Patient-specific implant modification for alloplastic bridging of mandibular segmental defects in head and neck surgery

Displacement of the remaining mandibular segments may occur after alloplastic bridging of mandibular segmental defects using patient-specific reconstruction plates. Consequently, additional surgical devices are required for correct plate positioning. Patient-specific reconstruction plates with a conventional one beam-like design (cPSRP) have been modified by adding two flanges and giving a Y-shape to the distal ascending implant part to allow for segment positioning without using additional devices. We aimed to evaluate reconstruction results after using these modified patient-specific reconstruction plates (mPSRP). We compared the reconstruction results for mPSRP and cPSRP and evaluated mandibular segment dislocations after reconstruction using digital image analysis of the pre- and postoperative radiological data sets. Analysis showed better reconstruction results with mPSRP than with cPSRP; mean dislocation values concerning shifts and rotations of mandibular segments were lower for mPSRP (x-axis: 2.9 mm vs 1.1 mm, 4.2° vs 3.6°; y-axis: 6.0 mm vs 2.0 mm, 3.5° vs 2.8°; z-axis: 3.9 mm vs 3.3 mm, 4.2° vs 1.2°). Significant differences were found for shifts along the y-axis (p = 0.039) and rotations around the z-axis (p = 0.041). Therefore, implant design modifications with additional positioning elements could help simplify surgical reconstruction procedures and improve reconstruction in head and neck surgery.