Purpose

Autologous micro-fragmented adipose tissue (MFAT) for treating symptomatic knee osteoarthritis (OA) is gaining interest although supportive data on clinical safety and efficacy are lacking. The study primarily aimed to evaluate (1) the short-term clinical effect, (2) the therapeutic response rate (TRR), and (3) the therapeutic safety of a single intra-articular autologous MFAT injection for symptomatic knee OA. Secondly, patient- and pathology-related parameters were investigated to optimize patient selection in future clinical practice.

Methods

Sixty-four subjects (37 unilateral, 27 bilateral) with mild-severe knee OA were enrolled in a single-centre trial. After liposuction, the adipose tissue was mechanically processed with the Lipogem® device, which eventually produced 8-10cc MFAT. Subjects were clinically assessed by means of the KOOS, NRS, UCLA and EQ-5D at baseline and 1, 3, 6 and 12 months after injection. Adverse events were recorded. The TRR was defined according to the OMERACT-OARSI criteria and baseline MRI was scored following the MOAKS classification.

Results

The TRR of the index knee was 64% at 3 months and 45% at 12 months after injection. Therapy responders at 12 months improved with 28.3±11.4 on KOOS pain, while non-responders lost -2.1±11.2 points. All clinical scores, except the UCLA, improved significantly at follow-up compared to baseline (p<0.05). In the bilateral cohort, no difference in baseline scores or TRR was found between the index knee and contralateral knee (n.s.). Numerous BML were negatively correlated with the TRR at 12 months (p=0.003). A post-injection inflammatory reaction was reported in 79% knees and resolved spontaneously within 16.6±13.5 days after MFAT administration without affecting the 12 month clinical outcome.

Conclusion

The study demonstrated an early clinical improvement but a mediocre response rate of 45% at 12 months after a single intra-articular injection with autologous MFAT. Assessment of bone marrow lesions on MRI can be helpful to increase the therapeutic responsiveness of MFAT up to 70% at 12 months. In comparison to repetitive injection therapies such as cortisone, hyaluronic acid, and PRP, administration of MFAT might become a relevant alternative in well-selected patients with symptomatic knee OA.