Forces Exerted in Craniofacial Distraction Osteogenesis.

Abstract

The purpose of this study was to develop a methodology for quantifying linear forces of distraction osteogenesis, and thereafter apply this methodology to measure and compare distraction force magnitudes between cranial vault distraction osteogenesis (CVDO) and mandibular distraction osteogenesis (MDO). Patients undergoing CVDO or MDO as inpatients had distraction forces acquired with a digital torque-measuring screwdriver. Torque measurements were then converted into linear distraction force values, which were then compared across distraction types and protocols with appropriate statistics. CVDO was performed on 7 patients (41.2%), and MDO was performed on 10 patients (58.8%). Across the entire cohort, the average maximum force per activation was 27.0 N, and the average elastic force was 10.7 N. Maximum force (CVDO: 52.9 N versus MDO: 12.9 N; P < 0.001) and elastic force (CVDO: 22.0 N versus MDO: 4.5 N; P < 0.001) were significantly higher in patients undergoing CVDO than MDO. Multivariate regression demonstrated that maximum activation force was significantly associated with sequential days of distraction (B= + 1.1 N/day; P < 0.001), distraction rate (B= + 8.9 N/mm/day; P = 0.016), distractor hardware failure (B= + 10.3 N if failure; P = 0.004), and distraction type (B= + 41.4 N if CVDO; P < 0.001). Cranial vault distraction requires significantly more linear distraction force than mandibular distraction. Maximum forces increase with each day of distraction, as well as with increased distraction rates. Linear distraction force methodology from this study may provide the foundation for future development of optimized procedure-specific or patient-specific distraction protocols.