Spontaneous Fractures of a Modern Modular Uncemented Femoral Stem.

Abstract

Femoral stem fracture following total hip arthroplasty is an uncommon event that requires immediate revision surgery. We report on four patients who experienced stem fractures of one design and a review of the US Food and Drug Administration adverse event reports on this design. Fracture surfaces of four EMPERION™ (Smith & Nephew, Memphis, TN) femoral stems were analyzed under optical and scanning electron microscopy. A search of the FDA's Manufacturer and User Facility Device Experience (MAUDE) that reports on all EMPERION™ adverse events was completed. Fracture surfaces exhibited characteristics consistent with a fatigue fracture mechanism. Sixteen MAUDE reports claimed stem fracture or breakage of EMPERION™ stems. The four cases of EMPERION™ stem fractures were likely driven by small stem diameter, high offset, and high patient weight. Modular stem-sleeve femoral systems are susceptible to fatigue failure under high stress and should only be used in appropriate patients, whom are not considered obese.