A biomechanical comparison of 3 different posterior fixation techniques for 2-level lumbar spinal disorders

Abstract

<jats:sec> <jats:title>OBJECT</jats:title> <jats:p>This study sought to make a biomechanical comparison of 3 different posterior fixation techniques for 2-level lumbar spinal disorders.</jats:p></jats:sec> <jats:sec> <jats:title>METHODS</jats:title> <jats:p>Eight fresh-frozen human cadaver lumbar spines (4 from L-1 to L-5, 4 from L-1 to S-1) were tested by applying pure moments of ± 8 Nm. Each specimen was first tested intact, and then the left facetectomies of L3–4 and L4–5 were performed to establish an unstable condition without removal of discs. Three instrumentation systems were then tested randomly: unilateral pedicle screw (UPS), UPS with contralateral translaminar facet screw (UPSFS), and bilateral pedicle screw (BPS). The range of motion (ROM) and the neutral zone (NZ) of L3–5 were measured.</jats:p></jats:sec> <jats:sec> <jats:title>RESULTS</jats:title> <jats:p>All fixation types could reduce the ROM of L3–5 significantly in flexion, extension, and lateral bending, compared with the intact state. In axial torsion, only BPS reduced the ROM significantly, compared with the intact state. The UPSFS technique provided intermediate stability, which was superior to the UPS in flexion-extension and lateral bending, and inferior to the BPS in lateral bending. Compared with the intact state, the NZs decreased significantly for UPS, UPSFS, and BPS in flexion-extension, while not significantly in lateral bending and axial torsion.</jats:p></jats:sec> <jats:sec> <jats:title>CONCLUSIONS</jats:title> <jats:p>In this study, among the 3 fixation techniques, BPS offered the highest stability, UPSFS provided intermediate stability, and UPS was the least stable for 2-level lumbar spinal disorders. UPSFS appeared to be able to offer a less invasive choice than BPS in well-selected patients with 2-level lumbar spinal disorders.</jats:p></jats:sec>

Translaminar facet joint screw insertion with a rapid prototyping guide template: a cadaver study

“…Accordingly, several modified techniques have been assessed by finite element analysis and biomechanical tests, for example, unilateral pedicle screw (UPS), UPS with contralateral translaminar facet joint screw (UPS þ TFS) and etc. The results show that the stability of UPS þ TFS is similar to that of BPS for both 1-level and 2-level lumbar spinal disorders [5][6][7]. Moreover, some recent clinical studies also indicate TLIF using UPS þ TFS by paramedian mini-incision is a safe, feasible and effective method to treat one or two segment lumbar degenerative disorders [8,9].…”

Biomechanics and Clinical Application of Translaminar Screws Fixation in Spine: A Review of the Literature

“…They concluded that UPS with contralateral TLS has superior flexion-extension and lateral bending compared with UPS but inferior lateral bending compared with bilateral pedicle screw. 53 However, Zhan et al 54 tested 12 fresh human cadavers, and found that both pedicle screw and TLS significantly reduced range of motion and increased stiffness compared with intact spine, and there is no significant difference in stability between the 2 constructs.…”

“…In the lumbar spine, Liu et al 53 compared the biomechanical properties of 3 posterior constructs, unilateral pedicle screw (UPS) versus UPS with contralateral TLS versus bilateral pedicle screw. They concluded that UPS with contralateral TLS has superior flexion-extension and lateral bending compared with UPS but inferior lateral bending compared with bilateral pedicle screw.…”

Biomechanical Characterization of Unilateral and Bilateral Posterior Lumbar Interbody Fusion Constructs

“…This approach is widely popular for single and multilevel spinal fusions for various lumbar disorders. Several posterior fixation techniques are currently available to promote spinal fusion with bilateral fixation being considered the “gold standard” [ 1 ]. This is a result of its ability to improve arthrodesis rates, increase fusion, and prevent nonunion.…”