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RISS 인기검색어
- 검색키워드
- 저자 : Ahmed ZIDAN (검색결과 4 건)
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Zidan, Ihab,Khedr, Wael,Fayed, Ahmed Abdelaziz,Farhoud, Ahmed The Korean Neurosurgical Society 2019 Journal of Korean neurosurgical society Vol.62 No.1
Objective : Corpectomy of the first lumbar vertebra (L1) for the management of different L1 pathologies can be performed using either an anterior or posterior approach. The aim of this study was to evaluate the usefulness of a retroperitoneal extrapleural approach through the twelfth rib for performing L1 corpectomy. Methods : Thirty consecutive patients underwent L1 corpectomy between 2010 and 2016. The retroperitoneal extrapleural approach through the 12th rib was used in all cases to perform single-stage anterior L1 corpectomy, reconstruction and anterior instrumentation, except for in two recurrent cases in which posterior fixation was added. Visual analogue scale (VAS) was used for pain intensity measurement and ASIA impairment scale for neurological assessment. The mean follow-up period was 14.5 months. Results : The sample included 18 males and 12 females, and the mean age was 40.3 years. Twenty patients (67%) had sensory or motor deficits before the surgery. The pathologies encountered included traumatic fracture in 12 cases, osteoporotic fracture in four cases, tumor in eight cases and spinal infection in the remaining six cases. The surgeries were performed from the left side, except in two cases. There was significant improvement of back pain and radicular pain as recorded by VAS. One patient exhibited postoperative neurological deterioration due to bone graft dislodgement. All patients with deficits at least partially improved after the surgery. During the follow-up, no hardware failures or losses of correction were detected. Conclusion : The retroperitoneal extrapleural approach through the 12th rib is a feasible approach for L1 corpectomy that can combine adequate decompression of the dural sac with effective biomechanical restoration of the compromised anterior loadbearing column. It is associated with less pulmonary complication, no need for chest tube, no abdominal distention and rapid recovery compared with other approaches.
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A hybrid MC-HS model for 3D analysis of tunnelling under piled structures
Zidan, Ahmed F.,Ramadan, Osman M. Techno-Press 2018 Geomechanics & engineering Vol.14 No.5
In this paper, a comparative study of the effects of soil modelling on the interaction between tunnelling in soft soil and adjacent piled structure is presented. Several three-dimensional finite element analyses are performed to study the deformation of pile caps and piles as well as tunnel internal forces during the construction of an underground tunnel. The soil is modelled by two material models: the simple, yet approximate Mohr Coulomb (MC) yield criterion; and the complex, but reasonable hardening soil (HS) model with hyperbolic relation between stress and strain. For the former model, two different values of the soil stiffness modulus ($E_{50}$ or $E_{ur}$) as well as two profiles of stiffness variation with depth (constant and linearly increasing) were used in attempts to improve its prediction. As these four attempts did not succeed, a hybrid representation in which the hardening soil is used for soil located at the highly-strained zones while the Mohr Coulomb model is utilized elsewhere was investigated. This hybrid representation, which is a compromise between rigorous and simple solutions yielded results that compare well with those of the hardening soil model. The compared results include pile cap movements, pile deformation, and tunnel internal forces. Problem symmetry is utilized and, therefore, one symmetric half of the soil medium, the tunnel boring machine, the face pressure, the final tunnel lining, the pile caps, and the piles are modelled in several construction phases.
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Zidan, Ihab,Fayed, Ahmed Abdelaziz,Elwany, Amr The Korean Neurosurgical Society 2018 Journal of Korean neurosurgical society Vol.61 No.6
Objective : Percutaneous vertebroplasty (PV) is a minimally invasive procedure designed to treat various spinal pathologies. The maximum number of levels to be injected at one setting is still debatable. This study was done to evaluate the usefulness and safety of multilevel PV (more than three vertebrae) in management of osteoporotic fractures. Methods : This prospective study was carried out on consecutive 40 patients with osteoporotic fractures who had been operated for multilevel PV (more than three levels). There were 28 females and 12 males and their ages ranged from 60 to 85 years with mean age of 72.5 years. We had injected 194 vertebrae in those 40 patients (four levels in 16 patients, five levels in 14 patients, and six levels in 10 patients). Visual analogue scale (VAS) was used for pain intensity measurement and plain X-ray films and computed tomography scan were used for radiological assessment. The mean follow-up period was 21.7 months (range, 12-40). Results : Asymptomatic bone cement leakage has occurred in 12 patients (30%) in the present study. Symptomatic pulmonary embolism was observed in one patient. Significant improvement of pain was recorded immediate postoperative in 36 patients (90%). Conclusion : Multilevel PV for the treatment of osteoporotic fractures is a safe and successful procedure that can significantly reduce pain and improve patient's condition without a significant morbidity. It is considered a cost effective procedure allowing a rapid restoration of patient mobility.
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