Computer-assisted planning of distraction osteogenesis for lower face reconstruction in gunshot traumas

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Abstract

Purpose

Reconstruction of gunshot wounds of the lower face remains a challenge for the maxillofacial surgeon. We present our experience with the use of virtual surgery using Computer-Assisted Design (CAD)/Computer-Assisted Manufacturing (CAM) techniques to create a custom-made distraction device and prefabricated cutting guides (for both fibula and jaw osteotomies) and for device positioning.

Materials and methods

We describe two cases of lower face reconstruction after gunshot wounds by osteogenic distraction osteogenesis (DO) and computer-assisted surgery (SurgiCase CMF 5.0® software, Materialise). Surgical osteotomies and placement of the custom-made distraction device were performed intraoperatively based on prefabricated guides.

Results

This fully digital preoperative planning improves the precision of osteotomies sites and distraction vectors. It largely reduces the operative time, with a greater operative safety.

Conclusions

Reconstruction by DO allows the bone and soft tissues to be simultaneously regenerated. However, the control of three-dimensional reconstruction of the lower face with distraction is difficult in facial gunshot patients because of the difficulties in locating anatomical landmarks. Surgical osteotomies are pre-planned and rapidly performed using a cutting guide. Precise placement of the distraction device is achieved without the need for subjective assessment of the sole surgeon. In our experience, the surgery has resulted in outcomes similar to those predicted by the computer-assisted planning.

Introduction

Lower face defects resulting from gunshot wounds often cause severe functional and cosmetic deformities. Distraction osteogenesis (DO) is already a well-established technique to treat those facial wounds, because this type of injury requires the reconstruction of bone and soft tissues (Labbé et al., 2005). As well as in bone elongation, it results in the simultaneous formation of new skin, muscles, and subcutaneous tissues. The objectives of this reconstruction are both functional and aesthetic: to restore facial contours, to provide labial function and also to provide masticatory function through dental rehabilitation. The principal interest of the DO is the simultaneous creation of the facial soft tissues. Therefore, there is no need to harvest muscles or composite flaps (free or pedicled). DO also recreates the alveolar ridge with its attached gum, suitable for dental reconstruction by osseointegrated implants. Thus, the problems of inflammation around dental implants are largely overcome (Taupin et al., 2012). DO is also interesting from an economic point of view due to the smaller cost for DO in comparison with free flaps (Wojcik et al., 2011). The total duration of treatment is longer than with microsurgery techniques, although the duration of hospitalization is shorter.

Previously, we have reported our experience of DO using a customized external device (DEOS) with an endless screw. This bidirectional device was successfully used for reconstruction of the lower and midface regions (Labbé et al., 2009). However, the three-dimensional control of the distraction remained very difficult in conventional operations based on the sole surgeon's experience, because of the difficulties in locating anatomical landmarks in those facial gunshot wounds. Preoperative planning of mandibular reconstruction has moved from mechanical simulations with stereolithographic models or dental model casts into almost completely virtual planning. Currently available software permits virtual surgery with digital control of the three-dimensional (3D) movements of mandibular stumps. Computer-assisted surgery also allows the design and the machining of surgical cutting and drilling guides, as well as of patient-specific pins for fixation of the device named Plate Implant for Flat Bones (PIFB) (Fig. 1).

Those digital simulations can overcome the technical problems of management of the spatial position of the reconstructed mandible, with reference to the upper jaw and occlusal plane.

Computer-assisted planning of DO (SurgiCase CMF 5.0®, Materialise, Leuven, Belgium) was tried in our last two cases of gunshot wounds. Here, we report our procedure and experience in the use of preoperative virtual surgery to better achieve acute intraoperative goals using a computer-aided design/computer-aided manufacturing (CAD/CAM) technique for mandibular distraction in gunshot wounds.

Section snippets

Patients

Two patients with gunshot injuries (from suicide attempts) underwent osteogenic distraction with the help of computer-assisted planning in our department since 2012. The patients were both male and were 42 and 63 years old. The facial lesions were described (Table 1) according to the classification system previously reported (Bénateau et al., 2001). The facial area is divided into three horizontal sections (level I is mandibular or lower face, level II is maxillary or midface, and level III is

Results

A summary of the demographics of the two patients is presented in Table 1.

The preoperative planning procedure lasted about 60 min, including the interactive Web session.

The surgical time was 170 min for the first patient and 140 min for the second one.

In the two cases, distraction was completed, with reconstruction of bone and soft tissues without the need for a flap.

For the two patients, the device was activated after a 5-days latency period at a speed of 0.5 mm twice per day. The patients

Discussion

Preoperative digital planning is accurate and allows an acute fixation of the distraction device in the required position. It also permits intraoperative guidance of the osteotomies and vector positioning control.

Compared with the relatively simple unidirectional distraction of long bones as described by Ilizarov, the three-dimensional distraction of the mandible is extremely complex (Gateno et al., 2000a, Gateno et al., 2000b). In our experience, preoperative digital planning allows

Conclusion

In conclusion, our results encourage the adoption of computer-assisted distraction planning to treat lower face reconstruction in gunshot wounds with DO. This procedure allowed better control and accuracy in repositioning the mandibular stumps, in determining the distraction vector, and in controlling bone alignment and mandibular symmetry. This developing technique enhanced the functional and cosmetic outcomes of lower face reconstruction by DO. This was performed with the help of precise

Conflict of interest

The authors declare that they had no financial interests, conflicts of interest or commercial associations relevant to this study.

References (21)

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