that was gaining favor among dentists. Austenal Laboratories had been
founded by Dr. Reiner Erdle and Dr. Charles Prange with the express
purpose of creating dental castings from new metal alloys. Since the
bronze age, man has tinkered with combinations of elemental metals (such
as copper, tin, iron, and zinc), but with the discovery of rarer elements,
such as chromium, cobalt, and molybdenum, “stainless” or “rustless” steel
became a possibility.
We are used to seeing the steel girders of an industrial factory or bridge
rust, a process of “oxidation” where the ambient oxygen in the air
combines (in the presence of water) with the iron in steel, forming iron
oxide through a series of chemical “redox” reactions. Surprisingly, these
same reactions can occur in the human body, where oxygen and water are
obviously present. A regular steel implant would catastrophically fail in a
person; it would be the work of metallurgists in the 20th century to
identify which metals were practicable for human use. Trial and error with
the available elements would determine which alloys were suitable, based
on their workability, stiffness, and affordability, but it would be a surgeon
from San Antonio who would unlock the secrets of alloys for Dr. Smith-
Petersen, Dr. Neer, and every surgeon who followed them until today.
Fracture care was dramatically improved with the advent of
radiography; surgeons could actually see, and then classify, fractures of
every bone of the body. Eventually, trauma doctors learned which broken
bones healed with plaster of Paris casts and which fractures required
operative intervention. Metal screws and plates (long, thin slabs of metal
with screw holes) were initially made of pure metals (e.g., aluminum,
silver, gold, and tin), but these proved to be too soft and weak to do the job
of buttressing bone while it healed. Iron was much stronger, but the
chemical reaction in the surrounding tissues made it impractical. Hoping
to minimize corrosion, the next logical step was to electrochemically coat
the plate with chromium (“galvanized steel”), but disastrously, where the
screw threads engaged the plate, the chromium plating was scuffed away,
exposing the steel to corrosion.
The only acceptable orthopedic implant would therefore be a through-
and-through alloy, but no biologic testing had ever been performed. The
Virginia-raised Dr. Charles Venable and his two San Antonio orthopedic
surgeon partners dedicated years testing screws in the forearm bones of
dogs, evaluating them with X-rays and microscopic analysis of the bones
marcin
(Marcin)
#1