With the latest technological advancements in 3D printing, highly complex bone reconstruction is now a reality.
Orthopedic specialists for years have been developing the technology to model and then create reconstructions of bone defects (often due to tumors or trauma). However, lead times, even up to a decade ago, were too long. It is only in the last few years that lead times have been reduced-allowing reconstruction to become feasible not just for complex cases, but for time-sensitive cases as well. With the latest 3D printing technology, turnaround time can be as fast as six weeks-a significant leaps from the previous six-plus-month lead time. This means new surgery options, more precise bone reconstructions, along with the real possibility of a higher quality of life for patients post-op.
Take, for example, one recent case involving chondrosarcoma of the pelvis, a type of bone cancer that is resistant to chemotherapy and radiation therapy. The portion of the bone with the cancerous tumor had to be removed, along with a margin of normal tissue. Long bone reconstruction is fairly straightforward because the arm and leg bones are essentially a cylinder shape. However, in this particular case, the cancerous tumor was in the pelvis and involved the socket portion that holds the hip joint. Reconstructing this area is already a tricky procedure, but in this situation, due to a lack of treatment options, a fast turnaround was also essential.
Dr. Ron Hugate, an orthopedic oncologist at Panorama Orthopedics and Spine Center, has had experience with complex cases such as this one. He recognized that this patient would be an ideal candidate for the 3D printing technology. The plan was to first remove cancer, and then reconstruct the pelvis and restore the patient’s functions.
Moving Beyond Traditional Solutions
“The cancerous tumor was in a difficult location-a lot of important structures are in the pelvis,” said Dr. Hugate. “Due to the complex shape of the pelvis, the implant could not be easily manufactured using traditional techniques”
Other issues with traditional techniques included limitations in shapes, sizes and surface treatments. “A newer trend in orthopedics involves using a solid implant with a porous structure-almost like a honeycomb-on the surface,” said Dr. Hugate. “This allows the bone and the soft tissues to actually grow into the implant”
Six-Week Lead Time
Dr. Hugate partnered with a team of engineers to create a personalized implant design. This was accomplished using patient imaging data: A CT scan was used to assess the bone topography, and an MRI to determine the extent of the tumor. Each imaging study was then merged together and converted into a 3D model.
Using the model, Dr. Hugate met with the engineers and specified design parameters for the implant (hip socket size and position, location of porous material, etc.). They then developed a surgical plan with the use of patient-specific models, guides and templates.
The implant is an exact replica of the removed bone, printed from titanium, a very strong, lightweight and metabolically inert metal, so there are no issues with corrosion or fatigue. The surface material qualities allow soft tissues and bone to grow into it, making it ideal for this scenario.
Along with the hip replacement, the surgery took under three hours. “We were able to preserve all of the major muscles that control walking,” said Dr. Hugate.
Dr. Hugate has also performed a reconstruction of an entire hemipelvis (half of a pelvis) using 3D printing technology. Both cases have gone well so far, which bodes well for future cases.