(17) OSA as a Consideration in Upper Jaw Surgery

Abstract: Segmental LeFort I osteotomy is useful for the management of transverse and vertical maxillary discrepancies. However, some patients in need of orthognathic surgery may also have risk factors for obstructive sleep apnea (OSA) in which clinicians must be conscious about how surgery will affect the soft palate, the most commonly involved area of obstruction (77.9%). 1 Furthermore, in patients who need palatal expansion and maxillary advancement for the purpose of increasing airway volume and treating OSA, it is important to consider whether the segmental LeFort I osteotomy will provide similar advancement of the palate compared to the single-piece LeFort. The purpose of this study is to identify any differences in length of the hard palate between the two groups in order to determine whether the palatal island advances in conjunction with the maxillary arch in a segmental Lefort. The investigators hypothesize that the distance between the anterior nasal spine (ANS) and posterior nasal spine (PNS) will be greater in that of a segmental than a single-piece LeFort.

The PNS was chosen as a reference point because it provides a consistent measurement on imaging and directly attaches to the soft palate. CBCT is a reliable imaging method for cephalometric assessment and was used to identify the ANS and PNS point on sagittal cut. 2 Distance between the two points was measured preoperatively and >6 weeks postoperatively, the time at which initial bone healing in the maxilla occurs.3 The difference between postoperative and preoperative ANS-PNS length was found and the means were compared between the two groups.

A retrospective cross-sectional study design was implemented. Measurements and analysis were performed by two independent reviewers with training in iCAT Vision. Extrapolation of data and statistical analysis was performed using two-sample t-tests. Statistical significance was determined to be P < 0.01 with 99% confidence interval (CI) to account for any variation in measurements.

108 patients ages 18-45 who underwent segmental or single-piece Le Fort I osteotomy from 2018 to 2022 were collected by running an electronic health record report with the above criteria. Of these, 59 patients were excluded because imaging was taken outside of the study timeframe, imaging was not reliable for measurement, or the procedure performed was a 2-piece Le Fort osteotomy without the creation of a palatal island. 24 patients were male and 25 were female, totaling 49 patients. 29 patients underwent single-piece LeFort and 20 patients underwent segmental LeFort. The mean difference between pre- and postoperative ANS-PNS distance was 0.21mm in the single-piece group and 2.14mm in the segmental group. The postoperative palatal length proved to be greater in the segmental LeFort group at >6 weeks (P < 0.01) with a CI = 99%.

This study serves as an initial analysis of the position of the hard palate when performing a segmental LeFort osteotomy. By observing an increase in palatal length when producing a palatal island, we can assume there to be a similar effect on the soft palate. However, soft tissue is variable between patients and thus an additional study should be done to examine the direct change in the position of the soft palate.

In addition to using palatal expansion for transverse discrepancies >7mm4, it may be reasonable to opt for palatal expansion with subsequent single-piece maxillary advancement for patients with risk factors for OSA or for patients undergoing maxillary advancement to treat their OSA. A future study that would help us better understand the effects of the two procedures on OSA would look at the cross-sectional area of the oropharynx in segmental vs single-piece LeFort.