Is the Low and Short Medial Horizontal Osteotomy a Predictive Factor for Postoperative Hypoesthesia in Sagittal Split Osteotomies?

Abstract

Statement of the problemThe purpose of this study is to determine whether a low and short medial horizontal osteotomy is a predictive factor for determining neurosensory outcomes of the inferior alveolar nerve in non-syndromic patients undergoing sagittal split osteotomies for dentofacial disorders. Materials and methodsA retrospective cohort analysis was conducted on subjects who received orthognathic surgery from 2017 to 2019 at Parkland Memorial Hospital. Inclusion criteria were a traditional osteotomy defined by Hunsck and Epker, or a low and short osteotomy, defined by Posnick.1,2 Exclusion criteria were the diagnosis of a syndromic condition, repeat surgery, or concomitant temporomandibular joint surgery. The predictor variable was the type of osteotomy performed, defined as either a low and short or traditional osteotomy. The primary outcome variable was neurosensory testing at the pre-operative visit and at the 6-week postoperative visit utilizing the NST criteria elucidated by Zuniga et al.3 Neurosensory outcomes were scored in the following manner: passing NST-A, NST-B, and NST-C were assigned scores of 1, 2, and 3, respectively. Failing NST-C was assigned a score of 4. These outcomes were used to measure the incidence of full sensory recovery (FSR), which was defined as postoperative NST testing that returned to the patient's pre-operative baseline (NST-A). Descriptive, bivariate, and multiple logistic regression analyses were performed with P < .05 used to determine statistical significance. ResultsTwenty-nine patients met the defined inclusion criteria. The average age at the time of surgery was 23 years old. The cohort consisted of 13 males and 16 females. Nineteen patients were treated with bilateral low and short osteotomies, and 10 patients were treated with bilateral traditional osteotomies. The mean NST outcome for all pre-operative visits in both cohorts passed was 1 bilaterally. The mean NST outcome for the low and short osteotomy cohort at 6-week postoperative visit was 1.26 and 1.42 on the right and left, respectively. The mean NST outcome for the traditional osteotomy cohort was 1.2 and 1.4 on the right and left, respectively. There were no significant differences between the type of osteotomy performed and the mean pre-operative neurosensory outcome on the left (P = 1) or right (P = 1). Furthermore, there was no significant difference between the type of osteotomy performed and the mean 6-week postoperative neurosensory outcome on the left (P = .7176) or right (P = .9265). FSR was achieved in low and short osteotomy cohort in 73.68% of patients on the right and 57.89% of patients on the left. Failure to achieve FSR at the 6-week follow-up was observed in both the right (P = .0207) and left (P =.0020) sides for the low and short cohort, which was statistically significant. FSR was achieved in the traditional osteotomy cohort in 80% of patients on the right and 70% of patients on the left. Failure to achieve FSR in the traditional osteotomy group was not significant on the right (P = .1679) or left (P = .1039) side. ConclusionThe occurrence of hypoesthesia after traditional bilateral sagittal split osteotomy has been reported to range from 7.3-52%.4 To the author's knowledge, no study to date has examined the incidence of hypoesthesia after the low and short osteotomy. The results of the present study suggest the low and short osteotomy is associated with a greater duration of postoperative hypesthesia compared to the traditional osteotomy at the 6-week mark.