Materials retrieval and analysis - Orthopaedic Biomaterials in Research and Practice - page 398

making such studies more difficult and rare. As indicated in earlier chap-
ters, we have only very poor estimates of true in vivo corrosion and wear
rates, even of long-used materials. With the exception of some isolated
experiments with instrumented implants, we know almost nothing about
the true stresses and strains in functioning devices or the effects of these
conditions on growth, repair, and remodeling of surrounding tissues.
If we were able to study successful devices, functioning in patients, at
routine removal and at patient death, in a systematic way, many of these
unknowns could be resolved. The result would certainly be a better selec-
tion of materials and devices for specific patients as well as better pro-
spective design of improved devices. In addition, there would be greater
confidence in performance predictions of current and new designs.
Ultimately, the study of devices and their materials, regardless of
whether they are successful or not, needs to consider all patient, sur-
gical, and device/material factors. This approach considers the perfor-
mance on a “whole case” basis. This means that the device, its history,
the patient's history, the clinical and surgical details, and all engineering
and clinical test data may contribute to the outcomes. It is the intent that
the retrieval studies described here will provide a systematic approach to
better understanding device performance.
Immediate aims of device retrieval and analysis studies
The systematic record developed by a uniform, mandatory (within an
institution) device retrieval and analysis (DRA) program serves three
more immediate aims:
1. Careful study of a device removed from a patient for cause may
contribute directly to the patient's ongoing medical care. Some of
the immediate outcomes may be helpful in choosing the material
and design of a replacement device and resolving differential diag-
noses on the basis of local inflammation or infection.
2. The completed record of the retrieval and examination of the
device represent an “expert” study of the device aspects of the
patient's treatment. Thus, they represent a unique resource avail-
able in the event of legal action associated with failure of the
device to function or with medical treatment associated with its
insertion or removal.
3. Device failures that are of a serious nature, are life threatening,
or are associated with a mortality must be reported to the FDA
through the Manufacturer and User Facility Device Experience
(MAUDE) system.* A well-developed mandatory DRA system
and record provide a mechanism for timely reporting while pro-
tecting the rights of all parties.
* The MAUDE database represents reports of adverse events involving medical devices.
The data consist of voluntary reports since June 1993, user facility reports since 1991,
distributor reports since 1993, and manufacturer reports since August 1996.