Radiographic Osseointegration Appears Similar Across Synthetic,Allograft,and Mixed Grafts in Custom 3D-Printed Cage Reconstruction of the Foot and Ankle: A Short Report

Abstract

Background:

Custom 3-dimensionally (3D)-printed titanium cages are increasingly used for managing critically sized bone defects (CSDs) of the foot and ankle. Little is known regarding the optimal bone graft (allograft, synthetic, or mixed) to enhance osseointegration. In this study, we compared radiographic osseointegration across synthetic, allograft, and mixed graft formulations in custom 3D‑printed cage reconstructions of foot/ankle CSDs.

Methods:

This was a single-institution retrospective cohort study of patients who underwent foot and ankle reconstruction for CSDs using a custom cage. Demographic and clinical variables included race/ethnicity, age, body mass index, number of prior ipsilateral foot/ankle surgeries, procedure type, cage type, and graft type. The primary outcome was evidence of radiographic osseointegration using a longitudinal mixed effects model at 6, 12, and 24 months. Secondary outcomes included reoperation rates, need for implant removal, and ipsilateral limb amputation, which are summarized descriptively.

Results:

A total of 62 patients were included (20 synthetic graft only; 23 allograft only; 19 mixed). Osseointegration proportions were 74% (synthetic), 64% (allograft), and 89% (mixed) at 6 months; 82%, 75%, and 95% at 1 year; and 100%, 92%, and 100% at 2 years for the patients we were able to follow, with no statistically significant differences in the mixed effects model (unadjusted odds ratios). There were no statistically significant differences in baseline patient demographics, comorbidities, or procedural indications among the 3 graft cohorts. The longitudinal mixed effects model found no statistically significant differences in radiographic osseointegration among the graft groups through 6, 12, and 24 months. We found an overall reoperation rate of 40%, an average of 3.6 reoperations performed on this 25 patient subgroup, and an overall amputation rate of 8%.

Conclusion:

In this single-institution retrospective cohort, we did not detect statistically significant differences in radiographic osseointegration or major postoperative outcomes among synthetic, allograft, or mixed graft formulations; larger prospective studies are warranted.