title: Biomechanical evaluation of acetabular cup implantation in cementless total hip arthroplasty.
abstract: OBJECTIVE
  To report biomechanical properties of the Biologic Fixation System (BFX) acetabular cup impacted into a normal canine pelvis and to compare the effect of implant positioned to and beyond the medial acetabular wall.
  
  
  METHODS
  In vitro cadaveric study.
  
  
  METHODS
  Hemipelves of mature, large-breed dogs (n=6).
  
  
  METHODS
  For each dog, 1 hemipelvis was reamed to the depth of the acetabular wall (group A) and 1 was reamed an additional 6 mm after penetration of the medial cortex of the acetabulum (group B). The hemipelves were implanted with acetabular cups and loaded in compression through a matching femoral prosthetic component until failure. Specimen stiffness, and failure displacement, load, and energy were determined from load and displacement data and results between groups compared with a paired t-test.
  
  
  RESULTS
  Mean failure load was greater in group A (3812 ± 391 N) than group B (2924 ± 316 N; P<.014). No other differences (P>.05) were observed between groups. Bone fracture (n=5) and cup displacement (1) occurred in group A whereas in group B there were 3 fractures and 3 cup displacements.
  
  
  CONCLUSIONS
  Although medial placement of the BFX cup affected compressive failure loads, failure loads for both groups exceeded normal physiologic loads.
  
  
  CONCLUSIONS
  Medial positioning of the acetabular cup does not appear to compromise acetabular implant-pelvic stability under normal physiologic loads. Because arthroplasty candidates often have abnormal acetabular architecture, mechanical properties of the cup placed in acetabula without a dorsal rim should be investigated.
authors: Veterinary Specialty Hospital, San Diego, CA, USA.
authors: Kate A
authors: KA
authors: Margalit
authors: Kei
authors: K
authors: Hayashi
authors: Josh
authors: J
authors: Jackson
authors: Sun Young
authors: SY
authors: Kim
authors: Tanya C
authors: TC
authors: Garcia
authors: K Tomo
authors: KT
authors: Wiggans
authors: Sean
authors: S
authors: Aiken
authors: Susan M
authors: SM
authors: Stover
mesh_terms: D000077:Acetabulum / Q000601:surgery*; D000818:Animals; D019644:Arthroplasty, Replacement, Hip / Q000379:methods / Q000662:veterinary*; D001696:Biomechanical Phenomena; D001843:Bone Cements; D004283:Dog Diseases / Q000601:surgery*; D004285:Dogs; D050723:Fractures, Bone / Q000601:surgery / Q000662:veterinary*; D006622:Hip Prosthesis / Q000662:veterinary; D016268:Internal Fixators / Q000662:veterinary*; D008422:Materials Testing / Q000662:veterinary; D013314:Stress, Mechanical
chemical_list: D001843:Bone Cements