Comparison of unilateral rostral, middle and caudal segmental mandibulectomies as an alternative treatment for unilateral temporomandibular joint ankylosis in cats: an ex vivo study.

Objectives: Temporomandibular joint ankylosis (TMJA) is the partial or complete inability to open the mouth due to intra- or extra-articular fibrous, bony or fibro-osseous tissue proliferation. Surgical procedures such as gap arthroplasty, condylectomy or wide extra-articular osteotomy have been recommended to treat this condition; these techniques are challenging, time-consuming and have been occasionally associated with postoperative recurrence, severe periarticular neurovascular iatrogenic trauma and death. Segmental mandibulectomy had previously been recommended as an alternative option for unilateral TMJA, but the location of mandibulectomy and extent of bone removal from the mandible region have not been mentioned in the literature. This study aimed to validate the area of the mandibular body (rostral, middle or caudal) and amount of bony tissue that should be osteotomized during a segmental mandibulectomy for treatment of unilateral TMJA in cats.
Methods: In this block study, 30 cadaver heads of domestic shorthair cats were randomly divided into three groups of 10 specimens each based on the mandibular region that would undergo segmental mandibulectomy (rostral, middle and caudal). The size of the removed mandibular segment and pre- and postoperative vertical range of mandibular motion were compared for statistical purposes.
Results: A significant statistical difference was observed between the pre- and postoperative vertical range of mandibular motion between the rostral, middle and caudal segmental mandibulectomies ( P <0.001). The mean postoperative recovered range of mandibular motion for the rostral, middle and caudal segmental mandibulectomies was 50.4%, 81.9% and 90.4%, respectively.
Conclusions and Relevance: The caudal segmental mandibulectomy showed the highest postoperative vertical range of mandibular motion. The removal of a minimum of 1.2 cm of the caudal mandibular body was required to achieve nearly full recovery of presurgical mouth opening in the specimens of this study. The caudal segmental mandibulectomy may eliminate the risk of iatrogenic periarticular neurovascular damage inherent to more invasive surgeries performed at the temporomandibular joint area. When performed unilaterally, the caudal segmental mandibulectomy is a viable surgical alternative that may show a similar outcome to other surgical techniques.