Mechanical evaluation of a carbonated apatite cement in the fixation of unstable intertrochanteric fractures

Acta Orthop Scand. 2002 Apr;73(2):157-64. doi: 10.1080/000164702753671731.

Abstract

We created three-part unstable intertrochanteric fractures in 6 pairs of aged, osteopenic, human, cadaveric femora. Fractures were reduced and fixed with a Dynamic Hip Screw (DHS) (Synthes, Paoli, PA). Two test groups were evaluated: 1. Fixation with DHS, and 2. Fixation with a DHS and calcium phosphate bone cement (Norian SRS (Skeletal Repair System)) augmentation of the fracture line and posteromedial calcar region of the proximal femur. Each femur was loaded to 1,650 N (2.5 body weight) for 10,000 cycles to simulate postoperative load transmission across the fracture construct during normal gait. The load was further increased successively by one body weight for another 10,000 cycles until failure. We evaluated fixation by measuring the amount of sliding of the lag screw of the DHS (shortening) and stiffness of the overall fracture construct (stability). SRS cement-augmented specimens had less shortening (1 mm versus 17 mm) and twice the initial construct stiffness compared to control specimens.

MeSH terms

  • Adult
  • Apatites / therapeutic use*
  • Bone Cements / therapeutic use*
  • Bone Screws
  • Fracture Fixation, Internal*
  • Hip Fractures / complications
  • Hip Fractures / physiopathology*
  • Hip Fractures / surgery*
  • Humans
  • Joint Instability / etiology
  • Joint Instability / physiopathology
  • Recovery of Function / physiology
  • Stress, Mechanical*
  • Weight-Bearing / physiology

Substances

  • Apatites
  • Bone Cements
  • carboapatite