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ABSTRACT: To evaluate the efficacy of unilateral pedicle screw fixation through the pedicle of fractured vertebra in combination with the short segment of pedicle screw in the treatment of thoracolumbar fracture of mild to moderate instability.
Twenty-six patients with single segment thoracolumbar fracture received unilateral pedicle screw fixation through the pedicle of fractured vertebra in combination with the short segment of pedicle screw from January 2008 to December 2009. There were 16 patients were male and 10 were female with an average age of 47.3 years (range from 39 to 60 years). Fracture severity score was constructed by using the load-sharing classification (4 points for 2 cases, 5 points for 14 cases, 6 points for 10 cases). By Frankel assessment system, 2 cases were in grade C, 3 in grade D, 21 in grade E. The assessment included anterior vertebral body height, the sagittal Cobb angle, the restoration of nervous function, visual analogue score (VAS) and Oswestry disability index (ODI).
The follow-up after the surgery was 13 - 26 months, with an average of 18.6 months. There were no fixation failure, defined as implant failure or ≥ 10° correction loss. The neurological status of 4 patients, who had an associated neurologic deficit preoperatively, was completely recovered. The Frankel grade of another case was re-rated D from the original C. The mean anterior vertebral body height increased from 57.0% ± 6.3% before the surgery to 93.1% ± 1.7% at the last follow-up(F = 455.276, P < 0.05). The sagittal Cobb angle decreased from 15.6° ± 4.7° before the surgery to 2.6° ± 5.2° at the last follow-up (F = 34.623, P < 0.05). VAS and ODI were 1.0 ± 0.7 and 17.0 ± 5.9 at the last follow-up.
Unilateral pedicle screw fixation through the pedicle of fractured vertebra combined with the short segment of pedicle screw is effective for thoraclumbar fracture with mild to moderate instability.
Zhonghua wai ke za zhi [Chinese journal of surgery] 03/2012; 50(3):234-7.
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ABSTRACT: To measure such operative parameters of unipedicular kyphoplasty as optimal entry point, angle and depth so as to provide rationales for its clinical management and formulate a standardized protocol for unipedicular vertebroplasty.
Ten dry thoracolumbar specimens were prepared for measurement. The entry and target points were defined according to the Roy-Camille method. A 3mm Kirschner wire was used to puncture and view in the anteroposterior and lateral aspects of radiography until a satisfying position. The outside oblique and upward oblique angles were measured on the radiographic pictures. After extraction, the depth of Kirschner wire was measured. The positions of entry point were changed and the largest upward oblique angle and largest declination angle measured on the radiographic pictures.
For safe puncturing, as the outside oblique and upward oblique angles enlarged from T(11) to L(3), the length enlarged from T(11) to T(12) and L(1) to L(3). The accepted error was that the largest upward oblique angle and largest declination angle enlarged from T(11) to L(3). The alteration range for outside oblique angle was extremely narrow.
The experimental results provide the guiding data for the operative management of unipedicular thoracolumbar vertebroplasty. If the pedicle is too small or the angle too narrow, the operative sophistication of vertebroplasty will be highly demanding.
Zhonghua yi xue za zhi 08/2011; 91(29):2051-4.
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ABSTRACT: To present a case series of patients with isolated posterior coronal fractures of lateral tibial plateau treated by direct exposure and buttress plate fixation through posterolateral approach.
Between May 2007 and April of 2008, eight middle aged patients were identified that had isolated posterior coronal fractures of the lateral tibial plateau. All eight patients underwent direct fracture exposure, reduction under visualization, and buttress plate fixation through posterolateral approach.
There were 1 case of split, two cases of pure depression and five cases of split-depression fractures. Four were associated fibular head split fractures without common peroneal nerve injuries. Five patients were injured from a simple fall on riding electrical bicycle while the knee was relaxed in 90 degrees position The articular displacement (8 cases) measured in CT scan was 10.5 mm in average (range 8-15 mm). The cortical split length (from the articular rim to the distal tip, 6 cases) was 2.8 cm in average (range 2.4-3.5 cm). The articular reduction was perfect in seven (absolutely no step-off) and imperfect in 1(<2 mm step-off) as measured by X-ray. With a mean follow-up of 10 months (6 cases > 12 months), the average range of motion arc was 119 degrees , four patients have flexion lag 10 degrees -20 degrees . The average SMFA dysfunction score was 15.8, and average HSS score was 98. All eight patients stated they were highly satisfied.
Direct posterolateral approach by dividing lateral border of soleus muscle, provides excellent fracture reduction under visualization and internal buttress plate fixation for posterior coronal fracture of the lateral tibial plateau. Good functional results and recovery can be expected.
Archives of Orthopaedic and Trauma Surgery 02/2009; 129(7):955-62. · 1.37 Impact Factor
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ABSTRACT: To analyze the pelvic stability after type I resection of iliac tumor.
Six adult cadaveric specimens were tested. The iliac subtotal resection models were established according to Ennecking's type I resection. Markers were affixed to the key region of the pelves. Axial loading from the proximal lumbar was applied by MTS load cell in the gradient of 0-500 N in the double feet standing state. Images in front view were obtained using CCD camera. Based on Image J software, displacements of the first sacral vertebrae (S1) of the resected pelves and the intact pelves were calculated using digital marker tracing method with center-of-mass algorithm.
Serious instabilities were found in the resected pelves. S1 rotational movements around the normal side femoral head of the resected pelvis were found. The average vertical displacement of S1 of the resected pelvis was (7 +/- 3) mm under vertical load of 500 newtons, which were 8.3 times compared to the intact pelvis. The average angle of S1 rotation around the normal side femoral head of the resected pelvis was (4.0 +/- 1.8) degrees, which were 12.5 times compared to the intact pelvis.
Biomechanical model of type I resection of iliac tumor are established. Essential pelvic reconstruction must be introduced because of the serious instability of the bone defection after tumor resection.
Zhonghua wai ke za zhi [Chinese journal of surgery] 04/2008; 46(5):378-80.
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ABSTRACT: The pelvis often needs to be reconstructed after bone tumor resection. A major challenge here for the orthopedic surgeons is to choose a method that gives the best performance which depends upon its biomechanical properties. In this study, a 3-dimensional finite element analysis (FEA) was used to analyze the biomechanical properties of reconstructed pelvis using fibula transplant fixed by four commonly used rod-screw systems.
A total pelvic finite-element model including the lumbar-sacral spine and proximal femur was constructed based on the geometry of CT image from a healthy volunteer. Three-dimensional finite element models of different implants including fibula, rod and screw were simulated using ways of solid modeling. Then various reconstructed finite element models were assembled with different finite element implant model and type I resected pelvic finite element model. The load of 500 N was imposed vertically onto the superior surface of L3 vertebral body, and the pelvis was fixed in bilateral leg standing positions. FEA was performed to account for the stress distribution on the bones and implants. The pelvis displacement of the different rod-screw fixation methods and the maximum equivalent stress (max EQV) on all nodes and element were figured out to evaluate the advantages and disadvantages of different reconstructive methods.
Stress concentration in the fibula transplant was extremely high in the reconstructed pelvis, but could be substantially decreased by internal fixation, which partially transferred the stress from the fibula to the rod-screw systems. High stress concentration was also found in the implants, especially in the connection sites between screw and rod. Among the four methods of fixation, a double rod system with L5-S1 pedicle and ilium screws (L5-S1 HR) produced the best performance: least stress concentrations and least total displacement.
According to the stability and stress concentration, the method of L5-S1 HR fixation combined with fibula transplantation is better than other fixation methods in pelvic reconstruction after type I resection.
Chinese medical journal 03/2008; 121(4):321-6. · 0.86 Impact Factor
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ABSTRACT: To develop a three-dimensional finite element model of normal total adult human pelvis and to establish a platform for biomechanical research of human pelvis.
186 series of traverse CT images of the pelvis, from the third lumbar vertebra (L3) to the upper third of femur, obtained with spiral CT scanning on a healthy man, aged 42, without diseases of lumbar vertebrae and pelvis, were processed. A three-dimensional finite element model of pelvis was constructed directly by producing the units and nodes with the pixels of the original CT films, using ANSYS finite analytical system.
A three-dimensional finite element model of normal human pelvis was constructed including lumbar and proximal femur, which could be divided into 207,248 nodes and 721,820 units.
The established three-dimensional finite element model of normal adult is valid and reasonable, and can be used for biomechanical analysis.
Zhonghua yi xue za zhi 01/2008; 87(47):3346-8.
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ABSTRACT: Osteosarcoma is characterized by high neovascularization and a high propensity for metastasis through bloodstream. This study was to examine whether there is evidence for vasculogenic mimicry in osteosarcoma and to illustrate mechanism of tumor blood vessels formation in osteosarcoma.
Osteosarcoma cell lines (U-2OS) were tested for their ability to form tubular networks in three-dimensional culture containing type I collagen. The structures of the tubular networks were observed with phase contrast microscope and transmission electron microscope (TEM). Morphometric studies using hematoxylin and eosin (HE) stain and CD31 immunohistochemical stain to show tumor-lined channels in human osteosarcoma were also performed.
Observation with light microscope and TEM showed that highly aggressive osteosarcoma cell lines (U-2OS) formed networks containing channels when grown in three-dimensional culture containing type I collagen, in the absence of endothelial cells or fibroblasts. Morphometric observation using HE stain and CD31 immunohistochemical stain showed that tumor cell-lined channels were also detected in vivo in osteosarcoma; by comparison, all vascular areas in the pedicle of osteochondroma or outside osteochondroma were endothelial-lined.
These observations strongly suggest that aggressive osteosarcoma cells may generate vascular channels that facilitate tumor perfusion independent of tumor angiogenesis and have the ability of vasculogenic mimicry.
Chinese medical journal 02/2004; 117(1):94-8. · 0.86 Impact Factor
