Abstract
The aim of this study was to assess the management of the condyle during the restoration of mandibular defects following tumour resection. A total of 41 patients who underwent simultaneous tumour resection and reconstruction with vascularized iliac myocutaneous flaps for mandibular defects, from September 2010 to October 2014, were included. These patients were divided into three groups: group 1, condyle preserved; group 2, condyle sacrificed; group 3, condyle frozen. Patients were followed up at 1, 3, 6, and 12 months for the evaluation of appearance, occlusion, and speech. The TMJ disability index (DI) and craniomandibular index (CMI) differed significantly according to the method of management, as well as the position and morphology of the reconstructed condyle ( P < 0.01); however, no statistically significant difference in mandible movement was observed between the groups. The DI and CMI values were significantly lower in group 1 patients compared to group 2 and group 3 patients. The results showed that TMJ function in group 1 patients was superior to that in group 2 and group 3 patients, and that function in group 3 patients was better than that in group 2 patients. In conclusion, the condyle should be preserved when benign mandibular lesions are situated near the condyle, as preservation has a positive effect on TMJ function and mandible movement.
The mandible is a distinct bony structure of the face that articulates with the cranial base via the condyles at the right and left temporomandibular joints (TMJs). The TMJs are classified as ginglymoarthrodial joints. The condyle rotates with the aid of the masticatory muscles and translates downward and forward within the confines of the TMJ capsule. The mandible is involved in mastication and phonation and maintains the lower facial profile.
Segmental mandibular resection is currently the most important technique in the management of oral cancer. Reconstruction of the mandible following resection is difficult and complex, and is essential for good functional and aesthetic outcomes, especially in the case of a large resection that includes the condyle . Only a few publications have reported the results of reconstruction for specific complicated mandible defects, such as the loss of the anterior mandible and lateral defects. Some studies have compared different flap options , but the sites of reconstruction have varied, and there is little consensus regarding the best flap for a particular defect.
Vascularized bone flap transplantation has been applied in the clinical setting for the restoration of mandible defects , and has become one of the main methods of mandible reconstruction. However, the management of the condyle in the case of defects of the posterior mandible remains problematic.
The present study focused on the use of vascularized bone flaps for mandible reconstruction and three different methods for managing the condyle. The postoperative facial appearance of the patients, position and morphology of the condyle (assessed using three-dimensional computed tomography (3D-CT) and X-ray images), and TMJ function were also assessed to provide reference data for the management of the condyle during the restoration of mandibular defects.
Materials and methods
Patients
Forty-one patients who underwent simultaneous tumour resection and reconstruction of the mandible with vascularized iliac myocutaneous flaps at the Department of Oral and Maxillofacial Surgery–Head and Neck Oncology, Hospital of Stomatology, from September 2010 to October 2014, were enrolled. Twenty-two of the patients were male and 19 were female. The age distribution of the patients was as follows: <20 years, n = 7; 20–30 years, n = 14; >30 years, n = 20 cases; the median age of the patients was 29 years.
The lesions were benign tumours of the mandible involving the posterior mandible and ramus that did not extend beyond the mandibular midline. With regard to the classification of the mandibular defects, 16 cases were mandibular ramus + body defects and 25 cases were condyle + mandibular ramus + body defects. All bone defects were <12 cm in length and none crossed the mandibular midline.
Institutional review board approval was obtained for this retrospective study. The assessments of appearance, speech, and the occlusal relationship were conducted by an independent investigator.
Surgical procedure
The patients included in this study had no mental disorders. They were conscious and cooperative during examinations, and were generally in a fair physical condition. CT scans were obtained for all patients for assessment.
All surgical procedures were performed using a two-team approach: one team for extirpative surgery and one for reconstructive surgery. After completion of the tumour resection, the surgeons constructed individually designed vascularized iliac myocutaneous flaps for mandible reconstruction. The iliac flap was shaped and modified as needed to fit the dimensions of the defect at the recipient site. Preoperative bite plates were made for the patients to ensure that the condyle was basically located in the middle of the glenoid fossa after reconstruction. The prepared iliac flap was removed from its primary location and transplanted into the recipient site. In this study, the articular disc was retained in all 41 resections of the mandible; however, preservation of the condyle depended on the circumstances of each individual case.
Condylar management and reconstruction
Three different methods were used to manage the condyle and perform the reconstruction in the 41 patients. The condyle was preserved in 12 cases (group 1). In these patients, the resection was performed along the mandibular sigmoid notch, or slightly below, using bone saws or drilling. The condyle was maintained in its original position and fixed to the end of the iliac flap to repair the mandible defect ( Fig. 1 ). In 24 cases, the condyle was sacrificed (group 2). In these cases, the condyle was excised along with the mandible. For the mandible reconstruction, the iliac flap was placed directly below the articular disc instead of the condyle, after slightly blunting the ends of the flap. In five cases, the condyle was frozen (group 3). The condyle was removed simultaneously with the mandible lesion, and the unaffected condyle, which could not be distinguished from the mandibular ramus, was separated from the ramus in vitro ( Fig. 2 ). The free condyle was placed in liquid nitrogen and frozen for 30 s, retained at room temperature for 5 min, and then frozen again; this procedure was conducted in three cycles. After the freezing treatment, the condyle was replanted at the end of the iliac flap to repair the mandible defect.
Postoperative follow-up
Postoperatively, flap monitoring was performed by clinical examination every 30 min for the first 24 h, every 1 h for the second 24 h, and every 4 h in the following days. When necessary, low-dose low-molecular-weight heparin was used as postoperative anticoagulation therapy. The patients were usually discharged between postoperative days 7 and 10 and scheduled for follow-up at 1, 3, 6, and 12 months for the evaluation of appearance, occlusion, and speech. The function of the reconstructed TMJ was assessed according to the TMJ function evaluation index . Furthermore, the position and morphology of the reconstructed condyles were reviewed using 3D-CT and X-ray examinations ( Figs. 3 and 4 ).
