Minimally-Invasive Surgery Accelerates Time to Union in Foot and Ankle Arthrodesis Independent of Synthetic Bone Graft Usage

Research Type: Level 3 - Retrospective cohort study, Case-control study, Meta-analysis of Level 3 studies Introduction/Purpose: Foot and ankle arthrodesis is commonly performed for arthritis, deformity, or joint instability. Minimally invasive surgery (MIS) has been increasingly adopted for its benefits in preserving soft tissue integrity and accelerating recovery. Additionally, synthetic bone grafts, such as MagnetOs™, offer alternatives to autografts for optimizing bone healing. However, the impact of MIS and synthetic grafting on union time, nonunion rate, infection, and revision rates remains underexplored. Methods: This retrospective cohort study analyzed 105 patients who underwent foot and ankle arthrodesis at a single institution (June 2021—July 2024). Patients were categorized into open vs. MIS groups, with the MIS cohort further divided into cases with vs. without graft. The primary outcomes were time to union, assessed via Kaplan-Meier survival analysis, and nonunion rate, analyzed using Fisher’s exact test. Secondary outcomes included infection and revision rates, analyzed using Fisher’s exact test and relative risk (RR) calculations. Results: MIS cases demonstrated significantly faster union than open procedures (median 86 vs. 151 days; log-rank p=0.0057). However, adding MagnetOs™ did not further reduce union time within MIS cases (83 vs. 86 days; log-rank p=0.1912). There was no significant difference in nonunion rates between groups. Relative risk of infection (RR=0.53, p=0.405) and revision (RR=0.40, p=0.067) did not differ between open and MIS cases. Among MIS cases, relative risk of infection (RR=1.50, p=1.000) and revision (RR=3.50, p=0.256) were also not significantly different with vs. without graft. Conclusion: MIS significantly reduces time to union in foot and ankle arthrodesis without increasing infection or revision risk. While MagnetOs™ did not further accelerate union, it was not associated with increased complications, supporting its safety. These findings suggest synthetic grafts may not be routinely necessary in MIS arthrodesis when joint preparation is satisfactory. Larger studies are needed to refine indications for synthetic graft use in foot and ankle arthrodesis.