title: Strut grafts in revision hip arthroplasty faced with femoral bone defects: an experimental analysis.
abstract: OBJECTIVE
  In total hip arthroplasty fixation of revision stems can be demanding due to femoral bone loss. Strut grafts are often used for bone augmentation and stabilization of the newly inserted prosthesis. The aim of this study was to assess the effect of strut grafts on primary stability under various stem fixation conditions.
  
  
  METHODS
  Two different revision stems (cylindrical and conical shape) were implanted into synthetic femora. Following a semicircular transfemoral osteotomy, three deficient femoral bearings were simulated (bony lid reattached with cable wires; weakened lid reattached with cable wires; strut grafts placed to the weakened lid with cable wires). Relative micro-movements were measured between prostheses and bones due to an axial moment applied to the stems.
  
  
  RESULTS
  Relative movements correlated to the stem shape. The cylindrical stem showed higher movements increasing significantly with a weakened bony lid and portrayed a slight decrease of movements with strut graft application. No unequivocal influence of the weakened lid could be detected for the conical implant. Strut graft application did not show an additional stabilizing effect.
  
  
  CONCLUSIONS
  The primary stability of the cylindrical fixation concept decreases with impaired fixation conditions of the femur. A clear restabilizing effect with strut grafts could not be proven. A decrease of primary stability due to the impaired bone could not be observed for the conical stem shape. Additionally, strut grafts do not enhance fixation for this stem shape. We conclude that surgeons should not rely on a stabilizing effect of strut grafts in revision hip surgery.
authors.affiliation: Laboratory of Biomechanics and Implant Research, Department of Orthopaedics, Traumatology and Paraplegiology, University Hospital Heidelberg, Schlierbacher Landstrasse 200a, 69118, Heidelberg, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Kinkel
authors.forename: Marc N
authors.initials: MN
authors.lastname: Thomsen
authors.forename: Jan
authors.initials: J
authors.lastname: Nadorf
authors.forename: Christian
authors.initials: C
authors.lastname: Heisel
authors.forename: Michael C
authors.initials: MC
authors.lastname: Tanner
authors.forename: Eike
authors.initials: E
authors.lastname: Jakubowitz
mesh_terms: D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000379:methods*; D001862:Bone Resorption / Q000209:etiology / Q000601:surgery*; D016025:Bone Transplantation; D005269:Femur / Q000601:surgery*; D006622:Hip Prosthesis; D006801:Humans; D011474:Prosthesis Design; D012086:Reoperation