In vitro comparison of personalized 3D printed versus standard expandable titanium vertebral body replacement implants in the mid-thoracic spine using entire rib cage specimens. (August 2020)

• Record Type: Journal Article
• Authors: Liebsch, Christian; Aleinikov, Viktor; Kerimbayev, Talgat; Akshulakov, Serik; Kocak, Tugrul; Vogt, Morten; Jansen, Jan Ulrich; Wilke, Hans-Joachim
• Is Part Of: Clinical biomechanics. Volume 78(2020)
• Publication Date: 2020-08
• Subjects: Vertebral body replacement implant -- Thoracic spine -- Rib cage -- Primary stability -- In vitro study -- Biomechanics; Biomechanics -- Periodicals; Osteopathic medicine -- Periodicals; Biomechanics -- Periodicals; Osteopathic Medicine -- Periodicals; 612.76
• DOI: 10.1016/j.clinbiomech.2020.105070
• Languages: English
• ISSNs: 0268-0033

Abstract

Abstract: Background: Expandable titanium implants have proven their suitability as vertebral body replacement device in several clinical and biomechanical studies. Potential stabilizing features of personalized 3D printed titanium devices, however, have never been explored. This in vitro study aimed to prove their equivalence regarding primary stability and three-dimensional motion behavior in the mid-thoracic spine including the entire rib cage. Methods: Six fresh frozen human thoracic spine specimens with intact rib cages were loaded with pure moments of 5 Nm while performing optical motion tracking of all vertebrae. Following testing in intact condition (1), the specimens were tested after inserting personalized 3D printed titanium vertebral body replacement implants (2) and the two standard expandable titanium implants Obelisc™ (3) and Synex™ (4), each at T6 level combined with posterior pedicle screw-rod fixation from T4 to T8. Findings: No significant differences ( P < .05) in primary and secondary T1-T12 ranges of motion were found between the three implant types. Compared to the intact condition, slight decreases of the range of motion were found, which were significant for Synex™ in primary flexion/extension (−17%), specifically at T3-T4 level (−46%), primary lateral bending (−18%), and secondary lateral bending during primary axial rotation (−53%). Range of motion solely increased at T8-T9 level, while being significant only for Obelisc™ (+35%). Interpretation: Personalized 3D printed vertebral body replacement implants provide a promising alternative to standard expandable devices regarding primary stability and three-dimensional motion behavior in the mid-thoracic spine due to the stabilizing effect of the rib cage. Highlights: 3D printed titanium vertebral body replacements provide adequate spinal stability. Primary stability and motion behavior are comparable to standard expandable devices. The rib cage contributes to implant stability in the mid-thoracic spine. Advantages regarding cell ingrowth and stress reduction have to be further proven.