Composite mandibulectomy: a novel animal model

Abstract

Objectives: Segmental mandibular defects can result after the treatment of various pathologic processes, including osteoradionecrosis, tumor resection, or fracture nonunion with sequestration. The variety of etiologies and the frequency of occurrence make the reconstruction of segmental mandibular defects a topic of significant interest. Despite these incentives, a well-established small-animal model of the segmental mandibulectomy, including composite resection, does not exist. The objective of this study is the creation of a reliable animal model that can be used to study the reconstruction of en bloc mandibular defects. Surgical techniques and an array of reconstructive options are described.

Study design: Description of an animal model.

Setting: Animal laboratory at a quaternary care university medical center.

Methods: We present an Animal Research Oversight Committee-approved prospective analysis of survival operations in the rat model. A detailed, stepwise description of surgical technique and relevant intraoperative anatomy is presented. Postoperative management, early pitfalls, surgical complications, and future applications are discussed.

Results: A total of 72 operations were performed by a single individual between July and October 2010. Two intraoperative and 9 postoperative complications were recognized. There were 6 orocutaneous fistulas, 2 abscesses, and 1 seroma. There were 4 fatalities, which were attributed to anesthetic complications (2, intraoperative), hematoma formation (1, postoperative), and foreign-body aspiration (1, postoperative).

Conclusion: This novel animal model reliably replicates the en bloc segmental mandibular defects seen in our patient population and can be manipulated to achieve a wide variety of research objectives.

Figure 1

Supine animal under general anesthesia. A curvilinear incision has been made at the left neck. The masseter (M) is visualized after retracting the overlying fascial flap (F). Note that the submandibular gland (*) has been elevated and retracted.

Figure 2

Supine animal under general anesthesia. The ventral mandible is exposed after lateralization of the masseter.

Figure 3

Supine animal under general anesthesia. A synthetic splint (S) has been affixed to the lateral mandible with threaded K-wires (*) in 4 points.

Figure 4

Supine animal under general anesthesia. A titanium miniplate is affixed to the mandible (*) after segmental mandibulectomy. The masseter (M) can be visualized laterally. The strap musculature (S) remains in the midline.