Alexis Dang, MD, is an orthopaedic surgeon and associate professor of orthopaedic surgery at UC San Francisco. A founding member of the UCSF Center for Applied 3D+ Technologies, he has integrated 3D printing into his research and clinical practice for nearly a decade. In this interview, Dang talks about the benefits to patients and surgeons and the first time he used a 3D-printed, patient-specific model for surgical planning. Dang also provides insight on the future of 3D-printed implants.
Q: What is the benefit of using 3D-printed models in clinical practice?
A: The big-picture benefit for orthopaedic surgery is that surgeons as well as patients are better prepared for the upcoming surgery when 3D-printed, patient-specific models are created prior to surgery. We take the patient’s CT or MRI scan and convert that data into 3D data, which we then print. For orthopaedic surgery, we usually print models of the bones but we’ve also made 3D prints of blood vessels, tumor masses and nerves depending upon the complexity of the surgery. Having a 3D print is invaluable for surgical planning and reducing OR time. It’s also very helpful for educating patients about why they need surgery or, in some cases, why they may not.
Q: In your experience, what are some cases in which 3D prints were especially useful?
A: For fracture cases that require CT scans, including ankle, knee and distal radius fractures, 3D prints provide a very good sense of what’s going on.
In a complex shoulder arthroplasty when there’s concern about glenoid bone stock, a 3D print helps determine if there's adequate bone to attach an implant. If there is not, we use a different implant design or a custom implant.
For cases in which the bones are healed but crooked – malunions – the bones need to be rebroken and set in the correct position to restore the anatomy. 3D prints allow us to practice osteotomies for these procedures.
Q: Is there a patient case you can share?
A: Yes – my first case using a 3D-printed surgical model. A 28-year-old veteran who had suffered a broken clavicle as a teenager developed shoulder pain over the years. He felt like his shoulders hunched forward and he couldn’t stretch them back, which interfered with his work as a professional photographer. We determined his pain was likely due to malunion of his clavicle.
We made a 3D print of the CT scan of his malunited bone as well as a mirror image of his healthy clavicle. We used this model to plan an intraoperative osteotomy and hardware placement. It would have been incredibly difficult to figure this out during surgery. The procedure was a success and the patient recovered well with improved function and range of motion. Presurgical planning with the 3D print made this a relatively routine surgery.
Q: Can you elaborate on the use of 3D printing for patient education?
A: In one situation I used a 3D print of a patient’s fractured ankle to show him how he would likely benefit the most from an ankle fusion rather than an ankle open reduction and internal fixation.
We also use 3D prints for nonoperative cases. For example, I see a lot of cases of shoulder fractures and shoulder instability. For a scapula fracture at the glenoid rim, there are certain criteria that require surgery and certain criteria that do not require surgery, so we print out that injury show it to the patient. If the fracture fragment is fairly small, the patient will likely do fine healing without surgery. Using the 3D-printed model, I can explain to the patient why the best choice is nonoperative treatment and the patient can visualize what’s going on.
Q: What other UCSF departments use 3D printing?
A: At UCSF, we started in orthopaedic surgery and have since expanded the 3D printing service throughout the medical center. The other high-volume users are tumor surgeons, pediatric cardiac surgeons, neurosurgeons and plastic surgeons. In the past, 3D models were purchased from medical device companies. Our ability to 3D-print in-house at UCSF has been a game changer.
For UCSF as a teaching institution, 3D printing is valuable for training and surgical simulations that more closely replicate what residents are going to encounter as clinicians.
Q: What are some of the most promising future applications for orthopaedic surgery?
A: I think there’s an opportunity to 3D-print implants in titanium or other metals that fit our patients geometrically better. These implants don’t necessarily need to be patient specific. Just having more size options would be very beneficial for patients. Also, it should soon be possible to print implants with porosity and latticing that are geometrically very similar to bone and more flexible as opposed to a solid block of metal. These applications have promise for improving the lives of patients.
UCSF Medical Center is recognized as “high performing,” the highest ranking, in hip fracture, hip replacement, knee replacement and back surgery (spinal fusion) by U.S. News & World Report’s 2021-2022 Best Hospitals survey.
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