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Busch A1,2, Blasimann A1, Henle P3, Baur H1,4
1Bern University of Applied Sciences, Department of Health Professions, Physiotherapy, Bern, Switzerland, 2University of Potsdam, University Outpatient Clinic, Sports Medicine & Sports Orthopaedics, Potsdam, Germany, 3Sonnenhof Orthopaedic Center, Department of Knee Surgery and Sports Traumatology, Bern, Switzerland, 4University of Bern, Institute of Sport Science, Bern, Switzerland
Background: The anterior cruciate ligament (ACL) rupture is a severe knee injury which is followed by short- and long-term effects such as pain, limited mobility, reduced sports participation, and may eventually lead to joint degeneration. Altered kinematics and kinetics in ACL reconstructed (ACL-R) patients compared to healthy participants with intact ACLs (ACL-I) are known and often attributed to an altered sensorimotor control. However, the knowledge about neuromuscular control deficits in ACL patients is sparse and studies often lack homogeneous patient cohorts.
Purpose: The aim of this pilot study was therefore to examine neuromuscular activity in a functionally relevant situation like stair descent in patients one year after ACL reconstruction.
Methods: Neuromuscular activity of vastus medialis (VM) and lateralis (VL), biceps femoris (BF) and semitendinosus (ST) was recorded by electromyography in ten ACL-R (age: 26±10 years; height: 175±6 cm; body mass: 75±14 kg, graft type: quadriceps tendon) and ten healthy matched controls (age: 31±7 years; height: 175±7 cm; body mass: 68±10 kg). A ten-minute walking treadmill warm-up was used for submaximal normalization of electromyographic data. Afterwards, participants had to descend ten times a six-step stairway at self-selected speed. The movement was separated into pre-activation (PRE), weight acceptance (WA) and push-off phase (PO) by ground reaction force data. Normalized root mean squares for each muscle, limb and movement phase were calculated. Kruskal-Wallis ANOVA compared ACL-R injured leg with the contralateral leg and the ACL-R injured leg with an ACL-I control leg (α=0.05).
Results: During weight acceptance (WA) the ST showed a 61% higher activation in the ACL-R injured leg compared to the ACL-I matched control leg (p = 0.031). In the push-off phase (PO), neuromuscular activity of VM of the ACL-R injured leg was reduced by 70% compared to the contralateral leg (p = 0.008). Furthermore, during push-off, VL in the ACL-R contralateral leg showed a 63% higher activation compared to the ACL-I matched leg (p = 0.006).
Conclusion(s): Altered neuromuscular activations are present one year after ACL reconstruction compared to the contralateral leg and the healthy matched control limb. Muscle specific alterations may implicate specific adaptations due to structural damage resulting from graft removal (VM, VL) or synergistic compensation to damaged ACL (ST). Based on these first pilot results, it can be concluded that current standard rehabilitation programs may not be able to fully restore sensorimotor control one-year post ACL reconstruction, and that consequently, therapy content of rehabilitation schemes possibly demand reconsideration.
Implications: Neuromuscular control deficits are present one-year post ACL reconstruction. Besides mechanical knee stability, restoration of full range of motion, strength recovery, sport specific movement patterns and psychological aspects, rehabilitation should especially focus on training of the sensorimotor system in various situations provoking mechanisms of active knee stabilization to restore neuromuscular control.
Keywords: ACL, neuromuscular control, rehabilitation
Funding acknowledgements: The study is supported by the Swiss National Science Foundation SNSF (project number: 176060, http://p3.snf.ch/project-176060).
Purpose: The aim of this pilot study was therefore to examine neuromuscular activity in a functionally relevant situation like stair descent in patients one year after ACL reconstruction.
Methods: Neuromuscular activity of vastus medialis (VM) and lateralis (VL), biceps femoris (BF) and semitendinosus (ST) was recorded by electromyography in ten ACL-R (age: 26±10 years; height: 175±6 cm; body mass: 75±14 kg, graft type: quadriceps tendon) and ten healthy matched controls (age: 31±7 years; height: 175±7 cm; body mass: 68±10 kg). A ten-minute walking treadmill warm-up was used for submaximal normalization of electromyographic data. Afterwards, participants had to descend ten times a six-step stairway at self-selected speed. The movement was separated into pre-activation (PRE), weight acceptance (WA) and push-off phase (PO) by ground reaction force data. Normalized root mean squares for each muscle, limb and movement phase were calculated. Kruskal-Wallis ANOVA compared ACL-R injured leg with the contralateral leg and the ACL-R injured leg with an ACL-I control leg (α=0.05).
Results: During weight acceptance (WA) the ST showed a 61% higher activation in the ACL-R injured leg compared to the ACL-I matched control leg (p = 0.031). In the push-off phase (PO), neuromuscular activity of VM of the ACL-R injured leg was reduced by 70% compared to the contralateral leg (p = 0.008). Furthermore, during push-off, VL in the ACL-R contralateral leg showed a 63% higher activation compared to the ACL-I matched leg (p = 0.006).
Conclusion(s): Altered neuromuscular activations are present one year after ACL reconstruction compared to the contralateral leg and the healthy matched control limb. Muscle specific alterations may implicate specific adaptations due to structural damage resulting from graft removal (VM, VL) or synergistic compensation to damaged ACL (ST). Based on these first pilot results, it can be concluded that current standard rehabilitation programs may not be able to fully restore sensorimotor control one-year post ACL reconstruction, and that consequently, therapy content of rehabilitation schemes possibly demand reconsideration.
Implications: Neuromuscular control deficits are present one-year post ACL reconstruction. Besides mechanical knee stability, restoration of full range of motion, strength recovery, sport specific movement patterns and psychological aspects, rehabilitation should especially focus on training of the sensorimotor system in various situations provoking mechanisms of active knee stabilization to restore neuromuscular control.
Keywords: ACL, neuromuscular control, rehabilitation
Funding acknowledgements: The study is supported by the Swiss National Science Foundation SNSF (project number: 176060, http://p3.snf.ch/project-176060).
Topic: Sport & sports injuries; Orthopaedics; Musculoskeletal: lower limb
Ethics approval required: Yes
Institution: Swiss Ethics Committees on research involving humans
Ethics committee: Ethics Committee of the Canton of Bern
Ethics number: 2017-02282
All authors, affiliations and abstracts have been published as submitted.
