| Large bone tissue defects has been a major problem in bone defect reconstruction in clinic for a long time. The bone healing process could be more approached to normal fracture healing with vascularized bone graft. And iliac bone graft has become the "golden standard" in autologus bone graft. The deep iliac circumflex artery(DCIA)and iliolumbar artery(ILA)were the most important vessels for iliac bone. However, the detail anatomy of the two above vessels was reported rarely, especially on their perforator branches. In this study, the DCIA and ILA, especially their branches, would be dissected in detail. Meantime, the spacial distribution of DCIA and ILA would be further analyzed with three-dimensional reconstruction technique, and the anatomical characteristics and regularity of the two vessels would be found out finally.Objective: To investigate the anatomical characteristics and regularity of the DCIA and ILA and find out anatomical evidence and new ideas on iliac tissue flap harvest.Methods: On 13 specimens, DCIA and ILA were finely dissected, respectively. The origin, distribution, anastomoses of the two vessels were measured and analyzed in detail. Three complete specimens were injected with red latex/barium sulfate suspension through the femoral artery. The injected specimens were scanned with 64-slice spiral CT and its data were imported into 3D reconstruction software. Finally, the skin, blood vessels and bone were reconstructed, and the DCIA and ILA vessels were analyzed and measured spacially.Results: The DCIA was divided into three segments, including inguinal ligament, iliac crest and terminal segment. The length of inguinal ligament, iliac crest and terminal segment were 7.6cm, 7.9cm and 8.6cm. The DCIA originated from the outside and the rear outside wall of external iliac artery or femoral artery. The DCIA sent out one or two perforator branches in iliac crest segment. The piercing points of these perforator branches in the deep fascia distributed among 3.6 ~ 5.6 × 3.8 ~ 5.5 cm above and outwards anterior superior iliac spine. The terminal branches of DCIA were divided into two parts, the terminal trunk and terminal perforator branch. The former was anastomosed with the iliac branch of ILA, and the latter pierced in the deep fascia, with its piercing points distributing among 7.0~9.5×6.4~8.8 cm as before. All the ILA originated from the internal iliac artery. The ILA gave off two branches(iliacus branch and lumbar branch) when passing between the obturator nerve and the lumbosacral trunk, posteriorly to the psoas major. The mean distance between origin of the ILA and bifurcation point to iliacus and lumbar branches was 6.5 cm. The iliacus branch divided into two branches: one artery curved forward and anastomosed with the iliacus branch of DCIA; the other artery supplied the tissue around the posterior superior iliac spine. The lumbar branch supplied the psoas major and the quadratus lumborum. The data after CT scan were imported into Materialise’s Interactive Medical Image Control System(Mimics). The skin, blood vessels and bone of injected specimens were reconstructed respectively. The combined specimens could be observed and measured optimally.Conclusion: The perforator branches of DCIA pierced the deep fascia regularly and constantly. And the iliac tissue flap could be pedicled with the perforator branches of DCIA. The larger iliac tissue flap could be harvested based on the anastomosis between the iliacus branch of ILA and the terminal trunk of DCIA. The ILA and its iliacus branch was one of the most constant and reliable vessels supplying the iliac bone, and could be used as the pedicle of free or pedicled iliac tissue flaps. And the three-dimensional digital model could provide an intuitive digital anatomical basis of clinical teaching and training.It was reported that the total morbidity rate was 19.37% after iliac tissue flap harvest, and the iliac fracture and pelvic instability were regarded as the major complications. When the iliac tissue flap was elevated from the anterior iliac region, the above major complications could be present at any time. If the iliac tissue flap was harvested larger, the bottom of the anterior superior iliac spine would be too narrow and the pull from the carpenter muscle would easily lead to pelvic fracture and avulsion of the anterior superior iliac spine. This study was to construct a three-dimensional finite element solid model of the pelvis by the finite element method, and biomechanical study of the pelvic stability would be studied.Objective: To investigate the biomechanics of the pelvis after different volume iliac bone harvested from iliac tissue flap, and to find out the safest surgical skills avoiding iliac fracture postoperatively.Methods: A healthy male volunteers underwent 64-slice spiral CT scan, the CT image data was imported into three-dimensional reconstruction software to build a three-dimensional model of the pelvis. With the ANSYS software, the complete three-dimensional model of the pelvis could be reconstructed. The iliac tissue flap was cut out on the model three different volumes of the iliac bone, including 20 × 20mm(Pelvis-20), 40 × 40mm(Pelvis-40), and 60 × 60mm(Pelvis-60), respectively. Load 500 N simulating human gravity and 10N?m torque simulating vertebral flexion, extension, lateral bending and rotation as normal physiological movement. In addition, load 750 N and 1500 N in the anterior superior iliac spine along the direction of the sartorius.Results: A complete finite element model of the pelvis could be built in the finite element analysis software, including cortical bone, cancellous bone, disc and the sacroiliac joints. The total number of nodes in the entire pelvis model was 676,414, the number was 451,963 units. There was no significance between the four pelvis models in an upright model, flexion, extension, lateral bending and rotation of five normal physiological movements. After loading 750 N stress in the anterior superior iliac spine, local displacement in Pelvis-40 and Pelvis-60 were larger than the Pelvis-20 and Intact pelvis significantly. In addition, when loading 1500 N stress, the four pelvis models were all prone to fracture at the anterior superior iliac spine.Conclusion: We built a complete model of the pelvis by finite element software and approached to a high degree of approximation of the model with the entity. Under normal physiological movement of the human body, the stress of the pelvis spread mainly through the sacrum, sacroiliac joint, greater sciatic notch, arcuate line spread acetabulum, until the back of the pelvis. The safest surgical technique was not more than 40×40mm size of the iliac bone at anterior iliac region. The depth of the bone and strenuous exercise were the main factors leading to postoperative fracture of the ilium. |
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