Neurocentral Synchondrosis Screws to Create and Correct Experimental Deformity: A Pilot Study

Abstract

Background Unilateral pedicle screw epiphysiodesis of the neurocentral synchondrosis (NCS) can produce asymmetric growth of the synchondrosis to create scoliosis in an immature animal model. Questions/purposes We asked whether a preexisting experimentally created scoliosis could be limited and corrected by modulating the growth of the faster-growing NCS by a similar method. Methods Nine 1-month-old pigs were assigned to each of three groups: (1) a sham group in which three animals received a sham operation but without a pedicle screw fixation; (2) an experimental group with double right pedicle screws placed across the NCS from T7 to T14 (scoliosis-untreated); and (3) an experimental group treated in the same way except a second set of double pedicle screws was placed in the left pedicles 6 weeks after the screws were placed on the right (scoliosis-treated). All animals were euthanized at 17 weeks, and radiographs and axial CT images of the spine were obtained. Results A scoliotic curve was not seen in any of the animals in the sham group, in three of three in the scoliosisuntreated group with an average of 34°, and in three of three in the scoliosis-treated group with an average of 20°. In comparison to the scoliosis-untreated group, the second set of pedicle screws produced a 41% correction of the scoliosis. Conclusions We found the pedicle screw inhibited the overgrowth of the NCS to prevent further curve progression and obtained some correction of the deformity. The NCS screw epiphysiodesis can create and reverse scoliosis in an immature pig model.

Novel porcine experimental model of severe progressive thoracic scoliosis with compensatory curves induced by interpedicular bent rigid temporary tethering

“…The curves obtained in this study are opposite to that found by using selective epiphysiodesis of the neurocentral cartilage, that is convex toward the non‐instrumented side. The curves obtained by neurocentral cartilage blocking show consistently the convexity toward the side of screw fixation …”

Utility of an allograft tendon for scoliosis correction via the costo‐transverse foreman

“…Historically, several investigators have investigated the feasibility of fusion‐less surgery in treating immature idiopathic scoliosis, yet only a few studies actually tested the correction power using large animal models . Recently, a porcine model which induces a moderate spinal curve by posterior spinal and concave rib tethering was developed .…”

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

“…Their findings suggested that injury to the NCC by pedicle screw insertion results in iatrogenic spinal stenosis (20 to 25 % narrowing). Zhang et al [6] reported that either unilateral or bilateral pedicle screws disturbed spinal canal growth in 4-week-old pigs resulting in narrowing of the hemi-canal area on the epiphysiodesis side. Pedicle screws have an influence on the development of symmetry and the canal parameters [32].…”

“…When a pedicle screw is inserted in the immature spine, penetration through the NCC is inevitable, which thus has raised a major concern regarding whether the passage of a pedicle screw through the NCC will affect the development of the growing spine. Some authors have postulated that pedicle screw instrumentation might cause damage to the NCC in the immature spine, leading to the inadequate development of the spinal canal, resulting in iatrogenic spinal stenosis [4][5][6]. In contrast, other authors maintain that pedicle screws can be safely placed in pediatric patients without a negative influence on the growth of the pedicles and the spinal canal [7][8][9][10].…”