New York—July 14, 2012
A new Hospital for Special Surgery study suggests that the current rehabilitation used for patients undergoing tendon-bone repairs such as rotator cuff surgery may be partially to blame for the high rates of failed healing after surgery. Experiments in a rat model of this injury suggest that immobilizing the limb for four to six weeks after surgery, rather than quickly starting physical therapy, improves healing.
“Before we did this study, we thought that delaying motion for a short period of time, seven to ten days, and then starting physical therapy would be the most beneficial to tendon healing. However, from the data in this study, it appears we should be immobilizing our patients for longer periods of time,” said Scott Rodeo, M.D., principal investigator of the study and co-chief of the Sports Medicine Service at Hospital for Special Surgery (HSS) in New York City.
Carolyn Hettrich, M.D., MPH, who was an HSS resident when she conducted the study, will present the study July 14 at the annual meeting of the American Orthopaedic Society for Sports Medicine (AOSSM), held in Baltimore.
The rotator cuff is a set of a four small muscles in the shoulder that allow the upper arm to rotate. When a rotator cuff is torn, the tendon part of the muscle tears away from the bone of the upper arm. During a repair surgery, a surgeon reattaches the tendon to the bone and a surgery’s success is dependent on how well the interface between the tendon and bone heals. Studies have shown that 20%-40% of patients undergoing rotator cuff surgery have failed healing. These patients who have had rotator cuff surgery have poorer outcomes, including decreased strength and decreased range of motion.
Rotator cuff surgery recovery usually consists of immobilizing the shoulder in a sling for seven to ten days, physical therapy with passive and assisted motion for six weeks, followed by physical therapy with active motion for six weeks. However, there is little data on the optimum rehabilitation program for rotator cuff surgery, and clinicians recognize there is a delicate balance between minimizing movement after rotator cuff surgery to protect the repair and allowing movement to prevent joint stiffness.
To explore the timing of postoperative rehabilitation, investigators at HSS conducted experiments using a rat model of patellar tendon injury and repair. The investigators used a small metal frame to hold the joint in place and then used a specially designed motorized device to precisely apply loads of strain. One group of rats received a low load 50 times per day (analogous to a leg extension with no weight), another group received a moderate load 50 times per day and a third group had their joint immobilized for the entire study period. The animals were studied at 4, 10, 21, and 28 days.
The researchers found that rats that had their joint immobilized had the best healing with significantly less fibrocartilage or scar tissue than rats in the other two groups. Scar tissue is weaker than original tissue, and oftentimes scar tissue forms at the interface between bone and tendon during tendon repair surgery. The rats that were immobilized also had better connective tissue organization, higher load to failure, better bone mineral density, and fewer dead cells in the area that was operated on. During the healing and inflammatory process, there is a regeneration and remodeling of tissues, which sometimes involves cell death that can lead to inflammation.
“Very surprisingly, all of the data supported immobilization. The biomechanics, the histology, everything,” said Dr. Hettrich. “The rats that were immobilized and didn’t have any load through that period of healing did the best. This study suggests that we might want to consider immobilizing human patients for a little bit longer to let some of the post operative inflammation calm down, because excess inflammation might be having a harmful effect.”
The investigators suggest that the best path to recovery for patients undergoing rotator cuff surgery might be to keep individuals in slings for six weeks and then start with passive motion therapy. However, studies are needed in humans to test this hypothesis and make firm clinical recommendations.
Dr. Hettrich is now an assistant professor of orthopedics in sports medicine at the University of Iowa. Dr. Rodeo’s laboratory will be presented with the Cabaud award for the study at the annual AOSSM meeting. The award is given to the best basic science/laboratory research paper at the meeting.
Other HSS investigators involved in the study include Patrick Birmingham, M.D., Xiang-Hua Deng, M.D., Selom Gasinu, Brandon Beamer, Mark Stasiak, Alice Fox, MSC, and Olivia Ying.
About HSS | Hospital for Special Surgery
HSS is the world’s leading academic medical center focused on musculoskeletal health. At its core is Hospital for Special Surgery, nationally ranked No. 1 in orthopedics (for the ninth consecutive year) and No. 3 in rheumatology by U.S.News & World Report (2018-2019). Founded in 1863, the Hospital has one of the lowest infection rates in the country and was the first in New York State to receive Magnet Recognition for Excellence in Nursing Service from the American Nurses Credentialing Center four consecutive times. The global standard total knee replacement was developed at HSS in 1969. An affiliate of Weill Cornell Medical College, HSS has a main campus in New York City and facilities in New Jersey, Connecticut and in the Long Island and Westchester County regions of New York State. In 2017 HSS provided care to 135,000 patients and performed more than 32,000 surgical procedures. People from all 50 U.S. states and 80 countries travelled to receive care at HSS. In addition to patient care, HSS leads the field in research, innovation and education. The HSS Research Institute comprises 20 laboratories and 300 staff members focused on leading the advancement of musculoskeletal health through prevention of degeneration, tissue repair and tissue regeneration. The HSS Global Innovation Institute was formed in 2016 to realize the potential of new drugs, therapeutics and devices. The culture of innovation is accelerating at HSS as 130 new idea submissions were made to the Global Innovation Institute in 2017 (almost 3x the submissions in 2015). The HSS Education Institute is the world’s leading provider of education on the topic on musculoskeletal health, with its online learning platform offering more than 600 courses to more than 21,000 medical professional members worldwide. Through HSS Global Ventures, the institution is collaborating with medical centers and other organizations to advance the quality and value of musculoskeletal care and to make world-class HSS care more widely accessible nationally and internationally.