The watchdog in the United States for medical devices is the esteemed government agency known as the Food and Drug Administration (FDA). The FDA, however, is flummoxed about how to handle 3-D printing of medical devices. It's not that the FDA has lost its smarts, it's just that the 3-D printing technology has spread so quickly, they are behind the curve.

In summer of 2014, the FDA approved the first 3-D-printed medical device for use in the United States. However, the agency never mentions the manufacturing technology in its approval letter. Instead, the device was reviewed as a 501(k) approval.

All Oxford Performance Materials, the maker of the OsteoFab Patient-Specific Cranial Device did was to prove it was "substantially equivalent" to similar devices on the market. Before this device was approved, 3-D-printed medical devices were approved on a patient-by-patient basis.

For now, the FDA plans to continue approval of 3-D-printed medical devices as if they were devices manufactured using more traditional methods. Susan Laine, an FDA spokesperson, told LiveScience at the end of the summer of 2013 the following:

"We evaluate all devices, including any that utilize 3-D printing technology, for safety and effectiveness, and appropriate benefit and risk determination, regardless of the manufacturing technologies used. In some cases, we may require manufacturers to provide us with additional data, based on the complexity of the device."

In late 2013, the FDA announced that it planned to publish approved guidance for this new technology by 2015. It appears that the regulators have an initial favorable reaction to the 3-D printing, which they prefer to call additive manufacturing.

At this point, it seems unlikely that the agency will make its self-imposed 2015 deadline for approval guidance. They are still in the stage of collecting data from all stakeholders.

During an interview with Plastics Today, Steven K. Pollack, Ph.D., director of the FDA's Office of Science and Engineering Laboratories, talked about the FDA's challenges in regulating 3-D printing in the medical device field.

"3-D-printing techniques have different technical considerations than standard manufacturing, with each type of 3-D printing technology having its own specific set of considerations," Pollack said. "However, devices constructed using 3-D-printing technology are subject to the same regulatory review standards as devices constructed using traditional manufacturing practices."

For now, manufacturers can continue to apply under the existing 501(k) approval system. Changes in processes move through the FDA at a snail's pace, but once approved, new processes come into being fast. Makers of 3-D medical devices must stay informed to stay in business.