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Treatment of distal humeral fractures using conventional implants. Biomechanical evaluation of a new implant configuration.

Windolf M, Maza ER, Gueorguiev B, Braunstein V, Schwieger K - BMC Musculoskelet Disord (2010)

Bottom Line: Compared to the LCP constructs, the "Frame" technique revealed significant higher construct stiffness in extension of the arm (P = 0.01).The stiffness in flexion was not significantly different (P = 0.16).Number of cycles to failure was found significantly larger for the "Frame" technique (P = 0.01).

View Article: PubMed Central - HTML - PubMed

Affiliation: AO Research Institute, AO Foundation, Clavadelerstrasse 8, 7270 Davos, Switzerland. markus.windolf@aofoundation.org

ABSTRACT

Background: In the face of costly fixation hardware with varying performance for treatment of distal humeral fractures, a novel technique (U-Frame) is proposed using conventional implants in a 180 degrees plate arrangement. In this in-vitro study the biomechanical stability of this method was compared with the established technique which utilizes angular stable locking compression plates (LCP) in a 90 degrees configuration.

Methods: An unstable distal 3-part fracture (AO 13-C2.3) was created in eight pairs of human cadaveric humeri. All bone pairs were operated with either the "Frame" technique, where two parallel plates are distally interconnected, or with the LCP technique. The specimens were cyclically loaded in simulated flexion and extension of the arm until failure of the construct occurred. Motion of all fragments was tracked by means of optical motion capturing. Construct stiffness and cycles to failure were identified for all specimens.

Results: Compared to the LCP constructs, the "Frame" technique revealed significant higher construct stiffness in extension of the arm (P = 0.01). The stiffness in flexion was not significantly different (P = 0.16). Number of cycles to failure was found significantly larger for the "Frame" technique (P = 0.01).

Conclusions: In an in-vitro context the proposed method offers enhanced biomechanical stability and at the same time significantly reduces implant costs.

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Related in: MedlinePlus

Construct stiffness. Stiffness obtained from quasi-static measurements for both study-groups at the beginning of the cyclic test in flexion, at the beginning of the cyclic extension test (after 2500 cycles) and after 7500 cycles. * indicates statistical significance.
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Figure 4: Construct stiffness. Stiffness obtained from quasi-static measurements for both study-groups at the beginning of the cyclic test in flexion, at the beginning of the cyclic extension test (after 2500 cycles) and after 7500 cycles. * indicates statistical significance.

Mentions: Construct stiffness in flexion as obtained from the quasi-static ramps at the beginning of the test was 91 ± 5 N/mm for the Frame constructs and 103 ± 8 N/mm for the LCP samples. This difference was not significant between groups (P = 0.16). The stiffness in extension (at the beginning of the extension test) was significantly higher for the Frame-group (281 ± 25 N/mm) compared to the LCP-group (161 ± 21 N/mm) (P = 0.01; Fig. 4). After 7500 cycles (5000 cycles of these in extension) this difference was still significant (P = 0.02).


Treatment of distal humeral fractures using conventional implants. Biomechanical evaluation of a new implant configuration.

Windolf M, Maza ER, Gueorguiev B, Braunstein V, Schwieger K - BMC Musculoskelet Disord (2010)

Construct stiffness. Stiffness obtained from quasi-static measurements for both study-groups at the beginning of the cyclic test in flexion, at the beginning of the cyclic extension test (after 2500 cycles) and after 7500 cycles. * indicates statistical significance.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2921352&req=5

Figure 4: Construct stiffness. Stiffness obtained from quasi-static measurements for both study-groups at the beginning of the cyclic test in flexion, at the beginning of the cyclic extension test (after 2500 cycles) and after 7500 cycles. * indicates statistical significance.
Mentions: Construct stiffness in flexion as obtained from the quasi-static ramps at the beginning of the test was 91 ± 5 N/mm for the Frame constructs and 103 ± 8 N/mm for the LCP samples. This difference was not significant between groups (P = 0.16). The stiffness in extension (at the beginning of the extension test) was significantly higher for the Frame-group (281 ± 25 N/mm) compared to the LCP-group (161 ± 21 N/mm) (P = 0.01; Fig. 4). After 7500 cycles (5000 cycles of these in extension) this difference was still significant (P = 0.02).

Bottom Line: Compared to the LCP constructs, the "Frame" technique revealed significant higher construct stiffness in extension of the arm (P = 0.01).The stiffness in flexion was not significantly different (P = 0.16).Number of cycles to failure was found significantly larger for the "Frame" technique (P = 0.01).

View Article: PubMed Central - HTML - PubMed

Affiliation: AO Research Institute, AO Foundation, Clavadelerstrasse 8, 7270 Davos, Switzerland. markus.windolf@aofoundation.org

ABSTRACT

Background: In the face of costly fixation hardware with varying performance for treatment of distal humeral fractures, a novel technique (U-Frame) is proposed using conventional implants in a 180 degrees plate arrangement. In this in-vitro study the biomechanical stability of this method was compared with the established technique which utilizes angular stable locking compression plates (LCP) in a 90 degrees configuration.

Methods: An unstable distal 3-part fracture (AO 13-C2.3) was created in eight pairs of human cadaveric humeri. All bone pairs were operated with either the "Frame" technique, where two parallel plates are distally interconnected, or with the LCP technique. The specimens were cyclically loaded in simulated flexion and extension of the arm until failure of the construct occurred. Motion of all fragments was tracked by means of optical motion capturing. Construct stiffness and cycles to failure were identified for all specimens.

Results: Compared to the LCP constructs, the "Frame" technique revealed significant higher construct stiffness in extension of the arm (P = 0.01). The stiffness in flexion was not significantly different (P = 0.16). Number of cycles to failure was found significantly larger for the "Frame" technique (P = 0.01).

Conclusions: In an in-vitro context the proposed method offers enhanced biomechanical stability and at the same time significantly reduces implant costs.

Show MeSH
Related in: MedlinePlus