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AAOS Now

Published 5/1/2008
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Jennie McKee

Study shows surgical skills are transferable

Hemiarthroplasty by high-volume THA surgeons yields better outcomes

Hemiarthroplasty and total hip arthroplasty (THA) are two different procedures. But a study presented at the 75th AAOS Annual Meeting seems to indicate that physicians who perform a high number of THAs can transfer those skills to hemiarthroplasty, and their patients may have better results than patients whose surgeons performed fewer THAs.

In their study, James Ames, MD; Jon Lurie, MD, MS; Ivan Tomek, MD, FRCSC; Wei-Ping Zhou, MS; and Kenneth Koval, MD, found that hemiarthroplasty patients treated by surgeons who perform a high volume of THAs had lower rates of mortality, dislocation, and superficial infection than patients whose surgeons didn’t perform as many THAs.

“To our knowledge,” wrote the researchers, “no previous report in the orthopaedic literature shows that the volume of one surgical procedure has an effect on outcomes following a different surgical procedure. There is certainly no previous report of the effect of surgical volume of THA and revision total hip arthroscopy (THR) on outcomes for patients following hemiarthroplasty for femoral neck fracture.”

Surgeons and patients
Researchers identified a cohort of 115,352 Medicare beneficiaries from 1994-1995 who had been treated with hemiarthroplasty for femoral neck fracture. Using claims data and the unique provider identification number assigned to each surgeon, researchers established the following classifications based on the number of procedures performed:

  • no volume (0 THA/THR per year)
  • low volume (1-10 procedures; 1-5 THA/THR per year)
  • mid-volume (11-49 procedures; 6-24 THA/THR per year)
  • high volume (> 50 procedures; >25 THA/THR per year)

Most hemiarthroplasty patients (67.1 percent) were operated on by surgeons who perform 0-5 THA/THR per year. A small fraction (3.8 percent) of the patients’ surgeons performed >25 THA/THR per year.

Findings
Compared to patients whose surgeons were in the “no volume” group, patients operated on by “high volume” arthroplasty surgeons had significantly lower mortality rates at 30 days (5.6 percent vs. 6.5 percent), 90 days (10.8 percent vs. 12.8 percent), and 1 year (22.3 percent vs. 23.8 percent) (
Fig. 1). The mortality difference persisted at 5 years (60.4 percent vs. 61.7 percent), but was no longer statistically significant. At each time interval, mortality rates decreased across each of the groups as surgical volume of THA/THR increased.

Dislocation rates were consistently lower among patients whose surgeons were in the “high volume” group, and were statistically significant at 1 year (Fig. 2). Within the three groups of surgeons with any THA/THR experience, the rate of dislocation trended down as arthroplasty experience increased.

At all time intervals, the rate of superficial infection following hemiarthroplasty was lowest among patients whose surgeons were in the “high volume” group (Fig. 3). Again, within the three groups of patients operated on by surgeons with any THA/THR experience, the superficial infection rates decreased as arthroplasty experience increased.

Revision surgery rates were statistically higher in the “high volume” group when compared to the “no volume” group. A plausible explanation for why the surgeons in the “high volume” group performed a higher rate of revision surgeries, said the researchers, may be the surgeons’ higher level of surveillance for radiographic abnormalities such as acetabular erosion and femoral stem loosening.

Disclosure information for the authors can be found at www.aaos.org/disclosure

Jennie McKee is a staff writer for AAOS Now. She can be reached at mckee@aaos.org