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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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Retropatellar pressure distribution of both prosthesis materials (left: rapid prototype material; right: standard prosthesis material) at a flexion angle of 120° in one representative specimen.
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fig6: Retropatellar pressure distribution of both prosthesis materials (left: rapid prototype material; right: standard prosthesis material) at a flexion angle of 120° in one representative specimen.

Mentions: No significant differences were measured in the knee rig between the two tested materials (Table 4). A maximum quadriceps load of 647 ± 131 N with RPM and 620 ± 88 N with SPM was necessary to extend the cadaver knee and caused comparable results during the whole cycle (P = 0.69). Furthermore the maximum retropatellar peak pressure of 6.92 ± 2.01 MPa with RPM and 6.83 ± 1.79 MPa with SPM showed no significant differences (P = 0.53). Little deviations could be noticed at the maximum of the contact area (Figure 6). RPM showed a tendency to a higher contact area with 402 ± 63 mm² compared to the SPM with a maximum contact area of 380 ± 61 mm². However, the change in contact area was not significant (P = 0.31). Similar behaviors between the RPM and the SPM in terms of kinematics of the femorotibial joint were depicted. Equivalent results of the patellar tilt of 4.95° ± 1.93° with RPM and 4.87° ± 1.86° with SPM as well as the patellar rotation of 5.29° ± 3.72° with RPM and 5.13° ± 3.47° with SPM could be obtained. The measurement of the lateral shift of the patella provided an average value of 4.87 mm (SPM ±2.0 mm; RPM ±2.2 mm) for both 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)

Retropatellar pressure distribution of both prosthesis materials (left: rapid prototype material; right: standard prosthesis material) at a flexion angle of 120° in one representative specimen.
© Copyright Policy
Related In: Results  -  Collection

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

fig6: Retropatellar pressure distribution of both prosthesis materials (left: rapid prototype material; right: standard prosthesis material) at a flexion angle of 120° in one representative specimen.
Mentions: No significant differences were measured in the knee rig between the two tested materials (Table 4). A maximum quadriceps load of 647 ± 131 N with RPM and 620 ± 88 N with SPM was necessary to extend the cadaver knee and caused comparable results during the whole cycle (P = 0.69). Furthermore the maximum retropatellar peak pressure of 6.92 ± 2.01 MPa with RPM and 6.83 ± 1.79 MPa with SPM showed no significant differences (P = 0.53). Little deviations could be noticed at the maximum of the contact area (Figure 6). RPM showed a tendency to a higher contact area with 402 ± 63 mm² compared to the SPM with a maximum contact area of 380 ± 61 mm². However, the change in contact area was not significant (P = 0.31). Similar behaviors between the RPM and the SPM in terms of kinematics of the femorotibial joint were depicted. Equivalent results of the patellar tilt of 4.95° ± 1.93° with RPM and 4.87° ± 1.86° with SPM as well as the patellar rotation of 5.29° ± 3.72° with RPM and 5.13° ± 3.47° with SPM could be obtained. The measurement of the lateral shift of the patella provided an average value of 4.87 mm (SPM ±2.0 mm; RPM ±2.2 mm) for both 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