Clinical trial NCT02634840: Assessment of Nerve Function After Mandible Surgery With a Modified Bilateral Sagittal Split Osteotomy Technique
Official title: A Modified Technique of Mandibular Ramus Sagittal Split Osteotomy for Prevention of Inferior Alveolar Nerve Injury: A Prospective Cohort Study and Outcome Assessment
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Neurosensory Function of Inferior Alveolar Nerve
Keywords: inferior alveolar nerve
neurosensory disturbance
bilateral sagittal spilt osteotomy
mandibular surgery
neurosensory function
Lead sponsor: Chang Gung Memorial Hospital
Sponsor class: OTHER
First posted: 2015-12-18
Enrollment: 57
Sex: ALL
Minimum age (years): 15
Standard ages: CHILD
ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Allocation: NA
Intervention model: SINGLE_GROUP
Primary purpose: TREATMENT

Brief summary: Several technical modifications based on the anatomical position of the neurovascular bundle and its bony mandibular canal have been developed, aiming to prevent injury to the intraalveolar nerve We hypothesized that the incidence of neurosensory disturbance (NSD) should be reduced using our bilateral sagittal split osteotomy (BSSO) technique, because direct intra-alveolar nerve injury can be avoided. The aim of this study was to introduce our modified BSSO technique and evaluate the subsequent incidence of postoperative neurosensory disturbance of the IAN.

Detailed description: The study was designed as a prospective cohort study. Consecutive patients scheduled for orthognathic surgery (OGS) conducted by the senior author at the Craniofacial Center, Department of Plastic and Reconstructive Surgery, Chang Gung Memorial Hospital between January and August 2013 were asked to participate. OGS procedures included mandibular BSSO with or without maxillary LeFort I osteotomy or genioplasty. Fifty-seven patients were enrolled. All patients received cone-beam computed tomography before surgery for intra-alveolar nerve (IAN) assessment and virtual surgery planning.

During surgery, corticotomy and osteotomy lines are modified from the Obwegeser-Dal Pont method. After corticotomy completion, a Dautrey osteotome is driven into the mandible medulla via the anterior corticotomy, keeping constant contact to the inner side of the buccal ramus cortex for the first 10mm. The osteotome, located anterior and lateral to the IAN, is then twisted with moderate force, gradually separating the proximal and distal segment cortices along the anterior opening to facilitate visualization. Possible resistance to open the cortices indicates incomplete corticotomies located in the medial cortex, or the posterior and inferior aspects of both corticotomy lines. Before the complete split, the IAN is evaluated for any exposure through the anterior opening . If the IAN is exposed or attached to the outer cortex, it can gently be replaced into the distal segment. Under visualization through the anterior opening, a straight 4 or 6 mm osteotome is then inserted lateral to and passed beyond the IAN, and then hit to split the posterior ramus cortex along the inner surface of the proximal segment to reach the posterior border.

A standardized record form was provided to all subjects before and after surgery. Gender, preoperative diagnosis and operative details were collected, including surgical plan, mandibular movement extent and concomitant surgical procedures i.e. LeFort I and genioplasty, problematic mandibular splitting and type of fixation. All BSSO procedures were divided into independent left and right sides. After successful splitting of the mandibular ramus, splitting results were categorized.

A 5-point scale self-assessment questionnaire was used during the routine follow up visits to evaluate IAN neurosensory disturbance (NSD) after the BSSO procedure. The subjective neurosensory status evaluation was performed preoperatively, one week, 6 and 12 months postoperatively or until normal sensation returned.

Eligibility criteria: Inclusion Criteria:

* patients receiving mandibular bilateral sagittal split osteotomy during orthognathic surgery with normal preoperative intraalveolar nerve function
* patients with cleft lip/palate or hemifacial microsomia were also included

Exclusion Criteria:

* craniofacial syndromic condition, abnormal psychomotor development or previous history of mandibular fracture

Primary outcomes:
measure: Incidence of NSD 12 months postoperatively in relation to IAN exposure during surgery
timeFrame: preoperative to at least 12 months after surgery or return of normal sensation; if no return of normal sensation, reevaluation after another 3 months with computer tomography and clinical exam
Secondary outcomes:
measure: Longitudinal incidence of NSD in relation to gender, age, affected side, preexisting deformity, third molar extraction and genioplasty
timeFrame: preoperative to at least 12 months after surgery or return of normal sensation; if no return of normal sensation, reevaluation after another 3 months with computer tomography and clinical exam
measure: Longitudinal incidence of NSD in relation to split type during surgery
timeFrame: preoperative to at least 12 months after surgery or return of normal sensation; if no return of normal sensation, reevaluation after another 3 months with computer tomography and clinical exam
measure: Longitudinal incidence of NSD in relation to IAN exposure
timeFrame: preoperative to at least 12 months after surgery or return of normal sensation; if no return of normal sensation, reevaluation after another 3 months with computer tomography and clinical exam
Other outcomes:
Locations:
Study officials:
affiliation: Chairman, Department of Surgery, Chang Gung Memorial Hospital
name: Lun-Jou Lo, MD
role: STUDY_DIRECTOR
References:
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citation: Westermark A, Bystedt H, von Konow L. Inferior alveolar nerve function after sagittal split osteotomy of the mandible: correlation with degree of intraoperative nerve encounter and other variables in 496 operations. Br J Oral Maxillofac Surg. 1998 Dec;36(6):429-33. doi: 10.1016/s0266-4356(98)90458-2.
citation: Ylikontiola L, Kinnunen J, Oikarinen K. Factors affecting neurosensory disturbance after mandibular bilateral sagittal split osteotomy. J Oral Maxillofac Surg. 2000 Nov;58(11):1234-9; discussion 1239-40. doi: 10.1053/joms.2000.16621.
citation: Kane AA, Lo LJ, Chen YR, Hsu KH, Noordhoff MS. The course of the inferior alveolar nerve in the normal human mandibular ramus and in patients presenting for cosmetic reduction of the mandibular angles. Plast Reconstr Surg. 2000 Oct;106(5):1162-74; discussion 1175-6. doi: 10.1097/00006534-200010000-00029.
citation: Hanzelka T, Foltan R, Pavlikova G, Horka E, Sedy J. The role of intraoperative positioning of the inferior alveolar nerve on postoperative paresthesia after bilateral sagittal split osteotomy of the mandible: prospective clinical study. Int J Oral Maxillofac Surg. 2011 Sep;40(9):901-6. doi: 10.1016/j.ijom.2011.04.002. Epub 2011 May 13.
citation: Colella G, Cannavale R, Vicidomini A, Lanza A. Neurosensory disturbance of the inferior alveolar nerve after bilateral sagittal split osteotomy: a systematic review. J Oral Maxillofac Surg. 2007 Sep;65(9):1707-15. doi: 10.1016/j.joms.2007.05.009.
citation: Agbaje JO, Salem AS, Lambrichts I, Jacobs R, Politis C. Systematic review of the incidence of inferior alveolar nerve injury in bilateral sagittal split osteotomy and the assessment of neurosensory disturbances. Int J Oral Maxillofac Surg. 2015 Apr;44(4):447-51. doi: 10.1016/j.ijom.2014.11.010. Epub 2014 Dec 9.