The increasing number of THA revisions in the United States: Why is it happening?
Kevin J. Bozic, MD, MBA, answers 4 Questions about the reasons for revision hip arthroplasty.
Over the years one of the better ways to improve our surgical results has been to review our failures. It appears we are seeing increasing numbers of total hip revisions in the United States. For this month’s featured interview, I have asked Kevin J. Bozic, MD, MBA, to share with us some of the experience and insight gained by looking at our failed primary total hip replacements.
Douglas W. Jackson, MD
Chief Medical Editor
Douglas W. Jackson, MD: What is the estimated number of revision total hip arthroplasties being performed in the United States and what are some of the explanations for the increased numbers?
Kevin J. Bozic, MD, MBA: According to the Nationwide Inpatient Sample (NIS) database, which is a stratified, statistically valid survey of inpatient hospital visits in the United States, there are almost 40,000 revision total hip arthroplasties (THAs) performed annually in the United States. This number has steadily increased over the past 20 years, and is expected to continue to increase over the next several decades. This increase is primarily due to an increased incidence of primary THA procedures, an expansion of the indications for THA to include younger, more active patients, and limitations in implant longevity.
Jackson: What are some of the more common causes that would require revision hip arthroplasty surgery?
Bozic: Between October 2005 and December 2006, the most common causes of revision THA in the United States (see chart) were hip instability (22.5%), mechanical loosening (19.7%) and infection (14.8%). This represents a change from previous studies which have implicated aseptic loosening, bearing surface wear and osteolysis as the primary indications for revision THA. These findings suggest that although implant factors play an important role in THA failure, there are also patient factors, eg, age, obesity, malnutrition, and other medical co-morbidities, and surgeon factors, eg, experience, years in practice, surgical technique, procedure volumes, and hospital affiliation, which clearly influence THA outcomes and revision rates.
Jackson: What are the average hospital charges for a revision hip arthroplasty?
Bozic: The average hospital charges associated with revision THA procedures varies based on the type of revision surgery performed. According to the NIS, the average hospital charge among all revision THA procedures in the United States is roughly $54,600. However, this can vary from a low of $42,200 for an isolated acetabular and femoral head exchange to a high of $69,400 for an arthrotomy/removal of prosthesis procedure.
Jackson: What should our readers know about the new coding for the various hip arthroplasty procedural codes?
Bozic: The United States is currently the only developed country in the world without a total joint arthroplasty (TJA) registry. In the absence of a national registry, administrative databases offer valuable insights into the cause of TJA failure and types of TJA procedures being performed in the United States.
Administrative databases have the advantage of extremely large sample sizes which reflect inclusion of patients and procedures from a wide variety of geographic and hospital settings. This enhances the external validity and generalizability of the findings from health services research studies which incorporate data from administrative databases. However, the value of administrative databases for use in health services research is dependent on the accuracy and clinical relevance of the administrative codes.
Prior to 2005, administrative databases were of limited use in evaluating the cause of failure and type of revision THA procedures performed, since there was a single ICD-9 diagnosis code (996.4, mechanical complication of an internal orthopedic device) used to describe most THA failures and a single, all-inclusive ICD-9 procedure code (81.54, revision THA) used to describe all THA revisions.
In 2005, researchers representing the American Academy of Orthopaedic Surgeons (AAOS) and the American Association of Hip and Knee Surgeons (AAHKS) made a proposal to the Center for Medicare & Medicaid Services and the National Center for Health Statistics to create a series of more specific, clinically relevant ICD-9 diagnosis and procedure codes related to revision TJA. The motivations for the requested coding changes were:
- to facilitate quality improvement through a better understanding of the mechanisms of failure following TJA;
- to provide more accurate and descriptive data inputs for a joint replacement registry in the United States; and
- to provide more precise and relevant economic data to enable payers to predict resource utilization related to specific diagnoses and types of revision TJA procedures.
Although these new administrative codes were adopted and introduced in October 2005, it is unclear how commonly and appropriately they are being used by surgeons and administrative coding personnel, and therefore what value they will provide in terms of elucidating the mechanisms of failure and the types of revision THA procedures are performed in the United States. Although, according to our study, the rate of adoption of the new revision THA-related ICD-9-CM diagnosis and procedure codes by surgeons and hospital administrative coding personnel is relatively high, continued education of clinicians and administrative coding personnel is needed to improve the accuracy and validity of these codes, and their value in elucidating the causes of THA failure.
For more information:
- Kevin J. Bozic, MD, MBA, is associate professor and vice chair of the Department of Orthopaedic Surgery at the University of California, San Francisco and Core Faculty, Philip R. Lee Institute for Health Policy Studies. He can be reached at 500 Parnassus Ave. MU-320W, San Francisco, CA 94143; 415-476-3900; e-mail: BozicK@orthosurg.ucsf.edu.
- Bozic KJ, Kurtz SM, Lau E, et al. The epidemiology of revision total hip arthroplasty in the United States. J Bone Joint Surg (Am). 2009;91: 128-133.
- Ulrich SD, Seyler TM, Bennet D, et al. Total hip arthroplasties: what are the reasons for revision? Int Orthop. 2008;32: 597-604.