A Surgical Guide For Mandibular Reconstruction Using The Scapular Chimeric Flap To Prevent Injury Of The Angular And Periosteal Branches
Joseph M. Escandón, MD1, Arbab Mohammad, MBBS2, Chihiro Matsui, MD3, Daniela Duarte Bateman, MD4, Eba Baig, MBBS2, Shivangi Saha, MBBS, MS, MCh5, Lei Yu Mon, MD6, Hiroshi Mizuno, MD3.
1University of Rochester Medical Center, Rochester, NY, USA, 2Aarupadai Veedu Medical College and Hospital, Puducherry, India, 3Juntendo University School of Medicine, Tokyo, Japan, 4Cleveland Clinic Lerner Research Institute, Cleveland, OH, USA, 5All India Institute of Medical Sciences, New Delhi, India, 6Okayama University Hospital, Okayama, Japan.
PURPOSE: Mandibular reconstruction using the scapular free flap is a common procedure. Nonetheless, the proximity of the infraspinatus muscle to the bone surface can be inconvenient while harvesting the flap. Also, because bone has a higher peripheral vascular resistance than soft tissue, the blood flow to the bone component of chimeric flaps can be insufficient with the thoracodorsal arteriovenous system alone. Therefore, we often supercharge the flap using the circumflex scapular artery. In this setting, it is crucial to visualize and protect the angular branch of thoracodorsal and periosteal branches of the circumflex scapular artery while performing an osteotomy. These vessels can be easily severed as they course in proximity to the insertion of the muscle at the scapular wing. Herein, we report the use of preoperative 3D computed tomography angiography (CTA) and 3D printed scapular models to prepare inexpensive surgical guides from autoclavable dental silicone impressions to aid the visualization of the angular and periosteal branches for flap harvest.
METHODS: We reviewed patients who underwent mandibular reconstruction between 2018-2020. Scapular models were prepared using a 3D printer. Drill markings of the perforating angular and periosteal branches were added to the models with the guidance of life-sized printouts of 3D CTA images of the subscapular artery. A simulation osteotomy on the model was carried out. The osteotomized bone model was used to mold the autoclavable dental silicone surgical guide for intraoperative use. All cases included harvesting chimeric latissimus dorsi and serratus anterior muscle flaps with the scapular bone flap. The angular and periosteal branches were located by placing the surgical guide on the muscle mass intraoperatively.
RESULTS: Eleven patients fulfilled the inclusion criteria, 6 males and 5 females. The average age of patients was 65.4±7.9 years. Three patients had ameloblastoma, three had medicine-induced osteonecrosis, four had mandibular gingival cancer, and one had radiation-induced mandibular osteonecrosis. The mean flap harvest time and total surgical time were 52.1±13.5 min and 633.8±36.8 min, respectively. The mean duration of osteotomy and bone plate fixation was 26.2±6.18 min. The difference between pre- and postoperative bone lengths for all cases using simulation surgery models (64.9±22.5 mm) and postoperative 3DCT (64.5±23.2 mm) was not significantly different. (1.6±0.9 mm; p=0.48). No injuries were caused to the angular and periosteal vessels and no complications such as flap necrosis, fistula, or surgical site infection were recognized in any of our cases. Four patients exhibited donor-site seroma. Overall, the flaps exhibited adequate perfusion. The cost of surgical guide preparation was only 5 USD per patient.
CONCLUSION: The use of a preparable surgical guide using sterilizable material allows to carry out precise scapular osteotomies without any vessel injury while harvesting the scapular flap. This method has shown to be accurate using pre and postoperative measurements. The proposed guide is of low-cost and readily available in all clinical settings in comparison to other models.
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