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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

The left plot shows the quadriceps load in N against the flexion angle of the SPM and the plot at the bottom shows the flexion angle against the quadriceps load of the RPM. The diagram in the center is a projection of both plots and compares the RPM material (y-axis) and the SPM (x-axis). Angles are identified in the upper right corner plot with flexion (F), extension (E) angle. The Deming-regression line with slope and standard deviation of the slope (crosses) are shown.
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fig5: The left plot shows the quadriceps load in N against the flexion angle of the SPM and the plot at the bottom shows the flexion angle against the quadriceps load of the RPM. The diagram in the center is a projection of both plots and compares the RPM material (y-axis) and the SPM (x-axis). Angles are identified in the upper right corner plot with flexion (F), extension (E) angle. The Deming-regression line with slope and standard deviation of the slope (crosses) are shown.

Mentions: For each measured specimen and each parameter, a linear regression was calculated by Deming-regression. Figure 5 represents a typical result obtained for quadriceps load measured for one specimen with both types of implant materials.


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)

The left plot shows the quadriceps load in N against the flexion angle of the SPM and the plot at the bottom shows the flexion angle against the quadriceps load of the RPM. The diagram in the center is a projection of both plots and compares the RPM material (y-axis) and the SPM (x-axis). Angles are identified in the upper right corner plot with flexion (F), extension (E) angle. The Deming-regression line with slope and standard deviation of the slope (crosses) are shown.
© Copyright Policy
Related In: Results  -  Collection

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

fig5: The left plot shows the quadriceps load in N against the flexion angle of the SPM and the plot at the bottom shows the flexion angle against the quadriceps load of the RPM. The diagram in the center is a projection of both plots and compares the RPM material (y-axis) and the SPM (x-axis). Angles are identified in the upper right corner plot with flexion (F), extension (E) angle. The Deming-regression line with slope and standard deviation of the slope (crosses) are shown.
Mentions: For each measured specimen and each parameter, a linear regression was calculated by Deming-regression. Figure 5 represents a typical result obtained for quadriceps load measured for one specimen with both types of implant materials.

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