Does bilateral gap arthroplasty increase the severity of obstructive sleep apnea in temporomandibular joint ankylosis patients

ABSTRACT PURPOSE Obstructive sleep apnea (OSA) is common in bilateral temporomandibular joint ankylosis (TMJA) patients. The purpose of this study was to compare the pre and postoperative apnea-hypopnea index (AHI) in subjects with TMJA undergoing bilateral gap arthroplasty (BGA). METHODS The investigators implemented a prospective cohort study on bilateral TMJA patients treated with BGA. Primary predictor variable was time (before and after BGA). Primary outcome variable was AHI and secondary outcome variable included posterior airway space (PAS), skeletal changes, Epworth sleepiness scale (ESS), minimum oxygen (MinO2), average oxygen (AvgO2) saturation, maximal incisal opening (MIO) at preoperative time (T0), 1-month (T1) and at 6-months (T2). The statistical test used were Greenhouse-Geisser test, Repeated measure ANOVA (1 way) followed by post hoc Bonferroni test. The p-value was taken significant when RESULTS The study sample included 12 (m:f=1:2) patients of bilateral TMJA with mean age of 14.9 + 4.8 years and mean follow-up of 6-months. Mean duration of ankylosis (DOA) was 10.5 + 6.9 years (median=12). Trauma was the main etiological factor in 11 (91.7%) followed by infection in 1 (8.3%). The mean increase in AHI index was 8.6 (T0 to T1) with p value=0.002 and 23.4 (T1 to T2) and was statistically significant (p=0.001). The mean decrease in PAS was 4.5 + 1.0 to 3.5 + 0.5 (T0 to T2) and was statistically significant (p=0.02). Mean difference in MinO2 was 6.8 (p value=0.015). Skeletal changes are consistent with clockwise rotation of mandible and statistically significant changes in horizontal and vertical dimension. The mean change in AvgO2 was statistically insignificant (p =1.0). Conclusion The present study concludes that gap arthroplasty in bilateral TMJA patients can lead to development or worsening of pre-existing mild to moderate OSA. Ramus-condyle reconstruction should be done to prevent the retro-positioning of mandible and worsening of OSA.