[Biomechanical study of atlantoaxial fixation for transverse ligament injury leading to atlantoaxial instability].

OBJECTIVE: To explore the three-dimensional movement of atlantoaxial joint, complete transverse ligament and cracked transverse ligament after posterior atlantoaxial fixation. METHODS: The fresh upper cervical cadaveric specimens were collected from 6 males dead from active craniocerebral injury. The average age was 39.7 years old (range: 26 - 57). The specimens were divided into 3 groups of intact (Group I), transverse ligament cracked (Group D) and posterior atlantoaxial fixation (Group F). They were tested consecutively. RESULTS: The range of sagittal movement increased when the transverse ligament became cracked. And it had significant difference compared with the Group I (P < 0.05). But the ranges of lateral flexion and rotation showed no significant difference. When posterior atlantoaxial fixation was performed, all three-dimensional movements decreased. And significant differences existed as compared with Group I (P < 0.05). CONCLUSION: Under normal conditions, the main movement of atlantoaxial joint is rotation with lesser sagittal movement and lest lateral flexion. The range of sagittal movement increases significantly when transverse ligament is cracked (P < 0.05), especially so for anteflexion movement. The increase of lateral flexion and rotation has no significant difference compared with Group I. When posterior atlantoaxial Fixation is performed, all three-dimensional movements decrease significantly as compared with Group I (P < 0.05), especially loss of rotation function.

[Effect of siRNA-Cox-2 on the growth inhibition and apoptosis of cartilage endplate chondrocytes].

OBJECTIVE: To investigate the influence of siRNA-COX-2 gene upon the growth inhibition and apoptosis of cartilage endplate chondrocytes and provide new methods and evidence for siRNA in gene therapy of cartilage endplate chondrocytes. METHODS: According to the sequence of COX-2 mRNA, COX-2 siRNA was designed, synthesized, cloned into the GFP reporter pcDNA6.2GW/EmGFPmiR vector and transfected into Hep cell line. The integrity of inset fragment was detected by colony PCR (polymerase chain reaction) and sequencing analysis. The cultured cartilage endplate chondrocytes were divided into 4 groups: control group (untreated), negative siRNA group (treatment with 30 nmol/L negative control siRNA), siRNA1 group (treatment with 15 nmol/L COX-2 siRNA) and siRNA2 group (treatment with 30 nmol/L COX-2 siRNA). The biological activity of recombinants was identified with the interference efficiency of COX-2 siRNA recombinant by real-time PCR and Western blot. And the effects of COX-2 inhibitor on the growth of chondrocytes were detected by WST-8 and the mRNA expressions of survivin, bcl-2 and bax genes measured by real-time PCR. RESULTS: The sequences of inset fragment in 4 siRNA expressing recombinants were correct. After COX-2 transfection, the expression of COX-2 mRNA in chondrocytes was 51.3% ± 7.2% in the siRNA1 group and 35.4% ± 3.6% in the siRNA2 group. Western blot showed that the expression of COX-2 protein decreased, especially in siRNA2 group (P < 0.05). And the cell survival rate was 100.0% ± 8.3% in the control group, 84.9% ± 4.2% in the negative control siRNA group, 52.5% ± 6.7% in the siRNA1 group and 48.9% ± 5.4% in the siRNA2 group (P < 0.05). Meanwhile, the expressions of mRNA of survivin and bcl-2 decreased while the expression of bax mRNA increased in degenerative cartilage endplate chondrocytes transfected with COX-2 siRNA (P < 0.05). CONCLUSION: COX-2-targeting siRNA inhibits the expression of COX-2, suppresses the proliferation of chondrocytes and induces the cell apoptosis. These effects may be attributable to the up-regulation of survivin and bcl-2 and the down-regulation of bax.

[Biological characteristics of human umbilical cord-derived mesenchymal stem cells and their differentiation into chondrogenic and osteogenic cells].

OBJECTIVE: To investigate the isolation and expansion of mesenchymal stem cells (MSCS) from human umbilical cord Wharton's jelly and their biological identities, and explore the possibility of inducing human umbilical cord-derived MSCS to differentiate into chondrogenic and osteogenic cells. METHODS: The hUCMSCs were isolated form human umbilical cord by tissue adherence and digested with collagenase NB4, dispase II and hyaluronidase. The morphology, proliferation and immunophenotype of the 3rd passage cells were analyzed, and then the chondrogenic and osteogenic differentiation was tested and evaluated by specific staining methods.cells were induced to chondrogenic and osteogenic differentiation in vitro. RESULTS: The isolation of hUCMSCs by digestion with collagenase NB4, dispase II and hyaluronidase was efficient. After seeded for 24 hours, the adherent cells showed spindle shape and fibroblast cell-like shape and the size of hUCMSCs was homogeneous. Flow cytometry analysis revealed that the hUCMSCs were positive for CD44, CD105, CD90, CD73, but were negative for CD45, CD34, CD14, CD19 and HLA-DR. These cells could be induced to differentiate into chondrogenic and osteogenic cells under proper inducing conditions. The hUCMSCs retained the appearance and phenotype even after being expanded more than 40 passages in vitro. CONCLUSIONS: The human MSCs could be isolated from human umbilical cord Wharton's jelly, and it was easy to propagate these MSCs. An in vitro method for isolation and purification of hUCMSCs from human umbilical cord has been established. The cultured cells were composed of only undifferentiated cells and their biological properties were stable. The hUCMSCs are expected to be a new type of stem cells of tissue engineering.

[Treatment of thoracolumbar mono-segmental fracture with posterior short-segment fixation in combination with intermediate screws: a short-term outcome].

OBJECTIVE: To observe the early clinic outcome of treating thoracolumbar mono-segmental fracture with posterior fixation in combination with intermediate screws. METHODS: From July 2006 to August 2008, 35 of 62 patients with thoracolumbar mono-segmental fracture were treated with in Group A and the remaining 27 with intermediate screw in combination with short segmental fixation in Group B. RESULTS: The relative height of fractured vertebrae and reduction rate showed significant differences [(84.2 +/- 2.8) vs (98.6 +/- 1.9), P < 0.05] between two groups while the change of segmental kyphotic angle showed no difference [(8.5 +/- 1.0) vs (8.1 +/- 1.3), P > 0.05]. CONCLUSION: Intermediate screw in combination with short segmental fixation has a better immediate efficiency in treating thoracolumbar mono-segmental fracture since it reduces the height of fractured vertebrae.

[Application of posterior short-segment fixation combined with intermediate screws in fresh thoracolumbar compressed fracture: short-term outcomes in 27 cases].

OBJECTIVE: To observe the short-term outcomes of the application of posterior short-segment fixation combined with intermediate screws in fresh thoracolumbar fracture. METHODS: Posterior short-segment fixation combined with intermediate screws was used in 27 patients suffering from fresh thoracolumbar fracture, 19 males and 8 females, aged 45 (22-71). X-ray photography was conducted before and after operation. RESULTS: The height of fractured vertebra was 57.6%+/-16.5% of the normal value before operation, and was restored to 93.8%+/-11.9% after operation; the segmental kyphosis angle on the sagittal plane was 20.8+/-9.4 degrees before operation, and decreased to 5.9+/-7.4 degrees after operation (both P<0.001). CONCLUSION: Using pedicle screws on the fractured vertebra via posterior approach conditionally helps reduce the fractured vertebra and correct the kyphosis, and enhance the stiffness of the internal fixation system as well.

[Comprehensive typing and surgical treatment of axial fracture with adjacent section instability: analysis of 17 cases].

OBJECTIVE: To study the clinical and radiographic characteristics of axial fracture with adjacent section instability and the diagnosis and surgical treatment thereof. METHODS: Seventeen patients of axial fracture with adjacent section instability, 11 males and 7 females, aged 34 (23-56) underwent different treatment patterns depending on the fracture type and stability of the atlanto-axial joint and C2-3: resection of C2-3 intervertebral disk and bone grafting, anterior interbody fusion and plate internal fixation, odontoid screw fixation, posterior C2 pedicle screw fixation, odontoid screw fixation combined with bilateral C-2 pedicle screw fixation. Follow-up was conducted for 12 (6-36) months. RESULTS: Postoperatively all patients were immobilized in a hard collar for 3 months. Bony fusion was obtained in all patients in 3 months. There were no operation-related complications, such as spinal cord injury, cerebrospinal fluid leakage, vertebral artery injury, etc. No re-dislocation was found. Neurological recovery was observed in the 3 patients who presented neurological deficits. CONCLUSION: The type of atlas fracture with adjacent section instability and the impact thereof on the stability of the atlanto-axial joint and C2/3 neck joint should be identified early. Surgical treatment results in better outcome.

[Posterior fusion versus posterior interbody fusion in segmental spinal fixation for aged spondylolisthesis].

OBJECTIVE: Clinical and radiographic results in 30 consecutive patients undergoing posterior lumbar fixation and posterior facet joint or posterior interbody fusion for Meyerding Grade II/III spondylolisthesis were assessed: (1) to address the suitability of a dynamic stabilization; and (2) to investigate whether there are differences in terms of clinical and functional results between these two types of arthrodesis. METHODS: Fourteen patients underwent posterior interface fusion (PLF) and implantation of TSRH-3D system. Posterior lumbar interbody fusion (PLIF) and placement of the same system were performed in 16 patients. Clinical, economic, functional and radiographic data were recorded both pre- and postoperatively. RESULTS: The average changes in Prolo Scale of economic and functional scores were 1.25 and 1.64 respectively, in patients undergoing posterior fusion; the average measured vertebral slippage was 48.6% (range 32%-65%) preoperatively and 17.5% (range 15%-25%) postoperatively. In patients undergoing PLIF, the average changes in economic and functional score were 1.18 and 1.39 respectively, and the average preoperative vertebral slippage was 44.2% (range 30%-55%) versus 20.3% (range 18%-26%) postoperatively. CONCLUSION: The use of a segmental pedicle screw fixation with TSRH-3D was able to successfully combine the goal of solid fusion with the requirements of nerve root decompression. When these two fusion techniques were compared, PLIF was superior to PLF because of an overall superior reliability and system resistance. But their clinical outcomes did not differ greatly (P > 0.05).

[Clinical analysis of surgical treatment of odontoid fracture].

OBJECTIVE: To evaluate the therapies and clinical outcome for different types of odontoid process fracture. METHODS: Twenty-one patients with odontoid process fracture were treated with different therapies for different Anderson-D'Alonzo classifications: three cases of type I were treated by traction of occipital-jaw band and fixed with head-neck-chest plaster at 6 weeks; thirteen cases of type II were treated by cannulated screws following skull traction and reduction; and for the cases of type III, one was fixed with screw when the fracture was reduced by skull traction, and four with atlantoaxial pedicle screw. RESULTS: All cases were followed up for a mean of 9 months (range: 3 - 48). All cases achieved bony union. No post-operative complication was found. CONCLUSION: Odontoid process fracture should be treated according to different types. Conservative treatment for type I fracture and cannulated screws for type II and low type III fracture can obtain a satisfactory outcome. Atlantoaxial pedicle screw should be chosen if the superficial type III fracture is not suitable for cannulated screw.

[Treatment of thoracic vertebrae fracture with vertebral pedicle-screw placement in selected injured vertebrae].

OBJECTIVE: To study the clinical effects of vertebral pedicle-screw placement in selected thoracic vertebrae with fresh fracture in reduction and fixation. METHODS: Twenty-five patients with thoracic vertebrae fracture, involving 1 vertebra in 13 cases, 2 vertebrae in 7 cases, and 3 vertebrae in 5 cases, underwent vertebral pedicle-screw placement in selected unilateral or bilateral injured vertebrae with relatively complete pedicle of vertebral arch. Pedicle-screw was inserted into the pedicle of the injured vertebra guided by fluoroscopy to achieve posterior pedicle screw fixation, the height of the collapsed vertebral body was recovered by popping up or extruding the vertebral pedicle-screw. The patients were followed up for 18 - 24 months. RESULTS: The postoperative X-films showed that the direction and length of the screws were satisfying without screw looseness and breakage of the internal fixation. No loss of spinal height of the injured vertebrae was seen after reduction. CONCLUSION: Pedicle-screw fixation of the injured thoracic vertebrae is effective in treatment of fresh thoracic vertebrae fracture.

Non-spinal-associated injuries with lumbar transverse process fractures: influence of segments, amount, and concomitant vertebral fractures.

BACKGROUND: Lumbar transverse process fractures (LTPFs) are often with concomitant non-spinal-associated injuries (NSAIs). The purpose of this study was to analyze the correlation between the NSAIs and the LTPFs of different segments, amount, and concomitant thoracolumbar/lumbar vertebral fractures. METHODS: A total of 1,181 patients with LTPFs or thoracolumbar/lumbar vertebral fractures were chosen between September 2006 and June 2010. The patients were divided into three groups: thoracolumbar/lumbar vertebral fractures without LTPFs, with associated LTPFs, and isolated LTPFs (iLTPFs). The correlation of the NSAIs of different sites and the LTPFs of different segments, amount, and concomitant thoracolumbar/lumbar vertebral fractures were analyzed between and within groups by χ test and logistic regression analysis. RESULTS: The incidence of NSAIs with iLTPFs and aLTFP groups were significantly higher than that of vertebral fractures without LTPF group (55.73% and 64.49% vs. 21.32%, respectively, p = 0.000). However, the incidence was not significantly different between the iLTPFs and the aLTFP groups (p = 0.106). The results with NSAIs of different sites were almost the same. L5TPFs were a stronger risk factor to NSAIs (relative risk [RR] = 15.72; 95% confidence interval [CI], 4.47-55.37; p = 0.000) in the iLTPF group (RR = 21.92; 95% CI, 6.68-71.92; p = 0.000) and in the vertebral fractures with associated LTPF group (RR = 9.42; 95% CI, 1.19-74.72; p = 0.034). L5TPFs were also a very important risk factor for pelvic injuries (RR = 46.10; 95% CI, 22.40-94.88; p = 0.000); 65.1% in L5iTPFs were accompanied with Tile-C pelvic injuries, slightly higher than in L5aTPFs (46.7%). L4TPFs were a risk factor to abdominal injuries within iLTPFs (RR = 2.27; 95% CI, 1.23-4.20; p = 0.009). CONCLUSIONS: The incidence of NSAIs is very high in cases with LTPFs, particularly with L5TPFs. A detailed investigation should be performed to search for NSAIs once LTPFs are identified so that appropriate treatment can be initiated. LEVEL OF EVIDENCE: Level III.

Combined single-level subtotal corpectomy and decompression for cervical spondylotic myelopathy treatment.

BACKGROUND: The purpose of this study was to summarize outcomes of patients with refractory multisegmental cervical spondylotic myelopathy (CSM) who were treated by combined single-level subtotal corpectomy and decompression of the intervertebral space using the anterior approach. METHODS: Forty-five consecutive patients with multisegmental CSM were included; their ages ranged from 37 to 72 years. Seventeen (37.8%) patients had noncontiguous or 'jumping' multisegmental CSM and 28 (62.2%) had contiguous multisegmental CSM. The mean preoperative Japanese Orthopedic Association (JOA) score was 8.1 points. All patients underwent combined single-level decompression of the involved intervertebral space and subtotal corpectomy together with subsequent fusion and internal fixation. An anterior approach was used for all patients. A cage filled with bone graft was inserted and internal fixation was performed after single-level intervertebral space decompression. Mesh filled with bone graft was inserted and plate internal fixation was performed after subtotal corpectomy. RESULTS: Follow-up data (average follow-up, 14 months) were available for all 45 patients; the mean postoperative JOA score was 13.2 points, which was significantly different from the preoperative JOA score. Bony fusion was achieved in all patients based on postoperative radiography, and no pseudoarthrosis was observed during follow-up. CONCLUSIONS: An excellent outcome can be achieved with the combination of single-level subtotal corpectomy and decompression of the intervertebral space using the anterior approach to treat multisegmental CSM.

Posterior short-segmental fixation combined with intermediate screws vs conventional intersegmental fixation for monosegmental thoracolumbar fractures.

Posterior short-segmental fixation is reliable for the management of thoracolumbar fractures; however, it is associated with recurrence of kyphosis and failure of fixation. This study compared the short-term results of short-segmental fixation combined with intermediate screws with those of conventional intersegmental fixation in the treatment of monosegmental thoracolumbar fractures. The records of 62 consecutive patients with thoracolumbar monosegmental fractures who underwent conventional 4-screw intersegmental fixation (35 patients) or short-segmental fixation combined with intermediate screws (27 patients) were reviewed. The study population included 43 men and 19 women (mean age, 44.1±13.6 years). The majority of fractures were L1 (28 [45.1%]) and T12 (21 [33.9%]) fractures. There were no significant differences between the 2 groups with respect to the preoperative relative height of the fractured vertebra or the segmental kyphotic angle. There was a significant difference in the restoration rate between the conventional and short-segmental fixation groups (62.6±38.7% vs 100.4±25.4%, respectively; P<.001). However, a statistically significant decrease in postoperative segmental kyphotic angle was noted in both groups (P<.001). The mean change of segmental kyphotic angle in the short-segmental fixation group was greater than in the conventional fixation group (14.4±6.8° vs 8.3±7.9°, respectively; P<.002). Patients in the short-segmental fixation group ambulated an average of 10 days earlier than those in the conventional fixation group. These findings indicate that compared to conventional intersegmental fixation, short-segmental fixation combined with intermediate screws more effectively restores fractured vertebral height, is associated with a decrease in the segmental kyphotic angle, and allows earlier ambulation.