title: Better primary stability with porous titanium particles than with bone particles in cemented impaction grafting: an in vitro study in synthetic acetabula.
abstract: OBJECTIVE
  Impaction bone grafting creates new bone stock after hip joint replacement. Utilizing a synthetic bone substitute instead of bone might increase primary stability and is not associated with graft shortage and pathogen transmission. This study compares the initial stability of a graft layer of porous titanium particles (TiP), cancellous bone particles, and a 1:2 bone-titanium mix in synthetic cemented acetabular reconstructions. Displacement was measured by radiostereometric analysis after cyclic loading (1 Hz, maximum stress 2.5 MPa). Shear stress resistance was quantified by a lever out test of the cup. Cement penetration was quantified from cross-sections.
  
  
  RESULTS
  Titanium reconstructions showed less residual displacement (0.13 ± 0.13 mm) than pure bone particle reconstructions (0.57 ± 0.18 mm) (p < 0.01). Titanium reconstructions were also more resistant to shear stress (p < 0.001). The bone-titanium mix showed intermediate results. Cement penetrated deeper into the bone particle graft layers (4.8 ± 0.7) than into the titanium graft layers (3.8 ± 0.5 mm) (p < 0.02).
  
  
  CONCLUSIONS
  Cemented acetabular revision reconstructions with porous TiP show better initial stability despite less cement penetration than bone particle reconstructions. Realistic preclinical in vivo testing should explore the hypothesis that porous TiP offer a safe alternative to the current gold standard of bone grafts.
authors: Department of Orthopaedics, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
authors: Lucas H B
authors: LH
authors: Walschot
authors: René
authors: R
authors: Aquarius
authors: B Willem
authors: BW
authors: Schreurs
authors: Pieter
authors: P
authors: Buma
authors: Nico
authors: N
authors: Verdonschot
mesh_terms: D000077:Acetabulum; D018786:Bone Substitutes / Q000737:chemistry*; D006622:Hip Prosthesis; D006801:Humans; D008422:Materials Testing; D016062:Porosity; D033081:Shear Strength; D013314:Stress, Mechanical; D014025:Titanium / Q000737:chemistry*
chemical_list: D018786:Bone Substitutes; D014025:Titanium
keywords: arthroplasty; in vitro; porous; stability; titanium