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.
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.
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.
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.
【摘要】 目的 探讨利用术前CT多平面重建（MPR）图像上钉道设计与术中确定枢椎峡部中心，指导后路寰枢经关节螺钉内固定徒手置钉的价值。 方法 选取成人头颈尸体标本9具，及寰枢关节不稳患者5例，螺旋CT扫描，取后路寰枢经关节螺钉内固定的理想钉道（经枢椎峡部中心点）所在平面重建并设计个体化钉道，确定安全的置钉范围。参考术前钉道设计与术中确定枢椎峡部中心，徒手行后路寰枢经关节螺钉固定。术后对实际钉道CT多平面重建，分析徒手实际置钉情况。 结果 后路寰枢经关节螺钉固定共28侧，术中徒手操作顺利，无重要血管神经损伤。手术实际钉道均在术前设计钉道的安全范围内。5例患者寰枢椎间术后较术前存在相对位移变化。 结论 根据螺旋CT MPR图像设计的个体化后路寰枢经关节螺钉内固定钉道，结合术中枢椎峡部中心显露，可指导临床安全地徒手置钉。【Abstract】 Objective To explore the clinical value of the free-hand technique on making the screw path of posterior atlantoaxial transarticular screw fixation, which guided in accordance with the preoperative design of the screw trajectory in spiral CT multilevel reconstruction (MPR) imaging and intra-operative exposure of the center of C2 isthmus. Methods The cervical spine segments of 9 human cadavers and 5 patients with atlantoaxial instability were scanned with spiral computed tomography. Then the CT MPR images of ideal screw trajectory of posterior atalanto-axial transarticular screw reconstructed through the central point of C2 isthmus were used for plotting individual safe screw trajectory. According to preoperative designing of the individual screw trajectory and intraoperative exposure of the center of C2 isthmus, free-hand operation made the transarticular screw path of posterior atlantoaxial screw fixation. Postoperative CT MPR image was used to analyze the actual screw trajectory in atlantoaxial complex, as well. Results The transarticular screws were inserted atlantoaxial joints in 28 sides. The free-hand operation of screw placement was successful, and no screw misplacement or major neurovascular injury was found. There was relative displacement between the atlas and axial vertebrae in 5 patients. Conclusion The free-hand technique of posterior atlantoaxial transarticular screw placement is reliable and safe which refers the preoperative individual screw trajectory designed by CT MPR image and intraoperative exposure of the center of C2 isthmus.
Objective To investigate the effectiveness of computer-assisted and robot-assisted atlantoaxial pedicle screw implantation for the treatment of reversible atlantoaxial dislocation (AAD). MethodsThe clinical data of 42 patients with reversible AAD admitted between January 2020 and June 2023 and met the selection criteria were retrospectively analyzed, of whom 23 patients were treated with computer-assisted surgery (computer group) and 19 patients were treated with Mazor X spinal robot-assisted surgery (robot group). There was no significant difference in gender, age, T value of bone mineral density, body mass index, etiology, and preoperative Japanese Orthopaedic Association (JOA) score, Neck Dysfunction Index (NDI) between the two groups (P>0.05). The operation time, screw implantation time, intraoperative blood loss, hand and wrist radiation exposure, and complications were recorded and compared between the two groups. Gertzbein classification was used to evaluate the accuracy of screw implantation. JOA score and NDI were used to evaluate the function before operation, at 3 days after operation, and at last follow-up. At last follow-up, the status of screws and bone fusion were observed by neck three-dimensional CT. Results The operation time and hand and wrist radiation exposure of the computer group were significantly longer than those of the robot group (P<0.05), and there was no significant difference in the screw implantation time and intraoperative blood loss between the two groups (P>0.05). All patients were followed up 11-24 months, with an average of 19.6 months. There was no significant difference in the follow-up time between the two groups (P>0.05). There was no significant difference in the accuracy of screw implantation between the two groups (P>0.05). Except for 1 case of incision infection in the computer group, which improved after antibiotic treatment, there was no complication such as nerve and vertebral artery injury, screw loosening, or breakage in the two groups. The JOA score and NDI significantly improved in both groups at 3 days after operation and at last follow-up (P<0.05) compared to those before operation, but there was no significant difference between the two groups (P>0.05). At last follow-up, 21 patients (91.3%) in the computer group and 18 patients (94.7%) in the robot group achieved satisfactory atlantoaxial fusion, and there was no significant difference in the fusion rate between the two groups (P>0.05). ConclusionComputer-assisted or robot-assisted atlantoaxial pedicle screw implantation is safe and effective, and robotic navigation shortens operation time and reduces radiation exposure.
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．
目的:探讨后路寰枢椎椎弓根螺钉内固定的术前计划方案,明确其手术指导意义。方法:选取经CT评估寰枢椎椎弓根螺钉置入可行的,并拟选择该手术治疗的上颈椎不稳患者15例,容积再现重建(VR)寰枢椎椎弓表面影像,了解个体椎弓后方表面解剖形态与骨性解剖标志。同时按寰枢椎椎弓根理想的钉道走行,多平面重建(MPR)个体椎弓根断面影像。术前根据这些解剖影像设计手术暴露路经、理想的进钉点与钉道轨迹。术中按该术前计划手术暴露,找到理想的进钉点并钻孔置椎弓根螺钉。将术中观察到的C1后弓及C2椎弓表面解剖,与术前CT重建影像对比。术后CT复查,评价螺钉置入情况。结果:15例术中观察到的C1后弓及C2椎弓表面解剖特征与术前CT容积再现的影像一致。参照寰枢椎椎弓CT影像解剖制定术前计划方案,术中按其逐一操作,手术简单、直观,无重要血管神经损伤,置钉准确。结论:根据CT容积再现与多平面重建的寰枢椎解剖影像,制定后路寰枢椎椎弓根螺钉内固定术前计划方案,指导手术安全、可靠。
ObjectiveTo investigate the procedure and effectiveness of posterior approach for operation of atlantoaxial subdural extramedullary nerve sheath tumors.MethodsBetween January 2012 and March 2017, 9 patients with atlantoaxial subdural extramedullary nerve sheath tumors were treated, including 7 males and 2 females, aged 25-62 years (mean, 45.4 years). There were 8 cases of neurinoma and 1 case of neurofibroma. The tumors were located at C1 in 1 case and C1, 2 in 8 cases. The disease duration ranged from 5 to 120 months, with an average of 45.9 months. The neural function was rated as grade D in 8 cases and grade E in 1 case according to the American Spinal Injury Association (ASIA) grading system. The Japanese Orthopaedic Association (JOA) score was 12.8±2.5. All patients underwent posterior cervical surgery. The laminae were replanted and fixed in 2 cases. The atlantoaxial or occipitocervical axis was not fixed in all patients.ResultsThe operation time was 90-343 minutes, with an average of 179.2 minutes. The intraoperative blood loss was 50-1 000 mL, with an average of 335.6 mL. No relevant complication occurred after operation. All patients were followed up 6-21 months (mean, 11.1 months). The postoperative X-ray films showed the good stability of the cervical spine. All patients had complete tumor resection and no recurrence. The replanted laminae achieved fusion and the internal fixation was firm. According to ASIA grading system, 3 patients of preoperative ASIA grade D had upgraded to grade E at 3 months after operation, while the remaining patients had no change in grading. The JOA score was 15.1±1.4 at 6 months after operation, which was significantly improved when compared with that before operation (t=4.221, P=0.003).ConclusionThe atlantoaxial subdural extramedullary nerve sheath tumor (including the ventral tumor) can be removed completely via posterior approach. The axis lamina can be replanted and fixed with the small titanium plate or lamina screw when necessary, and the atlantoaxial or occipitocervical fixation was not needed.