3D-printed titanium implants may successfully treat foot, ankle pathologies
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Use of patient-specific 3D-printed titanium implants may provide successful treatment of a variety of bone defects and deformities in difficult to treat foot and ankle and lower extremity pathologies, according to published results.
Samuel B. Adams Jr., MD, of Duke University Medical Center, and colleagues performed an arthrodesis of the tibia to the hindfoot using a custom 3D-printed titanium cage (4WEB Medical) and an intramedullary rod on a 46-year-old female patient with a distal tibia fracture with substantial distal-third tibia bone loss. Researchers collected plain radiographs approximately every 6 to 12 weeks and CT scans every 6 months, as well as the foot and ankle ability measure and American Orthopaedic Foot and Ankle Society ankle-hindfoot score preoperatively and at recent follow-up of 60 months after surgery.
Results showed successful bone incorporation of the talus, calcaneus and tibia on plain radiograph and CT scan. Researchers found the patient had a foot and ankle ability measure activities of daily living subscale score of 79 and a sports subscale score of 46. Functionality during both activities of daily living and sports-related activities were rated as 85% of what it was prior to injury, according to results. Researchers noted the patient had an AOFAS ankle-hindfoot scale score of 71, mainly due to the loss of sagittal and hindfoot motion, and the patient reported mild, occasional pain.
“Until the introduction of 3D printing into medicine, there were no reliable treatment options for large bone defects. This case report demonstrates that custom, 3D printed implants can be used to successfully treat these defects with longevity,” Adams told Healio Orthopedics. “However, research is still needed to improve bone ingrowth, prevent infection and optimize strength in these custom implants.” – by Casey Tingle
Disclosure: Adams reports no relevant financial disclosures.
Perspective
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Ettore Vulcano, MD
The main difficulty we have in orthopedic surgery is regenerating bone. After a fracture like the one presented in this case, there is inevitably, a loss of bone substance from the trauma itself. If you have two or three relatively large fragments of bone, you can reduce and stabilize the fracture with plate and screws, but when the fracture is comminuted you’re working with dust. These patients therefore require more complex procedures to reconstruct that bone defect.
One option is to shorten the patient’s leg to close down that gap. This will result in a limb length discrepancy that can either be addressed with a shoe lift, or surgically with a limb lengthening procedure. However, the latter is a technically challenging surgery that not all orthopedic surgeons are comfortable performing. Another option is to bridge the large bone defect by using bone graft. The difficulty with this method is that the larger the bone defect, the less likely it is that the graft will heal and incorporate. A 2 to 3 cm bone defect usually heals in under 60% of patients with lower extremity bone loss. With defects as big as the one presented in this case, then the likelihood of bone healing, at least in my experience, is slim. The cage represents a unique and creative way to try to make up for that defect. It is made with a titanium structure that mimics the rigidity of bone therefore allowing for bone to gradually grow over that cage to make up for the defect. In other words, the cage acts as a scaffold for new bone to grow over.
These cages have been used for several years now. There are other case series and reports that have described using this technique, with variable outcomes. As the bone defect size increases, the effectiveness of the cage decreases. However, the cages represent an extra weapon that orthopedic surgeons should keep in their armamentarium. Although the cage alone may not always be the answer to a problem, when combined with other techniques it may allow the treating physicians to address bone defects that would have otherwise required a significant shortening of the leg or even an amputation.Mount Sinai West
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