ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

alloy. In contrast, that of average 40.257με (4.0%) were observed at the part of low
elastic modulus that circled. Namely, that compared with the femoral nail made of a
titanium alloy, the original PEEK femoral nail has been confirmed to have occurred a
large strain (figure 5). Figure 6 shows the strain distribution of bone model in the
original PEEK femoral nail and the femoral nail made of a titanium alloy. Strains of the
lag-screw and the surrounding bone are related to the proportional, that strain of the
surrounding bone is greater the larger the strain of the lag-screw has been confirmed.
Occurrence of strain in the direction of long axis by the buffer was placed in the center
of each lag-screw, the promotion of bone healing was considered mechanism can be
expected. Our results are not necessarily appropriate than Adaptive Remodeling 1) . it is
the agenda that Some challenges the optimization of the shape and material in order to
converge to the strain conditions a more appropriate.
Fig 5. Analysis results of femoral nail (Strain).
Fig 6. Analysis results of bone model (Strain).
The stem of the original PEEK femoral nail is a feature that has been designed coneshaped
junction of each parts in contact with the surface. the design has been realized
continuous variation of material properties. Also in the stress distribution, stress that has
been reduced in stages according to the distal of the stem had been confirmed (Figure 7).
When attention is paid to the distal end of the stem, equivalent stress of the femoral nail
made of a titanium alloy was average 1,760MPa, that of the original PEEK femoral nail
was average 104MPa, stress concentration in the distal end of the stem can be relaxed
has been confirmed at the original PEEK femoral nail (Figure 7). Because the stem was
configured differently to a high elastic modulus from a low elastic modulus to the
elastic modulus progressively, worked with the action is considered to alleviate the stem
by elastic deformation of the distal end of the stem. Therefore, the original PEEK
femoral nail was the effect of suppressing the fracture of the distal end of the stem was
expected.