Evaluation of Lingual Fracture Pattern Following Sagittal Split With the Low and Short Medial Osteotomy.

Background: The lingual split scale (LSS) following sagittal ramus osteotomy (SRO) is an objective scale where LSS1 to 3 are variations of a favorable split, while LSS4 is an unfavorable split. LSS influences postoperative bone overlap, posterior interferences, and fixation methods. There is currently no study evaluating LSS following SRO using the low and short medial osteotomy modification.

Purpose: The purpose of this study is to describe the lingual fracture pattern of the distal segment through the LSS following SRO using the low and short medial osteotomy modification.

Study Design, Setting, And Sample: A retrospective cohort study of subjects undergoing SRO with the low and short medial osteotomy by a single surgeon at The University of Alabama at Birmingham between February 2020 and July 2024. Subjects with incomplete records were excluded.

Predictor Variables: Anatomic predictor variables were ramus width and length and the vertical height of the lingula. Procedural predictor variables were height and angle of the medial osteotomy, medial osteotomy relative to the lingula and to the mandibular canal, and third molar removal at the time of SRO.

Main Outcome Variable: The primary outcome variable was the LSS. LSS1 to 3 are variations of a favorable SRO split, while LSS4 is unfavorable.

Covariates: Covariates include age, sex, and previous mandibular osteotomies.

Analyses: The significance level was defined as P < .05. Multivariate regression analyses assessed variables that were near statistically significant (P < .2). Hemimandibles were correlated and the subject factor was accounted for using generalized estimating equations.

Results: The study sample had 210 subjects (419 hemimandibles). LSS variations of favorable splits resulted in 263 (62.8%) vertical fractures (LSS1), 8 (1.9%) horizontal fractures (LSS2), and 139 (33.2%) fractures along the mandibular canal (LSS3). Nine (2.2%) unfavorable splits (LSS4) were present. No variables were found to be significantly associated with unfavorable fractures (LSS4).

Conclusions And Relevance: SRO using the low and short medial osteotomy resulted in predictable LSS patterns. Favorable fracture patterns (LSS1 to 3) were present in 97.8% (410) of SROs, while unfavorable fracture patterns (LSS4) were present in 2.2% (9). No variables were identified to be significantly associated with unfavorable fracture (LSS4).