A prospective, double-blind, randomized controlled trial of treatment of atlantoaxial instability with C1 posterior arches >4 mm by comparing C1 pedicle with lateral mass screws fixation

Abstract

BackgroundC1 posterior arch screw placement is one of the most effective treatments for atlantoaxial instability (AAI), which can be performed by either pedicle or lateral mass screw fixation. This study attempted to compare the feasibility and clinical outcomes of C1 pedicle with lateral mass screw fixations for treatment of AAI with C1 posterior arches >4 mm.MethodsA total of 140 patients with AAI (C1 posterior arches measuring >4 mm) was enrolled in this single-center, randomized, double-blind trial. The subjects were randomly assigned into two treatments: C1 pedicle (group A) or lateral mass (group B) screw fixation. The patients, independent evaluating physicians and radiologists were blinded throughout the entire study. Patients were assessed before operation and in a series of follow-ups at 6 weeks, 6 months, 1 year, and 3 years post-surgery. The operation time, volume of blood loss, intraoperative complications, bone fusion rates, Japanese Orthopaedic Association (JOA) and visual analog scale (VAS) scores were monitored.ResultsAll 140 patients showed overall improvements in clinical symptoms after surgery. The mean follow-up time was 24.5 ± 13.0 months. In both groups, the mean JOA scores improved significantly at the time of final follow-up as compared to prior surgery (group A: 7.1 ± 1.4 vs 13.7 ± 1.9; group B:7.3 ± 1.8 vs 13.1 ± 1.4; improvement rates: 87.2 % (group A) and 86.5 % (group B)). The VAS scores also decreased significantly in both groups at the time of final follow-up as compared to prior surgery (group A: 6.0 ± 1.3 vs 1.7 ± 0.8, and group B: 5.7 ± 1.1 vs 2.1 ± 1.2). Bone fusion was achieved within 12 months postoperatively in the patients from both groups. The operation time was significantly shorter and volume of blood loss was significantly less in the patients from group A as compared to group B (p < 0.01). Furthermore, thirteen patients had burst bleeding from the C1-2 venous plexus and nine patients had immediate pain and numbness in the occipitocervical region due to C2 nerve roots irritation during lateral mass screw replacement, which were not observed in the patients with C1 pedicle screw insertion. No complications such as screw loosening, shifting, breakage, or AAI were observed in both groups.ConclusionsC1 pedicle screw fixation is less invasive and simpler, and has fewer complications. It renders better clinical outcomes than lateral mass screw fixation for treatment of AAI.Trial registrationCurrent Controlled Trials ChiCTR-IOR-15006748.

Clinical outcomes of posterior c1 and c2 screw-rod fixation for atlantoaxial instability

“…However, as opposed to the lateral mass screw, far more frequent and more severe complications may be seen. The C1 pedicle screw technique is a difficult technique to implement requiring experience and it brings along a higher risk of vertebral artery injury because of its close proximity (42). In this series of ours, we used C1 lateral mass screw, we tried to place bicortical screws as much as possible, but we used unicortical screws in cases which we deemed more suitable as a result of the assessments we made.…”

What Is the Superior Screw Fixation Technique for Posterior Decompression and Fusion in the Management of Cervical Spondylotic Myelopathy

“…In addition, improved biomechanical attributes of pedicle screws may not be of pertinent detail to this potentially frail demographic, limited in their daily activities. In the study by Yan et al, 13 outcomes were reported only in the immediate postoperative period, highlighting more cases of pain and numbness associated with lateral mass screws. The presence of immediate pain can easily be explained by the fact lateral mass screw placement requires soft tissue dissection to be extended until the far lateral margin of the facet is identified.…”

“…Group A had significantly shorter surgical times and blood loss as compared with group B ( P <0.01) 13. In addition, 13 (18.6%) patients in group B had burst bleeding from the C1–C2 venous plexus and 9 (12.9%) patients had immediate pain and numbness in the occipitocervical region because of C2 nerve root irritation, with no such complications experienced in group A (pedicle screw) 13. Residual neurological deficit is of great concern, as it may precipitate falls, and readmission in spondylotic patients.…”

“…A retrospective analysis carried out on 46 patients found no incidence of serious neurovascular complications and 26 of the patients demonstrated improved neurological status 12. A prospective double-blind randomized controlled trial of 140 patients comparing pedicle screw (group A) versus lateral mass screw (group B) fixation for atlantoaxial instability found that pedicle screws resulted in better clinical outcomes 13. Group A had significantly shorter surgical times and blood loss as compared with group B ( P <0.01) 13.…”

“…A prospective double-blind randomized controlled trial of 140 patients comparing pedicle screw (group A) versus lateral mass screw (group B) fixation for atlantoaxial instability found that pedicle screws resulted in better clinical outcomes 13. Group A had significantly shorter surgical times and blood loss as compared with group B ( P <0.01) 13. In addition, 13 (18.6%) patients in group B had burst bleeding from the C1–C2 venous plexus and 9 (12.9%) patients had immediate pain and numbness in the occipitocervical region because of C2 nerve root irritation, with no such complications experienced in group A (pedicle screw) 13.…”