Geographic variations in the rates of operative procedures involving the shoulder, including total shoulder replacement, humeral head replacement, and rotator cuff repair

Background: Although geographic variations in the rates of orthopaedic proc edures have been well documented, considerable controversy remains regardin g the factors that drive these variations, particularly the role of the ava ilability of orthopaedic surgeons. Moreover, little attention has been spec ifically focused on variations in the rates of commonly performed shoulder procedures, Methods: The current study documents state-to-state variations in the rates of total shoulder replacement, humeral head replacement, and rotator cuff repair and examines factors that might account for these variations. The re gional incidences of these three procedures,were analyzed with use of the H ealth Care Financing Administration Medicare database (MEDPAR, 1992), The r ates were age-adjusted, and variations were measured with use of high:low r atios, variation coefficients, and systematic components of variation. Pote ntial causes of variation were analyzed with use of Spearman and partial co rrelations as well as with Poisson regression. Results: Rates for the three procedures that were studied varied from one s tate to another by as much as tenfold. Humeral head replacement had the low est rate of variation according to all three measures. All three procedures were performed less often in states that were more densely populated. With the numbers available for study, no consistent, significant relationship w as found between the density of orthopaedists and shoulder surgeons and the rates of any procedure. Conclusions: The striking variations that were noted for these commonly per formed procedures showed that there is a clear need for well designed clini cal research to further define the factors that account for the variations and to examine the effectiveness and appropriate indications for the proced ures.