Does a Modified Endaural Incision Reduce Facial Nerve Injury and Improve Cosmesis When Compared to the Modified Pre-Auricular Incision for Management of Temporomandibular Joint Ankylosis?

Abstract

Background

Facial nerve injury (FNI) and unesthetic scar are distressing complications of temporomandibular joint (TMJ) surgery. Insufficient evidence on whether a modified endaural incision can reduce FNI and serve as an aesthetic alternative is a concern.

Purpose

The purpose of this study was to compare the postoperative FNI and surgical scar cosmesis using modified endaural incision (Inviscision approach [IA]) and modified preauricular incision (Alkayat-Bramley approach [ABA]) in TMJ ankylosis.

Study design, Setting, Sample

The authors implemented a single-centre, retrospective, cohort study. Subjects presenting to the Division of Craniomaxillofacial surgery at All India Institute of Medical Sciences, Rishikesh with TMJ ankylosis who underwent ankylosis release between January 2021 and December 2023 were identified through electronic medical record review. Inclusion criteria were the presence of unilateral or bilateral, Sawhney's type III or IV ankylosis. Exclusion criteria were pre-existing FNI, reankylosis cases.

Predictor/Exposure/Independent Variable

The primary predictor variable was surgical approach (IA vs ABA).

Main Outcome Variables

The primary outcome variables were FNI at 1 month and 6 months, measured using House-Brackmann scale, and scar cosmesis at 6 months using the Patient and Observer Scar Assessment Scale. Secondary outcome variables were dissection time for surgical exposure (minutes), intraoperative blood loss (milliliters), and other complications of infection, dehiscence, and hypertrophic scar.

Covariates

Covariates included demographics (age, sex), preoperative (side, location and Sawhney's type of ankylosis).

Analyses

The data were analyzed using descriptive statistics, student t-test, Mann-Whitney U test and regression analysis, with the level of statistical significance at P < .05.

Results

The study included 30 patients (40 joints: 20 in each group) with mean age of 22.45 ± 7.09 years in IA and 19.25 ± 7.06 years in ABA (P = .99). IA included 8 men (53.33%), 7 women (46.6%) and ABA had 5 men (33.3%), 10 women (66.6%) (P = .87). Postoperative FNI at 1 month accounted 45% in IA (n = 9) and 95% in ABA (n = 19), which was statistically significant (P = .001). At 6 months, FNI was 15% in IA (n = 3) and 70% in ABA (n = 14) that showed statistical difference (P = .003). For scar assessment at 6 months, the mean Patient and Observer Scar Assessment Scale score was 40.7 ± 17.2 for IA and 61.75 ± 17 for ABA, which was statistically significant (P = .001). IA had statistically significant shorter dissection time (IA = 25.45 ± 2.48 mins, ABA = 35.45 ± 3.97 mins; P = .0001) and lower amount of blood loss (IA = 52.15 ± 9.12 mL, ABA = 80.05 ± 8.91 mL; P = .0001). No statistically significant complications were observed.

Conclusion and Relevance

To conclude, IA shows better outcomes like shorter dissection time, reduced FNI, better scar cosmesis and can be proposed as a suitable alternative to traditional ABA in TMJ ankylosis surgery.