2009 Design of Medical Devices Conference Abstracts

Design of an Endoreactor for the Cultivation of a Joint-Like-Structure PUBLIC ACCESS

[+] Author and Article Information
E. May, J. L. Herder

 Delft University of Technology, The Netherlands

J. H. Kuiper, S. Roberts, S. Sivananthan, J. B. Richardson

 Keele University, UK

T. Grünhagen, J. Urban

 University of Oxford, UK

T. Douglas, P. H. Warnke

 University of Kiel, Germany

I. Z. Martinez, O. Johansen

 University of Tromsø, Norway

J. Med. Devices 3(2), 027527 (Jul 09, 2009) (1 page) doi:10.1115/1.3147270 History: Published July 09, 2009


To avoid revision surgeries in artificial joint replacements and to allow young people to have a joint replacement, using biological joint replacement created by tissue engineering is a promising alternative. Several research groups have tissue engineered bone [Warnke 2004] and cartilage [Chung 2007] separately. The tissue engineering of a joint, consisting of bone and cartilage is the next frontier. The present study focuses on the design of a novel device, named Endoreactor, that is employing the mechanosensitivity of cells to create a joint-like-structure (JLS) consisting of a bone and cartilage sandwich, similar to an amphiarthrosis, by applying a mechanical loading regime to a stem cell seeded scaffold construct during endocultivation. This way, the patients who will eventually need the new joint will serve as their own bioreactor, having the joint grow in their own body. In the JLS, the outside layers are designed to become bone, using a 6 mm thick scaffold with high stiffness. The center layer is a 4 mm thick scaffold which is compliant so as to experience more strain than the outside scaffolds to stimulate cartilage formation. Compression is realized by placing the JLSs between the long links of a kite-shaped four-bar linkage. This Endoreactor is powered by natural body motion through connection to the musculoskeletal system of the host, which in the experimental phase is a Gottingen minipig. The loading frequency and rest versus active time is dictated by the activity level of the minipig. This results in a natural loading pattern that is employed for the stimulation of cartilage formation in the JLS. A tensile force created during ambulation is converted into compressive action between the two long links of the mechanism. A mechanical stop limits the motion. This way controlled intermittent dynamic compression between 2.5% and 12.5% is realized in the cartilage layer of the JLS. All functions are integrated into a single piece compliant mechanism which is produced out of titanium using 3D rapid prototyping by selective laser melting technology. The mechanism can be fitted with cages that hold the scaffolds for bone and cartilage in place and protect them from external loads while being implanted. A safety spring was added to accommodate for large actuation excursions. A number of prototypes were produced and tested for fatigue, plastic deformation, failure load, and displacements of the long links at the JLS locations under different axial loads. These tests confirmed the proper mechanical functioning of the Endoreactor. Work with animal models making use of the device to culture an amphiarthosis-like joint is foreseen in the near future. This work was carried out at part of MYJOINT: Living Bioreactor—Growing a New Joint in a Human Back, EU FP6-2004-NEST-C-1, Proposal No. 028861.

Copyright © 2009 by American Society of Mechanical Engineers
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