Retrospective multi-centre study on head adapters in partial revision hip arthroplasty

Background: Instability and dislocation after total hip arthroplasty (THA) is a common reason for revision surgery. THA head-neck adapters promise the reconstruction of optimal femoral offset and leg length in revision THA (rTHA) while retaining stable implants. The aim of this retrospective multi-centre study is to report on the results achieved with the use of head adapters in partial rTHA, to avoid the instability of the implant. Methods: 55 cases of partial rTHA performed between February 2015 and April 2017 in 3 different hospitals using the Bioball Head Adapter (BHA) (Bioball Merete, Medical GmbH, Berlin, Germany) were retrospectively recorded. All patients were evaluated from a radiological point of view at an average follow-up of 3.5 years. Failure was defined as re-revision surgery for any cause as well as a subjective feeling of instability of the joint. Results: One failure was registered in an extreme case and radiological findings show no suggestive signs of radiolucencies or loosening and therefore all implants have been considered stable. Conclusions: Despite some limitations of this retrospective study and according to the relevant literature, our data confirms that BHA is a safe system that allows the flexibility to restore femoral offset and version, to adjust leg length, to minimise instability, to avoid unnecessary removal of otherwise well-fixed components thus improving tribology and reducing the risk of taper junction issues without major complications in partial rTHA.