The suprapedicle claw construct in anterior scoliosis surgery

Abstract

Proximal screw pullout is a well-recognized problem in anterior scoliosis surgery, with a rate of pseudarthrosis or screw pullout ranging from 15 to 30%. To prevent screw pullout at the top of the construct, the authors have devised the concept of a claw for the top instrumented vertebra. The claw consists of a classic anterior vertebral body screw inserted parallel to the inferior end-plate and in the posterior portion of the vertebral body 8 mm in front of the spine canal. After rib desarticulation, a laminar hook of a small size is inserted over the superior aspect of the pedicle of the same vertebra. The rod is then inserted into the two side openings of the screw and the hook. Compression across the hook and the screw is then performed, making a claw construct. This concept can also be extended in the case of early revision for a proximal screw pullout, where it is possible to revise the instrumentation with an offset connector linking the rod to the superior portion of the pedicle where the suprapedicule hook has been inserted. We report two cases where a suprapedicle claw was successfully used in anterior scoliosis correction of a right thoracic curve. Such a concept may represent the solution to proximal screw pullout in anterior scoliosis correction.

Fig. 1

Schematic representation of the claw construct on the saw bone. The vertebral screw is inserted at the inferior aspect of the vertebral body 8 mm in front of the spine canal and parallel to the inferior endplate. The laminar hook inserted in an offset configuration sits on the superior aspect of the pedicle

Fig. 2

Superior aspect of the canal intrusion of the laminar hook over the pedicle: this corresponds to the blade thickness and is 2 mm

Fig. 3

Lateral aspect of the spine after the claw construct has been made on the rod

Fig. 4

Case number 1: 48° King II right thoracic curve: the midsacral line passes through the disc T12–L1

Fig. 5

Postoperative correction with the suprapedicle claw construct at the level of T6

Fig. 6

Eleven-year-old patient with progressive 53° right thoracic scoliosis

Fig. 7

The intraoperative fluoroscopy picture shows satisfactory correction and positioning of the screws, which are all bicortical. The standing film on day 6 shows proximal screw pullout at the level of the 6th vertebra

Fig. 8

Revision with a suprapedicle claw is made, restoring the initial correction. At 6 months follow-up, the correction is stable