Biomechanical comparison of transpedicular versus intralaminar C2 fixation in C2-C6 subaxial constructs

• Published in: Spine (Philadelphia, Pa. 1976) Pa. 1976), 2011-01, Vol.36 (1), p.E33-E37
• Main Authors: Benke, Michael T, O'Brien, Joseph R, Turner, Alexander W L, Yu, Warren D
• Format: Article
• Language: English
• Subjects: Biomechanical Phenomena; Bone Screws; Cadaver; Cervical Vertebrae - diagnostic imaging; Cervical Vertebrae - surgery; Female; Humans; Male; Middle Aged; Prosthesis Design; Radiography; Range of Motion, Articular; Spinal Fusion - instrumentation; Spinal Fusion - methods
• ISSN: 0362-2436; 1528-1159
• DOI: 10.1097/BRS.0b013e3181eea6e2

Biomechanical study. To compare the relative rigidity of C2 transpedicular versus intralaminar fixation with and without offset connectors in C2-C6 subaxial constructs. Insufficient biomechanical data exists on C2 laminar fixation in subaxial constructs, and no study has considered C2-C6 subaxial constructs or the use of offset connectors. Six fresh-frozen cadaveric cervical spines underwent rigidity testing in the intact condition and after a destabilizing C3-C6 laminectomy. Specimens were instrumented with 20 mm pedicle and 20 mm intralaminar screws at C2, and with 14 mm lateral mass screws from C3-C6. In random order, three conditions (C2 pedicle screws, C2 laminar screws, and C2 laminar screws with offset connectors) were tested in flexion-extension, axial rotation, and lateral bending. Laminar screws in C2-C6 constructs were equivalent to transpedicular fixation in flexion-extension (P = 0.985), were significantly more rigid than pedicle screws in axial rotation (P = 0.002), and were significantly less rigid than pedicle screws in lateral bending (P = 0.002). Laminar screw constructs were more rigid than the intact condition in all planes.