Peter C. Amadio, M.D.

Despite recent advances, tendon repair often results in a finger that does not move normally. The research goal of Peter C. Amadio, M.D., has been to improve the results of tendon repair by addressing two interrelated issues:

• Wolff's law of soft tissue. The effect of loading on wound healing and soft tissue material properties. In tendon, this especially affects the nature of the rehabilitation protocol, timing of initiation of motion, and timing and gradation of loading of the repair.
• Tendon gliding beneath pulleys. The effect of tendon repair and lubrication on tendon gliding.

These two factors interact, as the ease of gliding will dictate how well the tendon moves under loading and how much loading is needed to initiate motion, while the amount of loading needed to initiate motion will affect the strength requirements of the tendon repair.

Focus areas

One of Dr. Amadio's National Institutes of Health-funded research projects is addressing these factors. Past research quantified the mechanics and kinematics of the tendon-pulley interaction, identified structural differences within tendon based on the loading environment, and also showed that these environments differed in the rate and quality of healing after similar injury. This was followed by work that tested the tribology and material properties of various tendon repair constructs, first in vitro and then in vivo.

In addition, Dr. Amadio and his colleagues compared the relative motion induced by various tendon gliding rehabilitation regimens in vivo. They noted that low friction repairs, combined with rehabilitation that provided better gliding, gave the best results in terms of tendon healing and final digit motion. They also investigated the impact of more complex gliding regimens on tendon healing, which included the timed augmentation of gliding with new therapies and the development of strong, low friction tendon repairs.

Dr. Amadio's research also investigated the fixation of lubricating substances such as hyaluronan and lubricin on the surface of tendon repairs and tendon grafts. Dr. Amadio's laboratory is currently investigating the effect of tissue engineering strategies on tendon healing and the reduction of adhesions. To accomplish this, he and his team are incorporating a bone marrow stromal cell-seeded and cytokine-augmented collagen patch into the repair site of their animal model in vitro. They are also investigating the effects of the tendon patch with surface modification on tendon repair in vivo.

Such therapies also have an effect on other tendon-associated pathologies where impaired tendon gliding appears to be a factor, such as carpal tunnel syndrome, and adhesions complicating tendon grafting procedures. Therefore, Dr. Amadio's group is also pursuing similar strategies to address these other clinical problems. Finally, his team is investigating the use of ultrasound for the early diagnosis of tendon adhesions and carpal tunnel syndrome.

The novel animal model developed in Dr. Amadio's laboratory investigates the etiology of carpal tunnel syndrome and enables the lab to look at the role of subsynovial connective tissue in carpal tunnel syndrome. He and his colleagues then compare, biologically and biomechanically, clinical results with their unique carpal tunnel syndrome animal model.

Research by Dr. Amadio and his team will identify and characterize the initiating mechanism underlying carpal tunnel syndrome development and then generate novel, mechanism-based interventions that will prevent, detect and treat carpal tunnel syndrome. They are also investigating the hypothesis that subsynovial connective tissue fibrosis in carpal tunnel syndrome is mediated by TGF-b and if TGF-b activation is blocked, subsynovial connective tissue fibrosis in their animal model will be reduced.

Significance to patient care

The carpal tunnel syndrome model developed in Dr. Amadio's laboratory will allow them to capture clinical insights more effectively and translate these research findings into improved patient outcomes.

The overall goal of the research is to identify and characterize the initiating mechanism underlying carpal tunnel syndrome development and generate novel, mechanism-based interventions that will prevent, detect and treat carpal tunnel syndrome.

Professional highlights

• Dean for Research Academic Affairs, Mayo Clinic, 2012-present
• Associate Dean for Research Infrastructure, Mayo Clinic, 2006-2011