Bionic Prosthetic Leg: From Peg Legs to ABB Robots

For most of history, losing a leg above the knee meant walking on a stiff peg and a crutch. A modern bionic prosthetic leg has a computer in the knee, sometimes a motor, and in the newest research a titanium anchor in the thigh bone and wires that read the user's own muscles. This post follows that path from Roman bronze legs and Victorian wooden limbs to the microprocessor knee, then looks at this autumn's news on bone and muscle connected knees and robotic foot trials. ABB robots come in on the factory side, where knee and ankle parts are made and tested.

A woman with an above knee amputation leaps on her prosthetic leg near the Atomium in Brussels, 2023. Photo: Axiles Bionics / Wikimedia Commons (CC BY-SA 2.0)

How artificial legs went from wooden pegs to locking knees

One of the oldest known artificial legs came from a Roman tomb near Capua in Italy: bronze plates fastened around a wooden core. For centuries after that, most leg amputees used a plain peg strapped to the stump or thigh. Peg legs were often made by local craftsmen rather than specialist limb makers. A peg for an above knee amputation had no knee joint at all, so the wearer swung the whole leg stiffly and usually needed crutches as well. The design was cheap and could be repaired at home, but walking on it was slow and tiring.

A Roman artificial leg of bronze plates over a wooden core, from a tomb near Capua. Photo: Wellcome Collection via Wikimedia Commons (CC BY 4.0)

The French surgeon Ambroise Paré, often called the father of modern prosthetics, designed an above knee leg in the 16th century with an adjustable harness and a knee that could lock. In the early 1800s the London maker James Potts built a leg with a wooden shank and socket, a steel knee joint and a foot moved by catgut tendons. It became known as the Anglesey leg, after the Marquess of Anglesey, who lost a leg at Waterloo. Wars kept driving demand. In 1919 the US Army ran reconstruction classes in France where men with above knee amputations learned to walk on metal frame pegs.

Men with above knee amputations in a reconstruction class at US Army Base Hospital No. 69 in Savenay, France, March 1919. Photo: U.S. Army Signal Corps via Wikimedia Commons (public domain)

Electronics arrived in the 1990s. Blatchford's Intelligent Prosthesis of 1993 is described as the first commercially available microprocessor controlled knee, and Otto Bock introduced the C-Leg in 1997. Sensors and a small computer in the knee adjust its hydraulic resistance many times per step, which keeps it stable on stairs and slopes, though the user still supplies the push. Össur's Power Knee followed in 2006 and added active power. In 2009 the US Army showed soldiers at Walter Reed climbing stairs on the X2, a newer microprocessor knee.

Staff Sgt. Alfredo De Los Santos climbs stairs on an X2 microprocessor knee at Walter Reed, December 2009. Photo: William Selby, U.S. Army via Wikimedia Commons (public domain)

Bone anchored, nerve controlled knees in 2026

On 12 October 2026 the German news site Denkstrom revisited a study from Hugh Herr's group at MIT, published in Science in July 2025. The team anchors a titanium rod in the remaining thigh bone and attaches a motorized knee to it. Surgeons also reconnect pairs of muscles with a method called AMI, and 16 wires carry signals from electrodes on those muscles to a robotic controller that sets the knee torque. Of 17 people tested, the two with both implant and muscle surgery did best at stair climbing, stepping over obstacles and bending the knee to set angles. Herr has estimated that approval may take about five years.

Hugh Herr, head of the biomechatronics group at the MIT Media Lab, in 2013. Photo: Joi Ito / Wikimedia Commons (CC BY 2.0)

The second piece of news is about fitting. Medtech Insight reported on 12 October 2026 that Pittsburgh company Humotech has launched a mobile clinic after a one year pilot. Amputees "test drive" several prosthetic feet on its Caplex robotic trialing system at local clinics, without knowing which model they are wearing. Chief executive Josh Caputo hopes the blinded data will persuade more insurers to pay for the service, which one payer currently covers. Today the choice of foot or knee often rests on a short trial and the prosthetist's judgement, so measured comparisons could change how limbs are prescribed.

A man with a below knee amputation walks across stones on an Axiles Bionics prosthetic foot, 2024. Photo: Axiles Bionics / Wikimedia Commons (CC BY-SA 2.0)

ABB does not make prosthetic legs, and we found no ABB project on bionic knees. Its robots could still play a part in the factory, though that is our suggestion and not a reported project. Knees, ankles and bone anchored adapters contain small precision parts in titanium, aluminium and carbon fibre, the kind of work a GoFa CRB 15000 cobot or IRB 1300 can load into CNC machines, deburr or inspect. ABB has already shown GoFa cobots fitted with PSYONIC Ability Hand prosthetic hands, as our post on prosthetic hands describes.

A researcher at a laptop beside two ABB GoFa cobots fitted with PSYONIC Ability Hands. Photo: ABB

Where powered legs and their factories go next

For users at home, the next steps are knees and ankles that feel like part of the body. In the MIT study, the two users with the full system reported a much stronger sense that the leg belonged to them. Powered ankles, bone anchored implants and muscle signal control will likely arrive one at a time, starting with clinical centres. A related field is the powered exoskeleton, which also adds motor power at the knee and hip, covered in our post on exoskeletons.

Dancer Adrianne Haslet-Davis performs on a bionic leg from Hugh Herr's MIT lab at TED in 2014. Photo: Steve Jurvetson / Wikimedia Commons (CC BY 2.0)

In factories, bionic legs are still built in small numbers, often with one off sockets shaped to each user. That favours flexible cells over long production lines. A cobot could machine a batch of knee housings in the morning and 3D print or trim sockets in the afternoon. Robots could also run the long fatigue tests that knees and feet must pass, bending a joint over and over for weeks. Programs like this are normally built and checked first in RobotStudio before a real part is touched.

An ABB GoFa cobot loading parts into a machine at a small factory. Photo: ABB

Cost is the first problem. John Brinkmann, an orthotist at Northwestern University, warned that cost could be a major barrier, since patients already struggle to get insurance to pay for ordinary prostheses. Bone anchored implants require surgery, can be removed only with another operation, and are not suitable for every patient. Prosthetists who are used to shaping sockets will also have to learn to tune motors and controllers. Cheaper robot made parts would help, but the price of the whole leg, surgery included, decides how many people get one.

An engineer runs a robot 3D print planned in ABB RobotStudio. Photo: ABB

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