Circumferential stabilization with ghost screwing after posterior resection of spinal metastases via transpedicular route

Abstract

Various surgical methods have been described for treating spinal metastases, namely, en bloc spondylectomy, minimally invasive techniques, and anterior and posterior approaches. The main goals in surgical intervention for these lesions are tumor removal and establishment of strong, durable stabilization. The least invasive method is always preferred. Posterior transpedicular spondylectomy meets all these needs, as this method achieves tumor excision and stabilization of the anterior and posterior spine through one posterior incision and in the same surgical session. The surgeon circumferentially excises a spinal metastasis and then achieves circumferential stabilization in the same session. Numerous circumferential stabilization methods have been used to date, including placement of free bone grafts or cages or acrylic grafts, or insertion of an acrylic graft supported by a Steinmann pin anteriorly and by posterior transpedicular fixators or a Luque rectangle posteriorly. This article describes seven cases of spinal metastasis in which an alternative circumferential stabilization technique known as "ghost screwing" was performed. The first step in this method is circumferential decompression, achieved with laminectomy followed by eggshell corpectomy via the transpedicular route. Then a short segmental transpedicular stabilization system is fixed to the vertebrae cranial and caudal to the laminectomy/corpectomy defect. Prior to fixing the rods in place, an additional screw is mounted on each rod such that the screw shaft protrudes into the defect space. Once the rods are fixed and the two extra screws are optimally positioned, acrylic bone cement is introduced into the defect site, encasing the ghost screws and forming an anterior graft upon hardening. The outcomes in our cases were excellent. All seven patients had uneventful postoperative periods and all experienced pain relief and were able to mobilize early. Direct connection of the anterior acrylic graft to the posterior fixation system via ghost screws makes this system strong and durable, and prevents subsidence or horizontal displacement of the graft. Such complications can be serious issues with other circumferential systems that use independent anterior and posterior fixators.