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 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 investigate the cl inical results and complications of minimally invasive anterior transarticular screw fixation and fusion for atlantoaxial instabil ity. Methods Between May 2007 and December 2010, 13 patients with atlantoaxial instabil ity were treated with minimally invasive anterior transarticular screw fixation and fusion under endoscope. There were 11 males and 2 females, aged 17-61 years (mean, 41.3 years). The time between injury and operation was 5-14 days (mean, 7.4 days). All cases included 6 patients with Jefferson fracture, 5 with odontoid fracture, and 2 with os odontoideum. According to Frankel classification of nerve functions, 2 cases were rated as grade D and 11 cases as graed E. The operation time, intra-operative blood loss, radiation exposure time, and complications were recorded and analyzed. The stabil ity was observed by X-ray films. The cl inical outcome was assessed using the Frankel scale, and the fusion rates were determined by CT scan threedimensional reconstruction at last follow-up. Results The mean operation time was 124 minutes (range, 95-156 minutes); the mean intra-operative blood loss was 65 mL (range, 30-105 mL); and the mean radiation exposure time was 41 seconds (range, 30-64 seconds). Thirteen patients were followed up 12-47 months (mean, 25.9 months). No blood vessel and nerve injuries or internal fixator failure occurred. The bone fusion time was 6 months, and the dynamic cervical radiography showed no instabil ity occured. At last follow-up, the neurological function was grade E in all patients. The fusion rate was 84.6% (11/13). No continuous bone bridge was seen in the joint space of 2 patients, but they achieved stabil ity. Conclusion Minimally invasive anterior transarticular screw fixation and fusion is a safe and effective procedure for treatment of atlantoaxial instabil ity.
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 surgical feasibil ity and cl inical outcome of transpedicle screw fixation in treatment of atlantoaxial instabil ity and dislocation. Methods From January 2007 to June 2009, 16 patients with atlantoaxial instabil ity and dislocation were treated with transpedicle screw fixation. There were 13 males and 3 females, with a mean age of 42 years (range, 24-61 years). The transpedicle screw fixation was employed in 5 patients with old odontoid fracture (4 of Anderson type II and 1 of type III), in 4 patients with fresh odontoid fracture, in 4 patients with traumatic disruption of transverse atlantal l igament, and in 3 patients with congenital odontoid disconnection for atlantoaxial instabil ity. All patients had symptoms of cervical pain and l imition of cervical motion, 10 patients compl icated by dyscinesia and hypoesthesia of extremities. The Japanese Orthopaedic Association (JOA) score before operation was from 5 to 13, with an average of 8.5. The image examination showed atlantoaxial instabil ity or dislocation in all patients. Granulated autogenous il ium (20-30 g) was placed onto the surface of the posterior arches of both atlas and axis in some patients with old fracture of odontoid process or disruption of transverse atlantal l igament. Results The mean operative time and bleeding amount were 1.6 hours (1.2-2.5 hours) and 100 mL (50-200 mL), respectively. All the incision healed by first intension. All patients were followed up for 3-18 months, with an average of 11.5 months. The JOA score 3 months after operation was from 12 to 17, with an average of 14.2. All screws were successfully placed in atlas and axis. No postoperative compl ications such as vertebral artery injury, dural rupture, exacerbation of neurological symptoms, wound infection, and broken srews were observed in 16 cases. Postoperative radiograph and CT showed that only one screw penetrated into vertebral canal, but there was no neurological symptoms. Bony fusion was observed after 6 to 18 months of operation, and atlantoaxial rotational function in all patients restored satisfactorily, but axial rotation was partially lost. Conclusion Transpedicle screw fixation in upper cervical spine for treatment of atlantoaxial instabil ity and dislocation is safe and rel iable
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 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.
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.
【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.