Efficacy of a Cellular Bone Allograft for Foot and Ankle Arthrodesis and Revision Nonunion Procedures

Background: Bone graft substitutes are often required in patients at risk for nonunion, and therefore, an allograft that most closely mimics an autograft is highly sought after. This study explored the utility and efficacy of a cellular bone allograft used for foot and ankle arthrodesis and revision nonunion procedures in a patient population at risk for nonunion. Methods: An institutional review board-approved retrospective review of consecutive patients who underwent arthrodesis and revision nonunion procedures with a cellular bone allograft was performed at a single academic institution. No external sources of funding were provided for this study. Inclusion criteria included patients who were more than 1 year after surgery or less than 1 year after surgery if they had undergone a second operative procedure for nonunion or if they had computed tomography-documented union. Forty operative procedures in 36 patients with a mean follow-up of 13 months (range, 6-25 months) were included for data analysis. All patients had at least one of the following risk factors associated with nonunion: current smoker, diabetes, avascular necrosis (AVN) of the involved bone, active same-site operative infection, history of nonunion, previous same-site surgery, or gap of 5 mm or greater after joint preparation. The primary outcome was radiographic union. Results: The union rate in this high-risk population was 83% (33/40). Univariate analysis demonstrated that the use of a cellular bone allograft helped mitigate the presence of risk factors known to cause nonunion. There was no significant difference in fusion rates among groups with current smoking, AVN of the involved bone, active same-site operative infections, history of nonunion, rheumatoid arthritis on medication, previous same-site operative procedures or infections, or a gap of 5 mm or greater after joint preparation. However, in this population, diabetic and female patients remained at a high risk of recurrent nonunion (P = .0015), despite the use of a cellular bone allograft. Chi-square analysis of patients with increasing numbers of risk factors directly correlated with an increased risk of nonunion (P = .025). Four wound complications were reported in this cohort that required irrigation and debridement (10%). Conclusion: These data demonstrated a union rate of 83% in patients with risk factors known to cause nonunion. The benefits of the use of a cellular bone allograft allowed for the avoidance of morbidity associated with autograft harvesting while still improving the local biology to facilitate fusion in a difficult patient population to attain a successful fusion mass. Level of Evidence: Level IV, retrospective case series.