Madrid hospital implants world's first 3D-printed metamaterial bone prosthesis, saving cancer patient's leg

A world-first implant

Surgeons at Madrid's Hospital General Universitario Gregorio Marañón have designed and implanted the world's first personalized bone prosthesis made of metamaterial, saving the leg of a 38-year-old French patient who faced amputation. Pierre Chazel had been diagnosed with a high-grade bone sarcoma in his tibia roughly three years ago. After an initial surgery and conventional implant, an infection left his bone so weakened that no commercial prosthesis could replace what the cancer and infection had destroyed. The only remaining option was below-knee amputation, which would have sacrificed the joint entirely.

The hospital turned to the Escuela Técnica Superior de Ingeniería Aeronáutica y del Espacio at the Universidad Politécnica de Madrid (UPM), where engineers applied aerospace technology to create a titanium structure that reproduces the mechanical functions of bone. The implant was 3D-printed at the hospital itself, based on radiological images of the patient's healthy leg. A digital twin of his sound tibia was built, and real loads (walking, climbing stairs, even stumbling) were simulated to calculate the precise internal geometry needed. The structure consists of a network of small titanium bars whose geometry distributes weight similarly to healthy bone, allowing surrounding bone tissue to grow around the implant.

The patient's recovery

Nearly a year after the surgery, Pierre has recovered mobility and walks without crutches. He has suffered no infection or complications related to the implant, and maintains knee alignment and movement. He can now carry objects in his hand while walking and no longer feels pain in his foot.

I have been able to support my leg again after two years and finally I am going to be able to walk again without crutches.

He described the prosthesis as something he neither sees nor feels: "It is what I have and it has gone well." The implant even withstood a fall that fractured Pierre's wrist and ankle while the tibia implant remained intact, according to surgeon Rubén Pérez-Mañanes.

Weight and strength

The metamaterial prosthesis weighs approximately 300 grams, according to both surgeon Rubén Pérez and UPM researcher Luis Saucedo-Mora, compared with close to a kilogram for a conventional prosthesis (Saucedo-Mora) or up to two kilograms for a solid conventional implant (Pérez). One source reported the weight as 150 grams without attribution. Pérez stated that the implant can withstand over 500 kilograms in simulation models, while conventional implants support between 100 and 150 kilograms.

We have achieved that it weighs 300 grams and that, according to simulation models, it supports up to 500 kilos.

Broader applications

The Gregorio Marañón, Spain's national reference centre (CSUR) for sarcomas of the locomotor system in adults and children, treats about 600 sarcoma patients per year. In Spain, approximately 2,600 new soft-tissue sarcoma cases and 400 bone sarcoma cases are diagnosed annually, representing an incidence of about 5 to 6 cases per 100,000 inhabitants. Two more patients have already been operated on with similar technology, and the team is working to extend the approach to additional sarcoma cases. The hospital has also applied 3D planning and virtual reality tools to other complex cases, including a 7-year-old boy named Manuel with a femoral sarcoma, where surgeons used 3D-printed tissue models and augmented-reality holograms to plan and guide the operation.