Stability of different wiring techniques in segmental spinal instrumentation

Abstract

The pullout force of sublaminar and transspinous wires for segmental instrumentation which had been inserted into different segments of human cadaver spines were compared. Four different types of wiring were tested: single and double sublaminar wires, button-wires according to Drummond's technique and button-wires with the additional use of two crimps for each spinous process. A total of 50 tests were performed. In all attempts the bone proved to be the limiting factor. None of the 300 fixed wires failed. Typical types of fractures appeared with different wiring techniques. There was no statistically significant difference between the sublaminar wiring techniques tested. However, there were significant differences between sublaminar and transspinous wiring. The transspinous techniques achieved between 30% and 45% of the pull-out strength of sublaminar techniques. The forces decreased with increasing cranialisation. In all techniques the values in the upper segment (D5-D3) were almost half those of the lower segment (L5-L3). The differences of the transspinous techniques increased cranially, in favour of the technique with additional crimps. Thus, the crimps have the strongest effect on weak spinous processes. This study demonstrates that in non-dynamic testing, the stability of the bone and not the type of wiring is the limiting parameter in segmental spinal stabilisation. As the wires are inserted in different areas, the transspinous technique shows significantly lower tension forces in comparison with sublaminar wiring.

Use of the Universal Clamp for deformity correction and as an adjunct to fusion: Preliminary results in scoliosis

“…Using this technique, Herrera-Soto et al [15] reported a correction of 69% at 2 years follow-up even without associated anterior release. If care is taken not to violate the dome-shaped neural canal when placing intraspinous wires, they obviate the neurologic risks associated with sublaminar wiring [24]. Unfortunately, the resistance to failure by cutout of intraspinous wires is roughly half that of sublaminar wires or laminar hooks [23,24].…”

“…If care is taken not to violate the dome-shaped neural canal when placing intraspinous wires, they obviate the neurologic risks associated with sublaminar wiring [24]. Unfortunately, the resistance to failure by cutout of intraspinous wires is roughly half that of sublaminar wires or laminar hooks [23,24]. Soft sublaminar bands distribute the stress over a larger area of bone than sublaminar wires or hooks, theoretically reducing the risk of failure at the device-bone interface [28].…”

“…Other treatments consist of various types of hybrid constructs with pedicle-screw fixation in the lumbar spine and other anchors in the thoracic spine [3,13,15]. Among these thoracic anchors, sublaminar wiring has safety issues [16][17][18][19], hooks impinge upon the spinal canal [20] and lack a stable hold on the vertebra [21,22], and intraspinous wires provide weaker fixation to the posterior arch than either laminar hooks [23] or sublaminar wires [24]. Various soft sublaminar bands have also been proposed as thoracic anchors.…”

Efficacy of interspinous process lumbar fusion with recombinant human bone morphogenetic protein-2 delivered with a synthetic polymer and β-tricalcium phosphate in a rabbit model

“…The most rudimentary form of interspinous fixation involves wiring the spinous processes, and the Daab plate and Wilson plate have since been developed [7,9,13]. Spinal instrumentation using the spinous process as an anchor offers limited flexibility [14], but recent studies of lumbar fusion surgery using the Tadpole system and CD Horizon Spire spinous process plate Ò have shown relatively favorable clinical outcomes [19,41].…”

A study of the mechanical stability of scoliosis constructs using variable numbers of sublaminar wires

“…Other studies have also shown that the stability of the constructs is lower in the upper thoracic spine. Heller et al [8] found that the tensile force required to cause failure of constructs using sublaminar wires was significantly lower in upper thoracic spine, progressively increasing in the lower segments. This problem can be overcome by wiring the two most proximal consecutive levels (construct C).…”