Bone sarcomas are commonly located close to the knee, often requiring resection of the joint. Although the knee joint can be replaced, function is often significantly impaired. In some cases, however, the tumor is just far enough from the joint that a “joint sparing” resection can be performed. This requires precise cutting of the bone for a safe margin around the tumor. It also requires precisely matched reconstruction of the missing bone. For both of these challenges, 3D printing is rapidly becoming a useful tool.
In this technique, the surgery is first virtually planned on a computer using the patient’s CT and MRI images. Using computer-aided design (CAD), a cutting guide specific to the patient’s tumor is designed and 3D printed. This is sterilized and placed snugly against the patient’s bone to guide a precise Fig 2: Using 3D printing, metal implants with complex geometries can be made to match resected bones and joints.
Metal implants can also be 3D printed. This allows for a complex shaped implant that exactly fits the bone resection (Fig 2). The outside of the prosthesis can even be printed with a porous surface that allows for ligament attachment and bone ingrowth. With “traditional” implants, such an exact fit was difficult to achieve and porous surfaces had to be applied onto the metal in a separate, time-consuming process.
These techniques are just now entering wider use and will need longer-term follow up to measure their durability and outcomes. But they are already opening up promising surgical options for patients with bone sarcomas.