Posterior Atlantoaxial Pedicle Screw Fixation Research Articles

267. One stage atlantoaxial pedicle screw fixation for unstable atlas burst fracture

BACKGROUND CONTEXT Treatment of unstable atlas fracture is controversial. Some studies showed external fixation could achieve good clinical effect. Some showed internal fixation could get initial stability and perfect reduction. PURPOSE To assess the clinical results of one stage the posterior atlantoaxial pedicle screw fixation and fusion for unstable atlas burst fracture combined with atlantoaxial instability. STUDY DESIGN/SETTING A retrospective study. PATIENT SAMPLE Twenty-eight (9 females, 19 males) patients with an average age of 41.8 (22-59) years between May 2016 and December 2018 were studied. OUTCOME MEASURES The preoperative atlanto-dens interval (ADI) and lateral mass distance (LMD) were measured. All patients were assessed clinically for neurologic recovery, atlantoaxial reduction and bone graft fusion. METHODS Twenty-eight (9 females, 19 males) patients with an average age of 41.8 (range, 22-59) years between May 2010 and December2012 were studied. The patients had various degrees of occipital neck pain, limited mobility and associated with neurological dysfunction. Degree C in 1 case and degree D in 5 cases were assessed by the ASIA impairment scale. The preoperative atlanto-dens interval (ADI) and lateral mass distance (LMD) were measured. Patients were treated with posterior atlantoaxial pedicle screw fixation and fusion. All patients were assessed clinically for neurologic recovery, atlantoaxial reduction and bone graft fusion. RESULTS All 28 patients were followed up for an average of 15.6 months (range, 10-24 months). No intraoperative vertebral artery injury and spinal cord injury were noted. Postoperative cervical spine x-ray and CT showed that the sagittal cervical spine alignment was restored and no spinal cord compression was found. At last follow-up, solid bony fusion was achieved in all patients with no loosening, displacement, instability or breakage of the screws. All patients except 1 were substantially improved neurological status. At last follow-up the ADI and LMD were statistically significant difference between pre- and postoperation. CONCLUSIONS The posterior atlantoaxial pedicle screw instead of occipitocervical fusion for unstable atlas burst fracture combined with atlantoaxial instability seems to be effective, but it is technically demanding to place screw into the lateral mass of the atlas. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Clinical Application and Efficacy Analysis of 3D Navigation Module in the Treatment of Atlantoaxial Instability

Background: Posterior cervical atlantoaxial pedicle screw fixation is a very effective treatment for atlantoaxial instability (AAI). However, due to the complex anatomy of the cranial-cervical junction, the accuracy and safety of posterior atlantoaxial pedicle screw placement remains extremely challenging. Objective: To quantitatively evaluate the safety and accuracy of the 3D navigation module to assist the posterior atlantoaxial fixation. Methods: A total of 20 AAI patients were selected between June 2014 and September 2015. The Mimics v10.1 and 3-matic software were used. The 3D navigation module was designed as a double-sided positioning hole guide with a guide rod. All patients underwent posterior atlantoaxial posterior pedicle screw fixation with 3D navigation module. The actual entry point and screw trajectory were measured after operation, which were compared with the ideal entry point and screw trajectory. The Japanese Orthopaedic Association (JOA) score was measured before and after surgery to evaluate the neurological function improvement. The average operation time, blood loss, and frequency of intraoperative fluoroscopy were counted. Results: The posterior atlantoaxial pedicle screw fixation with a 3D navigation module was successfully performed in all patients. A total of 80 atlantoaxial pedicle screws were implanted in the 20 patients. Postoperative CT scan showed that two pedicle screws deviated from the medial aspect of the atlas pedicle cortex and entered the spinal canal approximately 1 mm, without causing neurological complications. There was no significant difference between the ideal and actual entry points or ideal and actual screw trajectories of the atlas and axis (P > 0.05). The preoperative JOA score was 12.45 ± 1.15 and postoperative JOA score was 15.5 ± 0.89, with statistically significant difference (P < 0.05). Conclusion: It was safe and effective to use the 3D navigation module to assist the posterior atlantoaxial pedicle insertion, with a high accuracy of pedicle screw placement. Keywords: atlantoaxial instability, pedicle screw, 3D navigation module, rapid prototyping

A Modified Personalized Image-Based Drill Guide Template for Atlantoaxial Pedicle Screw Placement: A Clinical Study

BackgroundAtlantoaxial posterior pedicle screw fixation has been widely used for treatment of atlantoaxial instability (AAI). However, precise and safe insertion of atlantoaxial pedicle screws remains challenging. This study presents a modified drill guide template based on a previous template for atlantoaxial pedicle screw placement.Material/MethodsOur study included 54 patients (34 males and 20 females) with AAI. All the patients underwent posterior atlantoaxial pedicle screw fixation: 25 patients underwent surgery with the use of a modified drill guide template (template group) and 29 patients underwent surgery via the conventional method (conventional group). In the template group, a modified drill guide template was designed for each patient. The modified drill guide template and intraoperative fluoroscopy were used for surgery in the template group, while only intraoperative fluoroscopy was used in the conventional group.ResultsOf the 54 patients, 52 (96.3%) completed the follow-up for more than 12 months. The template group had significantly lower intraoperative fluoroscopy frequency (p<0.001) and higher accuracy of screw insertion (p=0.045) than the conventional group. There were no significant differences in surgical duration, intraoperative blood loss, or improvement of neurological function between the 2 groups (p>0.05).ConclusionsBased on the results of this study, it is feasible to use the modified drill guide template for atlantoaxial pedicle screw placement. Using the template can significantly lower the screw malposition rate and the frequency of intraoperative fluoroscopy.

Accuracy assessment of atlantoaxial pedicle screws assisted by a novel drill guide template.

Posterior atlantoaxial pedicle screw fixation is an effective technique for atlantoaxial instability (AAI). However, because of the complex anatomy of the cranio-cervical junction, it remains challenging to insert atlantoaxial pedicle screw precisely and safely. A novel drill guide template was designed for atlantoaxial pedicle screw placement in this study. The purpose of this study is to quantitatively evaluate the accuracy of atlantoaxial pedicle screw placement using the novel drill guide template. Between June 2014 and September 2015, 32 consecutive patients with AAI were included. Using the Mimics v17.0 and 3-matic v9.0 softwares, a novel drill guide template with two location holes and guide rods was designed. All patients underwent posterior atlantoaxial pedicle screw fixation assisted by the novel drill guide template. After surgery, the entry point and directions of actual and ideal screw trajectories were measured and compared. All patients underwent surgery successfully assisted by the novel drill guide template. A total of 128 atlantoaxial pedicle screws were placed for 32 AAI patients. Postoperative CT scans showed two screws in atlas deviated medially from the pedicle cortex and entered the spinal canal about 1mm but without symptoms. For both atlas and axis, there were no significant differences in entry point or directions between the ideal and actual screw trajectories (P>0.05). Significant differences were found in preoperative and postoperative Japanese Orthopaedic Association score and Visual Analogue Score (P<0.001). It is feasible to use the novel drill guide template for atlantoaxial pedicle screw placement. The accuracy of screw placement assisted by the novel template is high. More studies are needed to confirm the efficacy of this template.

Treatment of traumatic upper cervical instability with single posterior atlantoaxial pedicle screw system

Objective To investigate the clinical efficacy of atlantoaxial pedicle screw fixation plus bony fusion in treatment of traumatic upper cervical instability. Methods From October 2009 to August 2013, 29 patients with traumatic upper cervical spine instability were treated with posterior atlantoaxial pedicle screws. The patients underwent autografting (n=19) and allografting (n=10) for spinal fusion. Surgical outcomes were recorded including intraoperative blood loss, operation time, with or without nerve, blood vessel and spinal cord injury, wound healing and bone fusion rate. Results All operations were completed smoothly with operation time of 110 minutes (range, 85-135 minutes) and blood loss of 150 ml (range, 80-500 ml). At the follow-up of 10 months to 5 years (mean 18 months), bony fusion was detected for all the patients. Postoperative radiographs verified all patients were bony fusion with satisfactory cervical spine stability. No complications of reduction loss, fixation failure, and spinal cord or vertebral artery injury were observed except for 1 patient with low virulent infection and 2 with delayed wound healing. Conclusion Single posterior atlantoaxial pedicle screw fixation provides security and reliable stability in treatment of upper cervical instability, however wound healing problems should be taken seriously. Key words: Axis; Spinal injuries; Pedicle screws

One stage atlantoaxial pedicle screw fixation for unstable atlas burst fracture

Objective To assess the clinical results of one stage posterior atlanloaxial pedicle screw fixation and fusion for unstable atlas burst fracture. Methods A retrospective analysis of clinical data including 32 cases, which were admitted according to the inclusion and exclusion criteria between May 2010 and December 2013. There were 11 females and 21 males whose age ranged from 22 to 59 years (mean 41.8 years). X-ray, CT scan reconstruction and MRI were done before operation to evaluate the injury of ligament and fracture. There were 17 cases of unstable atlas burst fracture,including 5 cases Jefferson fracture,8 cases untypical Jefferson fracture, and 4 cases lateral mass fracture combined with anterior arch or posterior arch fracture. There were 15 cases combined with axial fracture, 9 cases combined with dens fracture, 4 cases with axial body fracture, and 2 cases with Hangman fracture. The patients had various degrees of occipital neck pain, limited mobility and neurological dysfunction. Degree C in 1 case and degree D in 5 cases were assessed by the American Spinal Cord Injury Association (ASIA) impairment scale. All patients were treated with one stage posterior atlantoaxial pedicle screw fixation and fusion. All patients were assessed clinically by neurologic recovery, atlantoaxial reduc tion and bone graft fusion. The preoperative and postoperative atlanto-dens interval (ADI), lateral mass distance (LMD) and VAS were measured and statistically analyzed. Complications were observed. Clinical outcome of last follow-up was evaluated by dynamic X-ray and CT scan. Results All patients were followed up. The follow-up time ranged from 10 to 24 months (mean 15.6 months). The healing time of bone fusion ranged from 5 to 10 months with an average follow-up time of 6.9 months. The average preoperative VAS score was 5.0±1.4 while the score of last follow-up was 1.0±0.7, with statistically significant differences. Neurological status improved in all patients but one. Four cases with grade D improved to E, and one cases with grade C improved to D. Postoperative cervical spine X-ray and CT showed that the sagittal cervical spine alignment was restored. The preoperative ADI was 4.6±1.2 mm, which was statistically significant different with last follow-up the ADI of 2.4±1.0 mm. There were statistically significant difference between preoperative LMD of 5.6±2.2 mm and postoperative LMD of 1.2±1.0 mm. Conclusion The posterior atlantoaxial pedicle screw for unstable atlas burst fracture combined with atlantoaxial instability seems to be effective. It is technically demanding to place screw into thelateral mass of the atlas. Key words: Cervical atlas; Spinal fractures; Atlanto-axial joint; Joint instability; Spinal fusion

The clinical effects of atlantoaxial pedicle screw combined with unilateral axial spinous process and lamina screws for atlantoaxial instability

Objective To investigate the clinical effects of the posterior atlantoaxial pedicle screw fixation combined with unilateral axial spinous process and lamina screws and allogeneic bone graft for atlantoaxial instability. Methods From March 2010 to April 2014, data of 10 patients with atlantoaxial instability who had undergone atlanto-axial vertebral pedicle fixation and interbody fusion combined with posterior atlanto-axial spines lamina nails were retrospectively analyzed. There were 6 males and 4 females with an average age of 39 (range, 16-62) years old. The inclusion criteria was atlantoaxial instability together with unilateral vertebral artery segment high cross deformity (7 patients) or atlantoaxial joint break bad involving unilateral pedicle (7 patients). 3 patients have spinal cord disease symptoms and physical signs, both suffered limited neck mobility and pain. The VAS scores were 1-8, with an average of 3.70±2.11. Preoperative X-ray, CT three-dimensional reconstruction and MRI were collected. X-ray and CT examination were performed 7 d and 1, 3, 6, 12 months after operation to evaluate the internal fixation and bone grafting fusion. Results There's no occurrence of cervical spinal cord and vertebral artery injury. Screws were successfully implanted. 1 case's incision occurred infiltration liquid 3 days after operation. For allograft rejection consideration, we changed the plan, and the infiltrating stopped 5 days later. Other incisions were all primary healing. VAS scores were 1.01±0.89 after operation, which was significantly reduced. X-ray showed good recovery of cervical sequence after the operation, and CT revealed 1 patient with atlas pedicle screw in the medial cortex damage. Spinal canal was without infringing, and the other screw positions were normal. 6 months after operation, X-ray or CT examination both showed bony fusion. Conclusion Atlantoaxial pedicle screw fixation combined with unilateral axial spinous process and lamina screws and allograft bone graft fusion for the treatment of atlantoaxial instability can observe good clinical effects. Key words: Cervical atlas; Axis; Joint instability; Internal fixators

Treatment options for Grauer type II odontoid fractures and clinical outcome

Objective To explore the treatment options for fresh Grauer type Ⅱ odontoid fractures and discuss corresponding clinical outcome.Methods The study involved 40 patients with fresh odontoid fractures including seven with type Ⅱ A fractures, 18 with type Ⅱ B and 15 with type ⅡC according to Grauer classification.There were five patients with incomplete cervical cord injuries.Type Ⅱ A fractures were treated by traction of occipital-jaw band or skull for 1-2 weeks and then fixed with head-neck-chest plaster or brace.Type Ⅱ B fractures were treated with anterior odontoid screw system fixation.Fifteen patients with type Ⅱ C fractures and three patients with type Ⅱ B fractures combined with severe fracture displacement were managed with posterior atlantoaxial pedicle screw fixation. Results All the patients were followed up for 6-24 months.Seven patients with type Ⅱ A fractures showed union after fixation with head-neck-chest plaster or brace for 3-6 months.Fifteen patients treated with odontoid screw fixation had good positions of screws, with no injury to the spinal cord, of which 14 patients obtained bone union, with union rate of 93.3％.Eighteen patients (including 15 patients with type Ⅱ C fractures and three with type Ⅱ B fractures combined with severe displacement) managed with atlantoaxial pedicle screw system showed no injury to the vertebral artery and spinal cord.Solid bone fusion was achieved.in 31 patients after 3 to 6 months.The X-ray and SCT scans verified proper fixation of the screws, with no deformation, loosening or breakage of the screws.Five patients with incomplete cervical cord injuries obtained neural function recovery at various degrees after surgery. Conclusions Conservative treatment cau be alternative to type ⅡA fractures.Anterior odontoid hollow screw fixation is better for type ⅡB fractures (non-displaced or reducible) and has advantages of minor trauma, fast postoperative recovery and high union rate.However, posterior atlantoaxial pedicle screw system fixation and fusion is suitable to type Ⅱ C and ⅡB fractures with severe displacement and has the advantages of stable three-dimension fixation, direct screw placement, intraoperative reduction, short-segment fixation and high fusion rate. Key words: Spinal fractures; Cervical vertebrae ; Fracture fixation