Spontaneous Fractures of a Modern Modular Uncemented Femoral Stem.

Overview

BACKGROUND: Femoral stem fracture following total hip arthroplasty is an uncommon event that requires immediate revision surgery. QUESTIONS/PURPOSES: 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. METHODS: 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. RESULTS: Fracture surfaces exhibited characteristics consistent with a fatigue fracture mechanism. Sixteen MAUDE reports claimed stem fracture or breakage of EMPERION™ stems. CONCLUSION: 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.