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Reconstruction after resection of tumor about the acetabulum represents a considerable challenge in reconstructive surgery. Between 1999 and 2003, three patients with periacetabular tumors underwent tumor resections (Ennecking type B) and pelvic ring reconstruction with microsurgical fibular flaps. Histological diagnosis showed osteosarcoma, giant cell tumor, and aneurysmoid bone cyst. All patients survived surgery without complications. The follow-up for patients ranged from 14 to 42 months. The average time for bone healing and full weight bearing was 13.6 weeks after surgery. In evaluations of the functional outcome using Enneking scoring system, two reached the score of excellent (>or= 23 points), and one reached the score of good (15 to 22 points). This report shows our experience in use of microsurgical fibular flaps for arthrodesis of the hip after periacetabular tumor resection, which restores the continuity of the pelvic ring with minimal shortening of the limb.

To investigate the method of separation of culture of bone microvascular endothelial cells (BMECs) of human femoral head in vitro.From October 2013 to January 2014,15 femoral heads without pathologic change from patients resected during hip replacement were selected involving 2 males and 13 females with a mean age of 71.2 years old ranging from 38 to 92. Cancellous bone in femoral head was bited into broken bone grain and transfered into medium in aseptic contidion. Cells were isolated by the methods of enzymic digestion and density gradient centrifugation,purified by differiential attachment. The characteristics of cells was observed by inverted microscope. vWF and CD31 immunofluorescence analysis was applied for identification of cells.The number of cells was positively correlated with patients' age after 24 hours in primary culture. The older patients had the less cells numbered. After 4 to 5 days' culture, primary cells appeared short spindle,polygon shaped and cobblestone-like morphology. After 7 to 10 days' culture, primary cells proliferated densely, became fusion, arranged in swirl, and contact inhibition appeared significantly. Immunofluorescence staining revealed the cells were 100% positive for vWF and CD31, and it showed that the cultured cells were BMECs.It was a simple, steady, effective method with good reproducibility, by which highly purified human BMECs can be obtained.

To evaluate the efficacies of unilateral versus bilateral pedicle screw fixation through the pedicle of fractured vertebra plus short-segment pedicle instrumentation (SSPI) in the treatment of thoracolumbar fractures.Between June 2008 and September 2010, a total of 46 patients with fractures of thoracolumbar junction, whose scores of load sharing classification (LSC) ranging from 5 to 7, underwent the combined treatment of SSPI and fracture level pedicle screw at our department. They were divided into 2 groups. Group I included 25 patients undergoing SSPI plus unilateral pedicle screw fixation through the pedicle of fractured vertebra (5 screws) while Group II included 21 patients had SSPI plus bilateral pedicle screw fixation through the pedicle of fractured vertebra (6 screws). The data of anterior body height compression (AVHC), sagittal Cobb's angle, internal fixation failure, restoration of nervous function, visual analogue score (VAS) and Oswestry disability index (ODI) were analyzed.The groups were similar with regards to age, gender, LSC, AVHC and sagittal Cobb's angle preoperatively. Blood loss volume and operative duration were less in the Group I (109.2 ± 30.68 vs 110.0 ± 32.06 min, t = -0.086, P0.05 and 376.0 ± 303.1 vs 409.5 ± 361.1 ml, t = -0.342, P0.05). They were followed up for a minimum period of 12 months. In follow-up period was 17.48 ± 4.14 months in Group I versus 18.33 ± 4.31 months in Group II (t = -0.683, P0.05). All patients with initial partial neurologic deficits improved at the final follow-up. Radiographic parameters and clinical outcomes were similar in both groups.Pedicle screw fixation through the pedicle of fractured vertebra plus SSPI is an excellent surgical therapeutic choice for patients with a LSC range of 5-7 thoraclumbar fractures. The efficacies of unilateral and bilateral pedicle screw fixation at fracture level are the same.

Thoracolumbar burst fracture is a common clinical injury, and the fracture mechanism is still controversial. The aim of this research was to study the formation of intracanal fracture fragments in thoracolumbar burst fractures and to provide information for the prevention of thoracolumbar bursts fractures and reduction of damage to the nervous system.A nonlinear three-dimensional finite element model of T11-3 segments was established, and the injury processes of thoracolumbar bursts were simulated. The intact finite element model and the finite element model after the superior articular were impacted by 100 J of energy in different directions. The distribution and variation of stress in the superior posterior region of the L1 vertebral body were analyzed. Abaqus 6.9 explicit dynamic solver was used as finite element software in calculations.A three-dimensional nonlinear finite element model of the thoracolumbar spine was created. In the intact model, stress was concentrated in the superior posterior region of the L1 vertebral body. The stress peak was a maximum for the extension impact load and a minimum for the flexion impact load. The stress peak and contact force in the facet joint had close correlation with time. The stress peak disappeared after excision of the superior articular process.The three-dimensional nonlinear finite element model was suitable for dynamic analysis. The contact force in the facet joint, which can be transferred to the superior posterior vertebral body, may explain the spinal canal fragment in thoracolumbar burst fractures.

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, P0.05). 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, P0.05). 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 thoracolumbar fracture with mild to moderate instability.

To build an effective nonlinear three-dimensional finite-element (FE) model of T(11)-L(3) segments for a further biomechanical study of thoracolumbar spine.The CT (computed tomography) scan images of healthy adult T(11)-L(3) segments were imported into software Simpleware 2.0 to generate a triangular mesh model. Using software Geomagic 8 for model repair and optimization, a solid model was generated into the finite element software Abaqus 6.9. The reasonable element C3D8 was selected for bone structures. Created between bony endplates, the intervertebral disc was subdivided into nucleus pulposus and annulus fibrosus (44% nucleus, 56% annulus). The nucleus was filled with 5 layers of 8-node solid elements and annulus reinforced by 8 crisscross collagenous fiber layers. The nucleus and annulus were meshed by C3D8RH while the collagen fibers meshed by two node-truss elements. The anterior (ALL) and posterior (PLL) longitudinal ligaments, flavum (FL), supraspinous (SSL), interspinous (ISL) and intertransverse (ITL) ligaments were modeled with S4R shell elements while capsular ligament (CL) was modeled with 3-node shell element. All surrounding ligaments were represented by envelope of 1 mm uniform thickness. The discs and bone structures were modeled with hyper-elastic and elasto-plastic material laws respectively while the ligaments governed by visco-elastic material law. The nonlinear three-dimensional finite-element model of T(11)-L(3) segments was generated and its efficacy verified through validating the geometric similarity and disc load-displacement and stress distribution under the impact of violence. Using ABAQUS/ EXPLICIT 6.9 the explicit dynamic finite element solver, the impact test was simulated in vitro.In this study, a 3-dimensional, nonlinear FE model including 5 vertebrae, 4 intervertebral discs and 7 ligaments consisted of 78 887 elements and 71 939 nodes. The model had good geometric similarity under the same conditions. The results of FEM intervertebral disc load-displacement curve were similar to those of in vitro test. The stress distribution results of vertebral cortical bone, posterior complex and cancellous bone were similar to those of other static experiments in a dynamic impact test under the observation of stress cloud.With the advantages of high geometric and mechanical similarity and complete thoracolumbar, hexahedral meshes, nonlinear finite element model may facilitate the impact loading test for a further dynamic analysis of injury mechanism for thoracolumbar burst fracture.

To detect the cartilage changes of hip joint with osteonecrosis of femoral head (ONFH) in stages II and III and provide evidence for understanding cartilage changes of femoral head of osteonecrosis before collapse.The cartilage changes of ONFH were determined by delayed gadolinium enhanced magnetic resonance imaging of cartilage (dGEMRIC). According to ARCO classification of ONFH, the samples were divided into three groups: Group A, 11 hips, stageII; Group B, 13 hips, stage III; Group C, 10 hips, normal. All participates underwent the tests by dGEMRIC. And the data of T1Gd were collected and analyzed.The values of T1Gd were 420 ± 60 (Group A), 361 ± 54(Group B) and 538 ± 26 (Group C) respectively. There was a significant difference among three groups. The values of T1Gd in the ONFH patients were lower than their healthy counterparts. The values of TIGd of Group B was 14% lower than those of Group A. And the difference was significant statistically.Cartilage of the femoral head undergoes abnormal metabolic changes before collapse. There is a loss of GAG in the cartilage and it aggravates with the worsening of ONFH.

To analyze retrospectively the formation and histological changes of sclerosis rim in patients with osteonecrosis of the femoral head (ONFH), and to study the relationship between bone morphogenetic proteins (BMP4) and sclerosis rim, so as to acquire experimental and theoretical basis on individualized treatment for ONFH patients.From November 2005 to November 2007, 184 hips of steroid-induced ONFH inpatients were collected. The mean age was (47 ± 7) years, the patients were divided into high (more than 54 years old), middle (40 - 54 years old) and low (less than 40 years old) age groups. Their clinical data were analyzed retrospectively according to gender and age. Parts of the femoral heads were selected for the study, including 18 hips in high age group, 11 hips in low age group and 20 hips in middle age group. Each 10 hips were selected with or without sclerosis rim. The femoral heads were cut along middle coronal plane, their weight-bearing and non-weight-bearing areas were used for the study. The specimens were processed by routine HE staining and picric acid-Sirius red staining and electron microscopy preparation and immunohistochemistry stain. The average optical density of BMP4 protein was calculated by image analysis software.The trabecular of sclerosis rim was thickening and disorder. But its osteocytes were normal and with high secretion. The ratio of sclerosis rim was 71.4% (105/147) in middle age ONFH patients, which was significantly higher than the low age group patients (45.5%, 5/11) and high age group patients (38.5%, 10/26) (P0.01). The optical density of BMP4 in middle age ONFH patients was 0.32 ± 0.14, which was significantly higher than the low age group 0.20 ± 0.17 and high age patients 0.19 ± 0.27 (P0.05). The optical density was 0.16 ± 0.11 in ONFH patients without sclerosis rim, which was significantly lower than with sclerosis rim (0.28 ± 0.13) (P0.01). The time from hip pain to joint replacement in patients with sclerosis rim was (49 ± 11) months, and (15 ± 2) months without sclerosis rim. There was significant difference between the two groups (P0.01).The formation of sclerosis rim is positively related to the expression of BMP4, and high expression of BMP maybe promote the formation of sclerosis rim.

To detect the blood perfusion of the necrotic area and the femoral head and neck junction in the patients diagnosed as osteonecrosis of femoral head (ONFH) with laser doppler flowmetry (LDF).From 2007 to 2008, 50 patients with ONFH 82 hips were performed core decompression and autologous stem cells transplantation. Group A was for ARCO stage II 46 hips (IIA 6 hips, IIB 22 hips, IIC 18 hips), and Group B was for stage III 36 hips (IIIA 20 hips, IIIB 10 hips, IIIC 6 hips). Blood perfusion of necrotic area and femoral head and neck junction with LDP were detected during the operation. Statistical analysis was made.In Group A, the perfusion volume of necrotic area was (30.2 +/- 3.0) PU, and the perfusion volume of femoral head and neck junction was (103.4 +/- 4.4) PU. In Group B, the perfusion volume of necrotic area was (30.6 +/- 2.8) PU, and the perfusion volume of femoral head and neck junction was (103.4 +/- 3.9) PU. In Group A and Group B, the perfusion volume of necrotic area was lower than that of femoral head and neck junction, and the difference was significant (P0.01).LDF can effectively detect that the perfusion volume of ONFH decreased, which provides a theoretical basis in order to further study the pathogenesis of ONFH. Meanwhile, there is application value of LDF on the study of ONFH.

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.

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.

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.