Modified internal curvilinear distraction device with a pre-embedding guide rail, drive screw, and universal joint for curvilinear lengthening of the mandible: A finite element analysis and animal experiment

Abstract

Objectives: The semiburied design of the traditional internal distractor has a relatively high risk of infection and aesthetic problems. To reduce these potential risks, a modified internal distractor with design of pre-embedding curvilinear rail, drive screw, and universal joint was invented. Its stress distribution characteristics and the effect on curvilinear distraction osteogenesis (DO) in vivo were further tested.

Materials and methods: Finite element analysis (FEA) was performed on a model of the human mandible and distraction device to measure the stress distribution during curvilinear DO. Six beagles underwent curvilinear DO and consolidation using the new device. Radiological and histological examinations were performed on the new bone.

Results: On FEA, the stress was concentrated in the condyle (128.6 MPa) and curved guide rails (324.8 MPa). Four of the six animals completed the DO period and were consolidated for 12 weeks. Secondary infections were not observed. Radiography showed that a new fan-shaped bone-15.5 ± 5.5 mm in length and 4.6 ± 1.6 mm in height-was formed in the bone gap. Micro-computed tomography and histological examinations of specimens indicated that the structure of the new bone was similar to that of the normal bone.

Conclusions: The modified internal curvilinear distraction device meets the mechanical strength requirement and achieve curvilinear DO in animal experiments.

Keywords: Animal experimentation; Distraction osteogenesis; Finite element analysis; Mandible; Rehabilitation.