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. 2022 Jan 11;21(1):3.
doi: 10.1186/s12938-021-00975-4.

Functionalization of screw implants with superelastic structured Nitinol anchoring elements

Isabell Hamann  1   2   3 , Stefan Schleifenbaum  4   5 , Christian Rotsch  6   4   5 , Welf-Guntram Drossel  6   7 , Christoph-Eckhard Heyde  4 , Mario Leimert  8
Affiliations

Functionalization of screw implants with superelastic structured Nitinol anchoring elements

Isabell Hamann et al. Biomed Eng Online. .

Abstract

Background: Demographic change is leading to an increase in the number of osteoporotic patients, so a rethink is required in implantology in order to be able to guarantee adequate anchoring stability in the bone. The functional modification of conventional standard screw implants using superelastic, structured Ti6Al4V anchoring elements promises great potential for increasing anchoring stability.

Methods: For this purpose, conventional screw implants were mechanically machined and extended so that structured-superelastic-positionable-Ti6Al4V anchoring elements could be used. The novel implants were investigated with three tests. The setup of the anchoring elements was investigated in CT studies in an artificial bone. In a subsequent simplified handling test, the handling of the functional samples was evaluated under surgical conditions. The anchorage stability compared to standard screw implants was investigated in a final pullout test according to ASTM F543-the international for the standard specification and test methods for metallic medical bone screws.

Results: The functionalization of conventional screw implants with structured superelastic Ti6Al4V anchoring elements is technically realizable. It was demonstrated that the anchoring elements can be set up in the artificial bone without any problems. The anchorage mechanism is easy to handle under operating conditions. The first simplified handling test showed that at the current point of the investigations, the anchoring elements have no negative influence on the surgical procedure (especially under the focus of screw implantation). Compared to conventional standard screws, more mechanical work is required to remove the functional patterns completely from the bone.

Conclusion: In summary, it was shown that conventional standard screw implants can be functionalized with Ti6Al4V-structured NiTi anchoring elements and the new type of screws are suitable for orthopedic and neurosurgical use. A first biomechanical test showed that the anchoring stability could be increased by the anchoring elements.

Keywords: Additive manufacturing; Biomechanic; Nitinol; Screw implants; Superelasticity.

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Conflict of interest statement

The authors declared that they have no competing interests.

Figures

Fig. 1
Fig. 1
Structure of the NiTi screw. A screw base body with hole; B additively manufactured guide sleeve (yellow); C structured NiTi anchor element (red) with guide sleeves (yellow); D threaded cone (orange)
Fig. 2
Fig. 2
CT-images of the NiTi-screw. A After implantation; B after setup the anchoring elements
Fig. 3
Fig. 3
Handling test. A Implantation of the NiTi screw; B CT image of the implanted NiTi screw
Fig. 4
Fig. 4
Pullout force of the standard screw (orange) and NiTi screw (red)
Fig. 5
Fig. 5
Mechanical work of the standard screw (orange) and NiTi screw (red)
Fig. 6
Fig. 6
Test setup of the handling test
Fig. 7
Fig. 7
Pullout test setup. A Screwing in the screw; B setup the anchoring elements; C pullout the set up screw
See this image and copyright information in PMC

References

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