Obese Patients Do Not Benefit from Bone Marrow Aspiration Concentrate Injection for Knee Osteoarthritis: A Prospective Cohort Study of 68 Patients.

Background: Bone marrow aspirate concentrate (BMAC) is considered one of the biological treatments for knee osteoarthritis (KOA). Patient selection remains a key factor to ensure that optimal treatment benefit and body mass index (BMI) are one of the key factors to be considered. This study aims to evaluate the influence of obesity on the duration of treatment benefit of BMAC for KOA.

Methods: This prospective cohort study enrolled 68 patients who underwent a single BMAC injection for early stage KOA. The patients were categorized based on their BMI into normal, overweight, and obese groups. Visual Analog Scale (VAS) for pain and Knee Injury and Osteoarthritis Outcome Score (KOOS) were the outcomes analysed. The duration of treatment benefit is estimated by Kaplan-Meier survival analysis.

Results: Sixty-eight patients (normal BMI = 43, overweight BMI = 15, obese BMI = 10) were enrolled in the study for analysis. While significant improvement in the outcome scores was noted compared to the baseline throughout the study period in the normal BMI and overweight group, the obese group returned to baseline parameters at 3 months follow-up. Patients in the normal BMI group demonstrated significant improvement in VAS (p < 0.001) and KOOS (p < 0.001) outcomes compared to the overweight and obese group. Survival analysis demonstrated a significant decline in the mean treatment benefit of 9.8 (95%CI [6.151-13.431], p = 0.027) months in normal BMI group to 6.6 (95%CI [3.473-9.727]) months and 4.1 (95%CI [2.760-5.440]) months in overweight and obese groups, respectively.

Conclusion: BMI is a significant factor that influences the benefit of BMAC injection for early knee OA. Hence, BMAC injection must be used with caution in individuals with high BMI.