Robot-Based Testing of Total Joint Replacements
Instabilities of artificial joints are prevalent complications in total joint arthroplasty. In order to investigate failure mechanisms like dislocation of total hip replacements or instability of total knee replacements, a novel test approach is introduce
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Robot-Based Testing of Total Joint Replacements Christoph Woernle, Michael Ka¨hler, Roman Rachholz, Ja´nos Zierath, Sven Herrmann, Robert Souffrant, Daniel Kluess, and Rainer Bader
Abstract Instabilities of artificial joints are prevalent complications in total joint arthroplasty. In order to investigate failure mechanisms like dislocation of total hip replacements or instability of total knee replacements, a novel test approach is introduced by means of a hardware-in-the-loop (HiL) simulation combining the advantages of an experimental with a numerical approach. The HiL simulation is based on a six-axes industrial robot and a musculoskeletal multibody model. Within the multibody model, the anatomical environment of the correspondent joint is represented such that the soft tissue response is considered during an instability event. Hence, the robot loads and moves the real implant components according to the data provided by the multibody model while transferring back the relative displacement of the implant components and the resisting moments recorded. HiL simulations provide a new biomechanical testing tool which enables comparable and reproducible investigations of various joint replacement systems with respect to their instability behaviour under realistic movements and physiological load conditions.
C. Woernle (*) • M. Ka¨hler • R. Rachholz Department of Mechanical Engineering and Marine Technology, University of Rostock, Rostock, Germany e-mail: [email protected]; [email protected]; [email protected] J. Zierath W2E Wind-to-Energy GmbH, Rostock, Germany e-mail: [email protected] S. Herrmann • R. Souffrant • D. Kluess • R. Bader Department of Orthopedics, University Medicine Rostock, Rostock, Germany e-mail: [email protected]; [email protected]; [email protected]; [email protected] H. Gattringer and J. Gerstmayr (eds.), Multibody System Dynamics, Robotics and Control, DOI 10.1007/978-3-7091-1289-2_9, # Springer-Verlag Wien 2013
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Fig. 9.1 Failures of total joint replacements. (a) Dislocation of a total hip replacement (THR). (b) Unstable total knee replacement (TKR)
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Introduction
Instability of artificial joints is still one of the most prevalent reasons for revision surgery (Fig. 9.1). With regard to total hip replacements (THR), dislocation of the femoral head represents a major reason for revision procedures [3]. Mechanisms linked to the dislocation process involve prior prosthetic or bony contact (impingement), and spontaneous separation due to dynamic forces. Similarly, instability and adverse kinematics in total knee replacements (TKR) has been reported as one of the most important reasons for implant failure [2]. As TKRs are by design less constrained than THRs, relative movement between joint partners is governed by restraining ligament and muscular forces. Therefore, instability mechanisms are given by excessive relative movement between the femoral and tibial compon
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