An antibiotic-releasing hip stem would undergo a 510k pathway as it classifies as a Class II combination device of a drug and device-based product. It does not sustain life so it may not require a PMA, but it is an implantable device that intimately interacts with human tissue, so at the very least, pre-clinical and clinical data is required. It’s primary mode of action would be to act as a mechanical stabilizer within a patient’s skeletal muscular system while secondarily preventing infection to the healing bone.

The claim should be stated in a way that is not to direct but not too ambiguous. One such claim should state: “This combination device will enhance hip function following hip failure while reducing the likelihood of infection at the implant site.” According to lecture, the FDA is very sensitive to the wording used when introducing a medical device to the regulatory pathways, therefore it’s important to use terms like “enhance” and “reduce” rather than “restore” and “eliminate” since the more definitive you are, the more you will have to prove in your studies.

An online search shows a sheep model as ideal for the aseptic loosening of a hip prosthesis because sheep display a similar extent of biochemical changes that resemble those found in human patients, such as bone resorption and membrane formation at the hip stem interface (1). A regular hip stem replacement is already an FDA-approved marketed device, so an IDE is not required since it can be proven to have substantial equivalence to predicate hip stems currently in the market. An antibiotic-releasing hip stem on the other hand is different because it is actively releasing a compound into the blood, a dual effect that most likely requires more studies that fall under an IDE.

(1) El-Warrak A, Olmstead M, Schneider R et al (2004b) An experimental animal model of aseptic loosening of hip prostheses in sheep to study early biochemical changes at the interface membrane. BMC Musculoskelet Disord 5:7