The anatomical basis for mandibulotomy: midline versus paramidline

Current Concepts of Ablative Surgery in Oral Cavity Cancer

Introduction

Ablative surgery has evolved over the years with the attempt to extirpate the tumor in its entirety with the understanding of the molecular tumor biology, pattern of tumor invasion of the tumors, as well as availability of better instrumentations.

Materials and Methods

Subset-based evaluation and management of oral cancer.

conclusion

For oral cancer, surgery is still the primary therapeutic option. To establish surgical adequacy, a wide excision with sufficient margins in all three dimensions must be carried out.

Stair-stepped mandibulotomy: Clinical indication, surgery program design, and operation points

For radical treatment of malignancies in the posterior region of the oral cavity and oropharynx, surgical exposure of the tumor by mandibulotomy is often required. Midline or paramedian vertical mandibulotomies are commonly performed in clinical practice, but these can damage the suprahyoid musculature and genioglossus, and weaken the swallowing and speech function of patients. Stair-stepped mandibulotomy is a new procedure, developed on the principles of functional surgery, that preserves the structure and function of the mandible whilst providing a clear field and avoiding damage to critical muscle attachments. Stair-stepped mandibulotomy is suitable for patients whose primary tumor is located in the middle and posterior part of the tongue or oropharynx, especially if the lesion involves extrinsic tongue muscles. In this case report, we draw on 2 cases of typical patients in our center to elaborate the surgery program design, operation points, advantages and disadvantages of stair-stepped mandibulotomy.

Midline versus paramedian mandibulotomy for tongue cancer surgery: analysis of complications

Midline and paramedian mandibulotomies both have distinct anatomical and surgical strengths. A retrospective study was performed at Chang Gung Memorial Hospital, Linkou Branch between 2014 and 2019 to investigate how the osteotomy site (midline (n = 221) or paramedian (n = 44)) and type (straight, notched, or stair-stepped) affect postoperative and post-radiotherapy complications in patients undergoing wide excision of tongue cancer with flap reconstruction. Midline mandibulotomies were predominantly of the straight osteotomy type, while paramedian mandibulotomies were mostly notched type (P < 0.001). Comparably low elective tooth extraction rates were found in both approaches (P = 0.556). Paramedian mandibulotomy showed a higher osteoradionecrosis rate (P = 0.026), but there was no significance in the sub-analysis of individual types. Paramedian sites were associated with more early infection (P = 0.036) and plate exposure (P = 0.036) than midline sites with the straight osteotomy type, but complication rates did not differ significantly for the notched and stair-stepped types. Paramedian sites (P = 0.020) and notched types (P = 0.006) were associated with higher odds of osteoradionecrosis in the univariable logistic regression analysis, but only the notched type remained significant in the multivariable analysis (P = 0.048). In conclusion, paramedian sites increased the rate of osteoradionecrosis, and correlation with the osteotomy type resulted in more osteoradionecrosis in notched types and more complications in straight paramedian mandibulotomies.

Complication analysis of three different designs of temporary mandibulotomy in tongue cancer treatment

BACKGROUND

Mandibulotomy helps access posterior oral cavity tumors. If osteotomy designs affect postoperative and postradiotherapy complications, needs to be tested clinically.

METHODS

Two hundred and eighteen patients who underwent midline mandibulotomy for primary tongue cancer wide excision and flap reconstruction at Chang Gung Memorial Hospital during 2014-2019.

RESULTS

There were 114 straight, 54 notched, and 50 stair-stepped osteotomy cases. Stair-stepped osteotomy had less advanced tumor stages (P = .009) and notched osteotomy more common single-plate fixations (P = .012). The former showed higher mandibular heights (P = .000) and more intact midline teeth (P = .011) than notched and straight ones. Straight osteotomy cases showed lower early infection rates (P = .039). Single-plate fixation was related to more flap dehiscence (P = .001) and oro-cutaneous fistulas (P = .035).

CONCLUSIONS

Complex osteotomy does not offer long-term benefits in midline mandibulotomies for primary tongue cancers and has higher early infections. Single-plate fixation increases postoperative complications.

[Influence of mandibulotomy approaches on oral function following radical resection of tongue carcinoma]

OBJECTIVE

This study aimed to compare the influences of postoperative oral function in patients with median or paramedian mandibulotomy during the radical resection of tongue carcinoma and to provide evidence for the choice of osteotomy location for mandibulotomy.

METHODS

The clinical data of 126 patients who underwent combined radical neck dissection with mandibulectomy and glossectomy followed by simultaneous reconstruction were analyzed retrospectively. The patients were divided into two groups according to the position of mandibulotomy: median mandibulotomy group (median group, n=60) and paramedian mandibulotomy group (paramedian group, n=66). The fourth edition of the University of Washington Quality of Life Questionnaire (UW-QOL) was used to compare the differences in oral functions, such as swallowing, mastication, and speech, between the two groups during regular follow-up. SPSS 24.0 software package was used for statistical analysis, and P<0.05 was considered statistically significant.

RESULTS

Six months after the operation, no significant differences in swallowing, mastication, and speech functions were found between the median and paramedian groups. However, the swallowing and speech functions in the paramedian group were better than those in the median group 1 year after the operation (P<0.05), whereas no statistical difference in mastication function was observed between the two groups.

CONCLUSIONS

Evaluation of the postoperative oral function results showed that paramedian mandibulotomy was a better surgical approach than median mandibulotomy. Paramedian mandibulotomy is worth prioritizing in the radical resection of tongue carcinoma.

Analysis of an in-house technique for temporary mandibulotomy and its impact on postoperative radiotherapy

The purpose of this study was to describe a newly developed procedure for temporary mandibulotomy and subsequent osteosynthesis. Clinical outcomes were evaluated, including complications and the impact on postoperative treatment, particularly postoperative radiotherapy. Twenty-four patients underwent temporary mandibulotomies for the surgical resection of malignancies located in the posterior oral or oropharyngeal region. All were treated with postoperative radiotherapy. An angulated median mandibulotomy was followed by osteosynthesis with three anchor screws directed towards the inferior aspect of the mandible. Anchor screws are modified conventional lag screws that include an additional biconcave washer. This modification prevents the screw heads from cracking into the cancellous bone during tightening, improving their biomechanical qualities considerably. Insertion of screws at any angle to the bony surface therefore becomes possible, which is a precondition for this technique. Minor complications occurred in two patients in the early postoperative period. However, complications causing bony non-union, leading to postponed postoperative radiotherapy were not noted in this cohort.

Medial mandibulotomies: is there sufficient space in the midline to allow a mandibulotomy without compromising the dentition?

Objectives

The objective of this study was to determine the frequency of complications in median and paramedian mandibulotomies. In addition, the interdental space in the median and paramedian region was calculated.

Study design

Retrospective study.

Setting

Tertiary care center.

Methods

A retrospective chart review was performed for all cases where a mandibulotomy was performed from 2002 to 2010. 117 charts (61 paramedian and 56 median) were identified. We included data on complications, which fell in the following 2 categories: plate and dental complications. For our second objective, we evaluated 40 different patients with base of tongue or tonsillar cancer treated with intensity modulated radiation therapy (IMRT). The interdental space between the lateral incisors and the canines was electronically calculated on the digital Panorex images.

Main outcome measures

Dental and plate complications were evaluated. We also assessed interdental space.

Results

Patient characteristics were not significantly different. The median group had significantly more dental complications (p=0.0375, RD=0.19 and 95% CI (0.0139-0.3661)). The paramedian group had significantly more plate complications (p=0.0375, RD=0.082 and 95% CI (0.0131-0.1508). The distance between the central incisors was significantly less than the distance between the lateral incisors and canines both at the crestal and apical levels (p=0.0086 and p<0.001).

Conclusions

There are significantly more dental complications in the median approach. There were significantly more plate complications in the paramedian group. In addition, there is significantly less space in the between the median region as compared to the paramedian region. This is the first study that documents the advantage of the paramedian approach for dental complications.

New modification of the mandibulotomy approach without lip splitting

BACKGROUND

A lower lip-splitting incision has traditionally been performed with different types of mandibulotomy approaches for obtaining wide access to oral and oropharyngeal cancers. However, lip splitting can be associated with unfavorable aesthetic results. We describe our new modification of a traditional mandibulotomy approach without lip splitting to avoid these morbidities. This is a case series in a tertiary referral center.

METHODS

The primary tumor site was the oropharynx in four cases, the oral cavity in two cases, and the parapharynx in one case. Each case was assessed for TNM staging, perioperative complications, status of the resection margins, tumor recurrence, and the aesthetic and functional results of the lower lip.

RESULTS

All the tumors were safely removed by means of our modified non-lip-splitting mandibulotomy approach through the combined intraoral and transcervical routes with adequate resection margins. There were no troublesome difficulties in reconstruction of the surgical defects with various major flaps. The cosmetic results were excellent with intact lip function.

CONCLUSION

We believe this new modified non-lip-splitting mandibulotomy approach could replace the conventional mandibulotomy approach for some selected malignant lesions, with excellent cosmetic and functional results of the lower lip.

Midline versus paramidline mandibulotomy: A radiological study

Mandibulotomy allows for wide exposure of deep oral cavity and oropharyngeal tumors and may be performed medial or lateral to the mental foramen. Medial mandibulotomy is divided into midline and paramidline. Midline mandibulotomy requires detachment of muscles which may lead to masticatory and swallowing problems and could potentially jeopardize the central incisors. Our study provides a basis for placement of bone cuts in mandibulotomy. The angles between the long axis of the two central incisors, the lateral incisor and canine bilaterally were measured in panoramic radiographs of 100 healthy patients. The distances between the roots were measured. The angle between the lateral incisor and the canine ranged from 1 degrees to 8 degrees compared to 1 degrees -4 degrees (P<0.001) between the central incisors. The distances between the lateral incisor and the canine were 1-6.2mm while the distances between the two central incisors ranged from 0.5 to 4.7mm (P<0.05). Although the measurements were taken from a younger group of patients compared to the usual age of presentation of oropharyngeal cancer, it shows that the paramidline mandibulotomy in which bony cuts are performed through a wider gap is the preferred approach.