Critical Literature Review of Bone Grafts and Orthobiologics for Foot and Ankle Arthrodesis to Facilitate Optimal Clinical Decision Making

Category: Basic Sciences/Biologics; Ankle Introduction/Purpose: With the extensive options of graft materials available to supplement hindfoot and ankle arthrodesis procedures, it is critical to understand the clinical evidence available, or lack thereof, before selecting a product. The purpose of this review was to summarize the available clinical evidence surrounding the utilization and efficacy of the various materials and biological agents [autologous (autograft), allogenic bone graft (allograft), demineralized bone matrix (DBM), calcium sulfate, calcium phosphate, tricalcium phosphate/hydroxyapatite, recombinant human bone morphogenetic protein -2 (rhBMP-2) or recombinant human platelet derived growth factor-BB (rhPDGF-BB)], and preparations (platelet-rich plasma or concentrated bone marrow aspirate) to promote bone healing in hindfoot and ankle procedures, with emphasis on the quality of the existing evidence to facilitate optimal clinical decision making. Methods: A literature review was performed on MEDLINE, SCOPUS, PubMed, and Google Scholar. The search was conducted in June 2023, capturing studies published in English since January 1, 2009, on patients of at least 18 years of age requiring graft material for hindfoot or ankle arthrodesis. Given the high heterogeneity in the literature and the rapidly expanding research on this topic, only comparative studies analyzing the outcomes following ankle or foot arthrodesis using different types of bone grafts were included, with primary focus on articles comparing newer biologic evidence against autograft, as the current gold standard. Results: Randomized controlled trials (RCTs), or Level I studies, for graft materials in foot and ankle arthrodesis procedures were rare and there was a lack of consistency in the time interval and definition/assessment quality of successful fusion vs. non-union or delayed union. The defined benchmark for successful fusion varied greatly, as well as the level of accuracy in the imaging method used to assess fusion (CT vs. plain radiograph). Only autograft and rhPDGF-BB/ β-TCP are investigated in multiple (≥5) RCTs, utilizing high benchmarks and quality for assessing fusion with CT scans. Overall, 24 studies were reviewed; 8 of the 24 were RCT studies, 7 studies were based on rhPDGF-BB/ β-TCP, 7 on autograft, 1 B2A study, 3 BMP-2 studies, 1 allograft, and 5 on other materials. Conclusion: There is a clear lack of high-quality evidence for most graft materials used in hindfoot and ankle fusion. Autograft is the most studied, followed by rhPDGF-BB/β-TCP. Other viable biologic agents and materials have been studied, but in lower quality comparative studies that were heterogeneous, precluding the generation of cumulative outcomes. For optimal clinical decision making, it is crucial to consider the availability of high-quality evidence, or lack of, when selecting the appropriate graft material. Future research will further investigate the role of orthobiologics and their potential to replace autograft to avoid donor site complications during hindfoot and ankle arthrodesis procedures.