Zellner Elizabeth G, Mhlaba Julie M, Reid Russell R, Steinbacher Derek M
Craniofacial Fellow, The Hospital for Sick Children (Sick Kids), Toronto, ON, Canada.
Medical student, Department of Surgery, Section of Plastic Surgery, Pritzker School of Medicine, University of Chicago, Chicago, IL.
J Oral Maxillofac Surg. 2017 Jan;75(1):167-177. doi: 10.1016/j.joms.2016.07.034. Epub 2016 Sep 13.
The goal of mandibular distraction in the Pierre-Robin sequence is to maximally expand the oropharyngeal airway. It has been hypothesized that a steep oblique distraction vector might allow greater airway enlargement compared with horizontal distraction. This study compared vector orientation in relation to airway volume and overall clinical outcome.
Micrognathic infants who underwent mandibular distraction with sufficient computed tomographic data were retrospectively reviewed. Demographic, diagnostic, perioperative, and distraction data were recorded. Groups were separated based on distraction vector (group 1, horizontal; group 2, oblique). Airway and mandibular volumes were measured using Mimics (Materialise, Leuven, Belgium). Morphologic and outcomes data were analyzed. Statistics involved 2-tailed t test, Pearson correlation, and analysis of covariance (ANCOVA).
Mean age at distraction was 40 days, with devices maintained for 82 days on average. Fifty percent of patients were girls and 65% had cleft palate. Forty computed tomograms were analyzed. Airway (1,234 vs 3,501 mm; P < .01) and mandibular (5,457 vs 11,827 mm; P < .01) volumes, minimal airway area (12.5 vs 63.7 mm; P < .01), and posterior airway space distance (2.3 vs 9.8 mm; P = .04) were significantly increased after distraction. Patients also had clinically improved sleep studies after distraction (apnea hypopnea index, 51.3 vs 5.5; P < .01). Vector analysis showed an average of 5.3° and 14.0° in groups 1 and 2, respectively (n = 10 each). Intergroup analysis showed a trend toward increased airway volume in horizontal vectors (548 vs 255% of preoperative volume; P = .058), with slightly longer distraction length (20.3 vs 16.6 mm; P = .17). However, ANCOVA regression analysis showed no difference in the relation between vector and length. Other morphologic data and sleep study outcomes (apnea hypopnea index, 7.0 vs 3.9; P = .09) also were not statistically different between groups. Longer lengths of distraction correlated with narrower anterior mandibular angle and longer mandibular body length.
Substantial airway enlargement occurs after mandibular distraction. Final airway volumes were similar between groups regardless of vector, which was confirmed by multivariate ANCOVA regression. The 2 methods achieved airway stabilization, with clinical outcomes similar between the 2 groups.
在Pierre-Robin序列征中，下颌骨牵张的目标是最大程度地扩大口咽气道。据推测，与水平牵张相比，陡峭的斜向牵张向量可能会使气道扩大得更多。本研究比较了牵张向量方向与气道容积及总体临床结局的关系。
对接受下颌骨牵张且有足够计算机断层扫描数据的小颌畸形婴儿进行回顾性研究。记录人口统计学、诊断、围手术期及牵张数据。根据牵张向量将研究对象分为两组（第1组为水平牵张；第2组为斜向牵张）。使用Mimics软件（Materialise公司，比利时鲁汶）测量气道和下颌骨容积。对形态学及结局数据进行分析。统计学分析采用双侧t检验、Pearson相关性分析及协方差分析（ANCOVA）。
牵张时的平均年龄为40天，牵张装置平均保留82天。50%的患者为女性，65%的患者患有腭裂。分析了40份计算机断层扫描图像。牵张后气道容积（1234 vs 3501 mm³；P <.01）、下颌骨容积（5457 vs 11827 mm³；P <.01）、最小气道面积（12.5 vs 63.7 mm²；P <.01）及后气道间隙距离（2.3 vs 9.8 mm；P =.04）均显著增加。牵张后患者的睡眠研究结果在临床上也有所改善（呼吸暂停低通气指数，51.3 vs 5.5；P <.01）。向量分析显示，第1组和第2组的平均角度分别为5.3°和14.0°（每组n = 10）。组间分析显示，水平向量组的气道容积有增加趋势（为术前容积的548% vs 255%；P =.058），牵张长度略长（20.3 vs 16.6 mm；P =.17）。然而，ANCOVA回归分析显示向量与长度之间的关系无差异。其他形态学数据及睡眠研究结局（呼吸暂停低通气指数，7.0 vs 3.9；P =.09）在两组间也无统计学差异。牵张长度越长，下颌骨前角越窄，下颌体长越长。
下颌骨牵张后气道显著扩大。多变量ANCOVA回归分析证实，无论牵张向量如何，两组最终的气道容积相似。两种方法均实现了气道稳定，两组的临床结局相似。
