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Rapid prototyping for in vitro knee rig investigations of prosthetized knee biomechanics: comparison with cobalt-chromium alloy implant material.

Schröder C, Steinbrück A, Müller T, Woiczinski M, Chevalier Y, Weber P, Müller PE, Jansson V - Biomed Res Int (2015)

Bottom Line: Friction coefficients between these materials and polytetrafluoroethylene (PTFE) were additionally tested as this latter material is commonly used to protect pressure sensors in experiments.No statistical differences were found between friction coefficients of both materials to PTFE.UHMWPE shows higher friction coefficient at low axial loads for RPM, a difference that disappears at higher load.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopaedic Surgery, Physical Medicine and Rehabilitation, University Hospital of Munich (LMU), Campus Grosshadern, Marchioninistraße 15, 81377 Munich, Germany.

ABSTRACT
Retropatellar complications after total knee arthroplasty (TKA) such as anterior knee pain and subluxations might be related to altered patellofemoral biomechanics, in particular to trochlear design and femorotibial joint positioning. A method was developed to test femorotibial and patellofemoral joint modifications separately with 3D-rapid prototyped components for in vitro tests, but material differences may further influence results. This pilot study aims at validating the use of prostheses made of photopolymerized rapid prototype material (RPM) by measuring the sliding friction with a ring-on-disc setup as well as knee kinematics and retropatellar pressure on a knee rig. Cobalt-chromium alloy (standard prosthesis material, SPM) prostheses served as validation standard. Friction coefficients between these materials and polytetrafluoroethylene (PTFE) were additionally tested as this latter material is commonly used to protect pressure sensors in experiments. No statistical differences were found between friction coefficients of both materials to PTFE. UHMWPE shows higher friction coefficient at low axial loads for RPM, a difference that disappears at higher load. No measurable statistical differences were found in knee kinematics and retropatellar pressure distribution. This suggests that using polymer prototypes may be a valid alternative to original components for in vitro TKA studies and future investigations on knee biomechanics.

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Related in: MedlinePlus

Schematic setting of the ring-on-disc rig with the demonstration of the axial compression force (FA) and the friction torque (MF) as well as the tested material combinations. The rotation of the ring occurs about the rotation axis, which is identic to the axial load transmission.
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fig2: Schematic setting of the ring-on-disc rig with the demonstration of the axial compression force (FA) and the friction torque (MF) as well as the tested material combinations. The rotation of the ring occurs about the rotation axis, which is identic to the axial load transmission.

Mentions: A tribological test setup according to ISO 6474 and Huber et al. was used to measure the friction coefficient (μR) [22]. The ring (friction area 160.2 mm²; radiusexternal = 10 mm; radiusinternal = 7 mm) rotated periodically with 1 Hz on the disc (diameter = 25 mm) with an amplitude of ±25°. Axial compression between ring and disc was adjusted with a manually controlled trapezoidal spindle. The compression was measured with a force transducer (HBM, Darmstadt, Germany), while the friction moment was detected with a beam using a half bridge strain gauge (HBM, Darmstadt Germany). This moment was converted into a force by using the geometrical parameters of the specimen (Figure 2). Both sensors were connected to a personal computer using an analog digital converter (compactDAQ with NI 9237 & NI 9236 modules; National Instruments, Austin, USA) and a self-written program code on LabVIEW (Version 2011, National Instruments, Austin, USA) to record sensors data continuously with a sample rate of 1000 samples per second.


Rapid prototyping for in vitro knee rig investigations of prosthetized knee biomechanics: comparison with cobalt-chromium alloy implant material.

Schröder C, Steinbrück A, Müller T, Woiczinski M, Chevalier Y, Weber P, Müller PE, Jansson V - Biomed Res Int (2015)

Schematic setting of the ring-on-disc rig with the demonstration of the axial compression force (FA) and the friction torque (MF) as well as the tested material combinations. The rotation of the ring occurs about the rotation axis, which is identic to the axial load transmission.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4388012&req=5

fig2: Schematic setting of the ring-on-disc rig with the demonstration of the axial compression force (FA) and the friction torque (MF) as well as the tested material combinations. The rotation of the ring occurs about the rotation axis, which is identic to the axial load transmission.
Mentions: A tribological test setup according to ISO 6474 and Huber et al. was used to measure the friction coefficient (μR) [22]. The ring (friction area 160.2 mm²; radiusexternal = 10 mm; radiusinternal = 7 mm) rotated periodically with 1 Hz on the disc (diameter = 25 mm) with an amplitude of ±25°. Axial compression between ring and disc was adjusted with a manually controlled trapezoidal spindle. The compression was measured with a force transducer (HBM, Darmstadt, Germany), while the friction moment was detected with a beam using a half bridge strain gauge (HBM, Darmstadt Germany). This moment was converted into a force by using the geometrical parameters of the specimen (Figure 2). Both sensors were connected to a personal computer using an analog digital converter (compactDAQ with NI 9237 & NI 9236 modules; National Instruments, Austin, USA) and a self-written program code on LabVIEW (Version 2011, National Instruments, Austin, USA) to record sensors data continuously with a sample rate of 1000 samples per second.

Bottom Line: Friction coefficients between these materials and polytetrafluoroethylene (PTFE) were additionally tested as this latter material is commonly used to protect pressure sensors in experiments.No statistical differences were found between friction coefficients of both materials to PTFE.UHMWPE shows higher friction coefficient at low axial loads for RPM, a difference that disappears at higher load.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopaedic Surgery, Physical Medicine and Rehabilitation, University Hospital of Munich (LMU), Campus Grosshadern, Marchioninistraße 15, 81377 Munich, Germany.

ABSTRACT
Retropatellar complications after total knee arthroplasty (TKA) such as anterior knee pain and subluxations might be related to altered patellofemoral biomechanics, in particular to trochlear design and femorotibial joint positioning. A method was developed to test femorotibial and patellofemoral joint modifications separately with 3D-rapid prototyped components for in vitro tests, but material differences may further influence results. This pilot study aims at validating the use of prostheses made of photopolymerized rapid prototype material (RPM) by measuring the sliding friction with a ring-on-disc setup as well as knee kinematics and retropatellar pressure on a knee rig. Cobalt-chromium alloy (standard prosthesis material, SPM) prostheses served as validation standard. Friction coefficients between these materials and polytetrafluoroethylene (PTFE) were additionally tested as this latter material is commonly used to protect pressure sensors in experiments. No statistical differences were found between friction coefficients of both materials to PTFE. UHMWPE shows higher friction coefficient at low axial loads for RPM, a difference that disappears at higher load. No measurable statistical differences were found in knee kinematics and retropatellar pressure distribution. This suggests that using polymer prototypes may be a valid alternative to original components for in vitro TKA studies and future investigations on knee biomechanics.

Show MeSH
Related in: MedlinePlus