Parkinson’s disease (PD) is a common age-related neurodegenerative disease affecting the dopamine-producing cells of the substantia nigra pars compacta of the basal ganglia, in turn impacting widespread networks within the central nervous system. The neurodegeneration associated with PD manifests in may motor and nonmotor impairments, which negatively affects movement and quality of life (QOL) The motor impairments inherent to PD have a negative impact on walking. People with PD exhibit reduced speed, step length, foot clearance, arm swing, and trunk rotation during walking. Dynamic trunk rotation range of motion (TRROM) contributes to stability during walking by dissapating forces, generated by the lower extremities, as they are transferred up the kinetic chain. Adequate force dissipation serves to keep the head stable thus optimizing critical vestibular and visual inputs to maintain balance while walking. Decrease dynamic TRROM during walking is a discriminating factor in people with PD who fall compared to people with PD who do not fall. While dynamic TRROM is decreased during walking in people with PD, the underlying cause is unclear. Research has shown that rigidity and passive constraints in muscle and connective tissue extensibility may contribute to decreased dynamic TRROM during walking. Currently, little is known about how decreased static TRROM relates to dynamic TRROM during walking in people with PD. A more precise understanding of the impact of static TRROM on dynamic TRROM during walking may improve the specificity of physical therapy treatment interventions aimed to improve walking performance and reduce the frequency of falls in people with PD. Measurement of static TRROM in people with PD is problematic. A valid, reliable, and clinically feasible method of measuring static TRROM has not been established in people with PD. While the goniometer is a standard measurement tool used clinically to measure joint ROM, measurement of static TRROM using a goniometer has not been validated in people with PD. A valid and reliable measurement technique is needed to objectively assess treatment effectiveness, quantify change in ROM over time, and monitor patient progress towards their functional goals. The aims of the present study are to 1) determine the reliability (inter and intrarater) and concurrent validity of a goniometer for measuring static TRROM in people with PD and 2) determine the degree to which static TRROM contributes to dynamic TRROM during walking in people with PD.
