Orthobiologic Injectables in the Ankle Joint: a Narrative Review

Background. The ankle joint is a frequent site of injury and bone remodeling, and often requires cartilage repair. Studies have shown that growth factors and bioactive compounds have regenerative properties capable of promoting cartilage restoration. Hyaluronic acid (HA) and orthobiologics like platelet-rich plasma (PRP) and adult stem cells (ASCs) are particularly interesting as therapeutic solutions for ankle carti-lage repair and have received considerable attention over the years.Methods. We performed a literature review to summarize the clinical uses and outcomes of HA, PRP and ASCs as reparative interventions in osteochondral lesions (OCL) and osteoarthritis (OA) of the ankle, when used alone and post-surgically.Results. In total, 50 studies were eligible and included in this review. HA was shown to be a safe treatment option with a low rate of adverse effects and overall clinical improvement for talar OCL when used alone and post-surgically. PRP was found to be superior to HA for talar OCL in non-surgical and post-surgical patients. Studies eval-uating HA injections for ankle OA noted a general improvement in pain and function post-injection with minimal adverse reactions, though there is mixed data regarding the efficacy of PRP injections for ankle OA. High-level randomized controlled trials are lacking for the evaluation of ASCs in talar OCL and ankle OA, though limited research has found them to be safe and efficacious.Conclusions. HA and orthobiologics can be considered for use as a pre-surgical treat-ment in ankle OCL and OA, or as a second-line treatment for patients who remain symptomatic after surgery. The safety profile and subjective improvement in clinical outcomes following orthobiologic treatments is promising, though requires additional investigation.