Consolidation Time and Relapse: A Systematic Review of Outcomes in Internal versus External Midface Distraction for Syndromic Craniosynostosis

Background: The choice between internal and external distraction osteogenesis for midface advancement in patients with syndromic craniosynostosis is based primarily on surgeon preference and expertise. However, differences in outcomes between the two techniques have been sparingly compared. In this work, the authors performed a systematic review to compare outcomes between internal versus external midface distraction. Methods: A systematic review was performed of studies published between 1998 and 2018 (61 studies included; n = 689 patients). Operative characteristics, early reoperations, complications, and relapse rates were extracted. Bias evaluation was performed using the Newcastle-Ottawa instrument. Statistical analyses were performed with independent samples t tests and linear regression analyses (p < 0.05 considered significant). Results: The authors found that external distraction was associated with more Le Fort III osteotomies and hardware adjustments (p = 0.023), whereas internal distraction was associated with more monobloc osteotomies and longer consolidation times (p = 0.008). No significant differences in the distance of midface advancement, reoperations, complications, or relapse rates were noted between internal versus external distraction, although external distraction trended toward a slightly higher relapse rate. Regardless of distraction protocol, consolidation time was found to be a strong negative predictor for relapse (beta = -0.792; p = 0.02). Conclusions: No significant differences were demonstrated in advancement distance, reoperative rates, complication rates, or relapse rates for internal versus external distraction for midface advancement. Regardless of distraction type, consolidation time was strongly inversely associated with relapse rates. The trend toward higher relapse in external distraction is potentially explained by the significantly lower consolidation times.