Age and synovitis affect the results of the treatment of knee osteoarthritis with Microfragmented Autologous Fat Tissue.

Purpose: This study aims to assess the effectiveness of Microfragmented Autologous Fat Tissue (MFAT) treatment for knee osteoarthritis and to investigate whether patients' pre-treatment clinical condition, such as synovitis, correlates with clinical outcomes, to identify potential predicting factors for the success or failure of the treatment.

Methods: In this prospective Cohort Study Level II multicentric trial, consecutive patients with a diagnosis of early/mild osteoarthritis and failure of previous conservative measures were enrolled to undergo diagnostic arthroscopy and a single MFAT injection. Patients were assessed with repeated scoring systems at baseline, 6 months, and 12 months after surgery. The demographic features, the arthroscopic findings, the immunophenotype of injected tissue and the histologic examination of synovia of failed patients were analyzed.

Results: Data from 91 patients showed a significant improvement in Lysholm, WOMAC scores at 1-year follow-up (p < 0.001). A significant decrease in VAS score was observed, while a significant improvement of measured flexion angle was registered at 1 year (p < 0.001). No major complications were reported. Age and synovitis were identified as significant factors influencing the clinical outcome (p < 0.05). Body mass index, previous or concomitant procedures, and specific cartilage defects had no influence. The mean number of injected adipose tissue-derived mesenchymal stem cells seem not to correlate with the clinical outcome.

Conclusion: MFAT is effective in reducing pain when used with a single dose injection in early/mild OA of the knee, without major complications. Age over 60 and synovitis may be predictive for persistent pain at one year and should be considered before indications.