Modern limb prosthetics are quite amazing. The sudden need for large quantities of replacement limbs, born out of recent, bizarre wars such as the US-Iraq mess, has kick-started the prosthetic industry. A great many problems still need to be solved; however none is perhaps as serious as the new trend now beginning to emerge.

One of the latest offerings is the Össur Power Knee. Quoting directly from their latest press releases, we get this:

"The world's first powered prosthesis for above-knee amputees, the POWER KNEE offers unprecedented levels of functionality and performance. It replaces true muscle activity to bend and straighten the knee as required.

When walking on level ground, the user is gently propelled forward, allowing greater distances to be covered without becoming as tired as before. On stairs and inclines the knee actively lifts the user up the next step, producing a secure and natural ascent, foot over foot. By gathering sensory information one step ahead of the prosthesis, the POWER KNEE is unique in its ability to anticipate and pro-actively provide the function appropriate to daily activities."

Truly sounds fantastic, a knee that anticipates the user's movements, and positions itself correctly to aid natural walking - as close as technology has yet come to an artificial leg joint functioning exactly like the original.

However, the Össur Power Knee costs about $96,000 (£48,000) to fit. This is a problem, as standard prosthetics, which do not move, limiting movement, and known by science to impart a great deal of stress and physical wear to the amputee's body, do cost an awful lot less than this.

The Power Knee and others have issued a strong kick up the posterior and wake-up call to the prosthetics industry. However, US health insurance and state-owned health providers in the UK and other countries simply will not pay $80,000 (£40,000) extra for a prosthetic with 'boast microprocessor controlled swing phase adjustment' when they can give the patient a cheap alternative instead. The alternative may not work very well, but the cost is reasonable.

As prosthetics continue to advance, they are going to become more complex, upping the price tag. Advanced prosthetics may therefore stall, in the coming years, unless there are ways to manufacture such advanced devices, much more cheaply, and offset the rising complexity.

3D Printing

3D printing - also known as "rapid prototyping" - transforms a blueprint on a computer into a real object by building up a succession of layers. Recently as of writing (June-August 2006), 3D printers have been able to print moving parts accurate enough to churn out cheap UAVs (Unmanned Arial Vehicles). Whilst nowhere near the precision engineering of a knee, the ability to 3D print UAVs demonstrates how quickly 3D printing is maturing. Within a decade it may very well be possible to 3D print limb prosthetics, slashing the cost apart.