BMAC for knee osteoarthritis: reading selected evidence

The question and scope

For adults with knee osteoarthritis, what do selected studies report about intra-articular bone marrow aspirate concentrate compared with saline or other injections for pain and function? This brief addresses BMAC injection for that condition. It does not evaluate marrow transplantation, isolated cells grown in a laboratory, or use alongside surgery.

Sources were checked on October 2, 2026 through targeted searches of PubMed-indexed literature and VA/DoD guidance. We selected a small saline-controlled trial, a larger multicenter active-comparator trial, and a randomized-trial review. The study summaries use PubMed abstracts and available disclosures. This is a focused source compilation, not an exhaustive search, full-text evidence appraisal, or independent medical review.

A small saline-controlled trial

Shapiro and colleagues’ 2017 trial involved 25 people with osteoarthritis in both knees. Each person received BMAC in one knee and saline in the other. Pain improved in both knees over six months, without a significant difference between treatments. No serious adverse events were reported.

Its small sample and paired-knee design limit how widely the result can be applied. It illustrates why improvement from baseline must be distinguished from improvement beyond the comparator.

MILES: comparison with corticosteroid

The 2023 MILES trial randomized 480 participants among cell-based interventions and corticosteroid comparators, including a BMAC group. Its primary endpoint analysis included 440 participants. At one year, none of the studied cell-based interventions was superior to corticosteroid for the primary pain outcomes. No procedure-related serious adverse events were reported.

The authors disclosed Marcus Foundation support and institutional or professional financial relationships, including an institutional interest in the adipose-product company. The PubMed record links a 2024 correction. These disclosures are context for appraisal, not grounds to substitute a different result.

A review of randomized trials

Han and colleagues’ 2024 review included eight studies totaling 937 patients. Some pain comparisons favored BMAC over hyaluronic acid statistically, but the differences did not exceed the review’s minimum clinically important difference. Clear clinically important advantages over other injection options were not demonstrated. The authors declared no conflicts of interest in the contribution.

The review’s combined count overlaps with individual studies; it is not additional independent evidence to add to the trial totals. Preparation differences and the selected comparators remain relevant when discussing applicability.

Guideline context and remaining questions

The 2026 VA/DoD provider summary finds insufficient evidence for or against several intra-articular approaches, including its category of bone-marrow-derived stem-cell injections. That broad guideline wording should not be read as a claim that all marrow products have identical composition or evidence.

The selected trials do not establish reliable cartilage restoration or a guaranteed reduction in the need for future surgery. Reporting no serious event within a study does not rule out uncommon harms or outcomes beyond its follow-up. The additional collection procedure also belongs in the discussion of the complete proposal.

Questions that make the comparison useful

Ask the clinician to identify the collection and preparation method and explain which study most closely matches it. Record whether the expected benefit concerns pain, function, imaging, or another outcome. Ask why that outcome is realistic, how it will be measured, and what would lead to changing the plan.

Compare the full proposed care pathway with alternatives, including evaluation, collection, administration, follow-up, and costs. Ask about harms and reasons the approach may be unsuitable for you. Full methods, adverse-event details, and all funding records were not independently audited here; those limitations should remain visible when the evidence is discussed.

Questions to bring

• Which randomized comparison most closely matches this BMAC proposal?
• Was the difference large enough to matter to patients?
• How do the collection procedure, uncertainty, and total cost compare with other options?

Sources and editorial context

This reference was compiled from the sources below and has not received independent clinical review. Use it to understand terms and prepare questions for a qualified professional who can consider your circumstances.