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BACKGROUND: Because of the non-homology of protein and gene between human and animals, to promote osteogenesis or spinal fusion of animals by construction of tissue-engineered bone with the human gene has influenced the experimental validation.OBJECTIVE: To construct the seed cell line for bone tissue engineering with stable expression of human bone morphogenetic protein 2 (hBMP2).METHODS: The full-length hBMP2 gene was cloned from human muscle tissues by nested RT-PCR and transfected to human bone marrow mesenchymal stem cells (hBMSCs) with lipidosome. The transfected hBMSCs were cultured with G418 in vitro to screen and purify the cells. A series of analyses such as RT-PCR, dot-ELISA, immunohistochemstry and alkaline phosphatase activity analysis were performed to evaluate the situation of hBMP2 expression and secretion at 48 hours and 3 weeks after the transduction. hBMSCs transduced with empty plasmid and the normal hBMSCs served as positive control and blank control groups, respectively, which were used for observation of cell growth, proliferation and biological characteristics of transfected cells. RESULTS AND CONCLUSION: The transfected hBMSCs appeared in small groups or clusters, and had a good proliferation after subculture in vitro. Some G418-resistance cell clones and calcium nodules were found when cultured with G418 in vitro. No significant difference was noted in the cell proliferation between the hBMP2 transfection group and two control groups. The ALP activity in the hBMP2 transfection group remained significantly higher than that in the two control groups (P < 0.01). At 48 hours and 3 weeks after transduction, hBMSCs could express actively hBMP2 by RT-PCR monitoring, and had a positive reaction of dot-ELISA and immunohistochemical analysis. The expression of hBMP2 gene in the experiment group at 48 hours was significantly higher than that at 3 weeks after transduction while there was no expression of hBMP2 gene in the two control groups. The above results show that the hBMSCs transfected by hBMP2 gene not only have potentials of normal proliferation and osteogenic differentiation, but also can stably express hBMP2.
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BACKGROUND:In clinical application, the structure of crista lambdoidalis of L5 was unclear. It needs to expose more tissue to define L5 entry point through transverse process or superior and inferior articular process. This increased the risk of trauma and iatrogenic superior intervertebral degeneration. Therefore, it is necessary to expose L5 entry point with a minimaly invasive way. OBJECTIVE:To investigate the accuracy of L5 pedicle screw insertion with the entry point of mastoid process slope by imaging. METHODS:Mastoid process was located on the base of L5 superior articular process. A cant was formed when the highest point of L5 mastoid process backward protuberance extended inwards and downwards. The cant was defined as mastoid process slope; it was lateral to pedicle medial superior side internaly, medial to transverse process root and superior to the top of crista lambdoidalis. The slope was first easily touched and exposed in lumbar posterior surgery through paraspinal muscle space approach. Fifty patients of lumbar spine disorders were treated by L5 pedicle screws fixation through the entry point of mastoid process slope. According to preoperative radiographic and CT images, pedicle screw insertion direction of the sagittal and transverse sections was calculated. The diameter of pedicle screw was 6.5 mm. The condition of intraoperative successful rate of screws placement at one time was analyzed. The accuracy of screw placement was evaluated by postoperative radiographic and CT images. RESULTS AND CONCLUSION:With the method of the mastoid process slope, the successful rate of screw placement at one time was 96% (96/100). Totaly 100 screws were inserted into L5. According to the criterion by Gertzbein, 95 screws (95%) totaly located in pedicles and 5 screws (5%) encroached on the pedicle from medial wal. Three (3%) out of 5 inaccurately placed screws cut out less than 2 mm of the inner wal, while 2 (2%) between 2 mm and 4 mm, without neurologic deficits. The method of mastoid process slope had a high successful rate of screw placement. Combined with preoperative X-ray films and CT images could obtain a high accuracy rate of screw insertion.
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Objective To investigate the feasibility of mono-segment pedicle instrumentation (MSPI)in management of thoracolumbar fracture (AO classification,A1 and A3) by being compared with short-segment(two-segment) pedicle instrumentation(SSPI).Methods Overall 141 patients with tape A1 or A3 thoracolumbar fractures,aged from 20 to 60 years (average,40.5 years),were enrolled in this prospective study.According to a simple randomized method,35 patients with type A1 fracture and 41 patients with type A3fracture were treated with MSPI,while 26 with type A1 fracture and 39 with type A3 fracture were treated with SSPI.Low back outcome score (LBOS) and ASIA2000 were used to evaluate clinical outcome.Eighteenth month postoperatively was assigned as the last follow up period.Wedge index (WI) and sagittal index (SI) of the affected vertebrae on radiography were measured and compared preoperatively,one week postoperatively and at the final follow-up.Results All patients were followed up successfully.The blood loss and duration of operation of MSPI group were significantly less than that of SSPI group,respectively.However,there were no significant differences of clinical outcome between two groups.For type A1 fracture,correction rate and correction loss of WI in MSPI group were better than those in SSPI group.For type A3 fracture,there were no significant differences of correction rate and correction loss of WI and SI between MSPI group and SSPI group; however,the failure rate of MSPI group was significantly higher than that of SSPI group.Conclusion For type A1 and partial type A3 thoracolumbar fractures,MSPI can provide the same or better fixation with less blood loss and operative duration than SSPI.Since MSPI for type A3.2 thoracolumbar fracture has a higher failure rate,the surgical indication should be strictly controlled.
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BACKGROUND: Kyphoplasty-assisted bone cement augmentation can be used in lumbar pedicle screw fixation of osteoporotic patients.OBJECTIVE: To assess the fixation strengths of loosened sacral screws augmented with kyphoplasty-assisted and traditional bone cement techniques.METHODS: Fresh sacra were harvested from nine osteoporotic cadavers. After testing bilaterally placed unicortical and bicortical pedicle screws, two unicortical pedicle screws with the traditional and kyphoplasty-assisted cement augmentations were established on the same sacrum. Following 2000 cyclic compression loading to screw head on a MTS machine, their maximum pull-out forces were recorded and compared. RESULTS AND CONCLUSION: The bone mineral densities of nine specimens were ranged from 0.61 to 0.77 g/cm2 (0.71 g/cm2 in average). The mean maximum pull-out forces of unicortical and bicortical screws, and traditional and kyphoplasty-assisted cement screws were 203, 325, 437, and 565 N, respectively. The pull-out force was significantly higher in bicortical screw compared with unicortical (P < 0.05); however, these two fixations exhibited markedly lower pull-out strength compared with two cement augmentation techniques (P < 0.05). The pull-out strength was significantly higher in kyphoplasty-assisted cement augmentation group compared with traditional bone cement technique (P < 0.05). In addition, a significant positive correlation was exhibited between bone mineral density and pull-out force for the four fixations (P < 0.05). Results demonstrated that traditional and kyphoplasty-assisted cement augmentations can serve as the salvage technique for loosening sacral screw. However, kyphoplasty-assisted augmentation can provide higher stability.
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Objective To analyze and evaluate the effect of posterior circumferential fusion for treatment of the mechanical instability of lumbar spine, and discuss the relative merits,indications and contraindications in this procedure. Methods Two hundred and two patients with mechanical instability of lumbar spine treated by the posterior instrumented circumferential fusion technique from January 2001 to January 2007. One hundred and thirty-two patients were selected who were treated with only one segment fusion and followed up for at least 1 year, of them 97 patients suffered lumbar spondylolisthesis, 35 patients suffered degenerative lumbar instability. X-ray was used to evaluate the fusion condition of the bone graft, and VAS and ODI questionnaire were applied to assess the pain of back and leg,and the conventional function. Results All patients were followed up for 12-84 months, averaged (43±23) months,125 patients got bone fusion, accounted for 94.7%(125/132). The VAS of low back pain was (6.71 ± 1.31) points before operation, while (3.20 ± 1.14) points after operation (P < 0.05) ,and the VAS of leg pain was (8.33 ± 1.78) points before operation,while (4.31 ± 1.15) points after operation (P< 0.05). The ODI was (68.6 ± 14.7) % before operation, while (13.6 ± 1.5) % after operation (P < 0.05). Conclusions Posterior circumferential fusion is a positive and excellent treatment for the mechanical instability of lumbar spine. With its merits, the high fusion rate and good clinical results can be received.
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Objective To evaluate the clinical efficacy of monosegmental pedicle instrumentation in management of thoracolumbar burst fractures. Methods A total of 67 patients with traumatic thora-columbar burst fractures (type A3.1 and A3.2) were treated with monosegmental pedicle instrumentation in our department from October 2003 to February 2008. Imageologic effect was observed by measuring sagittal index and wedge index via X-ray and clinical outcomes evaluated by using low back outcome score. Results All operations were performed successfully, with average operation duration of 93 mi-nutes and average intraoperative blood loss of 157 ml. Of all, 65 patients were followed up for 4-27 months (average 19.8 months), which showed that all the patients achieved bony fusion, with no implant failure except for one with screw loosening. The sagittal index and wedge index were 13.06°and 42.9% preoperatively and 4.47° and 21.78% postoperatively, with statistical difference (P <0.01). The final follow-up showed no significant correction loss except for two patients (P < 0.05). The low back outcome scores of all patients at follow-up were improved significantly (P < 0.05). Conclusions Monoseg-mental pedicle instrumentation has advantages of minimal invasion, short operative duration, less blood loss and less vertebral motion segment loss and hence is an effective and reliable operative technique for thoracolumbar burst fractures.
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BACKGROUND:Antedor canulated screw has been considered an ideal method to treat odontoid fracture.OBJECTIVE:To compare the biomechanical properties of different anterior screws.DESIGN,TIME AND SETTING:A randomized contrast study was performed at the Biomechanics Laboratory of Southern Medical University from March to September 2006.MATERIALS:Double-thread canulated screws and single-thread canulated screws were made of titanium alloy and provided by Shuangyang Medical Apparatus Co.,Ltd.,Suzhou.METHODS:A total of head-neck complexes (C0-C3) which were collected from 20 corpses were maintained in formaldehyde for less than 3 months;thereafter,the muscles and ligaments were removed to obtain the axis specimens so as to make type Ⅱ odontoid fracture models.The fracture samples were individually treated with double-thread and single-thread canulated screws,with 10 samples for each group.MAIN OUTCOME MEASURES:The shear stiffness and the maximum resistance of the two kinds of screw were tested in this study.RESULTS:The shear stiffness of the double-thread screw group was significantly higher than the single-thread screw group (P＜0.01 );however,there was no significant different in the maximum resistance between the two groups (P＞0.05).CONCLUSION:Double-thread canulated screws have a strong biomechanical stability for treating odontoid fracture;therefore,the first choice of the internal fixation should be double-thread canuiated screws for patients with osteoporosis or those who are susceptible to expanded screw pathway during surgical procedures.
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BACKGROUND:Hydroxyapatite (HA) artificial bone,as bone grafting substitute,would not cause inflammatory reaction or immunological rejection and possesses good biocompatibility after transplantation into human body.It is a novel implant material with bone conduction ability.OBJECTIVE:To investigate the efficacy of HA artificial bone in bilateral open-door posterior cervical expansive laminoplasty and to make a comparison with autogenous bone.DESIGN,TIME AND SETFING:A retrospective case analysis was performed at the Department of Spine Surgery,Hungpuyuan Branch,the First Affiliated Hospital of Sun Yat-sen University from March 2001 to December 2008.PARTICIPANTS:Seventy patients with cervical spondylosis complicated by compression in 3 or more segments or by cervical stenosis and additional fifteen patients with cervical stenosis complicated by cervical trauma were included in this study.METHODS:A bilateral open-door posterior cervical expansive laminoplasty was performed,in which,23 patients received autogenous bone transplantation (autogenous bone group) and 62 patients underwent HA artificial bone transplantation (HA group).MAIN OUTCOME MEASURES:① Japanese Orthopaedic Association (JOA) score pdor to and after surgery,surgery time,and intraoperative bleeding.② HA artificial bone-host biocompatibility.RESULTS:All eighty-five patients were followed up for more than 3 months.There was no significant difference in JOA scores no matter prior to or after surgery between the autogenous bone and HA groups (P＞0.05).The surgery time averaged 85.2 minutes (range 65-110 minutes) in the HA group and averaged 116.4 minutes (range 75-150 minutes) in the autogenous bone group.The intraoperative bleeding averaged 210 mL (range 130-400 mL) in the HA group and averaged 260 mL (range 170-500 mL) in the autogenous bone group.There were no material-host response and other severe complications found in each group,except HA artificial bone fragmentation in 3 patients from the HA group.CONCLUSION:HA artificial bone yields good efficacy and causes fewer complications in bilateral open-door posterior cervical expansive laminoplasty;in addition,it requires less time for surgery and causes less bleeding.