Spontaneous Fractures of a Modern Modular Uncemented Femoral Stem

HSS J. 2016 Oct;12(3):250-254. doi: 10.1007/s11420-016-9510-z. Epub 2016 Jun 21.

Abstract

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.

Keywords: modular stem; stem fracture; total hip arthroplasty; uncemented.