Rajanikanth B R, Kotharkar Akshata, Prasad Kavitha
Department of Oral and Maxillofacial Surgery, Faculty of Dental Sciences, M S Ramaiah University of Applied Sciences, Gnanagangotri campus, new BEL road, MSRIT post Mathikere, Bengaluru, 560054 India.
J Maxillofac Oral Surg. 2024 Oct;23(5):1296-1303. doi: 10.1007/s12663-023-02012-4. Epub 2023 Sep 8.
Success in skeletal surgery depends on adequate access and exposure of the underlying skeletal structures. The retromandibular approach exposes the ramus condyle region through the posterior border of the mandible by utilizing the space between marginal mandibular and buccal branches of the facial nerve. Length of this safety window and accessibility varies in each individual owing to the differing ramifications of peripheral branches of facial nerve. These variations cannot be adequately assessed through clinical studies. Cadaveric studies permit us to extensively explore the surgical area to demystify the branching pattern and its relationship to the adjacent structures.
Thirty well-preserved cadaveric facial halves were dissected using a retromandibular incision. Visibility and accessibility were objectively graded through a scale. The safety window and furcation distance were measured using caliper and scale. The appearance of the retromandibular vein was also noted.
Eighteen facial halves showed maximum accessibility wherein the surgeon is expected to visualize the condylar neck, subcondylar region and posterior half of ramus. In 8 facial halves, accessibility was limited to subcondylar and midportion of posterior ramus, and in 8 facial halves, accessibility was limited to the midportion of ramus of the mandible. Safety window ranged from 1.9 to 3.5 cms. Distance between the posterior border of mandible and bifurcation of the facial nerve ranged from 0.5 to 1.5 cms. Facial nerve was encountered in 24 facial halves during the retromandibular approach. Retromandibular vein was encountered in 23 facial halves during the retromandibular approach.
The retromandibular approach is a versatile approach to the condyle subcondylar area as it provides much-required visibility and accessibility. The facial nerve branching pattern and intercommunicating branches determine the safety window which is adequate in most cases. The retromandibular vein is a reliable landmark predicting the vicinity of the facial nerve.
骨骼手术的成功取决于对深层骨骼结构的充分显露。下颌后入路通过利用面神经下颌缘支和颊支之间的间隙，经下颌骨后缘显露髁突区域。由于面神经周围分支的不同分支情况，这个安全窗口的长度和可达性在个体之间存在差异。这些差异无法通过临床研究进行充分评估。尸体研究使我们能够广泛探索手术区域，以揭开分支模式及其与相邻结构的关系。
使用下颌后切口对30个保存完好的尸体面部半侧进行解剖。通过量表对可视性和可达性进行客观分级。使用卡尺和量表测量安全窗口和分叉距离。同时记录下颌后静脉的外观。
18个面部半侧显示出最大可达性，在此情况下外科医生有望看到髁突颈部、髁突下区域和下颌支后半部。在8个面部半侧中，可达性仅限于髁突下和下颌支后缘中部，在8个面部半侧中，可达性仅限于下颌支中部。安全窗口范围为1.9至3.5厘米。下颌骨后缘与面神经分叉之间的距离为0.5至1.5厘米。在下颌后入路过程中，24个面部半侧遇到面神经。在下颌后入路过程中，23个面部半侧遇到下颌后静脉。
下颌后入路是一种用于髁突下区域的通用入路，因为它提供了所需的可视性和可达性。面神经分支模式和交通支决定了安全窗口，在大多数情况下该窗口是足够的。下颌后静脉是预测面神经位置的可靠标志。
