Abstract
Introduction
The design and manufacture of patient specific implants at Hospital for Special Surgery (HSS) was started in the fall of 1976. The first implant designed and manufactured was an extra large total knee. This effort expanded to include all arthroplasty devices including hips, knees, shoulders and elbows along with fracture fixation devices. In the 1980s, the hospital was designing and manufacturing over 100 custom implants per year. This reduced significantly in the 1990s due to the introduction of modular total knee replacements. In 1996, HSS ceased manufacture due to rising costs and a greater regulatory burden. However, implants are still designed at HSS with manufacturing outsourced to commercial companies. Since 1976, the hospital has designed over 2500 implants.
Patient Population
Currently, we design implants for ∼30 cases per year, hips, knees, and upper extremity devices (mainly elbow). We've seen an increase in acetabular revision cases over the last few years and now design about 10 revision acetabular components each year.
Regulatory Challenges
Patient specific implants can be provided under a variety of regulatory pathways. Some have received 510(k) clearance as the manufacturer has provided a matrix of sizes; if the device fits within the matrix, the device can be supplied commercially.
For devices that fall outside of the 510(k) pathway, the process is more complex. The 2012 FDA Safety and Innovation Act attempts to clarify the ambiguous nature of the prior statute in which the number of custom implants allowed of a specific type was unclear, setting the limit to 5 units per year of a particular device type. However, such a low number has led to rationing by the device manufacturers and even cessation of manufacturing of custom implants by one of the major companies.
Another option available for obtaining patient specific implants is the Compassionate Use process. This process has been used, for example, when a patient needs a replacement of a part for a device that is not approved for use in the United States. The surgeon can request an exemption from FDA to use the part. To obtain this exemption, the surgeon must provide to FDA a justification letter explaining why using this device is in the best interests of the patient, a letter from a second surgeon who agrees with this conclusion, a letter from the implant company agreeing to manufacture the device, IRB approval from the institution where the device will be implanted, and consent from the patient. Though gathering this information can be time consuming, once the application is submitted, FDA has rapidly responded in providing exemptions (in less than two weeks).
Conclusion
Even with the increase in modular components and the variety of devices in the commercial market, the need still exists for patient specific implants at HSS. The regulatory environment creates additional challenges to obtaining these devices. In spite of these challenges, we are able to provide the devices required for our patients.
