C1-Ring Osteosynthesis (C1-RO) With Pedicle Screw To Treat Unstable Fractures:An Atlas Biomechanical Analysis

Background:Bohm [50] and Heiko Koller et al [59] proposed to use the mature scholars posterior atlas screw technology to treat the atlas fracture, and to restore bone atlas ring structure and stability with porous plate. However, the biomechanical study of the stability of C1-ring osteosynthesis (C1-RO) with posterior atlas screw technology is lack in domestic and international.Objective:Through the biomechanical study of the stability of C1-ring osteosynthesis (C1-RO) with posterior atlas pedicle screw technology,we hope to provide theoretical support for the clinical application of C1-ring osteosynthesis (C1-RO) with posterior atlas pedicle screw technology to treat unstable atlas fractures.Methods:We cut off the connection sites between the atlas arch and lateral mass and the transverse atlantal ligament (TAL) of the six complete occipital cervical spine (CO-4) moist samples,to made unstable atlas fracture model [12]. After Cl-ring osteosynthesis (C1-RO) with posterior atlas pedicle screw technology, we record C1-2 three-dimensional motion of the normal group,model group and the Cl-ring osteosynthesis (C1-RO) group in the 1.53Nm with camera,to evaluate the stability of reconstruction of unstable atlas fracture After C1-ring osteosynthesis (C1-RO) with posterior atlas pedicle screw technology.Results:In the complete group, the mean of range of motion (ROM) in flexion,extension,left/right lateral bending,left/right rotation is:12.65°,13.44°, 11.36°,11.61°,53.06°,53.70°; Atlas fracture model:24.53°,26.21°,21.21°, 21.45°,65.71°,67.04°; The Cl-ring osteosynthesis (C1-RO) group:14.84°, 14.30°,12.31°,12.54°,53.80°,55.01°. C1-2 range of motion in all directions (ROM) of the C1-ring osteosynthesis (Cl-RO) group were significantly greater than the complete group, P=0.000<0.05, significant difference; the C1-ring osteosynthesis (C°-RO) group was significantly less than the fracture group, P=0.000<0.05, significant difference; The C1-2 range of motion in all directions (ROM) between the complete group and the C1-ring osteosynthesis (C1-RO) group is similar, the flexion range of motion (ROM) compared between the two groups P= 0.083>0.05, the difference was not statistically significant,other ranges of motion (ROM) compared P> 0.05, the difference was not statistically significant.Conclusion:In unstable atlas fractures,the transverse atlantal ligament (TAL) can be ruptured,but other secondary structure is complete. With the TAL rupture, some instability in flexion may be present, but due to ring of C1 and other structural integrity after C1-ring osteosynthesis (Cl-RO) with posterior atlas pedicle screw technology, flexion instability is limited. After C1-ring osteosynthesis (Cl-RO), the stability provided by the secondary ligaments seems sufficient to maintain Cl-2 stability and translation of C1 on C2 within limits that do not endanger the spinal cord during physiological loading.