Posterior Cervicothoracic Instrumentation: Testing the Clinical Efficacy of Tapered Rods (Dual-Diameter Rods).

Abstract

Study design: Prospective study.

Objective: To study the clinical efficacy of tapered rods in posterior cervicothoracic instrumentation.

Summary of background data: The cervicothoracic spine is a junctional area with complex biomechanics. A variety of disorders affect this region, rendering it unstable. Numerous posterior constructs have been evaluated by in vitro biomechanical studies. There are no data available on the clinical efficacy of a screw-rod system utilizing tapered (dual-diameter) rods. This is the first study analyzing the efficacy of this system in clinical scenarios in the short term.

Materials and methods: All consecutive patients with cervicothoracic junctional pathologies undergoing surgical treatment by posterior instrumentation utilizing tapered rods, between April 2007 and April 2012 were included in the study. The tapered rod tapers from a diameter of 5.5-3.5 mm to accommodate thoracic pedicle screws and lateral mass screws/pedicle screws of cervical spine, respectively. The cases were periodically followed up. Postoperative radiographs and computed tomography scans were analyzed.

Results: There were 14 cases, 11 males and 3 females. The etiology was tuberculosis in 7 cases, neoplasm in 5, and 1 each of trauma and deformity. Three patients required combined anterior and posterior surgeries and remaining 10 were managed by posterior-only procedures. The average follow-up was 28 months. Three patients died (surgically unrelated reasons) and 1 was lost to follow-up. Excluding 2 patients with neoplastic and traumatic etiologies, patients with neurological deficit had significant improvement. One patient had postoperative cerebrospinal fluid leak which was recognized and corrected subsequently. No biomechanical failure occurred in any of the patients. No intraoperative complications were noted.

Conclusions: This study demonstrates that tapered rods are an excellent and a viable option to connect screws to stabilize cervicothoracic junction in the short term. This study complements the biomechanical studies previously reported.