Journal of Cranio-Maxillo-Facial Surgery xxx (2014) 1e4

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Inferior alveolar and mental nerve injuries associated with open reduction and internal fixation of mandibular fractures: A Seven Year retrospective study Qinyong Song a, Shanhui Li a, Pavan Manohar Patil b, * a

Department of Orthopaedics, Yantai Affiliated Hospital of Binzhou Medical University, Shandong Province 264100, China Department of Oral and Maxillofacial Surgery, School of Dental Sciences, Sharda University, Plot 32, 34, Knowledge Park 3, Greater Noida, 201308 Uttar Pradesh, India b

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Article history: Paper received 13 November 2013 Accepted 25 March 2014

Purpose: To document adverse neurosensory changes in the inferior alveolar nerve (IAN) and mental nerve (MN) after surgical mandibular fracture treatment and to identify risk factors associated with these changes. Materials and methods: A retrospective study of patients surgically treated for mandibular fractures. The primary study variable was the postoperative change in IAN/MN neurosensory examination after fracture fixation. Risk factors were categorized as demographic, anatomic, experience of the operator, fracture displacement and number of miniplates placed at each fracture site. Appropriate statistics were computed. Results: 209 patients with 293 fractures were analysed. One hundred twenty fractures (41%) were located between the lingula and mental foramen, and 173 fractures (59%) were located distal to the mental foramen. Two hundred seventeen (41%) were displaced by 5 mm or more. In 38 fractures (13%), the IAN/MN neurosensory status worsened after treatment. In a multivariate model, fracture displacement, operator inexperience and two plate fixation were associated with a statistically significant risk (P  0.05) for postoperative deterioration of IAN/MN sensation. Conclusion: Fixation with two miniplates, fracture displacement of 5 mm or more and operator inexperience were associated with an increased risk for deterioration of the IAN/MN neurosensory status after treatment of mandibular fractures. Ó 2014 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Keywords: Nerve injury Complication Mandible fracture Open reduction Miniplate fixation

1. Introduction Mandibular fractures are one of the most common fractures of facial skeleton because of its prominent position in maxillofacial region (Erdmann et al., 2008; Zhi and Zu-Bing, 2011; Zhou et al., 2013). Non-compressive miniplate fixation of mandibular fractures has gained popularity as a standard treatment around the world due to its low morbidity and complications (Stacey et al., 2006). However, surgical treatment of mandibular fractures can lead to neurosensory changes postoperatively. These changes may result from manipulation of the fracture fragments, tissue dissection and * Corresponding author. Tel.: þ91 9999970260. E-mail addresses: fforoffi[email protected] (Q. Song), lforoffi[email protected] (S. Li), [email protected], [email protected] (P.M. Patil).

retraction or the application of hardware (Seemann et al., 2010; Yamamoto et al., 2013). The prevalence of inferior alveolar nerve (IAN) injury after fracture treatment ranges from 0.4% to 91.3% (Akal et al., 2000). Estimates of permanent IAN neurosensory deficits after mandibular fracture range from 0.9% to 66.7% (Thurmuller et al., 2001) Patients complain of sensory disturbances such as pain, paraesthesia, dysaesthesia, hypoesthesia or anaesthesia involving the chin, lower lip and gums. These are unpleasant conditions which often cause litigation. The long-term goals of this retrospective study were to document the incidence of IAN/MN injuries, to identify risk factors associated with injury and optimize therapeutic approaches to restore neurosensory function. The results of this study may indicate the factors that can be predictive of IAN/MN injury and appropriate steps be initialized to prevent them. In cases where the

http://dx.doi.org/10.1016/j.jcms.2014.03.029 1010-5182/Ó 2014 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Please cite this article in press as: Song Q, et al., Inferior alveolar and mental nerve injuries associated with open reduction and internal fixation of mandibular fractures: A Seven Year retrospective study, Journal of Cranio-Maxillo-Facial Surgery (2014), http://dx.doi.org/10.1016/ j.jcms.2014.03.029

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Q. Song et al. / Journal of Cranio-Maxillo-Facial Surgery xxx (2014) 1e4

injury has occurred, some of these factors may be manipulated by the clinician to enhance recovery of IAN or MN function. 2. Material and methods We designed a retrospective study using a sample derived from the series of patients with mandibular fractures evaluated and treated by the Department Oral and Maxillofacial Surgery at School of Dental Sciences, Sharda University between June 2006 and May 2013. The Institutional Review Board approved the study. Inclusion criteria for study enrolment were 1) the presence of a mandibular fracture located between the lingula and symphysis, 2) the availability of preoperative and postoperative panoramic radiographs, 3) a level of mental status permitting an adequate neurosensory examination, 4) no post injury/pre-treatment neurosensory changes in the region of sensory supply from the IAN or mental nerve (MN) and 5) patients who have had a follow up of minimum of 3 years. Patients were excluded if they had a fracture proximal to the lingula, lacked the requisite imaging, presented with neurosensory changes prior to treatment, were incapable of completing an adequate neurosensory examination. Reasons for the latter included intoxication, severe head injury, or inability to communicate (sedated or intubated patients). Patients who were lost to follow up were also excluded. The predictor variables were grouped into the following sets: demographic (age and gender), anatomic (fracture location and displacement), post injury/pre-treatment neurosensory status (normal or abnormal), experience of the operator and number of miniplates applied for fixation of fractures. Fracture location was divided into 2 categories: fracture located between the lingula and mental foramen (location 1, these fractures place the IAN at direct risk for injury) and fractures distal to the mental foramen (location 2, these fractures place the mental nerve at both direct and indirect injury via drill bit injury and soft tissue trauma respectively). Reduction and fixation of the fractures at either location may result in IAN or MN injury. Fracture displacement was categorized as 5 mm or less and greater than 5 mm. One examiner reviewed the panoramic radiographs to determine degree of fracture displacement. Based on the neurosensory examination, post injury/pre-treatment IAN/MN neurosensory status was classified as being normal or abnormal. Those with abnormal IAN and MN examinations were considered to have primary IAN/MN injuries and were excluded from the study. Fracture treatment included open reduction and internal fixation (ORIF) using 4-hole titanium miniplates and screws of 2  8 mm dimension. Treatment was performed by a group of surgeons which included consultants (>3 years of experience) and residents (

Inferior alveolar and mental nerve injuries associated with open reduction and internal fixation of mandibular fractures: a Seven Year retrospective study.

To document adverse neurosensory changes in the inferior alveolar nerve (IAN) and mental nerve (MN) after surgical mandibular fracture treatment and t...
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