONSTRUCTION: A PILOT STUDY

A. Busch^1,2, H. Baur¹

¹Bern University of Applied Sciences, Bern, Switzerland, ²University of Potsdam, Potsdam, Germany

Background: Sensory information processing plays an important role in human movement control. It is believed that with the rupture of the anterior cruciate ligament (ACL) altered afferent information are centrally integrated resulting in biomechanical alterations. The sensorimotor performance can be quantified with the joint position sense (JPS) test. However, data during early rehabilitation after ACL rupture and reconstruction are limited.

Purpose: To measure sensorimotor performance and neuromuscular activity during an active JPS test in patients with ACL reconstruction compared to a control group.

Methods: Six participants with ACL rupture and reconstruction (two females, age: 22.5±3 years, height: 173±10 cm, weight: 72±10 kg) and six controls (two females, age: 23±3 years, 172±10 cm, weight: 72±13kg) performed a seated knee JPS test with a target angle of 50° flexion (0°=full extension). Measurement timepoints for the patient group were 5-8 weeks and 12-16 weeks post-surgery, while the control group were measured once. Per measurement timepoint two blocks of three minutes continuous angel reproduction for each leg were performed. A familiarization of 5 trials with visual feedback was provided prior to execution and the starting leg was randomized. The difference between reproduced and target angle was identified as angular error measured using an electrogoniometer. Neuromuscular activities of the muscles vastus medialis and lateralis as well as rectus femoris were recorded via electromyography and split into movement phases of pre-activation (150ms prior to movement onset) and extension to target angle (onset movement to reaching targeted angle). For statistical analysis the limb sides were processed as affected (ACL reconstructed), non-affected (contralateral) leg and matched affected leg (control group). Neuromuscular activity was normalized to submaximal voluntary contraction. Descriptive statistics and analyses of variance for repeated measures were used to compare the angular error and neuromuscular activity per group and leg (α=0.05). Informed consent was obtained from all participants and the study was ethically approved by the local legal authority (KEK No. 02200).

Results: No significant difference in angular error was found comparing the patient and control group at all measurement timepoints and legs. Nonetheless, the affected side revealed a mean angular error above 5° at both measurement timepoints. During pre-activation no significant differences in vastus medialis and lateralis were evident between all groups and legs. The recuts femoris demonstrated a significant (p=0.023) higher activation in the affected leg compared to the non-affected leg at the first measurement timepoint. No significant differences were found during extension to target angle in all muscles and between each group and leg.

Conclusions: The mean angular error >5° lies above the minimal detectable change reported in the literature. Therefore, sensorimotor performance seems to be clinically relevant impaired in the affected limb early after ACL rupture and reconstruction. Underlying neuromuscular activity showed no significant alterations compared to a healthy control group.

Implications: Sensorimotor deficits are present shortly after ACL reconstruction. Thus, a focus on neuromuscular training in the early rehabilitation phase should be emphasized. Training of the contralateral leg might elicit bilateral learning effects improving the affect side.

Funding acknowledgements: This study was part-financed by the Campus SLB Sonnenhof AG – Stiftung Lindenhof.

Keywords:
Joint position sense
EMG
Anterior cruciate ligament

Topics:
Musculoskeletal: lower limb

Did this work require ethics approval? Yes

Institution: Gesundheits-, Sozial- und Integrationsdirektion des Kantons Bern (GSI)

Committee: Kantonale Ethikkommission

Ethics number: 2200