Effect of Elastic Modulus on Biomechanical Properties of Lumbar Interbody Fusion Cage

This work focuses on the influence of elastic modulus on biomechanical properties of lumbar interbody fusion cages by selecting two titanium alloys with different elastic modulus. They were made by a new β type alloy with chemical composition of Ti-24Nb-4Zr-7.6Sn having low Young＇s modulus -50 GPa and by a conventional biomedical alloy Ti-6Al-4V having Young＇s modulus -110 GPa. The results showed that the designed cages with low modulus （LMC） and high modulus （HMC） can keep identical compression load -9.8 kN and endure fatigue cycles higher than 5× 10^6 without functional or mechanical failure under 2.0 kN axial compression. The anti-subsidence ability of both group cages were examined by axial compression of thoracic spine specimens （T9-T10） dissected freshly from the calf with averaged age of 6 months. The results showed that the LMC has better anti-subsidence ability than the HMC （p〈0.05）. The above results suggest that the cage with low elastic modulus has great potential for clinical applications.

A critical review on the biomechanical study of cervical interbody fusion cage

Anterior Cervical Discectomy and Fusion(ACDF)is the preferred surgical method for the treatment of severe cervical degenerative disc disease with radiculopathy or myelopathy,of which the objectives are to restore the normal height of intervertebral space and cervical lordosis through the implantation of cervical interbody fusion cage.The biomechanical performance of a cervical interbody fusion cage,which plays a significant role in achieving the goals of ACDF,is influenced by multiple factors.In this paper,various studies focusing on the biomechanical performance of cervical interbody fusion cage are reviewed.Furthermore,the research methods,biomechanical evaluation parameters and data analysis methods of these research are analyzed in order to obtain a comprehensive understanding of the progress and limitations of research in this field.Although great progress has been made to clarify the biomechanical behaviors of cervical interbody fusion cage,there is still controversy regarding the issues such as the relative contribution of multiple factors to the performance of cage,the interactions among these factors,as well as whether the effects of factors change with the process of intervertebral osseointegration and so on.Thus,investigations are still needed to improve the comprehension of cervical interbody fusion cage biomechanically.

Complications associated with posterior lumbar interbody fusion using Bagby and Kuslich method for treatment of spondylolisthesis

Objective To analyze complications associated with posterior lumbar interbody fusion (PLIF) in which two Bagby and Kuslich (BAK) interbody fusion cages were implanted.Methods A total of 118 patients with spondylolytic spondylolisthesis underwent single-level PLIF using two BAK cages filled with morselized autogenous bone. The major clinical and radiographic complications were analyzed after a follow-up with an average time of 2 years and 9 months.Results Complications were divided into intraoperative and postoperative complications. Intraoperative complications mainly included dural tear (4 patients, 3.4%), nerve root injury (3 patients, 2.5%) and suboptimal cage position (9 patients, 7.5%). No death was caused by the operation. Postoperative complications chiefly consisted of cage retropulsion (3 patients, 2.5%), cage subsidence (4 patients, 3.4%), and postlaminectomy arachnoiditis (2 patients, 1.7%). Pseudarthrosis was noted radiographically with evidence of motion between adjacent vertebra on lateral flexion-extension films and luciencies around the cages (2 patient, 1.7%), continuous posterior cage migration (2 patients, 1.7%) or continuous cage subsidence (2 patients, 1.7%). Two patients died, one from a traffic accident and the other from metastatic cancer 1 year postoperatively.Conclusions The results of this study indicate that PLIF with BAK cages is an effective but also technically difficult procedure. The relatively high incidence of complications reminds us of the importance of surgical indications and proper manipulations.