Application of the techniques of pedicle screw fixation in t horacolumbar spine has forcefully promoted the development of spinal surgery. Th e key to the techniques is that the pedicle screw insertion must be located into the sole exact routeway of the three-dimensional-space, that is, into the inn er vertebral body through the pedicle according to the exact arrow plane angle a nd horizontal plane angle. Recently great development has been made in the resea rch on the techniques of pedicle screw insertion in thoracolumbar spine, especia lly in the supervising means during operation. The means have been developed fro m the traditional X-ray perspective or photograph apposition to the application of computer-assisted technique. This paper reviews and discusses the current d evelopment and prospects in the research on the techniques of pedicle screw inse rtion in thoracolumbar spine.

Objective To evaluate the long term outcome of spondylolytic spondylolisthesis treated with Steffee system and posterolateral fusion. Methods Thirty- four patients were followed up for an average of 77.2 months. The follow- up study include slipping percentage, slipping angle, heights of intervertebral space and foramen, fusion rate, screw broken rate and clinical outcomes. Results 1) Solid fusion was obtained in 88.2％ of patients. screw broken rate was 2.9％ . 2) Comparison of pre- and post- operative slip showed correction rate of 45.1％ . The heights of intervertebral space and foramen increased, slipping angle decreased. 3) During the period of follow- up, recurrence of deformity was found. 4) The subjective outcome was better than the objective outcome. Conclusion 1) Lumbar spondylolytic spondylolisthesis with radicular symptom need complete decompression and reduction as much as possible. 2) A positive slipping angle indicates significant shearing force and the need of an interbody fusion to restore the weight- bearing capacity. 3) Objective criteria is more suitable to evaluate surgical outcome.

Objective To discuss the necessity of cervical spinal plating after single-level anterior decompression and fusion on mono-segmental cervical disc herniation and cervical spondylosis without obvious kyphotic deformity and segmental lability. Methods The ranges of motion of the two groups with and without plating were tested under the load of 2.0 Nm on cervical spine specimens taken from 16 fresh cadavers. Finite element method was used to calculate the strength of bony callus and the average stress of the parts adjacent to the fused segments at various time intervals. 45 cases after single-level anterior decompression and fusion with and without cervical plating were followed-up at least 3 years, and 33 ones without cervical plating, more than 10 years. Results The test of specimens showed a higher stability of the group with plating just after operation (P

Objective To evaluate the efficacy and safety of balloon kyphoplasty in the treatment of painful multi-vertebral osteoporotic compression fractures. Methods From October 2002 to April 2007, 42 patients (96 vertebrae) with painful multi-vertebral osteoporotic compression fractures underwent kyphoplasty. The group included 14 men and 28 women with an average age of 72.5 years (range 56-91 years). Each pro-cedure included insertion and insertion of balloon, fracture reduction and cement filling under "C"-arm monitoring. Preoperative and postoperative pain level, SF-36 score, vertebral height restoration, local kypho-sis correction and complications were recorded and analysed. Results All 42 patients tolerated the opera-tion well and were followed up for average 31.4 months (range 12-71 months). The mean VAS pain score decreased significantly from 7.1±2.4 preoperatively to 2.7±1.3 postoperatively, the mean height of anterior and medial vertebral body were (1.8±0.5) cm, (1.6±0.6) cm preoperatively and (2.3±0.6) cm, (2.2±0.7) cm postoperatively. No significant change of posterior vertebral height was recorded postoperatively.The mean correction of local kyphosis was 9.2°at each level. 6 of 8 subscahs measured by SF-36, including physical function, role function, bodily pain, vitality, role emotion, mental health, were significantly improved by the operation. Complications were found in 7 patients including 6 cases of cement leakage with no clinical symptoms (intradiscal cement leakage in two cases, paravertebral vessel leakage in two cases, paravertebral leakage in one case and cement leakage into canal in one case), and 1 case of pulmonary embelization with symptoms relieved after conservative treatment. Conclusion Kyphoplasty is effective and relatively safe for multi-vertebral osteoporotic compression fractures.

Objective To investigate the causes and clinical significance of cement leakage into disc space during kyphoplasty. Methods Since 2002, 178 patients with osteoporotic vertebral compression fractures underwent kypboplasty and 15 of them were detected intradiscal cement leakage and followed up more than 2 years (mean 2 years and 8 months). The mean injection of cement in these patients was 4.2ml.The series comprised 10 females and 5 males, with an average of 71.2 years old ( range, 54～84 years old).Visual analog scale was used to score back pain pre- and postoperatively. The height and MRI index of the involved disc were recorded and compared. Results The discs involved were as following: T10-11 for 4 cases,T11-12 for 1, T12L1for 4, L1-2 for 2, L2-3 for 3, L3-4 for 1. Cement leakage was detected in the disc above the fractured vertebrae in 10 cases, and in the disc below the fractured vertebrae in 5 patients. The back pain significantly alleviated and the average visual analog scale (VAS) score was decreased from 8.5±2.1 preoper-atively to 3.3±1.4 postoperatively (P< 0.05). The anterior disc height was (5.1±2.1)mm preoperatively and (4.8±1.9) mm at the final follow-up, the middle disc height was (7.4±3.2) mm preoperatively and (7.3±2.9) mm at the final follow-up, the posterior disc height was (4.9±2.5) mm preoperatively and (5.0±1.8) mm at fi-nal follow-up, the heights of intervertebral space were well maintained. The signal intensity decreased and became inconsistent in some discs, and the preoperative MRI index significantly decreased from 25482.4± 3467.5 to 18927.6±2519.4 at the final follow-up (t=1.967,P< 0.05). Conclusion Pain relief is impressive in patients with intradiseal cement leakage during kyphoplasty. However, cement leakage into disc space may accellerate the process of disc degeneration.

Objective To apply cervical pedicle screw system (CPSS) to treat cervical disorders and discuss its surgical indications, techniques and clinical effectiveness. Methods A total of 52 patients with middle and lower cervical spine lesions who underwent cervical transpedicular fixation were analyzed retrospectively. There were 41 males and 11 females aging from 16 to 62 years. The diagnosis of the patients were fractures and dislocations of cervical spine accompanied by complete paralysis (28 cases) or incomplete paralysis (19 cases) in 47 cases, and metastatic bone tumor in 5 cases. Prior to surgery, anteroposterior and lateral radiographs, CT scan through bone windows, and/or magnetic resonance images were carried out in all patients. During surgery, all screws were inserted into the pedicle under the guidance of lateral or oblique image intensifier to confirm the direction and insertion depth of screws. In 7 to 14 days after surgery, physical examination and roentgenograms evaluations were performed in all patients, and CT scans were obtained in 31 patients, the location of screws were evaluated with the radiographic examinations and CT scan. The follow-up period averaged 13 months (range, 1 to 36 months) in 38 patients. The authors experiences in achieving accurate pedicle screw insertion was introduced, the clinical value of using cervical pedicle screw system to manage cervical lesions was summarized, the possible complications of CPSS were analyzed, the candidates of using CPSS were discussed as well. Results Pedicle screws were inserted successfully in all cases, 9 cases were found to have nerve irritating symptoms by 10 pedicle screws when which were introduced into pedicles, however, by changing the direction of the screws, all symptoms disappeared and screws were successfully inserted. Postoperative radiographic evaluation confirmed proper insertion of screws except 2 screws perforating the lateral pedicle wall but without injury of the vertebral artery demonstrated on CT scans. In the followed-up, no screw breakage and loosening was observed. By applying distractive force between the screws placed into pedicles, the space between the affected vertebrae and discs could be increased, displaced anterior fragments of bone or disc could also be indirectly reduced from the spinal canal, and additional anterior decompression interventions might be avoided. Conclusion CPSS can be considered as one of alternative in posterior cervical internal fixation systems. However, specific caution must be taken. The candidates of utilizing CPSS should be properly selected.

Objective To observe the expression changes of heme oxygenase-1(HO-1) and its mRNA after spinal cord injury (SCI). Methods SD rats were randomly divided into normal (n=5), control (n=5) and experimental group (n=10). The rats were given no operation in the normal group, laminectomy only in the control and both laminectomy and traumatic injury in the experimental group. The SCI animal models were made by using a modified Allen's weight-drop device (50 g.cm) on T 12 . Rats were sacrificed at 1 and 3 days after injury. The distribution and content changes of HO-1 and its mRNA in spinal cord segments were observed by means of immunohistochemistry and in situ hybridization. Results Expression of HO-1 was mainly in neurons in the normal spinal cord. After injury, HO-1 expressed primarily in astrocytes and microglia and the distribution of positive cells closely correlated with intraparenchymal hemorrhage. Protein began to increase at the first day after injury. The expression intensity and the area of positive cells were (148.26?11.39) and (90.50?8.70)?10 3 ?m 2 respectively. At the third day, protein expressed more significantly with expression intensity of (128.03? 12.59) and area of (112.99?10.01)?10 3 ?m 2. The expression intensity and area of positive cells expressed by mRNA were (106.02?9.10) and (70.05?9.26)?10 3 ?m 2 respectively at the first day after injury, (85.82?9.07) and (87.37?10.95)?10 3 ?m 2 respectively at the third day after injury. There was significant difference between experimental and control groups ( P

Objective To summarize the surgical techniques and results of b oth-column acetabular fracture through combination of ilioinguinal and Kocher-La ngenbeck approaches. Methods Between March 1990 and July 2001, 66 patients affec ted by both-column acetabular fractures were treated surgically through the comb ination of ilioinguinal and Kocher-Langenbeck approaches. There were 39 males an d 27 females with an average age of 37 years (range, 19 to 56 years). According to Letournel classification, all patients were diagnosed as the both-column frac tures of acetabulum. Of 66 patients, 14 were associated with dislocation or subd islocation of femoral head, 8 with dislocation of ipsilateral sacro-iliac joint, and 8 with intra-articular fragments. The interval from injury to operation was within 2 weeks in 24 and more than 2 weeks in 42. The surgical indications were as follows: 1) dislocation of both column fractures over 3 mm; 2) anterior colu mn fracture associated with severe posterior column comminuted fracture or poste rior wall fracture; 3)injury lasting more than 2 weeks; 4) injury associated wit h femoral head dislocation; 5) injury associated with intra-articular fracture f ragment. Postoperative reduction quality and long-term radiographic results were evaluated according to the Matta and the Epstein criterion separately; the d’A ubigne rating scale was used for the functional results. Results The average ope rative time was 4 hours, the average blood loss was 1 400 ml. Anatomic reduction were obtained in 57 cases (86%), satisfactory reduction in 6 (9%) and unsatisfa ctory in 3 (5%). The follow-up were from 2 to 13 years with an average of 6 year s. The clinical results were 89% excellent and good, 6% fair and 5% poor respect ively; the roentgenographic results were 82% excellent, 10% fair and 8% poor res pectively. 5 cases(8%) with Grade Ⅲ heterotopic ossification were found in Ko cher-Langenbeck approach, and no heterotopic ossification was in ilioinguinal ap proach. There was 1 deep infection (1.5%) in the ilioinguinal approach, and no i nfection in the Kocher-Langenbeck approach. Conclusion The results achieved thro ugh the combined approaches were significantly better than that of the both-colu mn acetabular fractures using the extended iliofemoral approach. The combined ap proach is an ideal method for the operation of the both-column acetabular fractu res with an excellent exposure, satisfactory reduction, shorter operating time, less blood loss, and lower operative complication rate.

Objective To analyze the clinical results of percutaneous vertebr oplasty (PVP) for osteolytic spinal tumor. Methods Forty patients with osteolyt ic vertebral metastases or myeloma were selected from Feb. 2000 to Jun. 2003 to undergo percutaneous vertebroplasty. All patients complained of back pain. Among them, 6 cases had radiculopathy, and 1 had paraplegia. Based on CT or MR scanni ng, the posterior vertebral wall was involved in 21 cases. 42 PVP was performed on 59 segment levels under fluoroscopic or CT guidance, including 1 at cervical spine, 29 at thoracic spine, 27 at lumbar spine and 2 at sacrum, and biopsy was performed in 28 cases simultaneously. CT scanning was conducted after interventi on to assess the lesion filling and cement leakage, and all patients were asked to remain lying on bed for 4 hours prior to axial loading. In combination with P VP, radiotherapy, chemotherapy, medicament were administered before or after the intervention. Results The procedure was technically successful in all patients with an average injection amount of 6.5 ml cement per vertebral body. Partial or complete pain relief was achieved in 39 cases, associated with improved mobilit y in 38 cases, the symptoms of patients with radiculopathy and paraplegia were u nchanged. Two cases with severe multiple vertebral destruction underwent PVP at one segment, neither of them experienced improved mobility. In one case, the sev erity of pain was unchanged, while the other experienced partial pain relief for 48 hours. Leakages were detected with CT at 21 levels of 17 cases. 2 of 7 epidu ral leakage produced transitory radicular pain, which were relieved in 6 h and 8 h respectively. 2 with intervertebral foraminal venous leakage, 8 with paravert ebral leakage, and 6 with intra-disc leakage had no clinical symptoms. 37 cases were followed up from 2 to 32 months (average, 8.5 months). Exclusive of poor re sults in 2 patients, pain relief was sustained in 29 cases, and 6 patients exper ienced relapse of pain following partial pain relief, which was related to the d eterioration of tumors. Conclusion PVP of osteolytic spinal tumors is a minimal invasive procedure that provides immediate and stable pain relief with improved mobility. It can be combined with radiotherapy or chemotherapy.

Objective To evaluate the methods and results of revision surgery for posterior lumbar cage interbody fusion (cage-PLIF) with postoperative complications, and to analyse the surgical techniques for prevention of these complications. Methods From October 1996 to December 2002, 21 patients with postoperative complications of cage-PLIF underwent reoperations. There were 11 males and 10 females with an average of 43.4 years. The interval between primary and revision surgery ranged from 6 days to 1.5 years with an average of 0.6 year. 16 patients suffering from lumbar disc herniation were treated with the discecto-my and single uninstrumented cage fusion, 5 patients of lumbar spondylolisthesis were treated with cage-PLIF and pedicle screw instrumentation. The complications included cage displacement backward in 20 patients, forward in 1,and cage subsidence in 9 as well. 15 patients complained of low back pain wors-ening or leg radicular pain, of which 4 had intermittent claudication and 10 had leg numbness or weakness during rehabilitation. Revision surgery included re-implantation of the cage filled with iliac crest bone chips in 11 patients, iliac bone autograft after removal of original cages in 7 and decompression of involved nerve root witbout removal of migrated cage because of technical difficulty. Pedicle screw fixations were used in 12 and the intertransverse fusion both with autograft and allograft was added in 7. Results The mean follow-up was 14.2 months (ranged, 7 to 36 months). The cages presented slight retro-displacement in 4 patients shortly after reoperation, without involvement into spinal canal during the subsequent follow-up. Bony fusion occurred in 13 patients, and the pseudarthrosis in 3 patients without further migration of cages. The clinical symptoms relieved in 5 patients, improved in 9, no any change in 6, and worsened in 1. However, low back pain remained in 8 patients, and dysuria in 1 patiant at the last follow-up. Conclusion The results of revi-sion surgery are not satisfactory according to this study, the surgical treatments should be performed as soon as possible if conservative treatments is ineffective. The correct surgical indication and proper technical are the key of prevention of the postoperative complications.