Finite Element Analysis on Biomechanical Properties of Traditional Trajectory and Modified Cortical Bone Trajectory / 医用生物力学

Objective To study mechanical properties of traditional trajectory (TT) and modified cortical bone trajectory (MCBT) on osteoporotic vertebrae through finite element analysis. Methods The three-dimensional model of L4 segment was established, and pedicle screw (PS) (diameter 6.0 mm, length 45 mm) and MCBT screw (diameter 4.5 mm, length 40 mm) were placed on both sides of the lumbar spine. The pull-out strength and the load-displacement ratio of screws in two different screw trajectories under up, down, left, right working conditions were analyzed, and the stability between the screw and vertebral body under osteoporotic conditions was evaluated. Results Compared with TT, the pull-out strength of MCBT screw was increased by 13.1%. Compared with PS, the load-displacement ratio of MCBT screw under up, down and left working conditions was increased by 57.2%, 32.4%, and 31.6%. Under right working condition, although the load-displacement ratio of MCBT screw was higher than that of PS, no statistical difference was found. The load-displacement ratio of vertebral body in MCBT group under lateral bending and axial rotation was significantly higher than that in TT group. The load-displacement ratio of vertebral body in MCBT group under flexion was lower than that in TT group. Although the load-displacement ratio of vertebral body in MCBT group under extension was higher that that in TT group, no statistical difference was found. Conclusions MCBT is superior to TT in pull-out strength, screw stability and vertebral body stability under lateral bending and axial rotation, but its vertebral body stability under flexion and extension was weaker than that of TT. The research findings demonstrate the superiority of MCBT under osteoporotic conditions and lay the foundation for clinical application of MCBT.

No significant difference between chiari malformation type 1.5 and type I.

OBJECTIVE: Chiari malformation Type 1.5 (CM 1.5) was defined as the association of Chiari malformation Type I (CM I) and brainstem herniation. The objective was to demonstrate the difference of clinical features and surgical outcomes between CM 1.5 and CM I. PATIENTS AND METHODS: All CM 1.5 and CM I adult patients who underwent posterior fossa decompression with duraplasty at our institution between 2006 and 2010 were retrospectively reviewed. Clinical characteristics, imaging features, and long-term outcomes were compared between CM 1.5 and CM I patients. RESULTS: A total of 142 adult patients were enrolled, including 27 CM 1.5 and 115 CM I patients. The average follow-up period was 102 months. Age at diagnosis was significantly younger in CM 1.5 group than CM I group (p=0.039). And the degree of tonsillar herniation was significantly more severe in CM 1.5 group than CM I group (p<0.001). There was no significant difference in other clinical and imaging characteristics. Moreover, improvement of symptoms was observed in 21 CM 1.5 patients (77.8%) and 94 CM I patients (81.7%), and no significant difference was detected (p=0.637). There was no significant difference in the resolution of syringomyelia between CM 1.5 (72.7%) and CM I (76.5%) patients, either (p=0. 710). CONCLUSIONS: Although CM 1.5 patients presented with brainstem herniation and more severe tonsillar herniation, other clinical and imaging features and surgical outcomes were similar with CM I patients. We think CM 1.5 is just a subtype of CM I, rather than a unique type of Chiari malformations.

[Management of 42 complex intracranial aneurysms in hybrid operating room].

Objective: To analyze the efficacy and methods of hybrid operation in the treatment of complex intracranial aneurysms. Methods: Fourty-two patients with complex intracranial aneurysms were treated in hybrid operation room of Qilu Hospital of Shandong University between July 2011 and October 2016. Twenty-one cases of aneurysm clipping guided by intraoperative angiography, 10 cases of aneurysm clipping assisted by endovascular therapy, and 11 cases of aneurysm occlusion assisted by bypass surgery. Results: Thirty-five patients were followed up 6-36 months.Thirty-three (94.3%) cases were completely occlusion, 2 (5.7%) cases were recurrent in follow-up.One of the recurrence case was performed interventional embolization treatment, and the other was continuous follow-up. Conclusion: Hybrid operating room is beneficial to evaluate the surgical curative effect immediately. It could increase the occlusion rate of complicated aneurysms, and could provide an ideal platform for complicated intracranial aneurysm treatment.

[Clinical application of hybrid surgery for the treatment of cerebral arteriovenous malformations].

Objective: To investigate the application of hybrid technique for the treatment of cerebral arteriovenous malformations (CAVMs) and to assess the value of hybrid technique. Methods: The cases of CAVMs treated in Qilu hospital and People's Hospital of Xinjiang Uygur Autonomous Region from July 2011 to July 2016 were analyzed retrospectively.Two modes of hybrid surgery, "angiographic diagnosis-craniotomy lesion resection or/and hematoma clearance-intraoperative angiography evaluation" and "angiographic diagnosis-intraoperative embolization-craniotomy lesion resection or/and hematoma clearance-intraoperative angiography evaluation" were applied for all the cases.We placed an aneurysm clip as marker in surgery field during real-time angiography.If CAVMs residues occurred during surgery, we re-resected the residue according to the guidance of the marker (clip) and DSA imaging. Intra-operative angiography evaluated the results of CAVMs resection one more time.Postoperatively, follow-up CT scan was performed for all the patients. Results: Of all the cases with CAVMs, there were 8 cases of scale Ⅰ, 13 cases of scale Ⅱ, 10 cases of scale Ⅲ and 6 cases of scale Ⅳ according to Spetzler-Martin Scale.There were 28 cases of acute hemorrhagic CAVMs and 9 cases of chronic hemorrhagic CAVMs or no-hemorrhagic CAVMs.Intra-operative angiography showed CAVMs residues in 6 cases of acute hemorrhagic CAVMs and only one in chronic group.About 18.92% residual rate of CAVMs were found for the first time intra-operative assessment angiography.With the guidance of intra-operative angiography and aneurysm clip as Marker, all residues of CAVMs were resected totally.Follow up CT showed the hematomas disappeared in all the cases of acute hemorrhagic cases.The cure rate of CAVMs with hybrid surgery was 100% according to the final intra-operative assessment angiography. Conclusions: (1)Hybrid surgery for the treatment of CAVMs in one session could evaluate the results of CAVMs resection and instruct the surgical procedure according to real-time angiography.This model could improve the treatment safety and efficacy for patients with CAVMs.(2)Patients with higher Spetzler-Martin Scale (Ⅲ-Ⅳ) who need intra-operative embolization and patients with hemorrhagic CAVMs are more suitable for hybrid surgery.