title: Spontaneous Fractures of a Modern Modular Uncemented Femoral Stem.
abstract: BACKGROUND
  Femoral stem fracture following total hip arthroplasty is an uncommon event that requires immediate revision surgery.
  
  
  OBJECTIVE
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Biomechanics, Hospital for Special Surgery, 535 East 70th Street, New York, NY 10021 USA.
authors.forename: Chelsea N
authors.initials: CN
authors.lastname: Koch
authors.affiliation: Orthopaedic and Trauma Surgery, Hospital Clinico San Carlos, Madrid, 28040 Spain.
authors.forename: Laura Serrano
authors.initials: LS
authors.lastname: Mateo
authors.affiliation: University Orthopaedic Associates, Somerset, NJ 08873 USA.
authors.forename: Stephen
authors.initials: S
authors.lastname: Kayiaros
authors.affiliation: Orthopaedic Associates of Manhasset, P.C., General Orthopedics, Great Neck, NY 11021 USA.
authors.forename: Kevin A
authors.initials: KA
authors.lastname: Cassidy
authors.affiliation: Adult Reconstruction and Joint Replacement Division, Department of Orthopaedic Surgery, Hospital for Special Surgery, New York, NY 10021 USA.
authors.forename: Seth A
authors.initials: SA
authors.lastname: Jerabek
authors.affiliation: Adult Reconstruction and Joint Replacement Division, Department of Orthopaedic Surgery, Hospital for Special Surgery, New York, NY 10021 USA.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Gonzalez Della Valle
keywords: modular stem; stem fracture; total hip arthroplasty; uncemented