USING MUSCULOSKELETAL MODELING TO ASSESS MUSCLE FUNCTION AND GAIT ASYMMETRY AFTER A STRAYER PROCEDURE APPLIED TO A CHILD WITH CEREBRAL PALSY

• Autor(a) principal: Cunha, Luís Abílio Sousa Fonseca Machado
• Data de Publicação: 2023
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/157058
• topic: Jump gait; Cerebral palsy; Strayer procedure; Musculoskeletal modeling; Computed Muscle Control; Induced Acceleration Analysis; Domínio/Área Científica::Engenharia e Tecnologia::Outras Engenharias e Tecnologias

Cerebral palsy (CP) is a common group of neuromotor disorders with symptoms appearing during childhood. Children with CP often undergo orthopedic surgeries and treatment plans depending on the gait pattern and its severity. Jump gait is a gait pattern present in bilateral spastic CP and is characterized by a combination of ankle equinus, accentuated hip and knee flexion, lumbar lordosis, and anterior pelvis tilt. The modified Strayer procedure is a surgical intervention to treat equinus in ambulatory children with CP and is often accompanied by botulinum toxin type A (BTX) injections to aid in spasticity reduction. Musculoskeletal modeling is a promising approach to indirectly estimatemuscle function, includingmuscle force, andmuscle induced accelerations. Gait asymmetry is often studied as it is associated with pathological gait. This study aimed to analyze the improvements in gait function in one child with CP following corrective surgery for jump gait. Gait asymmetry, muscle forces and contributions to the center of mass accelerations during walking were assessed before, one and two years after surgery. Furthermore, comparison with typically developed children was also performed. Threedimensional marker coordinates and ground reaction forces (GRF) during walking were recorded and used as input for musculoskeletal simulations using OpenSim. Two years post-surgery, gait asymmetry reduced to levels similar to or lower than unimpaired gait. Overall joint kinematics improved, although the increase in dorsiflexion was not enough to achieve heel strike at first contact in the lower limb submitted to surgery. Estimates of muscle forces showed the child with CP relied more on proximal muscles to walk, mainly the vasti and hamstrings, before and after surgery. Soleus muscle forces increased following surgery, becoming the primary contributor to vertical support from the plantarflexors. Suggestions were made for treatment plans and for maintaining surgical improvements, such as strengthening of weakened muscles.