Monosegmental transpedicular fixation for selected patients with thoracolumbar burst fractures.
ABSTRACT A prospective cohort study on selected consecutive patients.
To evaluate the efficacy of an innovative operative technique called monosegmental transpedicular fixation for the treatment of some thoracolumbar burst fractures.
Short-segment pedicle screw instrumentation is accepted by many spinal surgeons as an acceptable technique for the treatment of thoracolumbar burst fractures. Preoperative evaluation using the spinal load-sharing makes this technique more reliable. To preserve more motion segments, some authors have advocated using monosegmental pedicle screw instrumentation (MSPI) to treat thoracolumbar fractures. However, up until now this kind of maneuver is only performed in cases of flexion distraction injuries.
A cohort of 20 patients with thoracolumbar burst fractures fulfilling the inclusion criteria were prospectively submitted to surgical treatment of monosegmental transpedicular fixation plus posterior fusion. All instrumentations were performed with pedicle screws inserted bilaterally into the fractured level and 1 adjacent level, either superior or inferior depending on the locating side of the intact endplate. All patients were followed up. The preoperative radiographs, the postoperative radiographs within 1 week of operation, and the radiographs of the most recent follow-up were evaluated for kyphosis correction recorded in the Sagittal Index and Load-Sharing Classification (LSC) index. The postoperative functional outcomes were evaluated using the Frankel Performance Scale together with the Denis Pain Scale.
Eighteen patients were followed up successfully with an average final follow-up of 24.7+/-8.0 months. The focal kyphotic angulations were corrected satisfactorily with the mean Sagittal Index of preoperative 16.5+/-6.6 degrees, initial postoperative 4.0+/-2.4 degrees, and latest follow-up 4.8+/-4.0 degrees. No obvious loss of correction occurred except for 2 patients who both scored 8 points on the LSC Score. Postoperatively, most patients attained both functional neurologic improvement and pain relief, and only a few complications were noted.
For selected thoracolumbar burst fractures, MSPI can provide the same or better fixation and preserve more motion segments than other methods of posterior pedicle instrumentation. With preoperative evaluation using the spinal LSC system, MSPI is effective and reliable for the treatment of thoracolumbar burst fractures when properly indicated.
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Article: 雙導程蝸桿蝸輪組之最佳化設計[Show abstract] [Hide abstract]
ABSTRACT: 本文是針對雙導程蝸桿及蝸輪做最佳化設計, 最佳設計分兩階段進 行. 第一階段以雙導程蝸桿公稱節圓直徑及蝸輪公稱模數為設計變數, 針 對導程角在變形, 應力, 第一自然振動頻率和幾何條件之束制下進行最大 化之計算, 以期達到高效率和最佳剛性的目的, 在確定雙導程蝸桿公稱節 圓直徑及蝸輪公稱模數後, 進行第二階段最佳化設計. 第二階段是以左右 側模數與公稱模數的差值和壓力角為設計變數, 針對齒面正向力在變形, 應力, 第一自然振動頻率, 避免根切, 中心距, 導程角, 壓力角等束制條 件下進行齒形正向力最小化之設計, 以降低因低速運轉時摩擦所造成之損 失, 進而確定出最佳之壓力角, 齒形角, 左右側模數與公稱模數的差值. 將上述兩階段最佳化所得之細部設計尺寸數據結合, 設計出一組在特定工 作環境下最佳傳動效率和高精度的雙導程蝸桿蝸輪組. This thesis deals with the optimum design of duplex worm andworm gear. Two-level optimization is employed in this thesis. In first level, the design variables are the pitch diameter of the duplex worm and module of worm gear. The objective is to maximize the lead angle of duplex worm subjected to constraints of displacements, stress and the fundamental natural frequency. The design purpose is to raise the transmission effiency and the stiffness. After determining the optimum values for the two design variables, the second level optimization is followed. In the second level optimization, the design variables are thedifference of the left and right modules as well as the pressure angle of the gear. The objective is to minimize the normal forces between worm and gear. Inaddition to the constraints used in the first level design, the geometric constraints such as undercut, center distance, lead angle and pressure angle are also imposed. Combining the optimum results obtained by the two level optimization process,an optimum set of duplex worm and worm gear can be generated for aspecific loading condition. Two examples demonstrate the optimum designs of duplex worm and worm gear systems.
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ABSTRACT: To study the outcome of patients with thoracolumbar fracture treated surgically or conservatively at the Armed Forces Hospital, Riyadh, Kingdom of Saudi Arabia, between the year 1989 through to 1999. The medical and surgical record of all patients diagnosed as having thoracolumbar fracture (thoracic 10-lumbar 12) between the years 1989 to 1999 were reviewed. The parameter studies included the personal patient data, type of fracture, mechanism and cause of injury and neurological affection. For the outcome, the method of treatment and recovery from neurological deficit, return to pre-injury activity and work as well as complications were noted. One hundred patients were treated for thoracolumbar fracture. Seventy two percent were related to motor vehicle accident, 37% had neurological deficit, 19 of them had complete lesion. Thoracic 12 Lumbar 1 constituted 63% of injury level. Forty-four patients were treated surgically whereas 56 had conservative treatment. At follow up, 17 patients had complete recovery from neurological deficit while 6 had partial recovery and 14 had no recovery at all. No major complication has occurred due to method of treatment in both groups. Treatment of thoracolumbar fracture was carried out using both surgical and conservative methods. In our view, surgical treatment is indicated in cases of instability or removal of retropulsive fragment if there is neurological deficit or to correct deformity. For other cases conservative treatment was selected and gave satisfactory results.Saudi medical journal 07/2002; 23(6):689-94. · 0.55 Impact Factor
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ABSTRACT: Thoraco-lumbar fractures (Th10-L2) in young adults are common and often associated with profound socio-economic consequences . Most of these result from motor vehicle accidents and falls from heights, which involve high kinetic energy and affect mainly males. Very often, patients are polytraumatized and present with associated thoracic and/or abdominal injuries. Initial in-hospital management is carried out following the Advanced Trauma Life Support (ATLS) guidelines, where priority is given to stabilization of vital functions and only then to neurologic functions. The traumatized spine is assessed using standard radiologic imaging, as well as CT scan. MRI can provide valuable information about neural tissue and disco-ligamentous injuries. Specific treatment decisions will then rely on both intrinsic (e.g., fracture morphology, neurologic status, mechanical instability) and extrinsic factors (e.g., age, occupation, level of physical activity). The main goal of surgical treatment is to protect the neural tissue by mechanically stabilizing the spine and additionally decompressing the spinal canal if necessary. We present here an overview of current treatment options available to surgeons for the treatment of thoraco-lumbar fractures.12/2009: pages 87-96;