Challenges of Transarticular Screw Fixation in Young Children: Report of Surgical Treatment of a 5-Year-Old Patient's Unstable Os-Odontoideum

Surgical procedures for atlantoaxial (C1–C2) fusion in young children are relatively uncommon. The purpose of this study was to report on a surgical treatment for a case of atlantoaxial instability caused by os-odontoideum in association with quadriparesis and respiratory paralysis in a 5-year-old girl. We present the patient's history, physical examination, and radiographic findings, describe the surgical treatment and a five year follow-up, and provide a literature review. The instability was treated by halo immobilization, followed by C1–C2 transarticular screw fixation using a computed tomography-based navigation system. At the five year follow-up, the patient had made a complete recovery with solid union. The authors conclude that C1–2 transarticular screw fixation is technically possible as in a case of atlantoaxial instability in a five-year-old child.

Computer-assisted C1-C2 Transarticular Screw Fixation "Magerl Technique" for Atlantoaxial Instability

STUDY DESIGN: A retrospective study. PURPOSE: To evaluate the surgical results of computer-assisted C1-C2 transarticular screw fixation for atlantoaxial instability and the usefulness of the navigation system. OVERVIEW OF LITERATURE: We used a computed tomography (CT)-based computer navigation system in planning and screw insertion in Magerl's procedure, which provides the most rigid atlantoaxial fusion, to avoid risk of vertebral artery (VA) tear by avoiding high-riding VA during screw insertion. METHODS: Twenty patients who underwent atlantoaxial fusion under the CT-based navigation system were studied. The mean observation period was 33.5 months. The evaluated items included the existence of VA stenosis by preoperative magnetic resonance angiography, surgical time, blood loss volume, Japanese Orthopaedic Association (JOA) score and Ranawat's pain criteria before surgery and at final follow-up, postoperative screw position evaluated by CT, and bony fusion. RESULTS: The mean operation time was 205 minutes, with the mean blood loss volume of 242 ml. The mean JOA score was 11.6 points before surgery and 13.7 at final follow-up. Occipital and/or cervical pain presented before operation was remitted or resolved in all patients. Evaluation of screw insertion by CT revealed correct penetration to atlantoaxial joints, with a perforation rate of 2.6%. There was no complication, including VA tear, and all patients who were followed-up during one year or more after surgery achieved bony fusion. Some subjects who appeared inappropriate for surgery from CT images were assessed as eligible for surgery based on the evaluation results obtained using the navigation system. CONCLUSIONS: It was demonstrated that the CT-based navigation system is an effective support device for Magerl's procedure.

Intraoperative Vertebral Artery Angiography to Guide C1-2 Transarticular Screw Fixation in a Patient with Athetoid Cerebral Palsy

We present a case of an athetoid cerebral palsy with quadriparesis caused by kyphotic deformity of the cervical spine, severe spinal stenosis at the cervicomedullary junction, and atlantoaxial instability. The patient improved after the first surgery, which included a C1 total laminectomy and C-arm guided righ side unilateral C1-2 transarticular screw fixation. C1-2 fixation was not performed on the other side because of an aberrant and dominant vertebral artery (VA). Eight months after the first operation, the patient required revision surgery for persistent neck pain and screw malposition. We used intraoperative VA angiography with simultaneous fluoroscopy for precise image guidance during bilateral C1-2 transarticular screw fixation. Intraoperative VA angiography allowed the accurate insertion of screws, and can therefore be used to avoid VA injury during C1-2 transarticular screw fixation in comorbid patients with atlantoaxial deformities.

Unilateral Posterior Atlantoaxial Transarticular Screw Fixation in Patients with Atlantoaxial Instability : Comparison with Bilateral Method

OBJECTIVE: Bilateral C1-2 transarticular screw fixation (TAF) with interspinous wiring has been the best treatment for atlantoaxial instability (AAI). However, several factors may disturb satisfactory placement of bilateral screws. This study evaluates the usefulness of unilateral TAF when bilateral TAF is not available. METHODS: Between January 2003 and December 2007, TAF was performed in 54 patients with AAI. Preoperative studies including cervical x-ray, three dimensional computed tomogram, CT angiogram, and magnetic resonance image were checked. The atlanto-dental interval (ADI) was measured in preoperative period, immediate postoperatively, and postoperative 1, 3 and 6 months. RESULTS: Unilateral TAF was performed in 27 patients (50%). The causes of unilateral TAF were anomalous course of vertebral artery in 20 patients (74%), severe degenerative arthritis in 3 (11%), fracture of C1 in 2, hemangioblastoma in one, and screw malposition in one. The mean ADI in unilateral group was measured as 2.63 mm in immediate postoperatively, 2.61 mm in 1 month, 2.64 mm in 3 months and 2.61 mm in 6 months postoperatively. The mean ADI of bilateral group was also measured as following; 2.76 mm in immediate postoperative, 2.71 mm in 1 month, 2.73 mm in 3 months, 2.73 mm in 6 months postoperatively. Comparison of ADI measurement showed no significant difference in both groups, and moreover fusion rate was 100% in bilateral and 96.3% in unilateral group (p=0.317). CONCLUSION: Even though bilateral TAF is best option for AAI in biomechanical perspectives, unilateral screw fixation also can be a useful alternative in otherwise dangerous or infeasible cases through bilateral screw placement.

Measurement of the Axial Isthmus for Atlantoaxial Transarticular Screw Fixation / 대한해부학회지

Pre-operative evaluation of the anatomy of the axis, such as the size and angle of the axial isthmus, is very important to minimize complications in atlantoaxial transarticular screw fixation. To provide basic data useful for atlantoaxial transarticular screw fixation in Korean, the width and height of the axial isthmus as well as ideal insertion angle of the screw were measured in this study. Fifty seven (male, 36; female, 21) dried axes obtained from Korean adult cadavers, 60.5 years old in average, were used. The shortest distance in the width and height of the axial isthmus was measured at the level of transverse foramen by using Vernier calliper. The ideal screw insertion angle was set up as an angle between a parasagittal line and the line passing through the center of the isthmus and screw insertion point which is located 2 mm lateral to and 3 mm superior to the posteromedial end of the inferior articular surface of the axis. The mean width of the axial isthmus was 8.14 mm (8.42 mm in male; 7.86 mm in female) in the right and 8.46 mm (8.80 mm in male; 8.12 mm in female) in the left side, and 8.61 mm in male and 7.99 mm in female. Although the width of the axial isthmus was slightly greater in the left and in male, there was no significant difference between both sides or sexes. The mean height of the axial isthmus was 7.17 mm (7.49 mm in male; 6.84 mm in female) in the right and 7.43 mm (7.90 mm in male; 6.96 mm in female) in the left side, and 7.69 mm in male and 6.90 mm in female. However there was no significant difference between both sides or sexes, as like in the width. In the atlantoaxial transarticular screw fixation, the axis with isthmus lesser than 5 mm in its width or height is regarded as risk group in general. The frequency of the risk group in the width was 3.5% (2 cases) in the right and 1.8% (1 case) in the left, while that in the height was 8.8% (5 cases) in the right and 7.0% (4 cases) in the left. The mean ideal insertion angle of the screw was 5.6 degrees, 4.4 degrees in the right and left side of male, and 4.7 degrees, 5.5 degrees in the right and left side of female respectively. However the insertion angle dispersed over a wide range between 0 degree ~ 12 degrees. In conclusion, measurement of the isthmus height and insertion angle, besides the isthmus width, should be involved in the pre-operative examination, to minimize complications during the atlantoaxial transarticular screw fixation.

Anatomic relationship of vertebral artery and screw trajectory of posterior atalanto-axial transarticular screw fixation / 中国矫形外科杂志

[Objective]To study the screw trajectory in the posterior atalanto-axial transarticular screw fixation.[Methods](1)The anatomical parameters related to the screw fixation were measured on 30 paired dry atlantoaxial specimens;(2)The X ray and CT scan were taken after C1、2 was fixed by posterior transarticular screws on 6 cadavers.These iterms were used to explore the anatomical relation of the vertebral artery and the screw trajectory in the posterior C1、2 fixation.[Results]The depth of the vertebral artery groove on the inferior surface of the superior facet of the axial was(5.86 1.45)mm;the vertebral artery groove extented the superior facet up to its medial third in 15 sides,up to the middle third and its lateral third respective in 35 and 9 sides,and the ideal screw trajectory medial angle of these specimens were(26.4?3.44)?,(16.1?2.44)?,(15.1?2.24)? respectively。The shortest distance between the vertebral artery and the screw trajectory lied in the topmost point of the vertebral artery groove of the axial on CT images,and the interval was(2.75～5.78)mm.[Conclusion]The position of vertebral artery groove of the axial is the key to decide the angle of the screw trajectory.The shortest interval between screw trajectory and vertebral artery,safe for posterior atalanto-axial transarticular screw fixation,locates on the inferior surface of the superior facet of the axial.

Modified posterior transarticular screw fixation for atlantoaxial instability / 中国矫形外科杂志

[Objective]To explore the techniques and effect of atlantoaxial instability with posterior transarticular screw fixation.[Method]A prospective clinical analysis was performed for the results of the modified posterior C1、2 transarticular screw fixation,in which the middle site of lower margin in the axial inferior articular process was used as the screw entry point in the procedure.Twenty cases of atlantoaxial instability underwent the modified C1、2 stabilization with morselized autograft from September 2001 to September 2006.There were 15 males and 5 females,averaged 32.2 years(range 17 to 49 years).Of them,4 cases suffered from fresh injuries,14 from old trauma,1 from congenital deformity,and 1 from intraspinal tumor.Postoperative indexes including the reduction extent of vertebral body,internal fixation,bone fusion,clinical symptoms and their complication were observed periodically.[Result]Bilateral screw fixation was used alone in 17 cases,with Gallie interspinous wiring for added stability in 3.Anatomical reduction of the atlantoaxial joints was achieved in19 cases,while rotational dislocation was restored to a great extent in 1.Fixation of all the internal devices was very well in the group.All cases were followed up from 16 to 64 months(21 months on average).C1、2 bony fusion was obtained in postoperative 2 to 3 months,clinical symptoms relieved and no complications occurred.[Conclusion]The modified posterior transarticular screw fixation using new screw entry site is recommended as an effective treatment for C1、2 instability due to its simple procedure and satisfying curative effect.

Anatomical measurement and clinical significance of anterior transarticular screw fixation / 中国矫形外科杂志

[Objective]To provide Chinese morphological data for anterior C1、2 transarticular screw fixation.[Method]With a digital vernier and a goniometer made in China,the anatomic parameters related to anterior C1、2 transarticular screw fixation were measured from 50 pairs of dried Chinese adult human C1 and C2 vertebrae.[Result]In the anterior transarticular screw fixation,the lateral angulation of the screw tract to the sagittal plane ranged from(10.8?2.10)? to(25.13?3.12)?,the posterior anguation to the coronal plane from(8.85?2.12)? to(26.96?3.09)?,the screw tract length was from(17.48?2.1) mm to(25.4?2.59)mm,the distance from medial part of C2 foramen to the middle of C2 body was(14.12?1.28)mm.[Conclusion]It is optimal for the anterior C1、2 transarticular screw fixation to place the anterior C1、2 transarticular screw with the length of 17 mm to 25 mm in lateral angulation ranged from 10? to 25? and the posterior angulation ranged from 9? to 27?.During the procedure,the dissecting distance from the middle of C2 to lateral should not exceed 14 mm.

Analysis of the Rate of High Riding Vertebral Artery Using Sagittal Reformatted Computed Tomography / 대한정형외과학회잡지

PURPOSE: The rate of high riding vertebral artery (VA) was investigated, and the rate in rheumatoid arthritis (RA) group was compared with that in non-RA group. MATERIALS AND METHODS: 67 consecutive patients were recruited. The male to female ratio was 44: 23. Sixteen patients were diagnosed as RA and 51 as cervical spondylosis. Sagittal reformatted view transecting mid-portion of the atlantoaxial facet joint was obtained and the height of the isthmus and the internal height of the axis were measured using a Picture Archiving and Communication System (PACS). High riding VA was defined as less than 5 mm of isthmus height or less than 2 mm of internal height. RESULTS: Thirty-six joints (26.9%) and twenty-seven patients (40.3%) showed high riding VA, and there was no significant difference between right and left side (8 right, 10 left, 9 both sides) (p=0.20). There was no difference among age distribution (p=0.06). In rheumatoid patients, the rate of high riding VA (10/16, 62.5%) was higher than in non-rheumatoid patients 17/51, 33.3%) (p=0.04). CONCLUSION: Preoperative evaluation of the VA using the reformatted CT should be performed in all patients who plan to undergo atlantoaxial transarticular screw fixation. In rheumatoid patients, possibility of high riding VA should always be considered.

The Results and Complications of the C1-C2 Transarticular Screw Fixation Methods

OBJECTIVE: To evaluate the accuracy and safety of C1-C2 transarticular screw insertion, we retrospectively review surgical records and postoperative radiological findings. METHODS: From January 2001 to October 2003, the C1-C2 transarticular screw fixation and posterior wiring with iliac bone grafts was performed in 16 pateints. 6 patients had rheumatoid arthritis which caused cervical instability, 3 patients had os odontoideum, 3 patients had type 2 odontoid process fracture, 3 patients had traumatic transverse ligament injury and 1 patients who had been managed with C1-C2 wire fixation had psoriatic arthritis. RESULTS: Osseous fusion was documented in 15 patients(93.8%). Only one patient was recorded screw loosening because of postoperative infection. One patient had only one screw placed because of abnormal anatomical structure, one patients was breakage of a Kirschner wire, and one screw was medial location to lateral mass of C1, but clinical results was excellent and radiological instability was not noted. CONCLUSION: The author's experience demonstrates that C1-C2 transarticular screw fixation with wired bone graft is a safe procedure with higher fusion rate but precaution is needed to avoid the neural damage, vertebral artery injury, and hardware failure.

Measurements of C1-2 region of Cervical Spine Using MRI for C1-2 Transarticular Screw Fixation / 대한척추외과학회지

STUDY DESIGN: The C1-2 region was measured using MRI for a C1-2 transarticular screw fixation. OBJECTIVES: To measure the first and second cervical spine, using MRI for a C1-2 transarticular screw fixation, and find the safe trajectory for the screw. SUMMARY OF LITERATURE REVIEW: Posterior atlantoaxial transarticular screw fixation is an excellent procedure that is associated with high fusion rates. However, there is a potential risk of vertebral artery injury. MATERIALS AND METHODS: Sagittal MR images, of the cervical spine transecting mid portion of the C1-2 facet joints, were obtained in 24 patients. The mean age of the patients was 45.5 years. The male to female ratio of the patients was 15:9. From the sagittal images the ideal screw trajectory was made, and 48 oblique axial MR images, depending on the ideal screw trajectory in the sagittal plane, were obtained. On the oblique sagittal images, the width of the isthmic portion of the C2, the ideal length of the transarticular screw, the ideal insertion angle of the screw and the ideal entry point were measured using a PACS digital measuring instrument. The location of the vertebral artery was also evaluated. RESULTS: The mean width of the isthmic portion of the C2 was 6.2 mm, ranging from 2.3 to 7.6 mm. The mean ideal screw length was 40.5 mm, ranging from 34.0 to 46.8 mm. The mean ideal insertion angle was 1.1 degrees, ranging from -2.4 to 4.7 degrees, medially. There were no significant differences in the width or the angle in relation to the sex of the patients. However, the length of the screw was significantly longer in the male (42.1 mm) than the female patients (38.0 mm). Three of 24 patients (3 of 48 C1-2 facet joints) had a narrow isthmus due to a high riding vertebral artery. CONCLUSIONS: A C1-2 transarticular screw fixation has a risk of injury to the vertebral artery. Therefore, the preoperative measurement of the C1-2 region and an evaluation of the vertebral artery are recommended in each patient. A magnetic resonance image is a useful method for easily evaluating the anatomic structure of the C1-2 region, with no additional study.

Atlantoaxial Instability due to Hypoplasia of the Odontoid Process

The authors present a case of a 39-year old man, admitted with neck pain and tingling sensation on his right upper extremity. On radiological investigation, atlantoaxial instability due to odontoid process hypoplasia and mild upper cervical cord compression by abnormal soft tissue were revealed. We performed posterior C1-2 transarticular screw fixation with posterior bone graft and could obtain good postoperative result.

Atlantoaxial Subluxation due to Psoriatic Arthritis

Atlantoaxial subluxation causing spinal cord compression at the craniovertebral junction may develop in patients with rheumatoid or psoriatic arthritis. There have been only a few reports of atlantoaxial subluxation in patients with psoriatic arthritis in the world. The authors report a case of psoriatic arthritis with atlantoaxial subluxation accompaning periodontoid pannus formation. This 53-year-old man with a 3-year history of psoriatic skin lesion presented with nuchal pain and myelopathy. We performed decompression by C1 total laminectomy with transarticular screw fixation and obtained remarkable improvement in motor function and immediate postoperative stability.

C1-2 Transarticular Screw Fixation as a Revision Surgery for Failed C1-2 Fusion: Case Report / 대한척추외과학회지

Odontoid process fracture, nonunion or atlantoaxial instability are generally treated with posterior fusion using sublaminar wiring techinique. And occiput to C2 fusion is performed in cases with posterior arch defect of atlas. However, occiput to C2 fusion can not stabilize unstable C1-2 segment before accomplishment of fusion. Therefore, postoperative external support is necessary. A 48-year old male patient visited our hospital due to weakness and spasticity of four extremities. 6 months ago, he got C1-2 fusion in other university hospital due to odontoid process fracture. 6 months after surgery, sublaminar cable was pulled out and grafted bone was absorbed. The neurological deficits were worsened(spasticity of four extremities with severe myelopathy, bed ridden state). JOA score was 4. Diagnosis of the patient was C1-2 instability with cervical myelopathy due to odontoid process fracture nonunion and posterior arch defect of atlas. C1-2 transarticular screw fixation and occiput to C2 fusion were performed.

Long Term Follow up and Clinical Results of Posterior C1/2 Fixation

OBJECTIVE: To determine the efficacy of various posterior fusion techniques in managing C1/2 instability. PATIENTS AND METHODS: Retrospective review of patients undergoing C1/2 posterior fusioin was undertaken with the aim of determining the long-term outcome of the selected procedures. Forty-two patients requiring posterior atlantoaxial fusion for various pathologies were treated with various instruments for internal spinal fixation. Forty-two patients underwent 45 procedures from 1990 to 1997, with a mean follow-up of 2.7 years(range 8 months-7 years) RESULTS: The most common disease processes were odontoid fracture(12 patients), os odontoideum(13), and rheumatoid instability(7). Nineteen interspinous wirings, 17 transarticular screw fixations, 9 halifax clamp applications were performed. Three of Halifax fixation and 2 of wiring failed in long term follow up. Among of them, bony fusion was failed in 3 patients which consequently required reoperation. All transarticular screw procedures resulted in successful fusions. CONCLUSIONS: Transarticular screw fixatioin has several potential advantages compare to other procedures as a technique for C1/2 posterior arthrodesis.

Transoral Anterior Decompression and Posterior Fusion of Irreducible Atlantoaxial Dislocation with Spinal Cord Injury: Case Report

We report a case of irreducible atlantaxial dislocation with spinal cord injury. The patient was a 36-year-old man who suffered from the sudden onset of shallow respiration and severe motor weakness after slip down. We have performed the one-stage operation, the transoral decompression, reduction and posterior interspinous wiring with bone fusion. Three weeks after surgery, the reduction state and posterior wiring procedure were failed, due to severe osteoporotic change. So, we have performed second operation, the transarticular facet screw fixation and occipito-cervical fixation with Steinmann pin, from which good postoperative stability and neurological improvements, were obtained.

Clinical Analysis of Posterior C1-C2 Fusion for Atlantoaxial Instability

The authors analyzed the surgical results of posterior C1-C2 fusion in 18 cases of atlantoaxial instability. Posterior C1-C2 wiring with bone fusion(11 cases), C1-C2 transarticular screw fixation(6 cases), and occipitocervical fusion(1 case) have been performed for unstable odontoid process fractures(10 cases), transverse ligament injury(4 cases), os odontoideum(3 cases), rheumatoid C1-2 instability(1 case). Follow-up examination was performed in all patientts after a mean postoperativeduration of 39.9 months. Follow-up x-rays showed successful stabilization in 17 cases(94%). Postoperative neurological evaluation showed improvement in 16 cases(89%), stabilization in 2 cases(11%) and there was no major operative complication.

Anatomical Suitability of Posterior C1/2 Transarticular Screw Fixation in Korean

Although C1-C2 transarticular screw fixation has become a popular surgical method of treating atlantoaxial instability, we remain concerned about the potential for injury to the vertebral artery. Because of the lack of an objective measuring method, surgical unsuitability has been decided on the basis of individual experiences as reported in 18-23% of cases. In this study, the point of screw intersection(the passing points) on the superior articular surface of C2 were measured and the directions of these were thus objectified. Sixty-four healthy volunteers underwent 1mm fine-slice C1-C2 CT scanning, and sagittal images were reconstructed at 3.5mm(3.5mm lateral image) and 6mm(6mm lateral image) lateral to the spinal canal. The C1/2 transarticular screw trajectories making the longest paths or violating the transverse foramen(dangerous trajectory) were drawn and the distance from their points of screw intersection on the superior articular surface of C2 were measured from the posterior rim of the superior articular surface of C2. When the space available for screw(SAS) posterior to the passing point of the dangerous trajectory was equal to or less than 3.5mm(major diameter of the commonly used screw), the case was considered unacceptable, when SAS was over 3.5mm but equal to or less than 4.5mm, screw placement were considered risky. The trajectories made the longest paths when they passed 3.6+/-1.6mm(mean+/-S.D.) and 2.8+/-1.7mm(mean+/-S.D.) anterior to the posterior rim of the posterior articular surface of C2 as seen on 3.5mm lateral images and 6mm lateral images, respectively. While four of 64 cases(6.3%) were unilaterally unacceptable or risky on 3.5mm lateral images, 21 cases(32.8%) were unacceptable or risky on 6mm lateral images(unilateral, 15cases; bilateral, 6 cases). When the trajectories inclined forward to 0%, 25%, 50%, 75% and 100% points of AP diameter of the superior articular surface of C2 from the posterior rim, the respective risks of the involvement of the transverse foramen increased to 0.78%, 1.5%, 25%, 74% and 100%, as seen on 3.5mm lateral images and 10.9%, 14%, 62.5%, 95% and 100%, on 6mm lateral images.

Posterior C1-2 Transarticular Screw Fixation in Atlantoaxial Instability

Posterior transarticular screw fixation is known to be one of the best surgical method for the atlanto-axial instability. Between April 1995 and February 1997, this technique was used in the treatment of 21 patients(10 men, 11 women) suffering from this condition. The average age at the time of operation was 39 years(range, 17 to 63). and mean follow-up period was 14(mean 3 to 25) months. The indication for fusion were nine cases, type II-A odontoid process fracture; three cases, type II-P odontoid process fracture; three cases, os odontoideum; three cases transverse ligament laxity due to rheumatoid disease; and three cases, transverse ligament injury without bone fracture. Eleven operations involved cases were operated with posterior C1, 2 transarticular screw fixation using a 3.5 mm cortical screw augmented th interlaminar iliac graft and sublaminar wire fixation. The other ten patients underwent the same surgery without sublaminar wire fixation. In two cases d screw were misplaced; one was placed lateromedially and the other caused widening of the joint capsule space, but there were corrected by reoperation. Patients were ambulated with Philadelphia neck collar on the first post-operation day. At the end of three months follow-up, bone union was seen in all cases, and the following conclusions may be drawn: 1) Immediately after surgery, ambulation is possible; 2) The rate of occurrence of bone union is high; 3) A halo vest is not needed; 4) Sublaminar wiring is also unnecessary.

C1/2 Transarticular Screw Fixation for Complicated Os Odontoideum: Case Report

C1/2 posterior transarticular screw fixation has become an accepted method of rigid internal fixation for patients requiring posterior C1/2 fusion. Especially,Surgery for Os odontoideum can be troublesome due to its severe tranlational instability, canal stenosis requiring decompressive laminectomy and defective C1 posterior arch. The author reports three cases of complicated Os odontoideum(one case of failed occipito-C2 fusion, two cases requiring C1 laminectomy) with C1/2 transarticular screw fixation and interarticular bone fusion. All required decompressive laminectomy and demonstrated highly unstable translational instabilities. On the basis of these experiences, it is postulated that C1/2 transarticular screw fixation seems to be superior to other methods in stabilization and fusion for complicated Os-odontoideum.