Influence of the diameter of cylindrical implants for spinal lumbar fusion on the ultimate strength of functional spinal units

Journal
Biomedical engineering : joint journal of the German Society for Biomedical Engineering in VDE and the Austrian and Swiss Societies for Biomedical Engineering  
Volume
43
Issue
9
Start Page
253
End Page
256
Citation
Biomedical engineering 43 (9): 253-256 (1998)
Publisher DOI
10.1515/bmte.1998.43.9.253
Scopus ID
2-s2.0-0032169263
Publisher
de Gruyter
Anterior lumbar interbody fusion (ALIF) has evolved as a minimally invasive technique for treating lumbar instability caused by degenerative lumbar disc disease. A practical surgical method is the lateral retroperitoneal approach in which cylindrical implants are inserted in the intervertebral space. The optimal diameter of these implants remains unclear. The purpose of this biomechanical study was to investigate the influence of implant diameter on selected mechanical properties of the functional spinal units (FSU). In fresh frozen bovine FSU the bone density was first determined and cylindrical implants were then inserted. The FSU were then tested under compression loading in a material-testing machine. A tendency of the 'failure loads' to decrease with increasing cylinder diameter was observed. The study reveals a strong correlation between bone density and loading capacity, with higher loads being sustained by the more strongly mineralized bone. In contrast to homogeneous material, in an FSU, larger cylinder diameter does not result in an increase in compression strength.
Subjects
ALIF
Cylinder diameter
FSU model
Measurement of compressive force
DDC Class
570: Life Sciences, Biology
610: Medicine, Health