The Impact of Patient Age on Foot and Ankle Arthrodesis Supplemented with Autograft or an Autograft Alternative (rhPDGF-BB/β-TCP)

A recent survey of orthopaedic surgeons asking about risk factors for nonunion following foot and ankle arthrodesis revealed that patient age is considered to be a relatively low risk factor, despite the potential for autologous graft quality to deteriorate with increasing age. The purpose of the current study was to evaluate the impact of patient age and graft type on fusion rates following hindfoot and ankle arthrodesis. METHODS: In this study, we analyzed data from a previously published clinical trial, comparing fusion success in 397 subjects who underwent hindfoot or ankle arthrodesis (597 joints) supplemented with either autograft or an osteoinductive autograft alternative, recombinant human platelet-derived growth factor-BB homodimer carried in beta-tricalcium phosphate (rhPDGF-BB/β-TCP). The odds of fusion success were compared among subjects older or younger than age thresholds of 55, 60, 65, 70, and 75 years. The odds of fusion success were also compared between autograft and rhPDGF-BB/β-TCP among subjects older than each age threshold. RESULTS: In the autograft group, the joints of subjects who were younger than the age thresholds of 60 and 65 years had >2 times the odds of successful fusion compared with those of older subjects. There was no significant difference in the odds of fusion success between the older and younger subjects at the age threshold of 55 years. In the rhPDGF-BB/β-TCP group, there was no significant difference in the odds of successful fusion between older and younger subjects at any age threshold. When the odds of fusion success were compared between the 2 graft materials in subjects who were older than each age threshold, rhPDGF-BB/β-TCP had approximately 2 times the odds of fusion success compared with autograft for all thresholds, except 55 years. CONCLUSIONS: The presented evidence suggests that age is an identifiable and concerning risk factor for hindfoot and ankle arthrodesis nonunion, a finding in contrast to the wider perception in the surgeon community. Notably, patients ≥60 years of age had significantly lower odds of fusion success with the use of autograft. The data reveal that use of rhPDGF-BB/β-TCP as an alternative bone-healing adjunct may help mitigate the risk of nonunion when these procedures are performed in the elderly population. LEVEL OF EVIDENCE: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.