Designs and techniques that improve the pullout strength of pedicle screws in osteoporotic vertebrae: current status.
Osteoporosis is a medical condition affecting men and women of different age groups and populations. The compromised bone quality caused by this disease represents an important challenge when a surgical procedure (e.g., spinal fusion) is needed after failure of conservative treatments. Different pedicle screw designs and instrumentation techniques have been explored to enhance spinal device fixation in bone of compromised quality. These include alterations of screw thread design, optimization of pilot hole size for non-self-tapping screws, modification of the implant's trajectory, and bone cement augmentation. While the true benefits and limitations of any procedure may not be realized until they are observed in a clinical setting, axial pullout tests, due in large part to their reproducibility and ease of execution, are commonly used to estimate the device's effectiveness by quantifying the change in force required to remove the screw from the body. The objective of this investigation is to provide an overview of the different pedicle screw designs and the associated surgical techniques either currently utilized or proposed to improve pullout strength in osteoporotic patients. Mechanical comparisons as well as potential advantages and disadvantages of each consideration are provided herein.
H. Lee Moffitt Cancer Center & Research Institute, Neuro-Oncology Department, Tampa, FL 33612, USA ; Department of Chemical & Biomedical Engineering, University of South Florida, Tampa, FL 33620, USA.
Thomas M
TM
Shea
Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA.
Jake
J
Laun
H. Lee Moffitt Cancer Center & Research Institute, Neuro-Oncology Department, Tampa, FL 33612, USA.
Sabrina A
SA
Gonzalez-Blohm
H. Lee Moffitt Cancer Center & Research Institute, Neuro-Oncology Department, Tampa, FL 33612, USA ; Department of Mechanical Engineering, University of South Florida, Tampa, FL 33620, USA.
James J
JJ
Doulgeris
Department of Mechanical Engineering, University of South Florida, Tampa, FL 33620, USA.
William E
WE
Lee
H. Lee Moffitt Cancer Center & Research Institute, Neuro-Oncology Department, Tampa, FL 33612, USA ; Departments of Neurosurgery and Orthopedics, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA.
Kamran
0000-0002-5085-8115
K
Aghayev
H. Lee Moffitt Cancer Center & Research Institute, Neuro-Oncology Department, Tampa, FL 33612, USA ; Departments of Neurosurgery and Orthopedics, Morsani College of Medicine, University of South Florida, Tampa, FL 33612, USA.
Frank D
FD
Vrionis
D000818:Animals; D001863:Bone Screws; D005260:Female; D006801:Humans; D008297:Male; D010024:Osteoporosis / Q000601:surgery*; D011474:Prosthesis Design; D013131:Spine / Q000601:surgery*