I was interested to see this recent article on The O&P Edge website comparing the relative merits of carbon fibre versus 3D printed prosthetic socket design. 

The study in question was undertaken by HP who, as I understand from recent conversations with UK based prosthetists and orthotists, seem to dominate the 3D printing market (in the UK prosthetic and orthotic market at least). Indeed the article refers to the fact that HP’s Multi Jet Fusion technology and durable HP 3D HR PA12 material were used in the study, so perhaps it is unsurprising the company is eager to extol the virtues of their products to all.

Of course, the benefits 3D printing can bring to the world of prosthetics and orthotics are by now well known -  it offers consistency and scalability in design; enhanced precision; the need to use less materials / reduce wastage; and the time efficiency it affords in production are its big selling points. As the article notes though, there is a lack of data benchmarking the performance of 3D printed models against traditionally manufactured carbon fibre models.

The tests undertaken by HP used both static and cyclic fatigue approaches to compare how a 3D printed socket compares against a carbon fibre printed socket. The article describes that under the static tests the prostheses were “strained to induce failure limits”. The study found that the 3D printed sockets were able to withstand a greater load before breaking than their carbon fibre equivalent. HP say they attribute this to “the material’s flexible yet strong properties”. It is another and perhaps less well known advantage to 3D printing that it allows one to use advanced materials to improve the strength-to-weight ratio of the model being produced. The 3D printed socket was also found to have failed more safely, though it is not clear how this was measured. In the cyclic fatigue assessments the 3D printed socket was found to be more resilient compared to its carbon fibre compatriot, which showed substantial cracking as a result of the tests. 

Needless to say this is all positive news for 3D printing technology and its suitability for use in prosthetic and orthotic provision. How significant these studies are for the actual users of the products is perhaps more open to debate. Cost, comfort and appearance are likely to remain much bigger concerns for those using the products than factors like ultimate load limits, but there is no reason to think 3D printed models are lagging behind their carbon fibre colleagues in any of these benchmarks either.