Achilles Pain Block

The purpose of this study is to better understand how the peripheral and central nervous system interact to produce the sensation of pain and motor patterns in patients with achilles tendinopathy (AT). These findings will motivate the development of future clinical studies that incorporate knowledge about pain processing and movement strategies in patients with tendinopathy. Participants with achilles tendinopathy will receive an anesthetic injection to the achilles tendon in order to examine how reduced pain, detected by the peripheral nervous system, alters task performance and perception of pain. We hypothesize that there are factors within the central nervous system that contribute to continued pain and disability in patients with chronic AT.

Twenty three people with Achilles tendinopathy (AT) and 23 people without AT will participate in this single visit clinical study. Participants will rate their pain with pressure to the heel, leg and elbow, climb stairs and perform a novel task in a motion capture system, and complete questionnaires on how pain affects their daily life. All subjects will complete these measures twice, and for participants with AT they will complete this battery of tests before and after an anesthetic injection to the area of pain. This study has 2 aims:

Specific Aim 1 compares measures of altered central processing in patients with chronic AT to adults without chronic pain; we hypothesize that patients with chronic AT will demonstrate signs of altered central processing, including central sensitization (lower pressure pain threshold), psychosocial factors (higher kinesiophobia), and/or altered motor control (lower ankle power during stair ascent).

Specific Aim 2 determines which indicators of altered central processing persist after a local anesthetic injection to the Achilles tendon in patients with chronic AT; we hypothesize chronic AT pain is perpetuated by altered central processing that persists in the absence of continued peripheral nociception.

Eligibility Criteria:
For patients with AT

Inclusion Criteria:

- Clinical diagnosis of chronic (\>3 months) AT, consisting of pain with pressure at the achilles tendon and report of pain that is aggravated by physical activity

Exclusion Criteria:

* History of foot or ankle surgery, bilateral lateral epicondyle tendinopathy
* Comorbidity that would be aggravated by placing hand in water (Raynaud's, thoracic outlet syndrome)
* Comorbidity (e.g. stroke, neurological disorder) that limits ability to participate in exercise
* Comorbidity (e.g. rheumatic disease, fibromyalgia) that contributes to pain with activity
* Peripheral neuropathy
* Previous adverse response to a local anesthetic injection
* Are pregnant
* Are a ballroom dancer

For control participants

Inclusion Criteria:

- Sex, Age and BMI-matched to participant with AT

Exclusion Criteria:

* No history of tendinopathy
* No condition that limited activity in the past 6 months
* History of foot or ankle surgery, bilateral lateral epicondyle tendinopathy
* Comorbidity that would be aggravated by placing hand in water (Raynaud's, thoracic outlet syndrome)
* Comorbidity (e.g. stroke, neurological disorder) that limits ability to participate in exercise
* Comorbidity (e.g. rheumatic disease, fibromyalgia) that contributes to pain with activity
* Peripheral neuropathy
* Are pregnant
* Are a ballroom dancer