# Unfavorable fractures during Sagittal Split Osteotomy. What are the Risk Factors? A Retrospective Tomographic Study

## TL;DR

This study identifies risk factors for unfavorable fractures during jaw surgery, finding that surgical technique is more important than anatomy.

## Contribution

The study provides new insights into the technical and anatomical risk factors for 'Bad Split' fractures during mandibular osteotomy.

## Key findings

- Technical execution of osteotomy is a more significant risk factor for BS than anatomical variables.
- Incomplete osteotomy at the basal level was the most frequent technical issue in BS cases.
- Class A BS was the most common type, associated with anterior lingula position and lower alveolar crest.

## Abstract

This study aims to analyze the epidemiology of “Bad Split” (BS) during Sagittal Osteotomy of the Mandible, identifying anatomical and technical risk factors associated with its occurrence.

A retrospective analysis was conducted on 157 patients (314 osteotomies) over five years. Multi-slice helical CT scans, both pre- and post-operative, were examined to classify BS and identify potential risk factors. Anatomical variables included the presence of third molars, edentulism, prior fixation systems, mandibular ramus dimensions, lingula position, and alveolar crest height. Technical aspects of osteotomy execution were also assessed. Measurements were performed using Dolphin Imaging Software 11.95 after orienting the skull in the Natural Head Position.

The incidence of BS was 3.2% (10 patients), with a slight left-side predominance (60%). Class A BS (distal fracture of the proximal segment) was the most common (60%). Anatomically, 83.3% of Class A cases had a more anteriorly positioned lingula and 66% presented a lower alveolar crest. Technically, 80% of BS cases showed deviations in osteotomy execution, with incomplete osteotomy at the basal level being the most frequent (60%).

This study suggests that technical factors, particularly osteotomy execution, play a more decisive role in BS occurrence than anatomical variables. Surgical precision is crucial, emphasizing careful osteotomy techniques to minimize the risk of BS, especially in anatomically predisposed mandibles.

Key words:Bad split, Intraoperative complications, Bilateral sagittal split osteotomy, Orthognathic surgery.