Injection of biologic agents for treating severe knee osteoarthritis: is there a chance for a good outcome? A systematic review of clinical evidence.

OBJECTIVE: Osteoarthritis (OA) is the most common degenerative joint disease and the leading cause of disability in the adult population worldwide. The knee is the most prevalent site of symptomatic arthritis. Treatment options for OA include drugs, surgery and, more recently, biological treatments. Injectable ortho-biological treatments include autologous and more rarely heterologous preparations employed inside and outside the operating room to assist bone and soft tissue regeneration. Our aim was to analyze the rationale for use of injectable ortho-biological treatments such as platelet-rich plasma (PRP) and mesenchymal cells from bone marrow, adipose tissue, and placenta/umbilical cord, in patients with severe OA of the knee (Kellgren-Lawrence grade 4). MATERIALS AND METHODS: A search in PubMed, ScienceDirect and Google Scholar databases was performed using the following keywords: 'knee osteoarthritis' and 'biological treatment' or 'PRP' or 'adipose' or 'mesenchymal' or 'staminal' or 'stem cells'. Manual research throughout the reference lists of all retrieved articles was further conducted. RESULTS: A total of 16 articles was selected for this systematic review. The rationale for use of each ortho-biological treatment was discussed. The clinical application showed different therapeutic protocols, different follow-up periods, different outcomes analyzed and small sample size. CONCLUSIONS: Our study did not demonstrate uniform beneficial effects for the use of injectable ortho-biological. This prevents any advice for routine application in the treatment of severe knee OA (K-L IV). Further prospective clinical trials with randomization, larger sample size, and preliminary power calculation are needed to justify the use of injectable biologic agents in grade IV knee OA in everyday practice.