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

Abstract

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.

Caudal and middle segmental mandibulectomies for the treatment of unilateral temporomandibular joint ankylosis in cats

“…Segmental mandibulectomy was previously suggested for the treatment of cats with unilateral TMJA. 21 However, one cat affected by bilateral TMJA in the present study underwent gap arthroplasty on the right TMJ and CSM on the left side. This patient did not show an inability to eat or drink during the postoperative period.…”

“…The authors of the present study previously evaluated the feasibility of segmental mandibulectomy for the treatment of unilateral TMJA in a cadaver cat model. 21 Rostral segmental mandibulectomies, CSMs and MSMs were compared, demonstrating significantly improved recovery of mouth opening when CSMs and MSMs were performed (90.4% and 81.9% recovery, respectively) compared with only 50.4% improvement with rostral segmental mandibulectomy. 21 To our knowledge, the present case series regarding the use of CSMs and MSMs for the treatment of unilateral TMJA is the first of its kind in client-owned cats.…”

“…As described in a previous study, 21 a full-thickness mucoperiosteal flap between the mandibular fourth premolar and first molar teeth was made. Sharp dissection with periosteal elevators separated the gingival and mucoperiosteal tissues from the ventrolateral surface of the mandibular body.…”

“…19 , 20 A recent study performed in cadaver heads of cats determined the mandibular region to be ectomized during a segmental mandibulectomy. 21 This research showed that caudal segmental mandibulectomy (CSM), performed between the first molar tooth and the angle of the mandible, and middle segmental mandibulectomy (MSM), performed between the fourth premolar and first molar teeth, could be suitable procedures for treating patients with unilateral TMJA. CSM and MSM could be considered alternative surgical options for patients affected by unilateral TMJA as they are less time-consuming, less challenging from an anatomical standpoint and safer.…”

“…As segmental mandibulectomies avoid the complex anatomy of the base of the skull and the temporomandibular region, we hypothesized that these techniques could decrease the risk of intraoperative iatrogenic trauma and postoperative complications associated with surgical procedures involving the TMJ and the base of the skull. 21 Thus, the purpose of this retrospective study was to evaluate the CSM and MSM applicability for the treatment of unilateral TMJA in three cats and one cat with bilateral TMJA that underwent gap arthroplasty on one of the TMJs and CSM on the contralateral mandible.…”