In vitro evaluation of the influence of the wave length and height in the wave-plate osteosynthesis.
OBJECTIVE
The aim of this study is to compare the mechanical characteristics of four different moldings of the wave-plate, with and without a polyamide block under the plate simulating the corticocancellous bone graft.


METHODS
Four different wave-plates were analyzed: (1) short-low (SL): wave length of four holes and 10 mm height; (2) short-high (SH): four holes length and 20 mm height; (3) long-low (LL): six holes length and 10 mm height; and (4) long-high (LH): six holes length and 20 mm height. The plate was assembled in a polyamide cylinder simulating a type B diaphyseal fracture, with the contact of one-third of the diameter, with and without a polyamide block under the plate, submitted to an application of an eccentric axial load (100 N/min).


RESULTS
Without the polyamide block under the plate there were no statistical differences between the different wave-plates: SL 64.8 +/- 3.5 N; SH 62.4 +/- 3.4 N; LL 60.3 +/- 3.9 N; LH 52.1 +/- 5.9 N. There were no differences in the stiffness as well. All four different moldings of the wave-plates tested with the polyamide block showed higher maximum strength compared with the plates without the block. The configuration with higher maximum strength was the LH-B (2,195.3 +/- 252.2 N). The plate with highest stiffness was the LL-B (90.5 +/- 7.5 N/mm).


CONCLUSIONS
We concluded that without the usage of the polyamide block under the plate neither the length nor the height changed the maximum strength and the stiffness. With the polyamide block, the maximum strength and the stiffness were significantly higher. The long and high wave-plate with the block showed higher maximum strength while the long and low the highest stiffness.
Kojima
Kodi E
KE
Department of Orthopaedic and Traumatology, Santa Casa Medical School, São Paulo, Brazil. kodikojima@uol.com.br
Hungria Neto
Jose Soares
JS
Fucs
Patricia M M B
PM
D001696:Biomechanical Phenomena; D001860:Bone Plates; D004867:Equipment Design; D005593:Fracture Fixation, Internal / Q000295:instrumentation* / Q000379:methods; D006801:Humans; D066298:In Vitro Techniques; D008422:Materials Testing; D013314:Stress, Mechanical; D013718:Tensile Strength