Causes of Total Hip Replacement Failure and Types of Revision Procedures
As more and more adults in the United States get total hip replacements, the number of revision (second) surgeries has also gone up. Experts say the reasons for this may be three-fold: patients are younger, many patients of all ages are more active, and implants aren't designed to last long enough.
With more and more revision total hip replacements, Medicare and Medicaid have had to develop diagnosis and procedure codes for surgeons to use when billing for related services. The diagnosis codes now reflect possible causes of hip revision.
Some of the more common reasons revision surgery is needed include loosening or dislocation of the implant, fracture of the bone or prosthetic device, or other mechanical complication(s). Surface wear of the implant and breakdown of the bone around the implant are two other diagnosis codes available.
At the same time, all revision operations are not the same. The type of procedure done depends on the cause of the problem. In some cases, both parts of the implant (acetabular or socket side and femoral or round, ball at the top of the thigh bone) must be removed and replaced.
Sometimes just one of those components needs revision. If the surgeon has to remove part or all of the implant, it may be necessary to place a spacer to hold the joint in place until a new joint can be put in place. Some implants have a separate plastic liner that fits between the shell or acetabular cup and the femoral head. If this part gets worn or broken, it has to be removed. Each of these surgeries has a code of its own.
Researchers can now use these new codes to track what's going on. How often are revisions needed? Who needs them? And why? Identifying common causes of failure and types of revisions will guide future research, especially designing better, more long-lasting implants. At the same time, tracking the type of revisions needed will help shape health-care policy.
Insurers and agencies such as Medicare who often pay for these procedures want to know if more resources will be needed in the future to cover the costs of hip revision procedures. Surgeons will be using this information to predict which patients are good candidates for total hip replacement.
This particular study looked at the data collected from over 51,000 total hip revision procedures performed in a single year (2005-2006). That was the first full year after the new codes were published. Information about each patient included age, sex, diagnosis, reason for implant failure, cost of the revision, and length of hospital stay. They also kept track of who was paying for the surgery and where the patient came from (geographical location).
All of this information came from a national database called the Nationwide Inpatient Sample. Each hospital enters this information about patients treated and discharged from their facility. After analyzing the data available on patients having a hip revision following a total hip replacement, the researchers looked for trends in diagnosis, frequency of each revision procedure, and patient characteristics.
Here's what they found:
Looking at types of revisions yielded some additional information. For example, most of the revisions (44 per cent) involved removing the entire implant. The number of patients who just had one side removed and replaced was fairly equal between the acetabular and the femoral components. Most revision procedures were done in urban nonteaching (large) hospitals.
Hospitalization was shorter and costs were less for patients just having one piece removed and replaced compared with patients having a complete removal of the implant. Geographic differences were seen in the south where the largest number of revisions took place.
The authors hope that as more surgeons use the new diagnostic and procedure codes, research on joint replacement revisions will be easier and faster. This is important because the U.S. is the only developed country without a national joint replacement registry to gather this type of information. Long-term studies using these codes will give valuable insight into ways to reduce hip joint replacement failures.
Kevin J. Bozic, MD, MBA, et al. The Epidemiology of Revision Total Hip Arthroplasty in the United States. In The Journal of Bone & Joint Surgery. January 2009. Vol. 91A. No. 1. Pp. 128-133.