Clinical Comparison of Two Spinal Reconstruction Techniques for Osteoporotic Vertebral Collapse: Conventional Pedicle Screw vs Modified CBT Screw

Presented at SMISS Annual Forum 2016
By Ryo Fujita MD
With Yoshihisa Kotani MD, PhD

Disclosures: Ryo Fujita MD None, Yoshihisa Kotani MD, PhD None

Introduction

Most of osteoporotic compression fractures can be treated conservatively, however, some cases lead to vertebral pseudarthrosis. This causes the deformity and neurologic problems requiring operative treatment. In our facility, the vertebral collapse has been treated by posterior spinal reconstruction with either pedicle screw (PS) or modified cortical bone trajectory screw (mCBT). The anterior column support has been made with OLIF recently. 

Aims/Objectives

To compare the clinical result of spinal reconstruction for osteoporotic vertebral collapse with either PS or mCBT. Additional analysis was made in terms of the effect of OLIF between mCBT only group (mCBT+OLIF(-)) and mCBT with OLIF group (mCBT+OLIF(+)) . 

Methods

A total of 38 patients received spinal reconstruction with mCBT in 28, and PS in 10. Those included 16 PLFs, 12 OLIFs, and 10 TLIFs. The mCBT+OLIF(-) and mCBT+OLIF(+) were 11 and 17 cases, respectively. Clinical evaluations were operation time, intraoperative bleeding, fusion rate, degrees of kyphosis correction, loss of correction, complications and overall functional outcome by the Japanese Orthopedic Association Back Pain Evaluation Questionnaire (JOABPEQ) score. 

Results

Mean Operation time was 213min in PS and 199min in mCBT. Mean Intraoperative blood loss was 550ml in PS and 325ml in mCBT. Mean intraoperative blood loss/Intervertebra was statistically less in mCBT (74.2ml) compared with PS (185ml). The degrees of kyphosis correction was 15.7 deg. in PS and 16.4 deg. in mCBT. Loss of correction was significantly smaller in mCBT (5 deg) compared to PS (11 deg). The fusion rate were 100% in both groups. There were 3 cases of screw loosening in PS, however all cases successfully fused. The degrees of kyphosis correction was significantly larger in mCBT+OLIF (+) (20 deg) compared to mCBT+OLIF (-) (10 deg). 

Conclusions

The spinal reconstruction for osteoporotic collapse often accompanies with postoperative screw loosening and loss of correction. Since the fixation strength of mCBT is mainly provided by hard cortex in lamina, it is less influenced by the degree of osteoporosis. In this study, mCBT showed a significantly less loss of correction, demonstrating the advantage of mCBT over PS. The combination of OLIF was useful for the effective anterior support and posterior MIS fixation in vertebral collapse with minimum canal compromise, however, there has been no report regarding correction and loss of correction in OLIF reconstruction. The combination of OLIF provided better sagittal plane correction, demonstrating the biomechanical advantage of mCBT and OLIF

for vertebral collapse treatment.