Common shoulder questions have plain answers

Sources

1. A four-arm, multicentre, single-blind phase 2/3 randomized trial of 480 knee OA patients (KL II-IV) compared autologous bone marrow aspirate concentrate, autologous adipose stromal vascular fraction and allogeneic umbilical-cord-tissue mesenchymal stromal cells against a corticosteroid injection control. At 12 months NONE of the three orthobiologic injections was superior to another, or to the corticosteroid control, and none of the four groups showed a significant change in MRI osteoarthritis score from baseline. No procedure-related serious adverse events occurred.

   Mautner K, et al. — Cell-based versus corticosteroid injections for knee pain in osteoarthritis: a randomized phase 3 trial.. Nature medicine, 2023. DOI: 10.1038/s41591-023-02632-w.

2. A randomized trial of 90 patients with KL grade 1-3 knee OA found bone marrow aspirate concentrate - the product most often sold as a 'stem cell injection' - was EQUIVALENT to, not better than, PRP through 24 months, with no statistically significant IKDC or WOMAC difference at any time point. Both arms improved from baseline and plateaued at 3 months.

   Anz AW, et al. — Bone Marrow Aspirate Concentrate Is Equivalent to Platelet-Rich Plasma for the Treatment of Knee Osteoarthritis at 2 Years: A Prospective Randomized Trial.. The American journal of sports medicine, 2022. DOI: 10.1177/03635465211072554.

3. A Level-1 systematic review of 8 randomized trials (937 patients) of bone marrow aspirate concentrate for knee OA found BMAC improved clinical scores versus baseline from one month, and beat hyaluronic acid on pain at 6 and 12 months with statistical significance - but those differences DID NOT EXCEED the minimal clinically important difference, and against other injections no significant difference appeared at all. Statistically detectable is not the same as noticeable.

   Han JH, et al. — Bone Marrow Aspirate Concentrate Injections for the Treatment of Knee Osteoarthritis: A Systematic Review of Randomized Controlled Trials.. Orthopaedic journal of sports medicine, 2024. DOI: 10.1177/23259671241296555.

4. The evidence overview underpinning the 2020 EULAR recommendations on intra-articular therapies pooled 29 quality-appraised systematic reviews. Hyaluronic acid showed a small effect on pain and function in KNEE OA but not in hip OA or shoulder capsulitis; intra-articular glucocorticoid showed small effects in knee OA and on function in hip OA and shoulder capsulitis; PRP showed benefit in knee OA but NOT in hip OA, and mesenchymal stem cells behaved similarly. Overall conclusion: most intra-articular therapies exert SMALL effects and are well tolerated.

   Rodriguez-García SC, et al. — Efficacy and safety of intra-articular therapies in rheumatic and musculoskeletal diseases: an overview of systematic reviews.. RMD open, 2021. DOI: 10.1136/rmdopen-2021-001658.

5. In a 2-year RCT, intra-articular triamcinolone given every 12 weeks for knee OA produced significantly GREATER cartilage volume loss than saline, with no significant pain benefit. The most widely used joint injection in medicine is itself associated with structural harm on repeat dosing - relevant context when a clinic frames a biologic as 'the alternative to steroid shots'.

   McAlindon TE, et al. — Effect of Intra-articular Triamcinolone vs Saline on Knee Cartilage Volume and Pain in Patients With Knee Osteoarthritis: A Randomized Clinical Trial.. JAMA, 2017. DOI: 10.1001/jama.2017.5283.

6. A Mayo Clinic single-blind placebo-controlled trial used each patient as their own control: 25 patients with BILATERAL knee OA received bone marrow aspirate concentrate in one knee and saline in the other. Pain fell significantly in BOTH knees at 1 week, 3 months and 6 months - and the relief, described by the authors as dramatic, did NOT differ significantly between the BMAC knee and the saline knee. No serious adverse events occurred.

   Shapiro SA, et al. — A Prospective, Single-Blind, Placebo-Controlled Trial of Bone Marrow Aspirate Concentrate for Knee Osteoarthritis.. The American journal of sports medicine, 2017. DOI: 10.1177/0363546516662455.

7. The August 2025 AAOS Evidence-Based Clinical Practice Guideline on Management of Rotator Cuff Injuries issued 25 recommendations and 4 consensus statements. Among its updates it clearly RESTRICTS the use of platelet-rich plasma and marrow stimulation in rotator cuff repair, limits prolotherapy in full-thickness tears, establishes CT as an adjunctive imaging modality, and endorses early mobilization after repair of small-to-medium tears.

   Ye Y, et al. — [Interpretation of the 2025 American Academy of Orthopaedic Surgeons (AAOS) on Management of Rotator Cuff Injuries Evidence-Based Clinical Practice Guideline].. Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi, 2026. DOI: 10.7507/1002-1892.202511084.

8. In the MOON Shoulder prospective cohort of 452 patients with symptomatic, ATRAUMATIC full-thickness rotator cuff tears, physical therapy succeeded in more than 70% of patients at 10 years: only 115 (27.0%) had surgery at any point over the decade. Patient-reported outcomes improved with physical therapy and did NOT decline over 10 years in those who never had surgery. The strongest predictor of early surgery was low patient expectation of physical therapy, not tear anatomy.

   Kuhn JE, et al. — The Predictors of Surgery for Symptomatic, Atraumatic Full-Thickness Rotator Cuff Tears Change Over Time: Ten-Year Outcomes of the MOON Shoulder Prospective Cohort.. J Bone Joint Surg Am, 2024. DOI: 10.2106/JBJS.23.00978.

9. A meta-analysis of nine randomized trials (n=629) in partial-thickness rotator cuff tears and tendinopathy found statistically significant SHORT-term (6 +/- 1 months) PRP effects on pain (MD -1.56), Constant-Murley (+16.48) and SPADI (-18.78), but NO long-term effect on pain or function except Constant-Murley - i.e. the benefit may not last.

   Xiang XN, et al. — Conservative treatment of partial-thickness rotator cuff tears and tendinopathy with platelet-rich plasma: A systematic review and meta-analysis.. Clin Rehabil, 2021. DOI: 10.1177/02692155211011944.

10. A randomized crossover trial of 51 patients compared percutaneous bone marrow concentrate plus platelet products with a HOME exercise programme for high-grade partial and full-thickness supraspinatus tears. The BMC group reported significantly greater improvement at three months (median change in DASH -11.7 versus -3.8; SANE +50.0 versus 0.0) with no serious adverse events. The comparator was an unsupervised home programme rather than supervised therapy or a sham injection, and patients could cross over at three months - so this is not a placebo-controlled result.

    Centeno CJ, et al. — Percutaneous bone marrow concentrate and platelet products versus exercise therapy for the treatment of rotator cuff tears: a randomized controlled, crossover trial with 2-year follow-up.. BMC Musculoskelet Disord, 2024. DOI: 10.1186/s12891-024-07519-6.

11. A network meta-analysis of randomized trials found double-row repair combined with platelet-rich plasma optimized retear rates after small-to-medium full-thickness rotator cuff repair - a result about SURGICAL TECHNIQUE plus augmentation, which is a different question from whether an injection of PRP helps an unoperated shoulder.

    Lavoie-Gagne O, et al. — Double-Row Repair With Platelet-Rich Plasma Optimizes Retear Rates After Small to Medium Full-Thickness Rotator Cuff Repair: A Systematic Review and Network Meta-analysis of Randomized Controlled Trials.. Arthroscopy, 2022. DOI: 10.1016/j.arthro.2022.03.014.