| ObjectiveTo clarify the length of the sternocleidomastoid muscle (SCM), the blood supply of the middle and lower SCM, the origin of superior thyroid artery (STA) and its blood supply range; to understand the morphological data, biomechanical characteristics of the clavicle; evaluate the clinical effect of sternocleidomastoid myocutaneous flap (SCMF) and single pedicle sternocleidomastoid myocutaneous flap (SSCMF) for reconstruction on oral and maxillofacial soft tissue defects after tumor dissection; evaluate the clinical effect of partial clavicle-sternocleidomastoid myocutaneous flap (PCSCMF)for reconstruction on composite oro-mandibular defect.Methods1.30 cadavers of adult with 60 sternocleidomastoids were selected to measure the length of SCM. The branch of STA was dissected. The same procedure was also done on 36 patients with radical neck lymph node dissection; the methylene blue solution was poured into muscular branch of STA to observe its blood supply with the agreement from patients.2.30 cadavers of adult with 60 clavicles were selected in the investigation. The width of the muscle attachment of SCM’s clavicular head, the maximum diameter (antero-posterior diameter) and the minimum diameter (vertical diameter) of the clavicle at the midpoint of the attachment were measured and recorded. Meanwhile, the distance from the midpoint of the attachment to the sterno-clavicular joint, and the relative bone length available in the medial clavicle segments were measured. In clinical, clavicle CT data was extracted from 20 patients with chest CT scans. The Mimics, Rhion, Magics were used to accurately three-dimensional analysis.1450N was forced along the long axis of clavicle at the distal end of the clavicle, then, the maximum stress value of the clavicle was measured:1221 Mpa, as a control. Then, clavicular defect model was designed on the basis of different lengths (20mm,40mm,60mm) and thickness (5mm, 8cm,1 lmm) at SCM’s attachment, the maximum stress value The residual clavicle were measured.3. Sternocleidomastoid myocutaneous flap (SCMF) or single pedicle sternocleidomastoid myocutaneous flap (SSCMF) was used to reconstruct the soft tissue defects after tumor resection in 54 patients. Among them, there were 39 SCMF and 15 SSCMF, the size of SCMF ranged from 4.0cm×4.5cm to 6.0cm×7.0cm, while the size of SSCMF ranged from 2.5cm×3.5cm to 3.5cm×4.0cm. All patients underwent regularly follow-up after 1,3,6,12,18months and were asked to complete the self-evaluation forms when 6 months after operation. At the same time, we used radial forearm flap (RFF) and pedicled pectoralis major flap (PMMF) as the control, the flap thickness, flap vascular crisis, the rate of lymph node metastasis, postoperative aesthetic and function in donor and recipient area of these three flaps were compared.4.33 patients with early mandibular gingival carcinoma received PCSCMF to reconstruct the composite oro-mandibular defect after the tumor resection and cervical lymph node dissection, and its clinical effect was evaluated. Among them, SSCMF was made in three patients and SCMF was made in the others.25 patients received simultaneous or secondary dental implantation. A total of 78 dental implants were implanted and denture rehabilitation was completed later. Survival of PCSCMF, the recovery of the local appearance and function, the stability of and effect of dental implant and the incidence of postoperative complications of clavicular fractures were regularly observed during the 1,3,6,12,18 months later follow up.Results1. The length of chest bone of the sternocleidomastoid was 15.2 to 21.7cm in male (mean 19.15± 2.25cm),13.8 to 18.5cm in female (mean 16.78±1.75cm). The length of lock bone of the sternocleidomastoid is 14.1 to 19.3cm in male (average 17.66±2.01cm), and the female is 13.2 to 17.6cm in female (average 15.27±1.49cm). Methylene blue solution was injected to the SCM branch of STA, and then the middle-lower part of sternocleidomastoid and its skin appeared blue. The mean diameter of the blue staining areas is about 6.1 to 10.7cm (mean 8.62±0.68cm), and the distance from the center point to the left supraclavicular margin is about 4.3 to 9.6 cm (average 6.47±0.59cm). Meanwhile, clavicular periosteum appeared blue by injection of methylene blue solution in to SCM branch of STA.2. For the available length of the inner end of the clavicle, males’was bigger than females’, left was bigger than right. The vertical and anteroposterior diameters of clavicle in males are bigger than women, but there were no significant difference between the diameters of bilateral clavicle. The width of the clavicular head attachment in the males was bigger than females and no significant difference was found between the left and right sides. When the thickness of clavicle osteotomy<8mm, the maximum stress value of the remaining clavicle didn’t significantly increased, so the probability of fracture is small. However, when the thickness≥11mm, the maximum stress value of the remaining clavicle was significantly greater than the complete clavicle. Therefore, the possibility of the remaining clavicle fracture is high. When the thickness of clavicle osteotomy≤8mm, the maximum stress value of the remaining clavicle was not affected by the length of clavicle graft.3. The harvesting time of versatile sternocleidomastoid flap was 34.1±5.0 minutes, and the thickness of the flap was 12.63±3.08mm. The survival rate of stemocleidomastoid flap was 100% without any vascular crisis and the postoperative cervical lymph node metastasis was found in 6 cases. For postoperative donor appearance, the score of SSCMF group was 4.60 ±0.51, while SCMF group was 4.28 ±0.72;For postoperative functional recovery, the score of SCMF group was 4.67±0.49, while SCMF was 4.33±0.70;for score of exterior in recipient area, SCMF group was 4.00±0.85, whereas SCMF group was 3.87±0.83. For score on function recovery in recipient area, SCMF group was 4.07±0.80, while the SCMF group was 3.85±0.84. The harvesting time of RFF was 59.3±8.4 minutes, the thickness was 8.56±1.66 mm. Postoperative vascular crisis was found in three cases with one case of failure to rescue, the survival rate was 97.56%(40/41), and the postoperative cervical lymph node metastasis was found in 5 cases. The average score of the appearance in donor area was 3.44±0.95; 3.61±0.95 for functional recovery in the donor area; 3.98±0.76 for postoperative appearance in repcipent area; 3.95±0.84 for functional recovery in the recipent area. The harvesting time of PMMF was 45.0±6.5mm, the thickness was average 21.44±4.27 mm. The survival rate was 100% without any vascular crisis and the postoperative cervical lymph node metastasis was found in 3 cases. The score was 4.00±0.89 for the appearance in donor area; 4.14±1.01 for functional recovery in the donor area; 3.29±0.96 for postoperative appearance in repcipent area flaps; and 3.24±1.00 for functional recovery in the recipent area.4. All clavicular graft and sternocleidomastoid flap survive well with no necrosis. One (1.28%) dental implant loosen was replaced with new dental implant, and other 77 (98.72%) dental implants were firm with good occlusion and masticatory. During the preparation of the partial clavicle flap, one patient (3.03%) with remaining clavicle fracture underwent rigid internal fixation by titanium plate. Effusion at collarbone area was removed in one patient (3.03%), and then local pressurized and bandaged was performed. There were an obvious gap between the clavicle graft and the remaining mandible in 6 cases (18.18%), but there was a good healing at the bilateral end between clavicle and mandible.ConclusionThe length of the SCM is enough, the anatomy of STA and its branch is constant while it provides a good basis for preparation of versatile sternocleidomastoid flap. The morphology of medial extremity of clavicular was relatively regular which could be harvested as clavicular graft to reconstruct the defects. However, because of the relatively less bone, the clavicle could only reconstruct small bone defect. The risk of remaining clavicle fracture would not be significantly increased when the clavicular graft was prepared appropriately. Versatile sternocleidomastoid flap with simple technique, high survival rate, lower trauma in donor and recipient area could be a reliable flap for reconstruction of tissue defects after oral tumor resection. PCSCMF also is a relatively simple but effective procedure in reconstructing small and medium composite mandibular defect, for its high survival rate, fewer complications, and satisfactory clinical results. Meanwhile, dental implants will help recover the occlusion as soon as possible and improve postoperative life quality for oral tumor patients. |
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