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
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
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: