The existence of intravertebral cleft impact on outcomes of nonacute osteoporotic vertebral compression fractures patients treated by percutaneous kyphoplasty: a comparative study.

STUDY DESIGN: A retrospective comparative study. OBJECTIVE: The purpose of this study is to assess radiologic features of intravertebral cleft (IVC) in nonacute osteoporotic vertebral compression fractures (OVCFs) patients, and analyze the existence of IVC impact on outcomes of percutaneous kyphoplasty (PKP). SUMMARY OF BACKGROUND DATA: The IVC sign is regarded as vertebral instability and the cause of persisting pain. It is more likely to happen at nonacute OVCFs patients. Patients with IVC sign have different outcomes from these without IVC treated by percutaneous vertebroplasty. There were rare reports about the outcomes of patients with IVC sign treated by PKP. MATERIALS AND METHODS: We divided 92 nonacute OVCFs patients (total of 113 vertebrae) into 2 groups according to the existence of IVC. Preoperative and postoperative Visual Analogue Scales, Oswestry Disability Index, kyphotic angulation (KA), and anterior vertebral height were recorded; the incidence and radiologic features of IVC were analyzed. RESULTS: The diagnostic sensitivity of IVC on plain radiograph, computed tomography, and magnetic resonance imaging were 35.4%, 89.3%, and 83.3%, respectively. The IVC group had an average correction KA of 9.14 degrees and reduction of ratio of compression of 20.09%, and the non-IVC group was 8.76 degrees and 20.23%, respectively. Cleft pattern of cement accounted for 64.6% in IVC group and 27.7% in non-IVC group. Five/7 of cement leakage in IVC group was intradiscal leakage, whereas 7/9 of cement leakage in non-IVC group was perivertebral leakage. CONCLUSIONS: Computed tomography and magnetic resonance imaging were more sensitivity to diagnose IVC sign than X-ray. PKP could improve pain, functional activity, KA, and anterior height of both IVC and non-IVC groups, however, there was more cleft pattern of cement and higher intradiscal cement leakage in the IVC group.

Wright's Technique with the Addition of Visualized Axial Cortical Windows in Odontoid Fractures.

This study sought to investigate and evaluate a modified axial translaminar screw fixation for treating odontoid fractures. We performed a retrospective study at Wenzhou Medical University Affiliated Second Hospital between March 2016 and June 2018. We retrospectively collected and analyzed the medical records of 23 cases with odontoid fractures. All patients were identified as type II odontoid fractures without neurological deficiency and serious diseases following the classification of Anderson. The average age, gender ratio, and body mass index (BMI) were 54.3 ± 11.1 years, 12 men to 11 women, and 22.6 ± 2.4 kg/m2 , respectively. Patients in this study accepted screw fixation using our modified axial translaminar screw fixation combined with atlas pedicle or lateral mass screw fixation. Within the technique, a small cortical "window" was dug in the middle of the axial contralateral lamina, such that the screws in the lamina were visualized to prevent incorrectly implanting the posterior spinal canal through the visualized "window." A total of 46 bone screws were accurately inserted into the axial lamina without using fluoroscopy. The length of all translaminar screws ranged between 26 and 30 mm, while the diameter was 3.5 mm. During the follow-up survey, the visual analog scale (VAS) and neck disability index (NDI) were measured. We provide a simple modification of Wright's elegant technique with the addition of "visualized windows" at the middle of the axial lamina. In all patients, screws were inserted accurately without bony breach and the screw angle was 56.1 ± 3.0°. Mean operative time was 102 ± 28 min with an average blood loss of 50 ± 25 mL. Postoperative hemoglobin and mean length of hospital stay were 12.0 ± 1.4 g/dL and 10.4 ± 3.4 days, respectively. The average follow-up time of all cases was 14.7 months and no internal fixation displacement, loosening, or breakage was found. All patients with odontoid fractures reported being satisfied with the treatment during the recheck period and good clinical outcomes were observed. At 1, 6, and 12 months, NDI and VAS showed that the symptoms of neck pain and limitations of functional disability improved significantly during follow-up. Our results suggest that the modified translaminar screw fixation technique can efficiently treat Anderson type II odontoid fracture, followed by the benefits of less soft tissue dissection, simple operation, no fluoroscopy, and accurate placement of screws.

Microendoscopic anterior approach for irreducible atlantoaxial dislocation: surgical techniques and preliminary results.

STUDY DESIGN: Surgical techniques and preliminary results. OBJECTIVE: To describe and evaluate the safety and efficacy of a new minimal invasive technique for the irreducible atlantoaxial dislocation (IADD). SUMMARY OF BACKGROUND DATA: Endoscope has been widely used in minimal invasive spinal surgery. However, there are no clinical reports regarding anterior approach for IADD in the literature. METHODS: Ten consecutive patients with IADD were treated by anterior release with microendoscopic aide and subsequently reduction, anterior transarticular screw fixation and morselized autologous bone grafts. There were 3 cases of odontoid dysplasia, 4, chronic odontoid fracture, 1, odontoid absence, 1 fasilar impression, and 1 malunion of odontoid fracture. According to Symon and Lavender's classification of disability, 6 cases were moderate disability, 3 severe nonbedbound, and 1 severe bedridden. The procedure was performed by the same surgeon (Yong-Long Chi). RESULTS: The new technique was performed successfully in all cases. All the patients underwent transarticular screw fixation and anterior morselized autograft fusion. The average operation time was 120 min (range, 90 to 150 min) and the mean estimated blood loss was 150 mL (range, 100 to 250 mL). Postoperative radiographs demonstrated that 9 cases restored anatomic position and 1 had partial reduction. According to the postoperative computed tomography all the screws were appropriately placed. Follow-up after surgery, longest is 16 months and minimal 8 months with a mean of 12 months, neurologic status was improved in all patients. There was no loss of fixation and solid fusion was achieved in all cases. CONCLUSIONS: Surgical technique of microendoscopic anterior release, reduction, fixation, and fusion is safe and reliable minimally invasive for treating IADD.

Implanting hydroxyapatite-coated porous titanium with bone morphogenetic protein-2 and hyaluronic acid into distal femoral metaphysis of rabbits.

OBJECTIVE: To assess the osseointegration capability of hydroxyapatite-coated porous titanium with bone morphogenetic protein-2 (BMP-2) and hyaluronic acid to repair defects in the distal femur metaphysis in rabbits. METHODS: Porous titanium implants were made by sintering titanium powder at high temperature, which were coated with hydroxyapatite by alkali and heat treatment and with BMP-2 combined with bone regeneration materials. And hyaluronic acid was further used as delivery system to prolong the effect of BMP-2. The implants were inserted into the metaphysis of the distal femur of rabbits. The animals were killed at 6, 12 and 24 weeks to accomplish histological and biomechanical analyses. RESULTS: According to the result of histological analysis, the osseointegration in BMP-2 group was better than that of the HA-coated porous titanium group. In push-out test, all the samples had bigger shear stress as time passed by. There was statistical difference between the two groups in 6 and 12 weeks but not in 24 weeks. CONCLUSION: Hydroxyapatite-coated porous titanium with BMP-2 and hyaluronic acid has a good effect in repairing defects of distal femur in rabbits, which is a fine biotechnology for future clinical application.

Feasibility of Modified Anterior Odontoid Screw Fixation: Analysis of a New Trajectory Using 3-Dimensional Simulation Software.

BACKGROUND: Anterior odontoid screw fixation (AOSF) has been suggested as the optimal treatment for type II and some shallow type III odontoid fractures. However, only the classical surgical trajectory is available; no newer entry points or trajectories have been reported. METHODS: We evaluated the anatomic feasibility of a new trajectory for AOSF using 3-dimensional (3D) screw insertion simulation software (Mimics). Computed tomography (CT) scans of patients (65 males and 59 females) with normal cervical structures were obtained consecutively, and the axes were reconstructed in 3 dimensions by Mimics software. Then simulated operations were performed using 2 new entry points below the superior articular process using bilateral screws of different diameters (group 1: 4 mm and 4 mm; group 2: 4 mm and 3.5 mm; group 3: 3.5 mm and 3.5 mm). The success rates and the required screw lengths were recorded and analyzed. RESULTS: The success rates were 79.03% for group 1, 95.16% for group 2, and 98.39% for group 3. The success rates for groups 2 and 3 did not differ significantly, and both were significantly better than the rate for group 1. The success rate was much higher in males than in females in group 1, but the success rate was similar in males and females in the other 2 groups. Screw lengths did not differ significantly among the 3 groups, but an effect of sex was apparent. CONCLUSIONS: Our modified trajectory is anatomically feasible for fixation of anterior odontoid fractures, but further anatomic experiments and clinical research are needed.

[Percutaneous microendoscopic anterior release, fixation and fusion for irreducible atlanto-axial dislocation].

OBJECTIVE: To evaluate the safety and efficacy of one-stage percutaneous microendoscopic anterior release, trans-articular fixation and fusion to reduce and stabilize for irreducible atlanto-axial dislocation. METHODS: Eight consecutive patients were treated by percutaneous microendoscopic anterior release, trans-articular C(1-2) fixation and bone graft fusion. The mean age was 33 years (range, 28-52 years). The pathology included odontoid dysplasia in 3 patients, chronic odontoid fractures in 2, odontoid absence in 1, fasilar impression in 1 and malunion of odontoid fracture in 1. The classification of disability was that proposed by Symon and Lavender. There were moderate disability in 4, severe non-bedbound in 3, and severe bedridden in 1. RESULTS: The new technique was performed successfully in all cases. All patients underwent trans-articular C(1-2) screw fixation and anterior bone graft fusion. The average operation time was 120 min (90-150 min), and the average estimated blood loss was 150 ml (100-250 ml). Seven cases resulted in anatomic reduction, 1 had partial reduction. The follow-up period was 8-16 months. The effective rate was 100%, and the excellent rate was 51.25%; the average improvement rate for the spinal canal decompression was 76.5%. There was no instrument failure or pseudarthrosis, and solid fusion was achieved in the all cases. The loss of axial rotation of cervical spine was 30-40 degrees . CONCLUSION: Percutaneous microendoscopic anterior release, fixation and fusion is an effective, reliable, and safe procedure for the treatment of irreducible atlanto-axial dislocation.

[Therapeutic effects and complications of percutaneous anterior screw fixation for odontoid fractures].

OBJECTIVE: To investigate the therapeutic effects and complications of percutaneous anterior screw fixation for odontoid fractures. METHODS: Twenty-eight patients with odontoid fractures, 21 males and 7 females, aged 38.6 (21-72), 12 with type II fractures and 16 with type III fractures, including 10 cases with shallow type III fractures, according to Anderson's classification system, underwent percutaneous anterior odontoid screw fixation with one screw implant. Five to seven days after the operation the patients got out of bed to conduct dirigation. Prostheses were used for 8-12 weeks post-operationally. The patients were followed up for 43.2 months (26-62 months). Radiological examination, including X-ray and CT examinations, and clinical examinations were carried out to observe the therapeutic effects. RESULTS: Radiological examination showed bony union in 25 cases (89.3%), and non-union developed in 2 cases, 1 case was switched to posterior fusion surgery because of redisplaced fracture. The union rate was 83.3% in the type II fracture, and was 93.8% in the type III. Majority of the patients resumed an excellent cervical motion. No severe complication such as esophagus and carotid artery injury related with puncture was found. One patient had temporary superior laryngeal nerve paralysis, The screw tail was detained at the superior margin of C3 vertebral body in 5 cases, the screw penetrate the tip of odontoid process in 1 case, and the screw thread failed to pass the fracture site entirely in 1 case. CONCLUSION: An innovative alternative method with the advantages of convenient procedure, less bleeding, gentle injury for surrounding tissue, and rapid recovery, percutaneous anterior odontoid screw fixation is similarly effective as open anterior odontoid screw fixation, for the treatment of odontoid fractures. Related complication is rare and not severe. The surgery has.

[The classification and its clinical value for extravertebral cement leakage complicated by percutaneous vertebral augmentation].

OBJECTIVE: To explore the category and its clinical value of extravertebral cement leakage complicated by percutaneous vertebroplasty and kyphoplasty. METHODS: After collecting clinical data of 56 patients underwent surgery of PVP or PKP between August 2001 and March 2005, extravertebral cement leakage was classified according to anatomical position, and its clinical value was analysed. RESULTS: Eighteen vertebraes presented cement leakage in all 43 vertebraes in PVP group. There were 15 vertebraes with one-place leakage, 6 vertebraes with perivertebral leakage, 5 spinal canal leakage, 2 intraforaminal leakage, 1 intradical leakage and 1 paravertebral soft tissues leakage respectively among them; and there were 3 vertebraes with two-place leakage. Four vertebraes presented cement leakage in all 22 vertebraes in PKP group. All 4 vertebraes had one-place leakage including 2 vertebraes with perivertebral leakage, 1 spinal canal leakage and 1 intraforaminal leakage. Five patients with cement leakage presented new symptoms including peritoneal irritation signs and spinal cord or nerve root injury, 3 patients recovered after conservative treatment, whereas the other 2 patients need decompression surgery. CONCLUSIONS: The types of perivertebral leakage and spinal canal leakage are common among extravertebral cement leakage followed by percutaneous vertebroplasty and kyphoplasty. The minority of patients with cement leakage presents new symptoms, and the majority of them has the same therapeutic effect except patients with spinal canal leakage on one day after surgery.

Percutaneous atlantoaxial anterior transarticular screw fixation combined with mini-open posterior C1/2 wire fusion for patients with a high-riding vertebral artery.

CONTEXT/OBJECTIVE: To describe the technique and clinical results of percutaneous atlantoaxial anterior transarticular fixation combined with limited exposure posterior C1/2 arthrodesis in patients with a high-riding vertebral artery. DESIGN SETTING: Zhejiang Spine Center, China. PARTICIPANTS: Five patients with a high-riding vertebral artery and an upper cervical fracture. INTERVENTIONS: Percutaneous atlantoaxial anterior transarticular screw fixation combined with limited exposure posterior C1/2 wire fusion. OUTCOME MEASURES: Computed tomography scans were used to assess the high-riding vertebral artery and feasibility of anterior transarticular screw fixation preoperatively. A Philadelphia collar was used to immobilize the neck postoperatively. Anteroposterior (open-mouth) and lateral views were obtained at pre/postoperation and at the follow-up. RESULTS: The operation was performed successfully on all of the patients, and no intraoperative operation-related complications such as nerve injury, vertebral artery, and soft tissue complications occurred. The mean follow-up period was 33.8 months (range: 24 to 58 months). No screw breakage, loosening, pullout, or cutout was observed. Bone union was achieved in all patients at the last follow-up. CONCLUSIONS: Our small case series results suggested that percutaneous anterior transarticular screw fixation combined with mini-open posterior C1/2 wire fusion is a technically minimally invasive, safe, feasible, and useful method to treat patients with a high-riding vertebral artery.

Comparison of Cervical Spine Anatomy in Calves, Pigs and Humans.

BACKGROUND CONTEXT: Animals are commonly used to model the human spine for in vitro and in vivo experiments. Many studies have investigated similarities and differences between animals and humans in the lumbar and thoracic vertebrae. However, a quantitative anatomic comparison of calf, pig, and human cervical spines has not been reported. PURPOSE: To compare fundamental structural similarities and differences in vertebral bodies from the cervical spines of commonly used experimental animal models and humans. STUDY DESIGN: Anatomical morphometric analysis was performed on cervical vertebra specimens harvested from humans and two common large animals (i.e., calves and pigs). METHODS: Multiple morphometric parameters were directly measured from cervical spine specimens of twelve pigs, twelve calves and twelve human adult cadavers. The following anatomical parameters were measured: vertebral body width (VBW), vertebral body depth (VBD), vertebral body height (VBH), spinal canal width (SCW), spinal canal depth (SCD), pedicle width (PW), pedicle depth (PD), pedicle inclination (PI), dens width (DW), dens depth (DD), total vertebral width (TVW), and total vertebral depth (TVD). RESULTS: The atlantoaxial (C1-2) joint in pigs is similar to that in humans and could serve as a human substitute. The pig cervical spine is highly similar to the human cervical spine, except for two large transverse processes in the anterior regions ofC4-C6. The width and depth of the calf odontoid process were larger than those in humans. VBW and VBD of calf cervical vertebrae were larger than those in humans, but the spinal canal was smaller. Calf C7 was relatively similar to human C7, thus, it may be a good substitute. CONCLUSION: Pig cervical vertebrae were more suitable human substitutions than calf cervical vertebrae, especially with respect to C1, C2, and C7. The biomechanical properties of nerve vascular anatomy and various segment functions in pig and calf cervical vertebrae must be considered when selecting an animal model for research on the spine.

A novel technique of two-hole guide tube for percutaneous anterior odontoid screw fixation.

BACKGROUND CONTEXT: Surgical stabilization is recommended for odontoid fractures with mechanical instability. Compared with C1-C2 fusion, percutaneous anterior odontoid screw fixation has the advantages of preserving C1/C2 motion and being a minimally invasive procedure. However, determining the optimal screw trajectory is often difficult. When an initial suboptimal K-wire hole is drilled, it is especially difficult to drill a second optimal K-wire trajectory because the initial hole will be entered inadvertently. PURPOSE: To design a novel device, two-hole guide tube, to make drilling a second optimal K-wire trajectory easier, and thus, avoid unnecessary additional surgical time and reduce the likelihood of needing to change the procedure to traditional open surgery. STUDY DESIGN: A technical report. METHODS: Fifty-three patients with odontoid fractures were treated by percutaneous anterior odontoid screw fixation in our hospital, and the initial K-wire trajectories of 16 cases (12 men and 4 women) among the 53 patients were imperfect. The two-hole guide tube was applied for drilling the second trajectory in each of these 16 cases. RESULTS: No complications associated with this technique occurred. Satisfactory results and good screw placement was achieved in all patients. Radiographic fusion was confirmed for 15 of 16 patients. None of the patients experienced clinical symptoms or screw loosening or breakage in this study. CONCLUSIONS: Our novel device, two-hole guide tube, can be used to reduce the difficulty associated with redrilling an optimal K-wire trajectory if the initial trajectory is imperfect during percutaneous anterior odontoid screw fixation. Moreover, by referring to the initial misplaced K-wire, a more accurate trajectory for the second K-wire can be achieved.

[Instability of C1,2 treated with transcutaneous anterior lateral mass fixation and bone grafting].

OBJECTIVE: Creating the method of transcutaneous anterior lateral mass fixation for instability of C(1,2). METHODS: The regular and safe angle and the distance between the median margin of vertebral artery and median line of superior and inferior margin of axis were measured with computerized tomography. Fifteen cases of C(1,2) instability including 7 cases atlanto-axial dislocation, 3 cases of Jefferson's fracture, 1 case of dental fracture and dislocation and 4 cases of fractures of anterior arch of C1 were treated with pertacuneous anterior lateral mass screws and bone grafting with new-designed hole instrumentations according to the measurement of 40 normal atlanto-axial vertebrae. RESULTS: In posterior-anterior ray the regular angle was 24.0 degrees +/- 3.7 degrees (right side), and 23.8 degrees +/- 1.8 degrees (left side); safe angle is 15.2 degrees - 30.3 degrees (left side) and 14.8 degrees - 32.1 degrees (right side), respectively. The distance between the median margin of vertebral artery and median line of superior and inferior margin of vertebral artery and median line of superior and inferior margin of lateral mass was (5.6 +/- 2.2) mm (right) and (5.8 +/- 1.9) mm (left). In lateral ray the regular angle was 24.1 degrees +/- 1.8 degrees, and safe angle 12.6 degrees - 26.8 degrees. All cases reach a satisfactory result of fixation without the injury of vertebral artery, spinal cord and esophagus. The acupuncture point recovers without infection. CONCLUSIONS: This operation procedure for instability of C(1,2) has the advantage of less trauma and bleeding, simply operation and bone grafting at the same time. The operation procedure is safe with reasonable instrument and selecting the correct puncture point, angle and depth.

Computed tomographic morphometric analysis of the pediatric occipital condyle for occipital condyle screw placement.

STUDY DESIGN: This study is a computed tomographic (CT)-based morphometric analysis of the pediatric occipital condyles as related to occipital condyle screw placement. OBJECTIVE: To quantify reference data concerning the dimensions of the immature occipital condyles to guide the placement of occipital condyle screw. SUMMARY OF BACKGROUND DATA: To the best of our knowledge, no published study has provided insight into the anatomy of occipital condyle of the pediatric population with different age groups. METHODS: Sixty-nine pediatric patients were divided into 4 age groups, and their occipital condyles were studied on CT scans. Condylar length, width, height, sagittal angle, and sagittal angle lengths were measured on Philips Brilliance 16 CT. RESULTS: The mean pediatric coronal height, sagittal length, and axial width noted statistically significant age-related differences were 9.0 mm, 21.3 mm, and 9.8 mm, respectively. The mean sagittal angle for all patients was 27.2 ± 5.1° (range, 15.1-41.0°). In 82.6% (114/138) of the occipital condyles, the anatomy could accept the occipital condyle screw (width ≥8 mm and height ≥6.5 mm). CONCLUSION: Our investigation provides insight into the anatomy of occipital condyle of the pediatric population with different age groups. As the pediatric occipital condyles have sufficient occipital bone for appropriate fixation or fusion, the occipital condyle screws fixation is a feasible technique for children. Even so, given the evolution of this technique being still in its infancy and the complexity inherent to the craniovertebral junction, a careful radiological analysis of occipital condyle must be required in preoperative planning and feasibility determination. LEVEL OF EVIDENCE: N/A.

[Effects of surface roughness of bone cements on histological characteristics of induced membranes].

OBJECTIVE: To explore surface roughness of bone cement and surround tissue on histological characteristic of induced membranes. METHODS: Bone cements with smooth and rough surface were implanted in radius bone defect, intramuscular and subcutaneous sites of rabbits, and formed induced membranes. Membranes were obtained and stained (HE) 6 weeks later. Images of membrane tissue were obtained and analyzed with an automated image analysis system. Five histological parameters of membranes were measured with thickness,area,cell density,ECM density and microvessel density. Double factor variance analysis was used to evaluate the effect of the two factors on histological characteristics of induced membranes. RESULTS: Membranes can be induced by each kind of bone cement and at all the three tissue sites. In histological parameters of thickness,area and micro vessel,there were significant differences among the membranes induced at different tissue sites (P = 0.000, P = 0.000, P = 0.000); whereas, there were no significant differences in histological parameters of cell density and ECM density (P = 0.734, P = 0.638). In all five histological parameters of membranes, there were no significant differences between the membranes induced by bone cements with different surface roughness (P = 0.506, P = 0.185, P = 0.883, P = 0.093, P = 0.918). CONCLUSION: Surround tissue rather than surface roughness of bone cements can affect the histological characteristics of induced membranes. The fibrocystic number, vascularity, mechanical tension and micro motion of the surround tissue may be closely correlated with the histological characteristics of induced membranes.

[Application of anterior percutaneous screw fixation in treatment of odontoid process fractures in aged people].

OBJECTIVE: To explore the efficacy of anterior percutaneous screw fixation in the treatment of odontoid process fractures in aged people. METHODS: From February 2001 to April 2009, 15 elderly patients with odontoid fracture were treated with anterior percutaneous screw fixation,including 13 males and 2 females; the average age was 69.3 years (ranged, 60 to 86 years). According to Anderson classification, there were 10 patients with type II fractures (type II A in 7 cases, type II B in 3 cases, based on Eysel and Roosen classification), 4 patients with shallow type III fractures, 1 patient with deep type III fractures. Thirteen patients were fresh fractures, 2 patients were obsolete fractures. All patients had varying degrees of neck or shoulder pain, and limit activity of neck. There were 4 patients with neural symptoms including 2 grade D and 2 grade C according to Frankel classification. All the patients were followed up and were assessed by radiology. Clinical examination included neck activity, neurological function and the degree of neck pain. Radiology examinations including anteroposterior, lateral, open mouth position and flexion-extension radiographs of cervical vertebra were performed. RESULTS: After surgery, all patients were followed up,and the duration ranged from 6 to 60 months (averaged 31.3 months). Two patients died of other diseases during the follow-up period (18 and 22 months after surgery respectively). All patients got satisfactory results, and all screws were in good position. As the screw was too long, esophagus was compressed by screw tail in one case. One case showed fibrous union, 12 cases had achieved solid bony union, 2 cases showed nonunion without clinical symptoms. The rotation of neck in 3 cases was mildly limited,the neck function of the remaining patients were normal. Four patients with symptoms nerve injuries improved after operation (Frankel E in 3 cases, Frankel D in 1 case). The symptom of neck pain had a significant improvement after surgery (P < 0.001). The VAS score decreased from preoperative (6.07 +/- 1.44) (4 to 8 scores),to postoperative (1.13 +/- 0.92) (0 to 3 scores). And there were no severe postoperative complications. CONCLUSION: The anterior percutaneous screw fixation is less traumatic than conventional approaches for aged people in dealing with odontoid process fractures. Most patients will achieve satisfactory clinical results, as long as the general conditions of them are comprehensively assess. However, this procedure should not be used in patients with comminuted odontoid fractures or severe osteoporosis.

Management of odontoid fractures with percutaneous anterior odontoid screw fixation.

Minimally invasive techniques have revolutionized the management of a variety of spinal disorders. The authors of this study describe a new instrument and a percutaneous technique for anterior odontoid screw fixation, and evaluate its safety and efficacy in the treatment of patients with odontoid fractures. Ten patients (6 males and 4 females) with odontoid fractures were treated by percutaneous anterior odontoid screw fixation under fluoroscopic guidance from March 2000 to May 2002. Their mean age at presentation was 37.2 years (with a range from 21 to 55 years). Six cases were Type II and four were Type III classified by the Anderson and D'Alonzo system. The operation was successfully completed without technical difficulties, and without any soft tissue complications such as esophageal injury. No neurological deterioration occurred. Satisfactory results were achieved in all patients and all of the screws were in good placement. After a mean follow-up of 15.7 months (range 10-25 months), radiographic fusion was documented for 9 of 10 patients (90%). Neither clinical symptoms nor screw loosening or breakage occurred. Our preliminary clinical results suggest that the percutaneous anterior odontoid screw fixation procedure using a new instrument and fluoroscopy is technically feasible, safe, useful, and minimally invasive.