Short Stem Total Hip Arthroplasty in Patients With DORR Type C Femur Configuration: Measured Subsidence

In hip arthroplasty, short stems represent a key advancement in the field of bone-preserving surgical techniques. Due to the relatively rapid establishment of short stems, the data situation is lagging behind in some areas, resulting in uncertainties in the indication in certain cases. One of these cases is proximal femurs with a Dorr type C configuration. This bone characteristic complicates the implantation of stems due to a thin cortical bone and a wide femoral canal and has been shown to lead to an increased complication rate. The aim of this study is to evaluate the clinical and radiological outcome of short stem implantation in Dorr type C femur. The study will include all patients who underwent implantation of the "Optimys" short stem from Mathys between January 1, 2018 and December 31, 2020 at the hospital Ordensklinikum Linz Barmherzige Schwestern. In addition, patients must have a type C femur according to Dorr. During a follow-up period of at least two years, the Harris Hip Score, the UCLA Activity-level Scale and the Singh Index are used to evaluate the clinical course. Radiological evaluation is carried out using pre- and postoperative X-rays, which together enable an EBRA-FCA.

A statement on the migration behavior of the cementless implanted short stem in Dorr type C femur is expected. To date, it has been controversially discussed whether a Dorr type C femur provides enough structural support to achieve good primary stability for a cementless implanted short stem with tapered-wedge design. If this were not the case, the excessive migration behavior would lead to subsidence and subsequently to aseptic stem loosening and even complete failure of the prosthesis.