Muensterland Center for Joint Diseases

Münster, Germany

Muensterland Center for Joint Diseases

Münster, Germany

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Maas A.,Aesculap AG | Kim T.K.,Seoul National University | Miehlke R.K.,Rhine Main Center for Joint Diseases | Miehlke R.K.,Muensterland Center for Joint Diseases | And 3 more authors.
BioMed Research International | Year: 2014

The objective of our study was to determine the mechanical stress conditions under tibiofemoral loading with an overlay of knee kinematics in deep flexion on two different mobile bearing designs in comparison to in vivo failure modes. This study investigates the seldom but severe complication of fatigue failure of polyethylene components at mobile bearing total knee arthroplasty designs. Assuming a combination of a floor-based lifestyle and tibial malrotation as a possible reason for a higher failure rate in Asian countries we developed a simplified finite element model considering a tibiofemoral roll-back angle of 22° and the range of rotational motion of a clinically established floating platform design (e.motion FP) at a knee flexion angle of 120° in order to compare our results to failure modes found in retrieved implants. Compared to the failure mode observed in the clinical retrievals the locations of the occurring stress maxima as well as the tensile stress distribution show analogies. From our observations, we conclude that the newly introduced finite element model with an overlay of deep knee flexion (lateral roll-back) and considerable internally rotated tibia implant positioning is an appropriate analysis for knee design optimizations and a suitable method to predict clinical failure modes. © 2014 Allan Maas et al.


Grupp T.M.,Aesculap AG | Grupp T.M.,Ludwig Maximilians University of Munich | Miehlke R.K.,Rhine Main Center for Joint Diseases | Miehlke R.K.,Muensterland Center for Joint Diseases | And 4 more authors.
Journal of ASTM International | Year: 2011

Excellent clinical long term results were reported from individual clinical centers for both of the two fundamental design principles-fixed and mobile bearing knee designs. Several pre-clinical studies are dealing with a direct comparison between fixed and mobile bearing knee replacements, but to our knowledge there is no published data comparing the in vitro wear and kinematic behaviour of mobile bearing designs with floating, rotating and posterior stabilized gliding surfaces. The objective of our study was to evaluate the influence of the tibio-femoral bearing type on abrasive wear, tibio-femoral kinematics and particle release for a mobile bearing knee system with three different design alternatives. Wear simulator testing on 12 e.motion® TKA devices (Aesculap, Germany) was performed according to ISO 14243-1. The knee replacements were tested for 5 million cycles on a customized 4 station knee wear simulator (Endolab, Germany) in the bearing configurations floating platform (FP), ultra-concruent rotating platform (UC) and posterior stabilized (PS). The amount of wear in the polyethylene gliding surfaces was estimated to 4.4±0.9 mg/million cycles (FP design) to 2.3±0.1 mg/million cycles (UC) and 5.2±1.0 mg/million cycles (PS). The amplitudes of A/P displacement during 5 million cycles showed a mean value of 3.7±0.33 mm (FP design), 2.3±0.14 mm (UC) and 2.9±0.26 mm (PS). For the I/E rotation angle, the amplitudes of the recorded mean values were 6.3°±0.82° (FP design), 3.7±0.41° (UC) and 4.9°±0.48° (PS). The polyethylene particle release (mean size and morphology) is comparable for the mobile bearing articulations FP, UC, and PS. The present study demonstrates the influence of different mobile bearing types on abrasive wear, tibio-femoral kinematics, and particle release under elimination of bearing material influences. Copyright © 2011 by ASTM International.


Miehlke R.,Rhine Main Center for Joint Diseases | Miehlke R.,Muensterland Center for Joint Diseases | Geyer R.,St Vinzenz Hospital | Clemens U.,Frutigen Hospital | Thiel B.,Muensterland Center for Joint Diseases
Journal of ASTM International | Year: 2012

In this study, 117 patients who had received the e.motion FP prosthesis between 2001 and 2003 were followed up for 5.5 years to assess the clinical and radiological outcomes and survival of this mobile platform prosthesis. As this design is intended to improve the mobility of the replaced knee, particular emphasis was placed on the clinical and functional results. The hypothesis was that they would be comparable to the excellent results reported in the literature of state-of-the-art total knee arthroplasty. After 66 months, the average Knee Society clinical and functional scores were 93.8 points (KSS-C) and 90.5 (KSS-F) points, respectively. The clinical and radiographical results were excellent, with a low rate of anterior knee pain of 2.3 %. Copyright © 2012 by ASTM International.


Grupp T.M.,Aesculap AG | Grupp T.M.,Ludwig Maximilians University of Munich | Giurea A.,University of Vienna | Miehlke R.K.,Rhine Main Center for Joint Diseases | And 6 more authors.
Acta Biomaterialia | Year: 2013

The objective of the present study was to evaluate the biotribological behaviour, in terms of wear and particle release, of bushings and flanges made of carbon fibre reinforced poly-ether-ether-ketone (CFR-PEEK) in articulation with a zirconium nitride (ZrN) multilayer surface coating in a rotating hinge knee system. For the bushings of the rotational and flexion axles and the medial and lateral flanges, a CFR-PEEK with 30% polyacrylonitrile fibre content was used in a new bearing combination with ZrN. In vitro wear simulation was performed for patients with metal ion hypersensitivity, using a new rotating hinge knee design with a ZrN surface articulation in comparison with the clinically established cobalt-chromium version. For the bushings and flanges made of CFR-PEEK subjected to wear simulation, the volumetric wear rates were 2.3 ± 0.48 mm3 million-1 cycles in articulation to cobalt-chromium as reference and 0.21 ± 0.02 mm3 million -1 cycles in the coupling with ZrN, a 10.9-fold decrease. The released CFR-PEEK particles were comparable in size and shape for the coupling to cobalt-chromium and ZrN with most of the particles in a size range between 0.1 and 2 μm. The study reveals comparable low wear and no macroscopic surface fatigue in a new rotating hinge knee design with highly congruent flanges and axles bushings made of CFR-PEEK articulating to a ZrN multilayer surface coating. Favourable wear behaviour of the newly introduced CFR-PEEK/ZrN coupling in comparison with the clinically established CFR-PEEK/cobalt-chromium articulation was found. © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.


Grupp T.M.,Aesculap AG | Grupp T.M.,Ludwig Maximilians University of Munich | Miehlke R.K.,Rhine Main Center for Joint Diseases | Miehlke R.K.,Muensterland Center for Joint Diseases | And 3 more authors.
ASTM Special Technical Publication | Year: 2012

Excellent clinical long term results were reported from individual clinical centers for both of the two fundamental design principles - fixed and mobile bearing knee designs. Several pre-clinical studies are dealing with a direct comparison between fixed and mobile bearing knee replacements, but to our knowledge there is no published data comparing the in vitro wear and kinematic behaviour of mobile bearing designs with floating, rotating and posterior stabilized gliding surfaces. The objective of our study was to evaluate the influence of the tibio-femoral bearing type on abrasive wear, tibio-femoral kinematics and particle release for a mobile bearing knee system with three different design alternatives. Wear simulator testing on 12 e.motion® TKA devices (Aesculap, Germany) was performed according to ISO 14243-1. The knee replacements were tested for 5 million cycles on a customized 4 station knee wear simulator (Endolab, Germany) in the bearing configurations floating platform (FP), ultra-concruent rotating platform (UC) and posterior stabilized (PS). The amount of wear in the polyethylene gliding surfaces was estimated to 4.4 ± 0.9 mg/million cycles (FP design) to 2.3 ± 0.1 mg/million cycles (UC) and 5.2 ± 1.0 mg/million cycles (PS). The amplitudes of A/P displacement during 5 million cycles showed a mean value of 3.7 ± 0.33 mm (FP design), 2.3 ± 0.14 mm (UC) and 2.9 ± 0.26 mm (PS). For the I/E rotation angle, the amplitudes of the recorded mean values were 6.3° ±0.82° (FP design), 3.7 ± 0.41° (UC) and 4.9° ± 0.48° (PS). The polyethylene particle release (mean size and morphology) is comparable for the mobile bearing articulations FP, UC, and PS. The present study demonstrates the influence of different mobile bearing types on abrasive wear, tibiofemoral kinematics, and particle release under elimination of bearing material influences. Copyright © 2011 by ASTM International.

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