|
. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 The prosthesis is an anatomic right and left
prosthesis with a 135 ° sloping angle and an 10 °
anteversion angle.The titanium alloy metaphysiary part drawing
(TA16V4) provides a suited metaphysiary filling, as, when
installed, it comes to rest both on the lateral face of the
greater trochanter and on the front and rear side of the
metaphysis ; its surface has horizontal fissures in order to
prevent sinking. Its rough surface is covered with a layer
of 70 micron hydroxyapatite intended to facilitate its
secondary fastening.The shaft part is also titanium ; it is smooth,
without hydroxyapatite, rather short and is available in 7
sizes : it is used for temporary centring pending the final
metaphysiary anchoring.70 combinations are possible, matching most
standard femurs.The fastening of both parts has been the
subject of numerous studies. The parts are cylindrically
inserted in one another and screwed.A finished element study has been conducted
prior to the use of the prosthesis. The purpose of the study
was to study the behaviour of both fastened parts in terms
of warping and constraints, mainly at the shaft / metaphysis
unit. Various components were studied: aluminium oxide
beads, metaphysis parts, shaft parts, cortical bones, upper
spongy bone and lower spongy bone. All 6 components were
subjected to a 2 000 N stress applied to the aluminium oxide
bead (Pauwels' diagram). The results show that the level of
stress is very low. The maximum figures (15.4 daN/mm2) were
found on the metaphysis part, in the area connecting the
stem holding the bead and the massive section. With the
assembly of both parts, the maximum stress value reached 8
daN / mm2, in spots only. It was found that the maximum
stress values (15 daN / mm2) were not dangerous for the
metaphysis and the shaft since the value is much lower than
the elastic limit of the respective material. In the same
way, the low level of stress found on the metaphysis / shaft
assembly shows the durability of that
combination.
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
