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Title: Musculoskeletal modelling to analyse and treat anterior cruciate ligament deficiency
Author: Azmi, Nur Liyana
ISNI:       0000 0004 7229 3383
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2018
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Anterior cruciate ligament (ACL) deficiency results in knee instability that includes an increase in internal tibial rotation and anterior tibial translation (ATT) as ACL is the primary restraint to anterior shear and internal rotation. Clinically, ACL deficient (ACLD) patients undergo surgery or/and rehabilitation programmes depending on their ability to cope or otherwise. However, the ACL reconstructed (ACLR) knees may still have residual instability in ATT and tibial internal rotation. Functional electrical stimulation (FES) has been used in conventional physiotherapy for ACL deficiency, including strengthening the muscles around the knee. The rehabilitation treatment focuses on strengthening the quadriceps muscle because it gets weakened after ACL injury or ACL reconstruction. However, stimulating the hamstrings, especially the biceps femoris long head (BFLH) with its insertion on the fibular head is a candidate to reduce the knee instability of ACLD and ACLR by applying a posterior pull and external rotation to the tibia. This thesis proposes that knee instability in ACLD subjects can be reduced by stimulating the BFLH muscle with FES. Here, a musculoskeletal modelling approach was used to simulate the function of FES. A new optimisation method was developed which allowed the inclusion of FES. There are three main studies present in this thesis. First, a pilot study was conducted in which healthy control subjects walked with and without FES of BFLH. It was found that selective activation of the BFLH can reduce the anterior tibial shear and tibial internal rotation torque at the knee in healthy subjects. Second, a validation study for the algorithm used in the musculoskeletal model was conducted in which the effect of FES stimulation of the BFLH on gluteus maximus activations was tested using electromyography (EMG). This study concluded that there were statistical correlations between peak and impulse of gluteus maximus activation between FES activation level and muscle activity of gluteus maximus as quantified by both EMG and the musculoskeletal model. In the final study, the validated model was used to compare the internal rotation torque, anterior shear force, speed and gluteus medius and gluteus maximus muscle activation between control, ACLD and ACLR groups during stance phase with and without FES stimulated on BFLH. This study found that the activation of BFLH with FES during stance phase was able to reduce the knee instability of the patient groups and triggered the compensatory mechanism for each patient group to react differently. Therefore, besides quadriceps, the rehabilitation treatment should focus on appropriate timed activation of the BFLH to improve the quality of life of patients.
Supervisor: Bull, Anthony Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral