Can Stem Cell Therapy Help Shoulder Arthritis and Rotator Cuff Injuries?

By Marc Darrow, MD, JD

Shoulder pain is often described as if it has one simple cause: an arthritic joint, a torn rotator cuff, or a bone spur seen on an X-ray. In reality, the shoulder is a coordinated system. The joint surfaces, rotator cuff tendons, labrum, biceps tendon, capsule, ligaments, and shoulder-blade muscles must work together to produce stable, comfortable motion.

This is why two people with similar imaging can have very different symptoms—and why treating the finding on a scan does not always treat the source of pain.

During a recent Living Pain-Free radio program, a caller discussed prior shoulder surgery, arthritis seen on imaging, and improvement after regenerative treatment. Stories like this can help patients understand why a nonsurgical evaluation may be worthwhile. They do not prove that the same procedure will help every shoulder, nor do they show that lost cartilage or a torn tendon has been completely regenerated. Each result depends on the diagnosis, severity of damage, overall health, rehabilitation, and many other factors.

The most useful question is therefore not simply, “Can stem cells fix my shoulder?” It is: Which structure is producing the pain, how repairable is it, and which treatment offers a realistic chance of improving function?

Shoulder pain may come from several structures

The shoulder has more than one joint and many potential pain generators. Symptoms can overlap, so a careful history and physical examination are essential.

Glenohumeral joint arthritis

The glenohumeral joint is the ball-and-socket joint formed by the upper arm bone and shoulder blade. Osteoarthritis can thin the joint cartilage, narrow the joint space, create bone spurs, and produce stiffness. Patients may describe a deep ache, grinding, night pain, or progressive loss of motion—especially difficulty reaching behind the back or above the head.

Arthritis can also develop after a fracture, instability, previous surgery, a longstanding massive rotator cuff tear, inflammatory disease, or osteonecrosis. These conditions do not all have the same treatment pathway.

Rotator cuff tendinopathy and tearing

The rotator cuff consists of four muscles and their tendons: supraspinatus, infraspinatus, subscapularis, and teres minor. Together, they center the ball in the socket and help lift and rotate the arm.

A tendon may become painful and degenerative without being torn. A tear may involve part of the tendon thickness or extend through the full thickness. Some tears are small and relatively stable; others retract, develop muscle atrophy and fatty change, or enlarge over time. The word “tear” alone does not determine whether surgery is required.

Labrum and biceps tendon

The labrum is a rim of fibrocartilage around the socket. It contributes to stability and provides an attachment for the long head of the biceps tendon. Labral and biceps-anchor abnormalities become common on imaging with age and may or may not be painful. When symptomatic, they can produce catching, clicking, pain with lifting, or pain in the front or deep inside the shoulder.

Capsule and supporting ligaments

The joint capsule and glenohumeral ligaments help control excessive translation of the humeral head. Laxity or prior dislocation may allow painful instability. Conversely, an inflamed, contracted capsule can cause adhesive capsulitis—“frozen shoulder”—with marked restriction of motion. Injecting an arthritic joint will not correct every instability pattern, and treating a tendon alone may not resolve pain caused mainly by capsular stiffness.

The acromioclavicular joint and referred pain

The smaller joint at the top of the shoulder, where the collarbone meets the acromion, can become arthritic and painful. Neck disorders may also refer pain into the shoulder and arm. A complete evaluation should consider both local shoulder structures and possible cervical nerve involvement.

Why arthritis on an X-ray may not be the only pain generator

X-rays are valuable for identifying joint-space loss, osteophytes, altered alignment, old fractures, and advanced joint destruction. However, an X-ray cannot show the entire pain mechanism. It does not directly show most tendon, labral, bursal, or ligament injuries.

Likewise, MRI and ultrasound findings must be matched to symptoms. Rotator cuff tears become increasingly common with age, including in people who report no shoulder pain. An imaging abnormality may be clinically important, incidental, or only one part of a larger mechanical problem.

The examination should ask:

  • Is motion restricted actively, passively, or both?
  • Is weakness caused by pain, tendon failure, nerve injury, or muscle atrophy?
  • Which movements reproduce the pain?
  • Is the shoulder unstable?
  • Is the primary tenderness at the joint, tendon attachment, biceps groove, or acromioclavicular joint?
  • Could symptoms be referred from the neck?

Diagnostic ultrasound can show the rotator cuff and biceps tendon dynamically, identify bursitis and joint fluid, and guide an injection to a specific structure. MRI may be important when tear size, tendon retraction, muscle quality, labral injury, occult bone disease, or surgical planning must be assessed. The purpose of imaging is to complete the clinical picture—not replace it.

What does “stem cell therapy” mean in the shoulder?

In orthopedic practice, the phrase commonly refers to bone marrow aspirate concentrate, or BMC/BMAC. Bone marrow is usually collected from the patient’s pelvic bone and processed during the same visit. The concentrate contains platelets, nucleated cells, signaling proteins, and a small population of mesenchymal stromal cells.

BMC is not a purified stem-cell product. It is also not the same as culture-expanded cells grown in a laboratory. Its proposed effects may come primarily from cell signaling, modulation of inflammation, and support of the local healing environment—not from injected cells simply becoming a new tendon or a new cartilage surface.

PRP is prepared from the patient’s blood and contains concentrated platelets and growth-factor signaling. PRP does not contain stem cells. It is easier to obtain, usually less invasive and less costly, and has been evaluated in more shoulder studies than BMC.

Both treatments are orthobiologics: preparations intended to use biologic signaling to influence pain and healing. Neither should be presented as a guaranteed tissue-replacement procedure.

Bone marrow concentrate versus PRP for shoulder problems

The choice should be based on the diagnosis, not on the assumption that the more complex treatment must be better.

Evidence for PRP in rotator cuff disorders

Studies of PRP for rotator cuff tendinopathy and partial-thickness tears have produced mixed results, partly because PRP formulations, injection targets, tear severity, and rehabilitation protocols differ. In a double-blind randomized trial, PRP produced better pain and function results than corticosteroid injection at three months in patients with tendinopathy or partial tears, but the advantage was not sustained at one year. (1)

A systematic review and meta-analysis concluded that PRP may improve pain and function over the medium and long term in rotator cuff tendinopathy, while also emphasizing heterogeneity among the studies. (2)

These results support PRP as an option for selected patients; they do not establish one universal protocol or prove tendon regrowth.

Evidence for bone marrow concentrate in rotator cuff tears

The clinical evidence for percutaneous BMC treatment is much smaller. A randomized crossover trial involving patients with symptomatic, non-retracted supraspinatus tears compared an ultrasound-guided BMC-plus-platelet protocol with exercise therapy. The treatment group reported better pain and function outcomes, and MRI findings suggested changes in tear size. However, the study was small, used a specific combination protocol, and cannot be generalized to every tear or every BMC preparation. (3)

BMC has also been studied as an addition to surgical rotator cuff repair. A case-controlled study reported improved tendon healing and fewer retears when bone-marrow-derived cells were placed at the repair site during arthroscopy. (4) That study concerned biologic augmentation of surgery, not an injection replacing surgery, and it was not a randomized trial.

This distinction matters. Evidence that a biologic preparation may support a surgically repaired tendon does not prove that the same preparation can reconnect a retracted tendon without mechanical repair.

Evidence for shoulder arthritis

Research on orthobiologic injections for glenohumeral osteoarthritis is much less developed than research for knee osteoarthritis. In a randomized, double-blind trial of 70 patients, both leukocyte-poor PRP and hyaluronic acid groups improved in pain and function, but PRP was not significantly superior to hyaluronic acid. (5)

Published evidence for BMC specifically in shoulder osteoarthritis remains limited. It may be considered in selected patients after a careful evaluation, but there is not enough high-quality evidence to state that it restores the arthritic shoulder or outperforms PRP.

Which rotator cuff tears may be treated nonsurgically?

Many shoulder conditions deserve an initial nonsurgical approach. Possible candidates include:

  • rotator cuff tendinopathy without a major tear;
  • small or moderate partial-thickness tears;
  • some chronic, degenerative full-thickness tears when strength and function remain acceptable;
  • tears without substantial retraction or advanced fatty muscle degeneration;
  • pain arising partly from associated bursitis, biceps disease, capsular or ligament injury, or mild-to-moderate arthritis; and
  • patients whose health, goals, or preferences make a carefully monitored nonsurgical plan reasonable.

Treatment usually involves more than an injection. Activity modification, progressive rotator cuff and scapular strengthening, restoration of mobility, correction of training errors, and gradual return to loading are central parts of care.

Trials comparing surgery with conservative care for degenerative tears show that exercise therapy can produce meaningful improvement for many patients. Surgery may provide an advantage for some tears over longer follow-up, and unrepaired tears can enlarge in certain patients. Nonsurgical care therefore requires reassessment rather than indefinite waiting when weakness or structural damage is progressing. (6)

When surgical evaluation should not be delayed

Regenerative treatment is not appropriate for every injury. Prompt orthopedic surgical evaluation is especially important when there is:

  • a sudden traumatic injury followed by marked weakness or inability to raise the arm;
  • a complete acute tear in an active patient, particularly when repairable tendon has retracted;
  • a subscapularis tear affecting anterior stability or biceps function;
  • progressive weakness, muscle atrophy, or fatty degeneration;
  • fracture, dislocation, infection, tumor, or major nerve injury;
  • severe arthritis with joint collapse, substantial deformity, or persistent disabling pain;
  • rotator cuff tear arthropathy, in which a massive cuff tear and joint destruction occur together; or
  • failure of an appropriately performed nonsurgical program with unacceptable pain and loss of function.

Timing can matter after a major traumatic tear. As a tendon retracts and the muscle develops fatty change, later repair may become more difficult or impossible. An injection should not be used to postpone evaluation of a potentially repairable acute injury.

Advanced glenohumeral arthritis may ultimately require shoulder replacement. In a shoulder with severe joint-space loss, major deformity, and profound stiffness, neither PRP nor BMC can be expected to recreate the missing architecture.

Can PRP or BMC regenerate cartilage and tendon?

The language used here must be precise.

Laboratory and animal studies show that platelets, stromal cells, and their signaling molecules can influence inflammation, collagen production, blood-vessel activity, and tendon-to-bone healing. These biologic observations help explain why researchers continue to study PRP and BMC.

Clinical proof is more limited. A patient can experience less pain and better function without growing a substantial amount of new tendon or cartilage. Improvements on MRI may represent changes in fluid, inflammation, scar tissue, partial filling, imaging technique, or genuine tissue response; they do not automatically demonstrate restoration of normal tendon organization and strength.

Similarly, a shoulder joint injection may reduce symptoms without rebuilding the broad cartilage loss of advanced osteoarthritis. At present, it is not responsible to promise that an injectable orthobiologic will:

  • regrow a normal rotator cuff tendon;
  • reconnect a retracted full-thickness tear;
  • rebuild an arthritic joint surface;
  • remove bone spurs;
  • reverse advanced muscle atrophy; or
  • guarantee avoidance of surgery.

The evidence supports discussing possible improvement in pain and function for appropriately selected patients. Structural regeneration remains an investigational question.

Why injection location matters

“A shoulder injection” is not a complete treatment description. Depending on the diagnosis, a clinician may consider the glenohumeral joint, a specific rotator cuff tendon or tendon attachment, the biceps tendon sheath, the acromioclavicular joint, supporting ligaments, or another identified structure.

Ultrasound guidance allows the physician to observe the needle and place the preparation at the intended target while avoiding nearby neurovascular structures. Guidance improves accuracy, but accurate placement cannot compensate for an incorrect diagnosis or an injury that requires mechanical repair.

The goal is a better-functioning shoulder—not a promise from an image

Stem cell therapy is not one treatment for every painful shoulder. Bone marrow concentrate may be considered for selected rotator cuff injuries or arthritic shoulders, but the evidence is still developing. PRP has a broader clinical research base for rotator cuff disorders and may offer a simpler option for some patients. Neither therapy reliably regenerates a normal tendon or restores an end-stage arthritic joint.

The caller’s improvement discussed on the radio is encouraging, but it remains one person’s experience. The most responsible approach is to identify the actual pain generator, determine whether the damage is mechanically repairable without surgery, explain the limits of the evidence, and combine any procedure with a structured rehabilitation plan.

Some partial and degenerative tears can be treated nonsurgically. Some complete traumatic tears need timely repair. Some patients with advanced joint destruction are best served by shoulder-replacement evaluation. Good regenerative medicine begins with knowing the difference.

References

  1. Kwong CA, Woodmass JM, Gusnowski EM, et al. Platelet-Rich Plasma in Patients With Partial-Thickness Rotator Cuff Tears or Tendinopathy Leads to Significantly Improved Short-Term Pain Relief and Function Compared With Corticosteroid Injection: A Double-Blind Randomized Controlled Trial. Arthroscopy. 2021;37(2):510-517.
  2. Hamid MSA, Sazlina SG. Platelet-rich plasma for rotator cuff tendinopathy: A systematic review and meta-analysis. PLoS One. 2021;16(5).
  3. Centeno C, Fausel Z, Stemper I, Azuike U, Dodson E. A Randomized Controlled Trial of the Treatment of Rotator Cuff Tears with Bone Marrow Concentrate and Platelet Products Compared to Exercise Therapy: A Midterm Analysis. Stem Cells International. 2020;2020:5962354.
  4. Hernigou P, Flouzat Lachaniette CH, Delambre J, et al. Biologic augmentation of rotator cuff repair with mesenchymal stem cells during arthroscopy improves healing and prevents further tears: a case-controlled study. International Orthopaedics. 2014;38(9):1811-1818.
  5. Kirschner JS, Cheng J, Creighton A, et al. Efficacy of Ultrasound-Guided Glenohumeral Joint Injections of Leukocyte-Poor Platelet-Rich Plasma Versus Hyaluronic Acid in the Treatment of Glenohumeral Osteoarthritis: A Randomized, Double-Blind Controlled Trial. Clinical Journal of Sport Medicine. 2022;32(6):558-566.
  6. Moosmayer S, Lund G, Seljom US, et al. Tendon repair compared with physiotherapy in the treatment of rotator cuff tears: a randomized controlled study in 103 cases with a five-year follow-up. Journal of Bone and Joint Surgery American Volume. 2014;96(18):1504-1514.

Medical disclaimer

This article is for educational purposes only and is not medical advice. It does not establish a physician-patient relationship. PRP and bone marrow concentrate procedures are not FDA-approved to treat shoulder arthritis or rotator cuff tears. Results vary, and no outcome or tissue regeneration can be guaranteed. Patients should receive an individualized evaluation and discuss established treatments, investigational status, risks, costs, rehabilitation, and surgical alternatives with a qualified clinician.