Comparison of Early Post-Operative Hypoesthesia After a Low and Short or Traditional Sagittal Split Osteotomy

Purpose The purpose of this study was to determine if there is a difference in postoperative neurosensory testing (NST) score at 6-weeks between subjects that received a mandibular sagittal split osteotomy (SSO) using a low and short osteotomy (LSO) or traditional osteotomy (TRO). The null hypothesis was that no significant difference exists in post-operative NST score between subjects that received SSO with a TRO or LSO. Methods A retrospective chart review was conducted of subjects that received orthognathic surgery by the oral and maxillofacial surgery department at the University of Texas Southwestern Medical Center (UTSW) from 2017 to 2019. All subjects that received SSO by either TRO as defined by Hunsuck and Epker(1,2) or LSO defined by Posnick(3) were included. Subjects with syndromic conditions, prior injury to the inferior alveolar nerve, history of peripheral neuropathy or pain conditions, and those undergoing simultaneous genioplasty, repeat surgery or concomitant temporomandibular joint surgery were excluded. Neurosensory outcomes of the inferior alveolar nerve (IAN) were measured using clinical NST at the pre-operative and 6-week post-operative visit over a 1-centimeter area of the labiomental fold. Chi-squared analysis and t-tests were performed between the cohorts and their respective outcomes. Values of p < 0.05 were considered statistically significant. The primary predictor variable was osteotomy type, and the primary outcome variable was NST score at the 6 weeks post-operative visit. Secondary outcome variable was IAN location within the proximal or distal segment. Results A total of 26 subjects met the defined inclusion criteria for a total of 52 osteotomies. There were 32 osteotomies in the LSO group, and 20 in the TRO group. The average age of the LSO group was 23.1 years (SD=10), and the average age of the TRO group was 22.4 years (SD=6). There was no significant difference in age between the two groups (p=0.84). All subjects were NST level A pass bilaterally at the pre-operative visit. No nerve injury was witnessed at the time of surgery among either group. All IANs contained within the proximal segments were left in place. There was no statistically significant difference in NST score between the two groups at the 6-week post-operative visit (p = 0.40). Of the total 52 osteotomies, there was no significant difference between NST score at the 6 weeks post-operative visit in subjects with IAN located in the proximal segment or the distal segment regardless of technique used (p = 0.52). Conclusion There is no difference in post-operative NST score at 6-weeks between subjects that received a traditional osteotomy or low and short sagittal split osteotomy. Regardless of technique, there is no difference in post-operative NST score at 6 weeks if the IAN is in the proximal or distal segment after completion of sagittal split. The purpose of this study was to determine if there is a difference in postoperative neurosensory testing (NST) score at 6-weeks between subjects that received a mandibular sagittal split osteotomy (SSO) using a low and short osteotomy (LSO) or traditional osteotomy (TRO). The null hypothesis was that no significant difference exists in post-operative NST score between subjects that received SSO with a TRO or LSO. A retrospective chart review was conducted of subjects that received orthognathic surgery by the oral and maxillofacial surgery department at the University of Texas Southwestern Medical Center (UTSW) from 2017 to 2019. All subjects that received SSO by either TRO as defined by Hunsuck and Epker(1,2) or LSO defined by Posnick(3) were included. Subjects with syndromic conditions, prior injury to the inferior alveolar nerve, history of peripheral neuropathy or pain conditions, and those undergoing simultaneous genioplasty, repeat surgery or concomitant temporomandibular joint surgery were excluded. Neurosensory outcomes of the inferior alveolar nerve (IAN) were measured using clinical NST at the pre-operative and 6-week post-operative visit over a 1-centimeter area of the labiomental fold. Chi-squared analysis and t-tests were performed between the cohorts and their respective outcomes. Values of p < 0.05 were considered statistically significant. The primary predictor variable was osteotomy type, and the primary outcome variable was NST score at the 6 weeks post-operative visit. Secondary outcome variable was IAN location within the proximal or distal segment. A total of 26 subjects met the defined inclusion criteria for a total of 52 osteotomies. There were 32 osteotomies in the LSO group, and 20 in the TRO group. The average age of the LSO group was 23.1 years (SD=10), and the average age of the TRO group was 22.4 years (SD=6). There was no significant difference in age between the two groups (p=0.84). All subjects were NST level A pass bilaterally at the pre-operative visit. No nerve injury was witnessed at the time of surgery among either group. All IANs contained within the proximal segments were left in place. There was no statistically significant difference in NST score between the two groups at the 6-week post-operative visit (p = 0.40). Of the total 52 osteotomies, there was no significant difference between NST score at the 6 weeks post-operative visit in subjects with IAN located in the proximal segment or the distal segment regardless of technique used (p = 0.52). There is no difference in post-operative NST score at 6-weeks between subjects that received a traditional osteotomy or low and short sagittal split osteotomy. Regardless of technique, there is no difference in post-operative NST score at 6 weeks if the IAN is in the proximal or distal segment after completion of sagittal split.