For decades, rotator cuff surgery has been treated as a mechanical problem. A tendon tears. A surgeon brings it back to bone. Anchors and sutures hold it in place. The operation succeeds if the repair is strong enough to heal.
Brian Feeley, MD, chief of sports medicine and shoulder surgery in the department of orthopedic surgery at University of California San Francisco, believes that understanding is no longer enough.
Dr. Feeley has spent years studying the biology that determines whether orthopedic repairs actually succeed. His research focuses not only on the tendon surgeons repair, but on the muscle, bone and cellular environment that surround it. The conclusion has changed how he thinks about one of orthopedics’ most common procedures.
“We have solved the biomechanics of repair,” Dr. Feeley told Becker’s. “What we haven’t solved is how much the health of the patient and the quality of the tissue affect outcomes.”
That shift may define the next era of rotator cuff care. The future is not simply a stronger anchor. It is a healthier shoulder.
The shoulder is not a construction project
Orthopedic surgeons are trained to think visually and mechanically, Dr. Feeley said. Can the tendon be pulled back to bone? Will the construct hold? Are the anchors strong enough? Is the repair technically sound?
Those questions still matter. But they do not fully explain why one patient heals well and another does not. “As we get more sophisticated with our knowledge of biology, it’s not just the tendon to bone that’s important,” Dr. Feeley said. “It’s not just the muscle. It’s how old is the patient and what is the strength and quality of the cells within the bone.”
He increasingly thinks of each joint as something more complex than a set of parts.
“At a cellular and subcellular level, we really need to treat each joint essentially as a mini organ,” he said. That idea reframes the entire procedure. A rotator cuff tear is not just a tendon detached from bone. It is an injury involving tendon, muscle, bone, age, cellular health, inflammation, degeneration and healing capacity. The surgeon may repair the tendon. Biology determines whether the repair becomes durable.
The muscle changes the answer
For Dr. Feeley, one of the most important variables is muscle quality. That includes muscle size, strength and what surgeons have traditionally called fatty infiltration. The term is widely used in orthopedics, but Dr. Feeley believes it does not fully capture what is happening.
“Fat infiltration isn’t the best term for it,” he said. The phrase suggests fat moves into the muscle from somewhere else. His research points to a different process. “It’s more that there is a cellular process within the muscle where cells differentiate into fat,” he said.
When a rotator cuff tear limits normal mechanical loading, muscle cells receive a different signal. A cell capable of becoming muscle may instead store energy as fat or become scar tissue. From an evolutionary standpoint, the process makes sense. For shoulder function, it can be devastating. That distinction matters because it suggests the process may not be fixed or inevitable.
“What we envision is that there are cells within muscle that are modifiable,” Dr. Feeley said. Those cells can move in different directions. They can contribute to muscle regeneration or they can become fat and scar. The opportunity is to guide them toward rebuilding.
“They are able to be stimulated into an active, pro-myogenic or muscle rebuilding state,” he said. That is where the next generation of treatment may emerge. The goal is no longer only to repair torn tissue. It is to influence how the tissue heals.
The patients in the middle
Timing has long shaped decision-making in rotator cuff care. Wait too long, and the tendon may retract. Muscle may degenerate. The tear may become irreparable. But the development of reverse shoulder replacement has changed that conversation for many older patients.
“In the last 10 to 15 years, we have gotten good at reverse shoulder replacement,” Dr. Feeley said. That advance created a reliable salvage option for patients who might once have had few choices after severe cuff degeneration.
The harder group is not necessarily the oldest patients. It is the patients in between. A 55-year-old with a repairable rotator cuff tear and early muscle degeneration may not be ready for shoulder replacement. The tendon may be fixable. The shoulder may still have years of function ahead. But the biology may already be changing in ways surgeons cannot fully reverse.
“Even with a successful repair, we don’t know 10 to 15 years down the line how well that muscle is going to be functioning,” Dr. Feeley said.
That uncertainty is pushing researchers to ask a different question. Can muscle quality be improved at or around the time of surgery?
“Are there ways at the time of surgery that we can improve muscle quality through local activation of muscle?” he said. “Is it something that needs injection into muscle? Is it something that needs a pharmacologic that patients take in that post-op state? Is it something that can be leveraged with physical therapy?”
Those are not abstract questions. They may determine which patients should have surgery, which should wait, and which need additional treatment beyond the repair itself.
When a repair fails — and when it still helps
Rotator cuff healing is not always binary. A repair may not fully heal structurally, yet a patient may still feel better and function well. Dr. Feeley pointed to earlier work showing that even when repairs are not entirely successful, many patients improve enough to return to daily life. “Our bodies are resilient, and we’re able to compensate without a perfect rotator cuff,” he said.
That reality makes decision-making more nuanced. In some patients, a smaller operation may still be the right first attempt, even if healing is not guaranteed. A rotator cuff repair in someone with a good but imperfect chance of healing may still spare them from a larger operation later. The challenge is identifying which patients need more than mechanical repair alone.
“What we need to do in the next decade is figure out ways to really leverage those at-risk patients to avoid the bigger surgery down the line,” Dr. Feeley said. That may mean optimizing bone quality. It may mean addressing psychosocial factors that affect recovery. It may mean developing treatments that improve tendon and muscle biology. Some of that work is beginning.
Dr. Feeley pointed to recent research suggesting that improving bone quality at the time of surgery may improve outcomes and decrease retear rates. Other studies have suggested psychosocial optimization can improve recovery. But important gaps remain.
“We still don’t have anything to improve tendon quality or muscle quality,” he said. That is the frontier.
The economics of better healing
As more rotator cuff repairs move into ASCs, the next era of biologic treatment raises difficult financial questions.
The mechanics of the operation are already expensive. Anchors, sutures and implants carry costs. But Dr. Feeley said those expenses are no longer the main limitation. The next generation of therapies may cost more.
That creates a challenge for ASCs, hospitals and payers. A treatment that costs $500 or $800 may be easier to absorb but may not meaningfully change outcomes. A treatment that costs $3,000 to $5,000 may be harder to justify upfront but could produce major value if it substantially reduces reoperations.
“There will be a point where there is value to the more expensive treatment,” Dr. Feeley said. That point is where orthopedic care and value-based care begin to collide. The system is built to pay for a procedure. Biology complicates that model.
A future rotator cuff repair may involve more than reattaching tendon. It may include medication to improve bone quality, therapy to improve muscle regeneration or an injection designed to change how tissue heals. That turns a familiar operation into a much more complex episode of care.
Dr. Feeley described how even adding a bone-health medication changes the clinical conversation. A simple discussion about arthroscopic repair can become a broader conversation about risks, benefits, rare complications and long-term healing.
“What was a 15-minute conversation is now a 30-minute conversation,” he said. Yet current payment models rarely reward that additional complexity.
“We are not going to be compensated for treating the complexity of the problem in a single surgical visit,” he said. That concerns him because the future of better outcomes may require more time, more counseling and more biologic optimization before and after surgery.
The system will have to decide whether it is willing to pay for that work.
“Why do frontline clinicians have to be incentivized to provide the innovative care we already know they can deliver, while worrying they’ll be financially punished for doing it?” Dr. Feeley said.
The same applies to ASCs and health systems.
“We don’t want ASCs and healthcare systems to feel punished by giving better care,” he said.
The therapy that could change recovery now
The innovation Dr. Feeley is most excited about is not a new implant. It is not a surgical device. It is a treatment already available in many physical therapy clinics: blood-flow restriction.
His laboratory recently published work examining how blood-flow restriction affects muscle recovery after rotator cuff injury. In a mouse model, researchers placed what he described as a mini-tourniquet distal to the rotator cuff. The intervention created intermittent, low-grade ischemia and reperfusion in the tissue. The result was striking.
“We are able to improve muscle quality,” Dr. Feeley said. The therapy appeared to help muscle grow, strengthen and function better. His lab used genetically engineered mice to study how progenitor cells transferred mitochondria to muscle, offering insight into the biological mechanism behind the improvement.
The scientific implications are important. The practical implications may be even more significant.
“This is a strategy that we could implement today with no additional cost across all rotator cuff repairs, even in a passive setting,” Dr. Feeley said. Patients do not necessarily need to perform aggressive exercise immediately after surgery to benefit.
“We weren’t making the mice lift weights with the blood-flow restriction,” he said. “They were essentially asleep for it.” That matters because many biologic innovations require new drugs, new devices or new reimbursement pathways. Blood-flow restriction is different. It is already used in rehabilitation settings. Physical therapists understand it. Patients often accept it.
For a field searching for scalable ways to improve muscle quality, that makes it unusually compelling. “We need to improve muscle quality after surgery,” Dr. Feeley said. “We need the muscle to get bigger. We need it to have less fat.”
Blood-flow restriction may not be the final answer. But it may be one of the first tools that can be adopted broadly while researchers continue developing more targeted regenerative therapies.
The future of rotator cuff care
For decades, rotator cuff surgery advanced by improving the repair. Surgeons debated single- versus double-row techniques. Anchors improved. Sutures strengthened. Arthroscopic skill advanced. The mechanical problem became increasingly solvable. Dr. Feeley believes that chapter is no longer where the greatest opportunity lies.
The next leap will come from understanding the shoulder as a living system, one whose ability to heal depends on muscle, bone, tendon, cells, age, loading, psychology and recovery.
That shift could change how surgeons select patients. It could change what happens during surgery. It could change what rehabilitation looks like afterward. It could also change how health systems define value.
Because the future of rotator cuff care may not be about whether a surgeon can repair the tendon. It may be about whether the entire shoulder is ready to heal.
At the Becker’s 32nd Annual Meeting: The Business and Operations of ASCs, taking place October 29-31 in Chicago, ASC leaders, surgeons and healthcare executives will explore strategies to drive growth, enhance operational performance, navigate reimbursement challenges and prepare for the future of ambulatory surgery. Apply for complimentary registration now.
