Abstract

Background: Early postoperative acetabular component shifts are often missed due to inadequate x-rays. After initiating a policy at our practice to obtain standardized pelvic radiographs immediately after hip resurfacing surgery, we began noticing asymptomatic, spontaneous early cup shifts. With careful x-ray analysis, we discovered that the incidence of shift was 0.9% (12 of 1285 cases).

Methods: Our primary study purpose was to identify and evaluate risk factors for cup shift, with a secondary aim to determine if cup shifts affected clinical outcomes. We retrospectively collected radiographic data from our clinical database to determine cup shifts. We further analyzed follow-up data from this database to evaluate clinical outcomes.

Results: All cups became radiographically stable after the initial shift. Approximately 90% of these cases had excellent clinical outcomes, while 2 cases (9.5% of shifts) were revised: one early for extreme malposition, and the other late for impingement pain. In 95% of shifted cases, the acetabular component moved into a more horizontal position. Mean absolute value of shift was 17° (range 10° - 36°). There were no cases of abnormal metal ion levels, even in the case that steepened and exceeded the RAIL guideline. When we compared cases before and after the new wedge-fit protocol, we noticed a drop in the incidence of cup shifts from 0.9% to 0.2% (p = 0.004).

Conclusions: Cup shifts often occur early and are asymptomatic, making them difficult to diagnose. With a series of early x-rays, we discovered rate of shift at our practice was 0.9%. With a new wedge-fit method of preparing acetabula, rate of early cup shift decreased significantly to 0.2%.

Keywords: Previously; Unrecognized; Arthroplasty

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Citation

Citation: Dani Gaillard-Campbell MS and Thomas P Gross. "Early Cup Shifts: A Previously Unrecognized Phenomenon in Hip Arthroplasty".Acta Scientific Orthopaedics 3.1 (2020): 15-21.

Copyright

Copyright: © 2020 Dani Gaillard-Campbell MS and Thomas P Gross. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.