Investigating cortical changes associated with patellar tendinopathy

Introduction: Tendinopathy, the clinical syndrome of pain and dysfunction in a tendon is debilitating, recalcitrant to treatment and therefore often termed a chronic condition. Importantly, it is not known how the central nervous system modulates or interprets tendon pain and whether it is similar to other chronic pain conditions. This study aims to investigate whether there are cortical excitability differences between people with and without patellar tendinopathy. Cortical excitability and inhibition are important determinants for muscle function and, as such, any differences between healthy and tendinopathic participants may provide data for the altered muscle function associated with tendinopathy and improve future rehabilitation directions. Cortical differences in other chronic musculoskeletal pain conditions have provided clinically useful direction of treatment. Methods: Male and female volleyball players aged over 18 years with and without patellar tendinopathy, matched for age, gender and activity level will be invited to participate in the study. Objective measures of single leg decline squat pain, tendon ultrasound and maximal voluntary leg extension torque will be recorded. Single and paired pulse transcranial magnetic stimulation (TMS) will be applied over the motor area projecting to the quadriceps muscle group to obtain measures of corticospinal excitability and intracortical inhibition. Stimulus-response curves will be obtained and the slope and peak values will be used to establish the strength of projection. Results of tendinopathic and healthy individuals will be compared. Pain severity and length of time of symptoms will be correlated with TMS measures to identify whether a relationship exists. Hypothesised Results: It is hypothesised that individuals with patellar tendinopathy will show differences compared with normals of reduced cortical excitability and that changes will be more pronounced with increasing chronicity of symptoms. Discussion: The incidence of tendinopathy is increased with aging and activity and may cause a person to become sedentary due to load related pain. Improving our understanding of this condition is vital. This will be the first study to examine the cortical changes in people with tendon pain. Differences identified will be correlated to clinically useful measures of severity of pain and length of time of symptoms to determine the effect of chronicity. This information may assist clinicians with early prognostic indicators for people presenting with patellar tendinopathy and help guide the use of interventions which target pain or muscle function.