It seems not a day goes by without some impressive milestone being reached in medical 3D printing. November 21 was no different, and that day’s breakthrough involved Zhang Jingui, an 84-year-old Chinese man, who was fitted with a 3D printed knee joint made from tantalum, a hard silver-gray metal.
Carried out by doctors from the First Hospital Affiliated to Southwest Hospital, the procedure involved filling a large bone defect with the 3D printed implant.
In a general sense, knee surgery of this kind isn’t rare: a whopping 62 per cent of people in their fifties are afflicted with some sort of arthritis, and 2.2 to 3.5 per cent of Chinese people have reported suffering from knee osteoarthritis.
These high numbers mean that Southwest Hospital alone performs around 400 knee replacement surgeries per year.
“Total knee replacement is the most effective way to treat late-stage knee diseases, as it can reduce the pain for patients and improve their quality of life,” commented Yang Liu, a professor and head of surgery at Southwest Hospital and member of the National Key Research and Development Program of China.
Traditionally, knee replacement procedures have involved the use of cement implants or bone grafts, both of which can cause problems that affect the lifespan and stability of the implant.
What’s exciting about this latest procedure is that 3D printing was used to create the patient-specific implant, and that tantalum—a hard metal that is less commonly used than titanium—was used to fabricate the medical device.
Usually, the high melting point of tantalum (3,020°C) makes it impractical to use on metal 3D printers. However, with specialist equipment, Southwest Hospital was able to 3D print Zhang Jingui’s knee implant in the material.
One of the secrets to making it 3D printable was designing a porous 3D model, which was also tailor-made for the patient’s particular knee problem using visual data from CT scans. Using the scan data, staff were able to digitally reconstruct the defective knee before virtually simulating the implantation procedure.
The 3D printing itself was carried out in collaboration with a local 3D printing bureau.
According to the surgeons involved, the 3D printed tantalum implant is more compact and stable than a titanium implant would have been, factors that simplified the surgical procedure and reduced the risk of complication.
Tantalum also offers better biocompatibility and improved bone ingrowth, meaning the patient can hopefully look forward to better freedom of movement and a longer life for his new knee.
Despite being 84 years old, the history-making patient has already been able to complete some basic leg movements, and could be up and walking out of the hospital in just four to five days.
