Click here to read the Cover Story, “Preoperative planning with 3-D printing may increase efficiency in total joint procedures.”
Three-dimensional printing has been available for several decades. However, the enthusiasm for use in hip and knee arthroplasties has only greatly increased in the past several years. While 3-D printing provides a host of potential advantages in lower extremity arthroplasty, it must be balanced with several known disadvantages.
At the current time, 3-D printing provides unique and distinct advantages in three scenarios: 1) complex primary procedures that have significant bony deformities secondary to prior trauma or congenital dysplasia; 2) revision procedures with massive bone loss (ie, pelvic discontinuities); and 3) tumor reconstructions where large portions of the pelvis, including both columns and the acetabulum proper, are often removed en bloc. In these three particular instances, 3-D printing may allow for optimization of biologic-friendly ingrowth surfaces, as well as optimization of implant positioning to minimize dislocations and damage to surrounding neurovascular structures.
On the other hand, surgeons must continue to be aware that primary and revision hip and knee arthroplasties remain soft-tissue procedures. Current iterations of 3-D printing do not assist with this integral portion of the procedure. In addition, and as with any innovation, current costs remain prohibitive to wide-spread adoption of such technology in primary procedures. Vigorous and thorough laboratory assessments must be completed prior to wide-spread utilization.
Matthew P. Abdel, MD, is a senior associate consultant in the Department of Orthopedic Surgery and associate professor of orthopedic surgery at the Mayo Clinic College of Medicine, Rochester, Minn.
Disclosure: Abdel has stock options with Imagen Technologies.
Improving surgeon accuracy
[Three-dimensional] printing of plastic “custom jigs” can enable the surgeon to precisely reproduce a preoperative plan at the time of surgery. This has tremendous potential utility for many fields in orthopedics, with one notable example being in the resection of a bone sarcoma. With traditional techniques (eg, standard X-ray fluoroscopy), the surgeon’s ability to precisely reproduce a preoperative resection plan has been shown to be inaccurate. Our group has shown that 3-D custom jig technology in this context can dramatically improve the surgeon’s accuracy and this can potentially allow the surgeon to resect sarcomas with confident margins, but also spare uninvolved nearby structures, such as joint surfaces. In fact, if the defect left behind precisely matches the preoperative plan, such custom jig technology can potentially allow the surgeon to implant a custom prefabricated implant that has been designed to fit exactly into the skeletal defect.
Jig technology as it stands can and already is being used to improve a surgeon’s accuracy in the resection of bone sarcomas and it can be cost effective compared to much more expensive computer navigation systems or robotics. However, it typically still can produce errors on the order of 2 mm to 3 mm. While this can be “buffered” into sarcoma resections, this seemingly small error may be enough to invalidate its use for custom prefabricated implants. To expand its utility for this, it is likely that jig technology needs further improvement. For example, our group has recently worked on adding simple physical extensions to the plastic jig and combining it with inexpensive basic intraoperative cameras to help with more precise placement of the jig on the bone.
If these promising improvements pan out, 3-D printing technology may allow for practical use of custom prefabricated implants in tumor surgery, and possibly in other orthopedic fields, which could indeed be of great utility to the orthopedic surgeon.
Kahn FA, et al. Clin Orthop Relat Res. 2013;doi:10.1007/s11999-012-2769-6.
Fazel A. Khan, MD, FAAOS, is the chief of orthopedic oncology at the Joint Replacement Center and assistant professor in the Department of Orthopedic Surgery at Stony Brook University Medical Center, Stony Brook, NY.
Disclosure: Khan reports no relevant financial disclosures.