Research topic: Investigated in an animal model the differences between post-surgical healing in the elderly versus the middle-aged after rotator cuff tear repair.
Research results: Demonstrated that middle-aged animal models of rotator cuff repair surgery showed more extensive remodeling, integration, greater organization and structural biomechanical recovery of the tendon-to-bone morphology when compared to older animal models of rotator cuff repair surgery
Patient care application of results: Development of new treatment methods, such as modified surgical techniques or augmenting surgical technique with growth factors to improve tendon- bone healing for older patients.
Simplified patient care application: Improve tendon-to-bone healing for older patients
Does Age Affect Surgically Repaired Rotator Cuffs?
OREF-funded study looks at pathophysiology of tendon-to- bone healing in older patients.
As the number of aging, physically active Americans increases, so does the prevalence of surgeries for symptomatic rotator cuff tears. Approximately one-quarter of U.S. adults will experience a rotator cuff tear at some point in their lives, with the incidence increasing to near 50 percent in adults over age 70. As a result, nearly 300,000 rotator cuff surgeries are performed every year in the United States, with a combined cost to the health care system of about $3 billion annually. Unfortunately, rotator cuff repair surgery has a fairly high rate—20 to 70 percent—of recurrent tearing. This is especially true for older patients.
These sub-optimal clinical outcomes for older patients may be the result of diminished healing potential for the rotator cuff tendons and/or deficiencies in the overall healing capability in the elderly patient population—a subject that has not been well-studied. With a 2011 Orthopaedic Research and Education Foundation (OREF) Resident Clinician Scientist Training Grant, Sandeep Mannava, MD, PhD, used an animal model to investigate the effects of age on tendon-to-bone healing in the surgically repaired rotator cuff. Dr Mannava and his research team: Johannes F. Plate, MD, PhD; Christopher J. Tuohy, MD; and Michael T. Freehill, MD, recently published their study findings in the April 2014 edition of The American Journal of Sports Medicine.
“Identifying the pathophysiology of tendon-to-bone healing in the aged is essential for improving outcomes after rotator cuff repair surgery,” said Dr. Mannava, a resident/physician scientist in the Department of Orthopaedic Surgery at Wake Forest University in Winston-Salem, North Carolina. “By unraveling the biologic mechanisms that underlie rotator cuff tendon healing, we have the potential to improve our understanding of tendon-to-bone healing, which may eventually lead to age-specific interventions for the management of rotator cuff tears,” he added.
Do older shoulders heal differently?
Dr. Mannava employed a small-animal model to study the rat rotator cuff, which shares remarkable similarities with the anatomy of the human shoulder. For the purpose of these experiments, a 10-month-old rat is considered middle-aged and a 28-month-old rat is considered old. A total of 56 rats underwent rotator cuff repair surgery during which a rotator cuff tear was artificially created and then surgically repaired in the rat subjects. The shoulders were harvested and studied, with two main objectives in mind:
“What we learned is that aged individuals heal differently than younger individuals,” said Dr. Mannava. “Our hypothesis was that the middle-aged rats would have increased healing potential and show more extensive remodeling and biomechanical integration of the repaired rotator cuff tendon after surgery when compared to the older rats and our data seemed to support this experimental hypothesis.”
“Further,” he added, “we saw greater organization and structural biomechanical recovery of the tendon-to-bone morphology in the middle-aged group. By establishing that there truly are differences in the aged healing environment, future studies can begin to examine what factors make the healing response less robust in aged individuals.”
Future molecular studies will examine in vivo osteointegration, tendon remodeling, and muscle healing to better define the cell signaling pathways and growth factor expressions that underlie rotator cuff healing.
If these factors can be confirmed, it is likely new treatment methods can be developed for older patients, whether by modifying surgical technique or augmenting surgical technique with growth factors to improve bone-tendon healing.
Improved outcomes for older patients
“The OREF grant is incredibly important in moving this research forward,” said Dr. Mannava. “This is a highly understudied area of orthopaedic research. Although we know clinically it’s a problem of aging, a lot of animal models for rotator cuff tears don’t account for age; we don’t see many basic scientists looking at the role of aging and its influence in the rotator cuff. I think this particular study is quite novel and it was made possible by the grant funding from OREF.”
Dr. Mannava is optimistic the results will have important implications for improving the outcome of rotator-cuff surgeries in older patients. “Ultimately, I hope that this advanced knowledge will improve patient outcomes, with expedited return to independent living and recreational activities for elderly patients who have undergone rotator cuff surgery.”