Clinical Application of the “Pedicle Exposure Technique” for Atlantoaxial Instability Patients With a Narrow C1 Posterior Arch

Abstract

The "pedicle exposure technique" is an effective alternative in patients with the C1 posterior arch measuring <4 mm. In consideration of a high screw entry point on the C1 posterior arch, similar to the C1 posterior arch screw technique, we propose that this new technique can reduce venous plexus and C2 nerve root injury while providing effective biomechanical stability.

Computed tomographic morphometric analysis of lateral inclination C1 pedicle screw for atlantoaxial instability patients with a narrow C1 posterior arch

“…Tan et al. [12] in his study also have mentioned the same problem and therefore, exposed the C1 “pedicle” by removing the outer portion that contains approximately 4 mm of long bone of the posterior arch. The posterior arch along the trajectory of the C1 posterior arch screw allowing us to enlarge the height of the screw entry point.…”

“…In order to form the posterior border of the vertebral foramen together with joining and completing the vertebral arch, a lamina projects are backwards and medially from each pedicle so as to complete the triangle of the vertebral foramen [16]. Similar to other pedicles, the connection of the C1 posterior arch and lateral mass conforms to the other vertebral pedicles in their anatomical structure and biomechanics [12]. The C1 pedicle screw placement technique is advantageous compared to inserting the pedicle screw directly into the lateral mass.…”

“…This starting point avoids the large venous plexus that surrounds the C2 nerve root beneath the C1 posterior arch [9]. Recently, the C1 pedicle screw technique has been popularized for C1 rigid stable fixation and has many advantages such as a high fusion rate and fewer complications; less venous plexus bleeding and irritation of the C2 nerve root; and greater cortical purchase and longer screw trajectory length than the atlas lateral mass screw technique, making it more suitable for short‐segment fixation [10–14]. However, the C1 pedicle screw technique still has certain limitations, which includes the thin outer bone of the C1 posterior arch such that the screw or drill may slip to the side during the operation, leading to damage to the vertebral artery.…”

“…However, the C1 pedicle screw technique still has certain limitations, which includes the thin outer bone of the C1 posterior arch such that the screw or drill may slip to the side during the operation, leading to damage to the vertebral artery. Thus, in situation like this, some surgeons would perform an alternate technique for patients with a C1 posterior arch measuring no more than 4 mm to avoid vertebral artery injury [12]. That may not achieve reliable biomechanical fixation.…”

Computed Tomographic Morphometric Analysis of Pediatric C1 Posterior Arch Crossing Screw Fixation for Atlantoaxial Instability

“…6 Recent studies suggested 3.5-mm screw in lateral mass and/or posterior arch of the pediatric atlas, paving a base for the atlantoaxial screw fixation in the pediatric population. [7][8][9][10] However, those methods placed venous plexus, nerve root, and vertebral artery injury at risk during the exposure of the C1 lateral mass or/and posterior arch. 11,12 Salvage methods are necessary in case of anatomical variations, traumatic or iatrogenic damage, or vertebral artery protection.…”