Bone Marrow Aspirate Concentrate Injections for the Treatment of Knee Osteoarthritis: A Systematic Review of Randomized Controlled Trials

Abstract

Background: Osteoarthritis (OA) poses a significant global burden, with conventional treatments like corticosteroid and hyaluronic acid (HA) injections commonly used. Emerging injectable biologics, including bone marrow aspirate concentrate (BMAC), show promise in OA management.

Purpose: To investigate the clinical efficacy of BMAC injection compared with other injection treatments for knee OA.

Study design: Systematic review; Level of evidence, 1.

Methods: A systematic review was conducted using PubMed, Embase, Cochrane Library, and Google Scholar to identify randomized controlled trials with Level 1 evidence that compared the clinical efficacy of BMAC with other injections. The visual analog scale for pain and the Pain subscale of the Knee injury and Osteoarthritis Outcome Score (KOOS) were used as clinical scores representing pain. For functional assessment, the Western Ontario and McMaster Universities Osteoarthritis Index and the International Knee Documentation Committee subjective form were used. For studies comparing BMAC with HA, each clinical score was standardized to pain and function scales based on the minimal clinically important difference (MCID).

Results: Eight studies, consisting of a total of 937 patients, were included. Patients treated with BMAC showed a significant improvement in clinical scores compared with baseline, starting at 1 month postinjection. For pain scores at 6-month (P = .033) and 12-month follow-up (P = .011), BMAC demonstrated favorable results over HA, with a statistically significant difference. However, these differences did not exceed the MCID. When BMAC was compared with other injections, no significant differences were observed in the degree of clinical score improvement. No serious adverse events or events significantly associated with BMAC compared with other treatments were reported.

Conclusion: BMAC injections demonstrated effectiveness in providing pain relief and functional improvement for patients with knee OA. When BMAC was compared with other intra-articular injection options, distinct differences surpassing the MCID were not evident. Further research is deemed necessary to investigate the role of BMAC in the treatment of knee OA.

Keywords: bone marrow aspirate concentrate; intra-articular injection; knee osteoarthritis; systematic review.

Figure 1.

PRISMA flow diagram of the study inclusion process. BMAC, bone marrow aspirate concentrate; RCT, randomized controlled trial.

Figure 2.

Risk-of-bias assessment (A) for each included study and (B) overall summary according to bias domain.

Figure 3.

Forest plot showing the results of the meta-analysis of clinical scores representing pain (VAS pain, KOOS Pain) at each follow-up time point. Each score was standardized to pain scales based on the reported MCIDs for VAS pain and KOOS Pain. BMAC, bone marrow aspirate concentrate; HA, hyaluronic acid; KOOS, Knee injury and Osteoarthritis Outcome Score; MCID, minimal clinically important difference; MD, mean difference; VAS, visual analog scale.

Figure 4.

Forest plot illustrating the meta-analysis results of clinical scores representing function (WOMAC, IKDC subjective form) at each follow-up time point. Each score was standardized to function scales based on the reported MCIDs for the WOMAC and the IKDC subjective form. BMAC, bone marrow aspirate concentrate; HA, hyaluronic acid; IKDC, International Knee Documentation Committee; MCID, minimal clinically important difference; MD, mean difference; WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index.

Figure A1.

Funnel plots showing the assessment of publication bias in the (A) pain and (B) function scores. For pain scores (A), asymmetry indicates underreporting of smaller studies with less significant results. Function scores (B) also show slight asymmetry, possibly reflecting a bias toward positive outcomes. However, this asymmetry should be interpreted cautiously, as it may result from study heterogeneity or a limited number of studies.