Implant Retrieval Research

The Mary and Fred Trump Institute for Implant Retrieval Analysis

HSS currently has the largest implant retrieval program, containing over 25,000 retrieved total joint implants. Since its start in 1977, the retrieval system had provided a means to evaluate the performance of orthopaedic implants by advancing our understanding of the wear and damage seen on retrieved total joint replacements and the underlying mechanisms that are responsible for the in vivo damage. With the large number of retrievals obtained from revision surgeries performed at HSS, we can evaluate the effect of implant design changes as well as work with clinicians to answer research questions that revolve around implant performance.

The implant retrieval system relies on the cooperation of staff in the Hospital’s operating rooms and in the Department of Pathology. After initial examination by pathologists, the retrieved implants arrive in the Mary and Fred Trump Institute within the Department of Biomechanics, where they for are cleaned, boxed, and cataloged into a database. The system allows access by investigators researching the performance of total joint replacements under the auspices of the Hospital’s Institutional Review Board, which oversees research involving human subjects.

Implants are stored in labeled boxes and bins so that they can be easily located for use in research projects.

Implant Retrieval Statistics

The retrieval collection spans implants used to replace nearly every joint in the skeletal system. The collection continues to grow, with about 1000 new implants collected each year.

Implants are collected from nearly all of the joints of the body.

The retrieval system continues to grow with about a thousand new Implants added each year.

Performance Analysis

Many techniques are available for analyzing retrieved implants with the goal of understanding their performance while they were implanted in patients. Performance can be examined based on the wear and deformation that the implant components underwent while implanted and how the local environment in the body may have changed or degraded the properties of the materials from which the implants were fabricated. Techniques include:

• Stereo light microscopy and digital microscopy
• Scanning electron microscopy (SEM) with back-scattered electron and energy dispersive x-ray analyses (EDAX)
• Laser and Computed Tomography (CT) scanning
• Fourier transform infrared microscopy (FTIR)
• Crosslink density measurements for ultrahigh molecular weight polyethylene
• Profilometry

Design and Development of New Implants

Implant analyses performed in the Mary and Fred Trump Institute are often integrated into the design and development efforts at HSS. These efforts combine the innovative ideas of the Hospital’s orthopaedic surgeons and biomechanical engineers, who collaborate to continually improve the performance of total joint replacements. Implant retrieval analysis is a vital part of the design cycle, by which evidence found on retrieved implants stimulate ideas to improve performance, ideas that can then be tested in computer simulations before being incorporated into new designs. The new designs are then developed in cooperation with orthopaedic implant manufacturers who license the new design technology from HSS and make it available to the orthopaedic community. As new designs are introduced, implants of that design begin to be retrieved during revision surgery, and the design cycle starts all over again. Such a cycle can take a decade, with only rational design changes sure to improve performance being adopted into new designs.