Mechanical Evaluation of Cross-Link Designs in Rigid Pedicle Screw Systems

Abstract

The use of cross-linkage in spinal fusion increases torsional stiffness in pedicle screw and hook constructs. This study 1) confirmed the effectiveness of cross-linkage in limiting torsional motion and showed the superiority of two cross-links to one cross-link in limiting torsional motion, 2) showed that increase of torsional stiffness of a cross-linked construct is proportional to the cross-sectional area of the cross-link, and 3) demonstrated that cross-links do not increases stiffness in the lateral flexion mode.

Does addition of crosslink to pedicle-screw-based instrumentation impact the development of the spinal canal in children younger than 5 years of age?

“…After hemivertebra resection, compression is applied on the convex side to close the excision gap. Ideally, placement of pedicle screw 15°medially enhances the rotational stability [20]. However, unlike adult spine, young children's pedicle is tiny and often asymmetric in size, likely unable to withstand the significant compressive force.…”

“…Thus additional use of implants are proposed to support the pedicle-screw-based instrumentation, like additional rod connecting laminar hooks to facilitate closing the excision gap [28]. Based on previous biomechanical testing, the crosslink can improve the axial stability of the instrumentation [19][20][21][22]. Hence, we recommended using a crosslink as an alternative to enhance the stability of the total instrumentation in our study.…”

“…Thus, to enhance the fixation stability, a crosslink is added as an adjuvant implant between the bilateral rods in the posterior instrumentation constructs. Although there was a clinical study argued that the use of the crosslink in spine surgery may be avoidable [18], many biomechanical tests have demonstrated that the addition of the crosslink to bilateral rods locked to pedicle screws increases the torsional stiffness of the construct significantly [19][20][21][22][23][24]. Kuklo et al [22] reported that a single crosslink contributed to a significant reduction in the range of motion of the instrumented vertebrae (by 21 %) relative to pedicle screw-only instrumentation.…”

Mechanical Performance of the New Posterior Spinal Implant: Effect of Materials, Connecting Plate, and Pedicle Screw Design

“…24,32,33 These studies have revealed that cross-linkage did not significantly increase the stiffness of posterior implants for compression/flexion motion. In the present study, the increase in stiffness of SS-Plate-B implants was 22.2% compared to the SS-SB variant (P Ͻ 0.001).…”

Biomechanical comparisons of different posterior instrumentation constructs after two-level ALIF: A finite element study

“…Such extreme loading conditions may very well change the fixation stability under different compressive preloading situations. According to Brodke et al [37] and Dick et al [38], pedicle screw fixation with an added cross-link can improve stability in an axial rotation, but there is a negligible change in stiffness during lateral bending. Comparing the BPSR with the BPSR-CL for lateral bending and axial rotation, we noted similar results.…”