Biomedical Engineering Reference
In-Depth Information
Fig. 6.8
A five-step processing scheme for transformation of pine wood or rattan to a porous
hydroxyapatite scaffold. Reproduced with permission of The Royal Society of Chemistry [
246
]
6.6
Osteosynthesis
Broken legs, however, are not healed by speculation over the future but for the time
being by decent plates and screws. Nothing special, in particular, has to be said about
the basic materials because the classics dominate the field: stainless steel (316L)
and titanium alloys (Ti6Al4V or Ti6Al7Nb). Fracture fixation demands mostly high
strength alloys in cases as shown in Fig.
6.1
and even more for complex femur or
tibia fractures. The classic alloys match perfectly the endo-prosthetic mechanical
requirementsand thus...end of the debate?
Nothing is less true. The reason we devote a section to osteosynthesis devices is
that we want, once again, to point to possible failure of even the best material when
used under wrong conditions. For many devices, the main progresses will be situated
in design rather than in 'naked' materials properties. In Chap.
3
, corrosion between
screw head and osteosynthesis plate was cited as a location of fretting corrosion
(see
149
). In a device recently introduced by Zimmer, locking caps are used.
8
It
allows to achieve angular stability of the screw and it meets simultaneously the
8
Zimmer GmbH. Info: www.zimmer.com.
