title: Effects of various anchoring components and loading conditions on primary stability of acetabular revision implant.
abstract: OBJECTIVE
  In revision total hip arthroplasty, until today, orthopaedic surgeons are missing evidence-based guidelines on cementless acetabular cup fixation.
  
  
  METHODS
  5 finite element models were generated featuring the following anchorage strategies: 1 short peg, 1 long peg, 2 long screws, 3 short screws and zero anchoring components for reference. The micromotions at the implant-bone interface were analyzed for 3 different loadcases, "Seated leg-crossing" (joint force 940 N, impingement force 750 N), "Normal gait" (joint force 1820 N), and "Stumbling" (joint force 4520 N).
  
  
  RESULTS
  Within the same loadcase, percentages of interface area below 28 µm are nearly identical in all anchorage strategies. The average percentage of interface area below 28 µm is 31% for "Seated leg-crossing", 17% for "Normal gait", and 11% for "Stumbling". Maximal von Mises stresses in "Normal gait", for example, reach 12 MPa in the short peg, 48 MPa in the long peg, 15 MPa in 1 of the 2 long screws, and 85 MPa in 1 of the 3 short screws.
  
  
  CONCLUSIONS
  Common orthopaedic practice, to use peg or screw fixation alternatively according to bone availability or other clinical aspects, can be confirmed. The short peg may be a good alternative to the long peg with regard to the preservation of bone stock. However, the current study implies that the extent of potential osseointegration depends less on the chosen anchorage strategy but strongly on postoperative loading conditions. Total hip patients should be instructed on adequate postoperative activities.
authors: Department of Orthopaedic, Trauma and Plastic Surgery, Laboratory for Biomechanics, Leipzig University, Leipzig - Germany.
authors: Christian
authors: C
authors: Voigt
authors: Department of Orthopaedic, Trauma and Plastic Surgery, Laboratory for Biomechanics, Leipzig University, Leipzig - Germany.
authors: Andreas
authors: A
authors: Schaller
authors: Faculty of Mechanical and Power Engineering, Leipzig University of Applied Sciences (HTWK), Leipzig - Germany.
authors: Carsten
authors: C
authors: Klöhn
authors: Department of Orthopaedic, Trauma and Plastic Surgery, Laboratory for Biomechanics, Leipzig University, Leipzig - Germany.
authors: Roger
authors: R
authors: Scholz
mesh_terms: D000077:Acetabulum / Q000601:surgery; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation*; D001863:Bone Screws; D020342:Finite Element Analysis; D006622:Hip Prosthesis; D006801:Humans; D016348:Osseointegration; D011474:Prosthesis Design; D016059:Range of Motion, Articular; D012086:Reoperation; D016474:Weight-Bearing