The output depends on the polarization of the input. Suppose polarization axes x and y parallel with the fast and slow axis of the waveplate:
This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The bending structural stiffness of each plate was obtained from four-point bending tests according to ASTM F Kruskal-Wallis test showed no significant difference in the bending structural stiffness between the three plate models.
Rank-transformed two-way ANOVA showed significant influence of plate type, fracture type, and interaction plate versus fracture on the stiffness of the montages. The straight-DCP produced the most stable model for types B and C fractures, which makes its use advantageous for complex nonosteoporotic fractures that require minimizing focal mobility, whereas no difference was found for type A fracture.
Our results indicated that DCPs, in Wave-plate osteosynthesis or wave form, can provide adequate biomechanical properties for fixing diaphyseal femoral fractures in cases where more modern osteosynthesis systems are cost restrictive. Introduction The current standard of care for femoral fractures is the intramedullary nail, but there are situations in which the use of plates is indicated, like narrow medullary cavity, bone deformities, and open growth plate.
Metal plates have been used for the fixation of fractures since the end of the 19th century. The DCP, designed with oblong holes to provide interfragmentary compression when tightening the screws, was introduced in [ Wave-plate osteosynthesis ]. As opposed to the wide surgical approach required by this technique, it has been suggested that less manipulation of the bone fragments would result in faster bone healing by preserving the fracture site vasculature [ 5 ].
Consequently, osteosynthesis techniques were modified [ 246 — 8 ] to minimize damage to the soft tissue and periosteum in order to preserve the fracture vascularization [ 27 ]. The authoritative work of Heitemeyer et al. Appropriate stress distribution is fundamental to proper bone remodeling during fracture healing.
Within a certain range of values, compressive stresses drive bone growth, whereas tensile stresses favor connective tissue or fibrocartilage formation [ 10 ].
They found that fracture sites were experiencing high stresses and plate fatigue failure in the absence of medial support. The wave plate shifts the neutral axis toward the lateral cortical region, so that the bone is in compression, while the plate is in tension [ 1112 ].
The Locking Compression Plate LCP is a more recent improvement to the straight-DCP technology that shares similar characteristics and mechanical performance to external fixators. In this system, the fixation screws are locked in the plate [ 14 — 16 ].
The LCP design minimizes contact with the bone, which reduces the damage to the periosteum and the resulting bone necrosis as well. Currently, there are no studies comparing directly the effectiveness of these three plate systems within the same model. To assess whether patients receiving the DCP plate are receiving adequate fracture care, the stiffness of each plate design was tested in simulated models of types A, B, and C diaphyseal femoral fractures AO classification [ 18 ].
Materials and Methods 2.
Static Bending Test of the Plates Four-point static bending tests were conducted on hole 4. The wave plates were shaped from straight plates as described by Blatter et al. Briefly, the plate was bent at the third and fourth screw holes on either side of the plate center to form a 5 mm high wave Figure 1.
A special apparatus was used to support and load the plates. According to ASTM Fthe loading rollers should be positioned so that two plate screw holes would be located between them, while the support rollers should be placed two screw holes away from the loading rollers.
For testing the wave-DCP, however, the distance between the two loading rollers had to be increased to eight screw holes to encompass the whole wave between them, while the support rollers were still positioned two screw holes away from the loading rollers Figure 1.
According to ASTM Fthe plate bending structural stiffness can be calculated according to 1: Position of support and loading points wave-DCP.
Static Compression Test of the Montages Simulating Fractures The test specimens were divided into three simulation groups, corresponding to types A, B, and C diaphyseal femur fractures AO classification [ 18 ].
Each plate type was tested in all three fracture groups. Test specimens consisted of two dense wooden rods Pouteria pachycarpa Piresmm long and 26 mm in diameter, attached with a different type of osteosynthesis plate. The model used for the static compression tests has been used previously to simulate the physiological axes of the femur to approximate physiological loading conditions in experimental compression tests [ 20 — 22 ].
Wood has been a material of choice for such kind of tests [ 23 — 25 ] and was chosen, because it presents more uniform mechanical properties than human cadaveric bone and serves as a good anchor for the fixation screws [ 22 ].
Although the wooden rods do not mimic the real bone, they were used because the interest was in the relative stiffness among the montages, not in the absolute stiffness. Straight- and wave-DCPs Synthes number.The wave plate was chosen for the treatment of non union femoral diaphyseal fractures, due to the use of a DCP plate initially, which should be removed, even though it was already causing an injury of the periosteal flow due to bone contact beneath the plate.
The Wave plate is a fixation system for open reduction and internal fixation (ORIF) of calcaneal fractures designed to be performed through a sinus tarsi approach. In conventional plate osteosynthesis, anatomic reduction is sought because it increases stability, whereas in locking plate osteosynthesis the quality of the reduction is less vital, provided that the local soft tissues (and therefore vascularization of the fragments) are maintained intact.
From the point of view of the stiffness, the DCP can still be safely used for the osteosynthesis the of healthy (non-osteoporotic) bones, either as wave plate for simple fractures or as straight plate for complex fractures, in situations where the high cost of the .
The Wave plate is a fixation system for open reduction and internal fixation (ORIF) of calcaneal fractures designed to be performed through a sinus tarsi approach.
In conventional plate osteosynthesis, anatomic reduction is sought because it increases stability, whereas in locking plate osteosynthesis the quality of the reduction is less vital, provided that the local soft tissues (and therefore vascularization of the fragments) are maintained intact.