Early failure of a non-cemented femoral stem after minimal-invasive total hip arthroplasty: cause analysis and classification.

In this paper, we present a 77-year-old female patient with an early failure of a non-cemented femoral stem 6 months after implantation. We evaluate possible reasons for the implant failure in our case against the literature. Risk factors for stem failure include a BMI >30, varus implantation, a high femoral canal cortex ratio, and a small implant. It should be distinguished between modular and non-modular stems as well as cemented and non-cemented. Early failure would be <1 year postoperatively, late failure >1 year postoperatively. A classification of stem failure differentiating time and cause is suggested as this seems to be missing in the literature.