PRP and Stem Cells for Shoulder Pain and Rotator Cuff Tears

Marc Darrow, MD, JD

“Can stem cells help my shoulder?” is a reasonable question, but it is not the first question I want to answer. I want to know why the shoulder hurts, which movements have become difficult, and whether the painful structure matches the findings on the examination and imaging.

A person with a partial tendon tear, a person with a tendon that has pulled away from the bone, and a person with advanced arthritis may all describe shoulder pain. Their treatment choices are different. A treatment that helps one of those problems cannot automatically be expected to help the others.

On our Living Pain-Free radio program, a caller described improvement after regenerative treatment despite previous shoulder surgery and arthritis on imaging. That experience is encouraging, but it remains an individual account. It is not proof that every similar shoulder will respond, or that the treatment replaced lost cartilage.

What part of the shoulder is causing the pain?

The rotator cuff consists of four muscles and their tendons, which help lift, rotate, and stabilize the arm. The supraspinatus is one of those tendons and is a common site of tearing. A partial-thickness tear affects part of the tendon’s thickness; a full-thickness tear extends through it. A full-thickness defect is not necessarily a massive tear, and its size, retraction, and muscle quality matter.

Other potential problems include biceps tendon disease, bursitis, labral injury, capsular stiffness, arthritis, and instability. More than one condition can be present. The practical task is to decide which findings explain pain, weakness, or loss of movement.

For example, difficulty raising the arm after an injury may reflect pain, substantial tendon damage, nerve dysfunction, or a combination. That distinction is more useful than assuming that every painful shoulder needs the same injection.

Why an MRI finding is only part of the evaluation

I want imaging to help explain a patient’s symptoms. It should not replace the history and examination. An abnormal tendon on a scan may contribute to pain, but it may not explain every symptom.

X-rays help evaluate joint space, bone alignment, and arthritis. Ultrasound can assess accessible tendons and bursae during movement and can guide an injection. MRI may be needed to define a tear’s extent, retraction, muscle changes, deeper joint abnormalities, or the anatomy relevant to surgery.

If a patient has substantial weakness or a new traumatic tear, identifying the structural problem is especially important. Less pain after an injection does not necessarily mean the tendon is mechanically sound.

What does stem-cell treatment mean for a shoulder injury?

In our shoulder research, we studied preparations obtained from the patient’s own bone marrow. Whole bone marrow is aspirated without concentration. Bone marrow concentrate, or BMC/BMAC, is processed to concentrate selected marrow components. The preparation contains a mixture of cells and signaling substances, including a small population of mesenchymal stromal cells. It is not a purified stem-cell injection. (1)

The biologic rationale involves interactions between cells, growth factors, inflammation, and the local tissue environment. That rationale should not be converted into a promise that an injection will grow a normal tendon or repair every tear.

PRP is different: it is prepared from blood and contains concentrated platelets. It has no stem cells. These preparations should be described accurately so that patients understand what was studied and what is being proposed.

What does research show about PRP for rotator cuff problems?

A double-blind randomized trial followed 99 patients with partial-thickness tears or rotator cuff tendinopathy after PRP or corticosteroid injection. The PRP group had greater improvement at three months, but there was no significant difference in reported outcomes at one year or in conversion to surgery. (2)

The important point is that both the diagnosis and the follow-up period matter. A short-term advantage does not establish permanent repair. Differences in platelet preparations, injection targets, tendon damage, and accompanying rehabilitation also make studies difficult to compare.

Some patients may value a period of better function even when tissue restoration has not been demonstrated. Others need a treatment that addresses a mechanical deficit. Those are different decisions.

What does research show about bone marrow injections?

Our clinic’s published observations

Our 2019 shoulder study followed 47 patients with 50 treated shoulders affected by rotator cuff tears or osteoarthritis. Patients reported improvements in pain and function after BMC or whole bone marrow injections. This was observational research without a randomized untreated comparison group. (1)

I consider that information worth sharing, including its limitations. The study documented symptom changes; it did not demonstrate that missing cartilage grew back or that a retracted tendon was reattached. The full explanation of our shoulder bone marrow study includes its functional measurements and reported results.

A randomized study of marrow and platelet products

A 2024 report studied 51 patients with supraspinatus tears. It compared a combined BMC-and-platelet treatment with home exercise, allowing exercise participants to cross over after three months. The injection group showed greater early improvement, and the treated patients were followed for two years. (3)

The combined preparation means the study cannot isolate the effect of marrow alone. Crossover limits a sustained randomized comparison, and the authors disclosed commercial interests related to the treatment. These findings warrant attention, but they do not establish the same benefit for every tear or for advanced shoulder arthritis.

Supporting tendon repair during surgery is a different use

In a case-controlled study, Hernigou and colleagues reported better healing when bone marrow concentrate was added during rotator cuff repair. The tendon was surgically repaired; the marrow was an adjunct. This should not be presented as evidence that an office injection reconnects a tendon without surgery. (4)

What if the main problem is shoulder arthritis?

If joint-space loss, stiffness, and arthritic joint pain dominate the clinical picture, the decision differs from treatment of an isolated tendon problem. PRP and marrow research for glenohumeral arthritis is limited, and it does not establish reliable restoration of an end-stage joint.

Our dedicated guide, Bone-on-Bone Shoulder Arthritis: PRP, Stem Cells, and Shoulder Replacement, compares the relevant injection evidence with surgical options. It also addresses a family’s question about an 89-year-old mother considering reverse replacement.

What can injections realistically change?

Less pain, better sleep, and easier use of the arm are meaningful outcomes. They should be measured directly. They do not, by themselves, establish structural healing.

An MRI change also needs interpretation in the context of the imaging method, tendon anatomy, examination, and strength. A better-looking image does not necessarily mean a tendon has regained normal load-bearing capacity.

I would not promise that an injection will remove a bone spur, reconnect a markedly retracted tendon, reverse advanced muscle degeneration, or reconstruct a severely arthritic joint. The realistic discussion concerns the specific condition and the improvement the patient needs.

Why the injection target matters

“A shoulder injection” does not identify the structure being treated. An injection into the glenohumeral joint is different from treatment directed at a rotator cuff tendon, bursa, or another symptomatic structure.

Ultrasound can help visualize the target and needle placement. Accurate placement is useful, but it cannot correct an incorrect diagnosis or make an injection substitute for necessary mechanical repair.

When is surgery an important part of the discussion?

A sudden injury followed by marked weakness or inability to raise the arm deserves prompt assessment. Tendon retraction, progressive muscle changes, instability, and persistent disability also affect the decision. A torn tendon can become more difficult to repair as its condition changes.

Long-term research reinforces why follow-up matters. A randomized trial of small-to-medium full-thickness tears found increasing advantages for primary repair over physiotherapy in its five- and ten-year reports. The 2024 fifteen-year follow-up continued to favor repair. This does not make surgery necessary for every tear, but it challenges the assumption that symptom management alone is always enough. (5)

Fracture, dislocation, suspected infection, or a major nerve problem requires its own evaluation. An injection should not delay that assessment. Similarly, extensive arthritis and profound stiffness may call for replacement evaluation rather than repeated treatment of the surrounding soft tissues.

How I judge whether a treatment has helped

I want to know what you can do more comfortably: reach overhead, dress, sleep on the affected side, carry an object, or return to an activity you value. I also want to know whether weakness is improving or worsening.

A useful plan connects the diagnosis with a realistic goal and includes reassessment if function is not improving. The goal is a shoulder you can use with greater confidence, with a clear explanation of what treatment can and cannot accomplish.

For condition-specific information, read our articles on partial supraspinatus tears, frozen shoulder, and bone-on-bone shoulder arthritis.

Regenerative medicine therapies have not been FDA-approved for orthopedic conditions such as shoulder pain. This educational article does not establish that an injection can repair every tendon injury or replace appropriate surgical care. (6)

References