PT  - JOURNAL ARTICLE
AU  - Xavier, Fred
AU  - Jauregui, Julio J.
AU  - Cornish, Nathan
AU  - Jason-Rousseau, Rebecca
AU  - Chatterjee, Dipal
AU  - Feuer, Gavriel
AU  - Hayes, Westley
AU  - Kapadia, Bhaveen H.
AU  - Carter, John N.
AU  - Yoshihara, Hiroyuki
AU  - Saha, Subrata
TI  - Regional Variations in Shear Strength and Density of the Human Thoracic Vertebral Endplate and Trabecular Bone
AID  - 10.14444/4007
DP  - 2017 Jan 01
TA  - International Journal of Spine Surgery
PG  - 7
VI  - 11
IP  - 1
4099  - https://www.ijssurgery.com/content/11/1/7.short
4100  - https://www.ijssurgery.com/content/11/1/7.full
SO  - Int J Spine Surg2017 Jan 01; 11
AB  - Background Previous studies investigated the overall mechanical strength of the vertebral body; however, limited information is available on the biomechanical properties of different regions within the vertebral endplate and cancellous bone. In addition, the correlation between mechanical strength and various density measurements has not been studied yet.Methods Thoracic (T10) vertebrae were harvested from fifteen human cadaveric spines (average age: 77 years old). Twelve cylindrical cores of 7.2 mm (diameter) by 3.2 mm (height) were prepared from each vertebral body. Shear was produced using a stainless steel tubular blade and measured with a load cell from a mechanical testing machine. Optical and bulk densities were calculated before mechanical testing. Apparent, material, and ash densities were measured after testing.Results Material density and shear strength increased from anterior to lateral regions of both endplate and cancellous bone. Endplate shear strength was significantly lower in the anterior (0.52 ± 0.08 MPa) than in the lateral region (2.72 ± 0.59 MPa) (p=0.017). Trabecular bone maximum load carrying capacity was 5 times higher in the lateral (12 ± 2.74 N) (p=0.09) and 4.5 times higher in the central (10 ± 2.24 N) (p=0.2) than in the anterior (2 ± 0.60 N) regions. Mechanical strength positively correlated with ash density, and even moreso with material density.Conclusion Shear strength was the lowest at the anterior region and highest at the lateral region for both endplate and cancellous bone. Material density had the best correlation with mechanical strength. Newer spinal implants could optimize the loading in the lateral aspects of both endplate and cancellous bone to reduce the likelihood of screw loosening and the subsidence of disc replacement devices.This study was reviewed by the SUNY Downstate Medical Center IRB Committee; IRB#: 533603-2.