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Modular systems and lightweight construction concepts - new possibilities for the defect-specific treatment of hip joint diseases

Modulare Systeme und Leichtbaukonzepte - neue Möglichkeiten zur defektspezifischen Behandlung von Hüftgelenkerkrankungen
: Prietzel, Torsten; Schmidt, Michael; Kopper, Michael; Töppel, Thomas; Hanus, Sybille; Grunert, Ronny

presentation urn:nbn:de:0011-n-4710377 (2.4 MByte PDF)
MD5 Fingerprint: ce71a9f74ad3a153ce81024ff634e375
Created on: 9.2.2018

Biomedizinische Technik 62 (2017), No.s1, pp.S232
ISSN: 0013-5585
ISSN: 1862-278X
Deutsche Gesellschaft für Biomedizinische Technik (DGBMT Jahrestagung) <51, 2017, Dresden>
Dreiländertagung Medizinische Physik <2017, Dresden>
Abstract, Electronic Publication
Fraunhofer IWU ()
Tumorendoprothetik; Leichtbau; Textil; Generative Fertigung

In tumor endoprosthetics, implants are applied to reconstruct the proximal femur. The main problems of these implants are often the high weight and the biomechanically not optimal attachment of soft tissue. The aim of this work is the development of a long-term stable biomechanically correct implant of a proximal femoral replacement. Based on lightweight construction concepts from vehicle construction, a topology optimization was performed with an existing modular implant basic body. The additive manufacturing process laser beam melting was applied to produce the implant with the material TiAl6V4. The individual modules were coupled by a specially designed polygon interface. To disconnect the interface, a joining instrument was used which applies a force at two defined points and thus elastically deforms the internal contour of the interface. This allows the reversible joining of the modular components. In order to fix the muscles anatomically correctly, textile attachment points made of multifilament polyester were produced by embroidery. A functional model of a modular implant was produced. On the basis of a topology optimization, the new implant has a mass reduction of 400 g compared to a proximal femoral set, which was assembled from the MML system. The greatest savings potential was found in the trochanter module (weight reduction by 55%). The load-bearing structures consisted of TiAl6V4, whereas the shell of the neck module was made of polyethylene. The reversible coupling was implemented by a polygonal interface. The force closure took place by switching off the external force effect and thus the deformation of the round bore hole into an elliptical geometry, which resulted in a "jamming" of the spigot. According to ISO 7206 the fatigue strength of the implant was determined. The test implantation at a body donor showed that the implant can be placed under realistic conditions.