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Short stem total hip arthroplasty (SHA) has gained increasing popularity as it conserves bone stock and is supposed to allow revision with a conventional stem. However, no study has evaluated whether the revision of a SHA with a standard total hip arthroplasty (THA) stem provides sufficient primary stability to allow osseous integration. A neck preserving SHA (Metha) and a standard THA (CLS) stem were implanted into six composite femurs respectively and dynamically loaded (300–1700 N, 1 Hz). Primary stability was evaluated by three dimensional-micromotions (3D micro motion) at five points of the interface. Then, a revision scenario was created by removing the SHA and using the same CLS stem as a revision implant (CLS-revision group), with subsequent evaluation of the 3D micro motion according to the primary CLS stem. The 3D micro motion pattern significantly differed in the primary situation between the short and the standard stem. The highest 3D micro motion were registered proximally for the Metha and distally for the CLS stem. Revising the Metha with a CLS stem revealed a bony defect at the calcar. However, the 3D micro motion of the CLS-revision group were not significant higher compared to those of the primary CLS stem. Our results show, that SHA (Metha) and standard THA (CLS) provide a good primary stability, however with different pattern of anchorage. The CLS stem reached a similar stability in this revision scenario as the CLS in the primary situation, wherefore it can be assumed that in uncomplicated revisions the Metha short stem can safely be revised with a CLS standard stem.

A radiographic study of a singular type of threaded cup, revised due to aseptic loosening, was performed with Einzel-Bild-Roentgen-Analyse (EBRA) to detect eventual risk factors and patterns of loosening. Fifty-three cups of 50 patients were revised. Forty-two cups could be measured with EBRA. No cup had obvious osteolysis, 33 cups demonstrated early migration, and all cups had migrated at the time of revision. Twenty-eight of the cups had a change of inclination and 21 of anteversion, respectively. The mean migration was 1.9 mm in the medial and 7.9 mm in the cranial direction; the mean wear rate was 0.2 mm/year. Cups with early migration had a higher migration rate. All male patients had early migration; medially placed cups had less migration than the other cups. Wear was not significantly affected by the migration of the implant. No cup had a complete radiolucent line, and the only radiographic sign for loosening was the change of position of the cup. Medial placement showed less migration in case of loosening. Regular radiographic follow-up is recommended for the examined implant, and the cup should not be used in the future.