Orthopaedic surgeons and their young, active patients are all too familiar with acute Achilles tendon ruptures. That’s because these traumatic—and often devastating—injuries are on the rise. Every year, as many as 2.5 million individuals sustain a ruptured Achilles tendon. About half of these unlucky athletes are in their 20s and 30s, and 75 percent of the time the injury occurs during recreational sports activities.

Although surgical repair is an increasingly common treatment for Achilles tendon rupture, little is known about how best to manage the rehabilitative process.

Joshua A. Gordon, MD, began exploring the impact of postoperative rehabilitation after Achilles tendon injury thanks to a 2013 Orthopaedic Research and Education Foundation (OREF) Resident Clinician Scientist Training Grant made possible by the Ira A. Roschelle Family Foundation. Under the guidance of veteran research scientist Louis J. Soslowsky, PhD, Dr. Gordon and his research team investigated biologic and biomechanic parameters, and began to uncover the specific effects of various rehabilitation protocols.

The basic science perspective
Dr. Gordon 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 biologic changes that might occur with altered rehabilitation strategies. They specifically explored 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.”

Instead of 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 biologic properties after proscribed immobilization of the Achilles tendon versus nonimmobilization for different periods of time.

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

Quantifying healing parameters
The “hop test” is the current “gold standard” for deciding when a patient can return to normal activity following surgical repair of a ruptured Achilles tendon. However, 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 biomechnical 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—process. 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 are taking the opportunity to explore how such alignment data could be used to make meaningful predictions about mechanics.

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

Impact on clinical practice
When asked what he finds most promising about the study, Dr. Gordon pointed 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 an 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 suggest that alignment may be clinically translatable as a partly predictive measure of 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,” he said.

The promise of improving 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 individuals,” 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 collaborative work environment brings out the best and most interesting ideas; there is nothng quite like solving a problem together. I don’t think I can step away from that.”

OREF is crucial
While in medical school, Dr. Gordon participated in the Howard Hughes Research Scholar’s Program, working in the National Human Genome Research Institute at the National Institutes of Health. There, he did research in genetics and developmental biology in Dr. Yingzi Yang’s laboratory. That experience—and his current work as a research fellow at the University of Pennsylvania McKay Orthopaedic Research Laboratory—may have helped him obtain funding for his first grant application. Or, he mused, “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 AA, Bostick G, Reid D, Blitz S, Jomha N: The incidence of Achilles tendon ruptures in Edmonton, Canada. Foot Ankle Int 2005 Nov;26(11):932–936.
2. Levi N: The incidence of Achilles tendon rupture in Copenhagen. Injury 1997 May;28(4):311–313.
3. Freedman BR, Gordon JA, Soslowsky LJ: The Achilles tendon: Fundamental properties and mechanisms governing healing. Muscles Ligaments Tendons J 2014 Jul 14;4(2):245–255.