Though numerous academic hospitals around the world are steadily adopting 3D printed models and implants to deal with unusual or life-threatening cases, Chinese surgeons are really pushing the 3D printing envelope when it comes to surgical applications. Just last month, they even used a 4D printed tracheal stent to save the life of a patient. But these applications are also inspiring new insights into conventional surgical procedures, as is illustrated by a two recent surgeries in the Southwest Hospital of the Third Military Medical University in China. Two patients with severe ankle joint deformities were helped with 3D printed bone grafts, which not only made treatment more precise than when relying on conventional implants, but also significantly decreased the surgery’s impact a patient’s health.
Bone defects and joint diseases are becoming increasingly common in society, and can be caused by the severe trauma of car accidents, for instance, but also by bone tumors and degenerative old age diseases. In these cases, the malformed bones and joints make movement very painful. “The exact position of bone defects, in for instance the foot and ankle joints, can make walking especially painful for patients. It also impedes their ability to walk normally,” said Professor Yang Liu, Director of the Joint Surgery department of Southwest Hospital and leader of this 3D printing research initiative. The professor added that about 10 percent of all orthopedic and joint surgery patients have bone defects in some shape or form.
Right now, there are already two treatment methods available for these complications. One is to remove bone tissue from other parts of the body and transplant it to the problem area. But this has the significant disadvantage of being limited by the amount of available transplantable material. The body only has so much bone, and removing too much from other locations comes with significant risks. The other method is also undesirable, as it relies on bone transplants from other patients or cadavers. This unfortunately brings an additional rejection risk to the table. These transplanted bone structures are also typically not as hard as they should be.
But 3D printing can offer a third alternative, as shown by the 3D printed bone grafts that were developed at the Southwest Hospital of the Third Military Medical University. These have already been successfully transplanted into two patients. The two female patients were 60 and 57 years old, respectively. One of them suffered from serious arthritis and bone defects in both ankle joints. Back in 2014, she already received a bone transplant for her left foot, but that means there’s a serious lack of available bone material now that the right foot is also troubling her. She has therefore refused conventional treatment. The other patient suffered from a complex bone deformity and an uneven surface caused by a previous correction.
Both unusual cases thus needed a custom solution. To achieve the desired therapeutic effect, surgeon and Associate Professor of the Joint Surgery department Duan XiaoJun first gathered CT scan data from both patients. Together with his surgical team, that data was used to develop a precise digital model through extensive modifications and design improvements. That final model was sent miles and miles away to the Shaanxi Institute for Materials Engineering. There, the models were used to 3D print custom implants and accompanying steel plate fixtures.
As Director Yang Liu explained, these 3D printed grafts are far easier to work with. “The ankle implant fixation made with 3D printing technology is tailor-made, solves the problem of bone defects in patients, and also deals with the difficulties involved in fixture resetting. Such customized technology can greatly improve the likelihood of surgical success,” he said. “As a medical application, 3D printing technology requires close collaboration between clinicians, 3D graphics designers, and material engineers.”
The director further argued that the 3D printed grafts, made from an allogeneic bone implant material, have certain other advantages over conventional treatment methods. Firstly, the material is available in much, much larger quantities than a patient’s own bone tissue, which is unique. Secondly, the fixation components were custom made to fit the patient’s own bone structure. Unlike standardized artificial joint fixtures, they fit perfectly and reduce the risk of recurring bone defects and subsequent surgeries.
Finally, the material exhibits the exact hardness properties of human joints, making it a perfect substitute for the real thing. The surgeons therefore hope that these two successful operations will further promote the use of 3D printing in bone and joint defect surgeries. When compared to conventional treatment methods, the Chinese surgeons say, their new procedure is far more precise and less impactful on the patients.