Concept of Relative Deficiency of Growth Factors in Hindfoot Fusion

The purpose of this study was to quantify the levels growth factors (PDGF‐ AB, VEGF, IGF‐1, TGF‐β1) within bone samples at the fusion site of diabetic patients undergoing hindfoot fusion to determine any correlation with successful fusion. Methods The study included 10 adult diabetic subjects from one U.S. center, with an average age of 57.9 years (range 49‐71). Interventions included hindfoot fusions with fixator (n=8) and pantalar fusions with fixator (n=2). During each procedure, a bony bed sample was taken from the fusion site, and frozen. This local bone bed was analyzed for growth factors using ELISA kits. A PRP concentration was applied to each fusion site during the procedures. Results Three of the ten patients sustained a non‐union outcome. After normalizing to BCA total protein levels, a 70% decrease in PDGF‐AB (0.044 pg/μg non‐union to 0.149 pg/μg union; p=0.016) and a 44% decrease in VEGF (0.522 pg/μg non‐union to 0.924 pg/μg union; p=0.031) was observed in the three non‐ union bone samples compared to the fusion group. No difference existed in the levels of IGF‐I between the groups. Insignificantly higher levels of TGF‐β1 were detected in the non‐union group (0.199ng/μg non‐ union to 0.142ng/μg union; p=0.544). Conclusions Differences in local growth factor levels exist between DM and non‐DM patients’ bone. Potentially, growth factor levels (PDGF‐AB, VEGF) in bone may affect the outcome of successful arthrodesis in diabetic patients. This study supports the concept that growth factor levels within the fusion site of a diabetic patient may affect the outcome of a successful hindfoot fusion.