On August 31, 2006, an operation took place at the Royal Perth Hospital in Australia which could lead to a complete change in surgery for hip joint endoprosthesis. A woman patient received an acetabular reconstruction cage that was individually produced for her instead of the hospital using standard “off the shelf” implants. The technology used to create the individual implant was Selective Laser Melting (SLM), supplied by MCP Tooling Technologies.
Prior to the operation, the surgeons took X-ray pictures of the patient’s hip using a CT scanner. Bio-engineers from the Royal Perth Hospital then computer designed a 3D data file of an acetabular cup that fitted the patient’s existing bone structure exactly. SLM technology requires only a standard 3D data file of the implant geometry. This data file is mathematically sliced in parallel layers of even thickness of just 0.05 mm. The SLM parts are built up layer by layer, using, for example, titanium, cobalt-chrome, or stainless steel powder being melted locally by an intensive infrared laser beam which traces the layer geometry. New layers are built successively on the previous surface until the whole implant part is generated. During the building process, the building chamber of the SLM machine is filled with Argon inert gas in order to achieve the best mechanical properties of the metal implant.
The 3D data file was e-mailed to MCP in Germany and the individual implant was generated within a day and sent back overnight to Perth. The implant was created in titanium alloy. The surgery, carried out by Professor David Wood from Royal Perth Hospital, went exceptionally well, taking only 2 hours. According to the surgeons, and as a comparison, contouring a standard cage for the patient would add approximately an extra hour to the operationtime that can now be saved. The dimensional accuracy and fit of the individual plate was excellent.