Investigations into the architecture of the gastrocnemius, vastus medialis, and vastus lateralis, and monitoring changes in response to physiotherapy

Background The vastus medialis (VM) and vastus lateralis (VL) form part of the quadriceps femoris group in the anterior thigh. A balance between these two muscles is key to maintaining normal tracking of the patella in the trochlear groove during flexion and extension of the knee joint, and an imbalance between them is thought to be implicated in the aetiology of patellofemoral pain (PFP). Patellofemoral pain is one of the most common musculoskeletal presenting conditions among young, athletic individuals, and particularly affecting females. First line treatment usually involves physiotherapy, either to strengthen the VM or to stretch the VL. However, there is a lack of evidential data in the literature regarding the effect of these interventions on the architecture of these muscles. Aims This thesis, drawing upon a selection of previously published work of the author, aims to review, integrate, and critically appraise these published works. The body of work presented in this thesis is organised under the following themes: 1. Describe the detailed anatomy of the gastrocnemius and VM by a series of dissection studies and clarify the existence of the proposed subdivisions of the VM: the vastus medialis longus (VML) and the vastus medialis oblique (VMO). 2. Explore the potential of using ultrasound (US) to visualise muscle architecture, first on the gastrocnemius then the VM; validate the method for measuring the VMO fibre angle. 3. Obtain normative values for the pennation angle and insertion level of the VMO in a cohort of young, asymptomatic individuals, and further investigate the dichotomy between active and sedentary individuals. 6 4. Investigate the effect of physiotherapy on the architecture of the VMO, and how this effect was influenced by the following factors: different exercise techniques, electro-muscular stimulation, and cessation of the physiotherapy. 5. Investigate the effect of stretching exercises and myofascial release on the pennation angle of the VL and VMO. Methods Dissection studies were carried out on cadaveric specimens donated for anatomical education and research under the Human Tissue Act (2004). For the ultrasound investigations, young, asymptomatic volunteers were recruited, given an initial ultrasound (US) scan, then scanned again following a physiotherapy programme. Ethical approval was obtained from the host institution, and all volunteers gave informed consent. Results The research publications presented here describe the detailed anatomy of the gastrocnemius, VML and VMO, and present normative values for the pennation angle and level of insertion of the VMO in young, asymptomatic individuals. Ultrasound is shown to be a reliable tool for investigating the architecture of the VL and VM in vivo, and for monitoring the effects of physiotherapy interventions on these muscles. Furthermore, suitable subjects for such interventions can be identified in clinic by an ultrasound scan. Conclusions Gastrocnemius: there was a significant mean difference of 1.74 (±1.43) cm between the medial and lateral bellies in a sample of 84 cadaveric lower limbs. Vastus medialis and lateralis: physiotherapy interventions to strengthen the VMO, or to stretch the VL, have a measurable effect on the architecture of the muscles, which can be detected using ultrasound. Ultrasound is a safe, non-invasive, inexpensive imaging modality, and has the potential to provide a powerful tool in the clinic to measure initial VL and VM muscle fibre 7 angle in PFP cases, identify suitable patients for this type of treatment, and monitor their progress.