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Research Profiles

Joshua A. Gordon, MD

Examining Achilles Tendon Rehabilitation Strategies

Joshua A. Gordon, MD Resident Clinician Scientist Training Grant
Research topic: Investigated the biomechanical and biological changes that occur with different rehabilitation strategies for Achilles tendon ruptures

Research results: Understanding of the biological and biomechanical advantages with immobilization or with non-immobilization regimens for treating Achilles tendon rupture.

Patient care application of results:
Understanding of which treatment regimen—immobilization or non immobilization—is best for treating Achilles tendon rupture

Examining Achilles Tendon Rehabilitation Strategies

OREF grant recipient tests strategies following surgical repair
Sharon Johnson

Acute Achilles tendon ruptures are all too familiar to orthopaedic surgeons and active young people. These traumatic and often devastating injuries are on the rise. Every year, as many as 2.5 million individuals sustain a ruptured Achilles tendon, 75 percent of the time while engaged in recreational sports activities.1 About half of these unlucky athletes are in their 20s and 30s.2

The Achilles tendon is the bridge between the musculoskeletal structures of the calf and the foot that enables the propulsive force required for walking, running and jumping. Although surgical repair is an increasingly common response to Achilles tendon rupture, little is known about how best to manage the rehabilitative process.

Under a 2013 Orthopaedic Research and Education Foundation (OREF) Resident Clinician Scientist Training Grant made possible by the Ira A. Roschelle Family Foundation, Joshua A. Gordon, MD, began exploring the impact of post-surgical rehabilitation after Achilles tendon injury. With the guidance of veteran research scientist Louis J. Soslowsky, PhD, Dr. Gordon and his research team investigated biological and biomechanical parameters, and began to uncover the specific effects of various rehabilitation protocols.
Bringing basic science to the rehabilitative process in a collaborative environment
Dr. Gordon, who had trained in the biological and medical sciences, teamed with Benjamin Freedman BS, an engineering postdoctoral candidate in the McKay Orthopaedic Laboratory at the University of Pennsylvania. They designed a set of experiments to investigate the biomechanical and biological changes that might occur with altered rehabilitation strategies, specifically exploring biomechanical properties such as stiffness, range of motion and tendon failure.

“We took these biomechanical explorations further by also examining the biologic response from the tissues,” Dr. Gordon said. “We looked at the quantity and organization of the tissues after various rehabilitation protocols. We also tested some new techniques, already being studied in Dr. Soslowsky’s lab, that more easily translated measures of collagen alignment.”

Rather than using polarized light microscopy, the established method for laboratory study, Dr. Gordon proposed using high-frequency ultrasound (HF-US). If effective, HF-US could easily and noninvasively measure the process of collagen alignment at various stages of rehabilitation.

Damaged achilles tendons underwent early, intermediate and late rehabilitation protocols to compare functional performance and biological properties after proscribed immobilization of the Achilles tendon versus nonimmobilization for different periods of time.

“If we were to find biomechanical advantages with specific rehabilitation protocols, either immobilization or non-immobilization, or different time-periods, we could develop more effective treatment regimens for use by treating clinicians and physical therapists,” Dr. Gordon explained.

Quantifying the parameters of Achilles tendon healing
The current gold standard for deciding when a patient can return to normal activity following surgical repair of a ruptured Achilles tendon is the “hop test.” This test requires the patient to hop on the injured foot for a set distance. The hop test offers only a qualitative gauge for functional performance. In addition, because the test fails to factor in muscle strength, balance and other biomechanical properties, results can be misleading.

The HF-US proposed in Dr. Gordon’s study would introduce quantitative measures to an otherwise purely qualitative and sometimes unreliable process3. Further, the quantitative measures proposed in the research drill down to the tissue, cellular and molecular levels. Although linking such measures to meaningful clinical results presents another challenge, Dr. Gordon and his team took the opportunity to explore how such alignment data could be used to make meaningful predictions about mechanics.

“We’re looking at the specific mechanical properties of tissues, in terms of organization and even varied protein expression,” explained Dr. Gordon. “This research has the potential to bring the post-operative evaluation process a long way from asking how far a patient can hop.”

Results could improve established clinical practice
Asked what he finds most promising about the study, Dr. Gordon points to the opportunity to make a difference in patients’ lives.

“Right now, we just don’t know what the best means of treatment is when someone spontaneously ruptures their Achilles tendon. This study could change all that. We are already finding that longer immobilization creates stiffer, but better organized healed tissues. Further, some early modeling data suggests that alignment may be clinically translatable as a measure that is partly predictive function. It’s very exciting work.”

Although the work is ongoing and Dr. Gordon is hesitant to interpret the results just yet, he has a hypothesis.

“I think it might be all about finding the sweet spot, not too much but not too little. The animal studies will give us the tools to figure that out. I think we have the chance to really help some people.”

The promise of such improvements in clinical practice is one of the reasons Dr. Gordon hopes he will be able to incorporate research into his practice for the long term.

“I really enjoy interacting with patients and helping the individual,” Dr. Gordon said. “But I think that the greatest good for the greatest number comes from being able to do research that clinicians everywhere can use to help more patients. Also, the nature of the collaborative work environment brings out the best and most interesting ideas; there is nothing quite like solving a problem together. I don’t think I can step away from that.”

Support from and for OREF is crucial to further research
While in medical school Dr. Gordon had the benefit of working in the National Human Genome Research Institute at the National Institutes of Health (NIH), doing research in genetics and developmental biology in Dr. Yingzi Yang’s laboratory as a participant in the Howard Hughes Research Scholar’s Program. That experience and his current work as a research fellow at the University of Pennsylvania McKay Orthopaedic Research Laboratory may have contributed to his very first grant application being funded, although he mused that “it might just be beginner’s luck.” Dr. Gordon is hoping this bit of good fortune can evolve into a beginner’s “streak.”

“I can’t say enough about what the OREF grant has meant for me,” Dr. Gordon emphasized. “It was critical. Without this grant I couldn't have gotten the project underway.”

Dr. Gordon hopes others see the value of supporting OREF so that orthopaedic research can continue.

“I firmly believe that supporting OREF is crucial to keeping our field an active part of the research and medical community, and keeping orthopaedics on the forefront.”

Sharon Johnson is a contributing writer for OREF. She can be reached at communications@oref.org.

References

1. Suchak, A.A., et al., The incidence of Achilles tendon ruptures in Edmonton, Canada. Foot & ankle international / American Orthopaedic Foot and Ankle Society [and] Swiss Foot and Ankle Society, 2005. 26(11): p. 932-6.

2. Levi, N., The incidence of Achilles tendon rupture in Copenhagen. Injury, 1997. 28(4): p. 311-3.

3. Freedman BR, Gordon JA, Soslowsky LJ., The Achilles tendon: Fundamental properties and mechanisms governing healing. Muscles Ligaments Tendons J, 2014. 14;4(2):245-55



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