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A novel device for resistance-free biomechanical testing of the metaphysis of long bones.

Mackert GA, Hirche C, Harhaus H, Kotsougiani D, Hoener B, Kneser U, Harhaus L - BMC Musculoskelet Disord (2014)

Bottom Line: In the evaluation of both testing procedures, the results of the right and left tibiae were compared according to the rat they originated from.The mean failure Load (fL) did not differ significantly (p < 0.231) between Group 1: 81.34 ± 11.972 N SD and Group 2: 79.63 ± 10.345 N SD.We suggest that the new ball-mounted platform device, when compared to other existing techniques, generates more accurate test results when used in the three-point bending/breaking test of the metaphysis of long bones.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department for Hand-, Plastic- and Reconstructive Surgery - Burn Care Center - BG-Trauma Clinic Ludwigshafen, Department for Plastic Surgery of the University of Heidelberg, Ludwig-Guttmann-Str, 13, 67071 Ludwigshafen, Germany. leila.harhaus@bgu-ludwigshafen.de.

ABSTRACT

Background: Biomechanical testing is an essential component of bone research. In order to test the metaphyseal region of long bones, a typical location for the nowadays increasing field of osteoporotic bone changes, three-point bending and breaking test devices are suitable and widely used. The aim of our study was to increase the effectiveness of this method by using a newly developed ball-mounted platform design. This new design eliminates the negative effects of friction, present in previous studies, caused by the lengthening of the distal tibia along its diaphyseal axis while sliding over the surface of a fixed aluminum block.

Methods: 70 tibiae of 35 twelve week old, female Sprague Dawley rats were separated into two groups for a metaphyseal bending/breaking test. Group 1 was made up of the rat's right tibiae, Group 2 of the left tibiae. Group 1 was tested on a solid metal block according to previously established testing devices whereas Group 2 was tested on the newly designed device: the resistance-free gliding, ball-mounted platform. Stiffness (N/mm), yield Load (N), and failure Load (N) were registered. In the evaluation of both testing procedures, the results of the right and left tibiae were compared according to the rat they originated from.

Results: Stiffness (S) showed highly significant differences (p = 0.002) with 202.25 ± 27.010 N/mm SD (Group 1) and 184.66 ± 35.875 N/mm SD (Group 2). Yield Load (yL) showed highly significant differences (p < 0.001) with 55.31 ± 13.074 N SD (Group1) and 37.17 ± 12.464 N SD (Group2). The mean failure Load (fL) did not differ significantly (p < 0.231) between Group 1: 81.34 ± 11.972 N SD and Group 2: 79.63 ± 10.345 N SD.

Conclusions: We therefore conclude that, used in the three-point bending/breaking test, the mobile, ball-mounted platform device is able to efficiently eliminate the influence of friction in terms of stiffness and yield load. Failure Load was not affected. We suggest that the new ball-mounted platform device, when compared to other existing techniques, generates more accurate test results when used in the three-point bending/breaking test of the metaphysis of long bones.

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Related in: MedlinePlus

Example of the graphical visualization of the data (distance (mm) travelled by the stamp and force (N) exerted by the stamp) recorded by the “testXpert” software during the bending and breaking test performed on the newly designed mobile, ball-mounted platform.
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Figure 5: Example of the graphical visualization of the data (distance (mm) travelled by the stamp and force (N) exerted by the stamp) recorded by the “testXpert” software during the bending and breaking test performed on the newly designed mobile, ball-mounted platform.

Mentions: During the trials, the “testXpert” software continuously recorded the force (in newtons) which was applied via the stamp on the tibia metaphysis. The force (in newtons) was graphically plotted against the stamp’s traveled distance (Figure 5). From this graph, the stiffness (S), which is defined as the resistance an elastic body exerts against deformation [28], was represented by the slope of the curve prior to the yield load. The yield load (yL) is the point where elastic deformation transforms into plastic deformation and first microfractures occur. It was assessed as a decrease in stiffness of more than twice the SD. The highest point on the graph, where the largest force was applied onto the tibia, was assessed as the maximum Force (Fmax). We also calculated the failure Load (fL) which is the force (in newtons) at the point of breakage.


A novel device for resistance-free biomechanical testing of the metaphysis of long bones.

Mackert GA, Hirche C, Harhaus H, Kotsougiani D, Hoener B, Kneser U, Harhaus L - BMC Musculoskelet Disord (2014)

Example of the graphical visualization of the data (distance (mm) travelled by the stamp and force (N) exerted by the stamp) recorded by the “testXpert” software during the bending and breaking test performed on the newly designed mobile, ball-mounted platform.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4125708&req=5

Figure 5: Example of the graphical visualization of the data (distance (mm) travelled by the stamp and force (N) exerted by the stamp) recorded by the “testXpert” software during the bending and breaking test performed on the newly designed mobile, ball-mounted platform.
Mentions: During the trials, the “testXpert” software continuously recorded the force (in newtons) which was applied via the stamp on the tibia metaphysis. The force (in newtons) was graphically plotted against the stamp’s traveled distance (Figure 5). From this graph, the stiffness (S), which is defined as the resistance an elastic body exerts against deformation [28], was represented by the slope of the curve prior to the yield load. The yield load (yL) is the point where elastic deformation transforms into plastic deformation and first microfractures occur. It was assessed as a decrease in stiffness of more than twice the SD. The highest point on the graph, where the largest force was applied onto the tibia, was assessed as the maximum Force (Fmax). We also calculated the failure Load (fL) which is the force (in newtons) at the point of breakage.

Bottom Line: In the evaluation of both testing procedures, the results of the right and left tibiae were compared according to the rat they originated from.The mean failure Load (fL) did not differ significantly (p < 0.231) between Group 1: 81.34 ± 11.972 N SD and Group 2: 79.63 ± 10.345 N SD.We suggest that the new ball-mounted platform device, when compared to other existing techniques, generates more accurate test results when used in the three-point bending/breaking test of the metaphysis of long bones.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department for Hand-, Plastic- and Reconstructive Surgery - Burn Care Center - BG-Trauma Clinic Ludwigshafen, Department for Plastic Surgery of the University of Heidelberg, Ludwig-Guttmann-Str, 13, 67071 Ludwigshafen, Germany. leila.harhaus@bgu-ludwigshafen.de.

ABSTRACT

Background: Biomechanical testing is an essential component of bone research. In order to test the metaphyseal region of long bones, a typical location for the nowadays increasing field of osteoporotic bone changes, three-point bending and breaking test devices are suitable and widely used. The aim of our study was to increase the effectiveness of this method by using a newly developed ball-mounted platform design. This new design eliminates the negative effects of friction, present in previous studies, caused by the lengthening of the distal tibia along its diaphyseal axis while sliding over the surface of a fixed aluminum block.

Methods: 70 tibiae of 35 twelve week old, female Sprague Dawley rats were separated into two groups for a metaphyseal bending/breaking test. Group 1 was made up of the rat's right tibiae, Group 2 of the left tibiae. Group 1 was tested on a solid metal block according to previously established testing devices whereas Group 2 was tested on the newly designed device: the resistance-free gliding, ball-mounted platform. Stiffness (N/mm), yield Load (N), and failure Load (N) were registered. In the evaluation of both testing procedures, the results of the right and left tibiae were compared according to the rat they originated from.

Results: Stiffness (S) showed highly significant differences (p = 0.002) with 202.25 ± 27.010 N/mm SD (Group 1) and 184.66 ± 35.875 N/mm SD (Group 2). Yield Load (yL) showed highly significant differences (p < 0.001) with 55.31 ± 13.074 N SD (Group1) and 37.17 ± 12.464 N SD (Group2). The mean failure Load (fL) did not differ significantly (p < 0.231) between Group 1: 81.34 ± 11.972 N SD and Group 2: 79.63 ± 10.345 N SD.

Conclusions: We therefore conclude that, used in the three-point bending/breaking test, the mobile, ball-mounted platform device is able to efficiently eliminate the influence of friction in terms of stiffness and yield load. Failure Load was not affected. We suggest that the new ball-mounted platform device, when compared to other existing techniques, generates more accurate test results when used in the three-point bending/breaking test of the metaphysis of long bones.

Show MeSH
Related in: MedlinePlus