To study project of simpl icity and util ity for screw-plate system by pedicle of atlanto-axis mani pulatively hand by X-ray film and CT to prove the one success rate of putting screws. Methods Formulate personal program was used in operation by image save transmission of X-ray film and CT during January 2002 and September 2006 in 31 patients. There were 18 males and 13 femals, aged from 23 to 61 years old with an average age of 43.5 years. Putting screw points bypedicle of atlas were measured: left (19.93 ± 1.32) mm, right (19.16 ± 1.30) mm; putting screw obl iquity angle to inside by pedicle of atlas: left (23.72 ± 2.09)°, right (23.35 ± 1.91)°; putting screw obl iquity angle to side of head by pedicle of atlas: (9.00 ± 1.20)°. Screw points by pedicle of axis: left (13.14 ± 0.82) mm right (13.85 ± 0.79) mm; putting screw obl iquity angle to inside by pedicle of axis: left (24.52 ± 1.26)°, right (20.42 ± 1.42)°; putting screw obl iquity angle to side of head by pedicle of axis: (25.00 ± 3.00)°. The domestic location toward speculum was employed in operation and putting screw points and angles were formulated by X-CT program. The pedicle screws of suitable diameter and length were of exception and screws into pedicle of atlanto-axis were put by hand. Results Pain of the greater occipital nerve occurred in 2 patients after operation and was fully recovered by treatment 1 month after operation. The lateral cortical bone of pedicle was cut by 2 screws, but the spinal cord and vertebral artery were fine. The atlas and the fracture of odontoid process of axis were completely replaced in X-ray films of all patients 1 day after operation.The position relation of lag screw and vertebral artery or spinal cord was very good in CT sheets. All cases were followed up with an average of 10.5 months during 9 months to 5 years and 4 months, and obtained atlantoaxial arthrodesis. The breakage of screw and plate was not found in all cases. According to JOA score standard, 16 cases were excellent, 12 were good, 2 were fair, 1 was poor, and the excellent and good rate was 90.32% . Conclusion The personal design and cl inical appl ication of X-ray films and CT sheets are of great significance to screw-plate system by pedicle of atlanto-axis because of simpl ification of designs and methods and better personal ity.
ObjectiveTo evaluate the stability of the fixation technique for the crossed rods consisting of occipital plate and C2 bilateral lamina screws by biomechanical test.MethodsSix fresh cervical specimens were harvested and established an atlantoaxial instability model. The models were fixed with parallel rods and crossed rods after occipital plate and C2 bilateral laminae screws were implanted. The specimens were tested in the following sequence: atlantoaxial instability model (unstable model group), under parallel rods fixation (parallel fixation group), and under crossed rods fixation (cross fixation group). The range of motion (ROM) of the C0-2 segments were measured in flexion-extension, left/right lateral bending, and left/right axial rotation. After the test, X-ray film was taken to observe the internal fixator position.ResultsThe biomechanical test results showed that the ROMs in flexion-extension, left/right lateral bending, and left/right axial rotation were significantly lower in the cross fixation group and the parallel fixation group than in the unstable model group (P<0.05). There was no significant difference between the cross fixation group and the parallel fixation group in flexion-extension and left/right lateral bending (P>0.05). In the left/right axial rotation, the ROMs of the cross fixation group were significantly lower than those of the parallel fixation group (P<0.05). After the test, the X-ray film showed the good internal fixator position.ConclusionThe axial rotational stability of occipitocervical fusion can be further improved by crossed rods fixation when the occipital plate and C2 bilateral lamina screws are used.
Objective To improve the safety of the percutaneous anterior transarticular screw fixation (PATSF) by measuring the parameters related to PATSF. Methods Spiral CT scan and three-dimensional reconstructions of the atlantoaxis were performed in 50 adult volunteers. The section of inner margin of atlantal superior articular facet, the coronal plane ofvertebral artery cavity, and the sagittal plane of atlano-axis were obtained with multiplanar reconstruction on hel ical CT. The atlantoaxial vertebral structure and the direction of vertebral artery cavity were observed. The parameters related to PATSF were measured and analysed. Results The suitable position of screw insertion was 4.0 mm from the midpoint of the axoidean anteroinferior margin. The maximum external angle of PATSF was (29.89 ± 1.41)°; the minimum external angle was (4.37±0.87)°; the maximum backward angle was (32.41 ± 1.66)°; the optimal external angle was (17.13 ± 0.88)°; the optimal backward angle was (17.62 ± 1.03)°; and the optimal screw length was (41.57±0.79) mm. The atlantoaxial articular facial diameter was (16.71 ± 1.61) mm; the maximum distance of atlantal lateral displacement was (6.96 ± 1.09) mm; and the ratio of them was 41.80% ± 5.69%. Conclusion The optimal insertion of PATSF is safe and rel iable. The screw can be inserted when the displacement of the atlantal lateral mass is in a certain degree.
Objective To explore the effectiveness of fixation of atlas translaminar screws in the treatment of atlatoaxial instability. Methods A retrospective analysis was made on the clinical data of 32 patients with atlatoaxial instability treated with atlantoaxial trans-pedicle screws between March 2007 and August 2009. Of them, 7 patients underwent atlas translaminar screws combined with axis transpedicle screws fixation because of fracture types, anatomic variation, and intraoperative reason, including 5 males and 2 females with an average age of 48.2 years (range, 35-69 years). A total of 9 translaminar screws were inserted. Injury was caused by traffic accident in 4 cases, falling from height in 2 cases, and crushing in 1 case. Two cases had simple odontoid fracture (Anderson type II), and 5 cases had odontoid fracture combined with other injuries (massa lateralis atlantis fracture in 2, atlantoaxial dislocation in 1, and Hangman fracture in 2). The interval between injury and operation was 4-9 days (mean, 6 days). The preoperative Japanese Orthopaedic Association (JOA) score was 8.29 ± 1.60. Results The X-ray films showed good position of the screws. Healing of incision by first intention was obtained, and no patient had injuries of the spinal cord injury, nerve root, and vertebral artery. Seven cases were followed up 9-26 months (mean, 14 months). Good bone fusion was observed at 8 months on average (range, 6-11 months). No loosening, displacement, and breakage of internal fixation, re-dislocation and instability of atlantoaxial joint, or penetrating of pedicle screw into the spinal canal and the spinal cord occurred. The JOA score was significantly improved to 15.29 ± 1.38 at 6 months after operation (t=32.078, P=0.000). Conclusion Atlas translaminar screws fixation has the advantages of firm fixation, simple operating techniques, and relative safety, so it may be a remedial measure of atlatoaxial instability．
Objective To compare the effectiveness of robot-assisted and traditional freehand screw placement in the treatment of atlantoaxial dislocation. Methods The clinical data of 55 patients with atlantoaxial dislocation who met the selection criteria between January 2021 and January 2024 were retrospectively analyzed. According to different screw placement methods, they were divided into the traditional group (using the traditional freedhand screw placement, 31 cases) and the robot group (using the Mazor X robot-assisted screw placement, 24 cases). There was no significant difference in gender, age, body mass index, etiology, and preoperative visual analogue scale (VAS) score, cervical spine Japanese Orthopaedic Association (JOA) score between the two groups (P>0.05). The operation time, intraoperative blood loss, operation cost, and intraoperative complications were recorded and compared between the two groups. The VAS score and cervical spine JOA score were used to evaluate the improvement of pain and cervical spinal cord function before operation and at 1 month after operation. CT examination was performed at 3 days after operation, and the accuracy of screw placement was evaluated according to Neo grading criteria. Results All the 55 patients successfully completed the operation. The operation time, intraoperative blood loss, and operation cost in the robot group were significantly higher than those in the traditional group (P<0.05). A total of 220 C1 and C2 pedicle screws were inserted in the two groups, and 94 were inserted in the robot group, with an accuracy rate of 95.7%, among them, 2 were inserted by traditional freehand screw placement due to bleeding caused by intraoperative slip. And 126 pedicle screws were inserted in the traditional group, with an accuracy rate of 87.3%, which was significantly lower than that in the robot group (P<0.05). There were 1 case of venous plexus injury in the robot group and 3 cases in the traditional group, which improved after pressure hemostasis treatment. No other intraoperative complication such as vertebral artery injury or spinal cord injury occurred in both groups. All patients were followed up 4-16 months with an average of 6.6 months, and there was no significant difference in the follow-up time between the two groups (P>0.05). Postoperative neck pain significantly relieved in both groups, and neurological symptoms relieved to varying degrees. The VAS score and cervicle spine JOA score of both groups significantly improved at 1 month after operation when compared with preoperative scores (P<0.05), and there was no significant difference in the score change between the two groups (P>0.05). Conclusion In the treatment of atlantoaxial dislocation, the accuracy of robot-assisted screw placement is superior to the traditional freedhand screw placement.
Objective To explore the feasibility and effectiveness of spinal pedicle screw internal fixation through endoscope-assisted posterior approach for the treatment of traumatic atlantoaxial instability. Methods Between September 2008 and September 2010, 44 patients with traumatic atlantoaxial instability received spinal pedicle screw internal fixation through endoscope-assisted posterior operation (micro-invasive surgical therapy group, n=22) or traditional surgical therapy (control group, n=22). There was no significant difference in gender, age, type of injury, disease duration, and preoperative Japanese Orthopedic Association (JOA) score between 2 groups (P gt; 0.05). The blood loss, operation time, length of the incision, improvement rate of JOA, and graft fusion rates were compared between 2 groups to assess the clinical outcomes. Results The blood loss, operation time, and length of the incision in the micro-invasive surgical therapy group were better than those in control group (P lt; 0.05). All incisions were primary healing. Of 88 pedicle screws, 7 pedicle screws penetrated into the interior walls of cervical transverse foramen in the micro-invasive surgical therapy group and 8 in the control group, but there was no syndrome of vertebral artery injury. All patients of the 2 groups were followed up 12 to 37 months (mean, 26 months). Bony fusion was achieved in all cases within 3 to 12 months (mean, 5.3 months). No loosening or breakage of screw occurred. At 6 months to 1 year after operation, the internal fixator was removed in 6 cases and the function of head and neck rotary movement were almost renewed. The JOA score was significantly improved at last follow-up when compared with preoperative score (P lt; 0.05), and no significant difference in JOA score and improvement rate between the 2 groups at last follow-up (P gt; 0.05). Conclusion The micro-invasive surgical therapy can acquire the same effectiveness to the traditional surgical therapy in immediate recovery of stability, high graft fusion rate, and less complication. Moreover, it can significantly reduce the operation time, blood loss, and soft tissue injury, so this approach may be an ideal way of internal fixation to treat traumatic atlantoaxial instability.
Objective To explore and evaluate the accuracy and feasibil ity of individual rapid prototype (RP) drill templates for atlantoaxial pedicle screw implantation. Methods Volumetric CT scanning was performed in 8 adult cadaveric atlas and axis to collect Dicom format datas. Then three-dimensional (3D) images of atlas and axis were reconstructed and the parameters of pedicles of 3D model were measured by using software Mimics 10.01. The 3D model was saved by STLformat in Mimics. The scattered point cloud data of 3D model were processed and the 3D coordinate system was located in software Imageware 12.1. The curves and surfaces of 3D model were processed in software Geomagic Studio 10. The optimal trajectory of pedicle screw was designed and a template was constructed which accorded with the anatomical morphology of posterior arch of atlas and lamina of axis by using software Pro/Engineer 4.0. The optimal trajectory of pedicle screw and the template were integrated into a drill template finally. The drill template and physical models of atlas and axis were manufactured by RP (3D print technology). The accuracy of pilot holes of drill templates was assessed by visually inspecting and CT scanning. Results The individual drill template was used conveniently and each template could closely fit the anatomical morphology of posterior arch of atlas and lamina of axis. Template loosening and shifting were not found in the process of screw implantation. Thirty-two pedicle screws were inserted. Imaging and visual inspection revealed that the majority of trajectories did not penetrate the pedicle cortex, only 1 cortical penetration was judged as noncritical and did not injury the adjacent spinal cord, nerve roots, and vertebral arteries. The accuracy of atlas pedicle screw was grade 0 in 15 screws and grade I in 1 screw, and the accuracy of axis pedicle screw was grade 0 in 16 screws. Conclusion The potential of individual drill templates to aid implantation of atlantoaxial pedicle screw is promising because of its high accuracy.
To cure patients suffering from atlanto-axial instability following old fracture of odontoid process concomitant with stenosis of lower end of cervical spinal canal, a new operative method was designed. It included atlanto-axial fusion by Gallie technique and resection of right half of the laminae of C3-C7 spine at one stage. A female of 63 years old was treated. She was admitted with neck pain and numbness of the upper and lower limbs. A history of neck injury was noted in enquiry. In physical examination showed the sensation of pain of the upper limbs was decreased and the muscle power of the upper and lower limbs ranged from III degree to IV degree. The X-ray film and MRI suggested that there was instability of the atlanto-axial joint with stenosis of 4th-6th cervical spinal canal. The operation was satisfactory. After operation, the patient was followed up for 11 months. The physical examination indicated that sensation of the upper limbs had recovered to normal and the muscle power of the upper limbs reached IV degree and that the lower limbs reached V degree and X-ray showed bony fusion of the atlanto-axial joint. The conclusions were: 1. The stability of atlanto-axial joint was reconstructed with expanding of the spinal canal at the same time. 2. The duration, risk and cost of the therapy were reduced, and maintenance of the stability of the cervical spine throughout whole period of treatment was recommended.