title: Mechanical evaluation of hip cement spacer reinforcement with stainless steel Kirschner wires, titanium and carbon rods, and stainless steel mesh.
abstract: BACKGROUND
  In two-stage treatments for infections after total hip arthroplasty, antibiotic-loaded cement spacers help treat the infection by antibiotic elution and prevent contraction. However, such spacers are weak and may fracture while awaiting replacement, impairing functionality. We evaluated whether a Kirschner wire (K-wire) mounted into the spacer reinforced its strength along with the effects of the reinforcing material, position, and intensity.
  
  
  METHODS
  Spacers without reinforcing materials constituted the control group. As reinforcing materials, stainless steel K-wires (diameters 3 and 6 mm), titanium alloy and carbon fibers (diameter 3.175 mm), and stainless steel meshes (inner and outer diameters, 6 and 9 mm, respectively) were inserted into the spacer mold before filling with cement. The spacers complied with ISO 7206-4; a compressive load was applied using a testing machine with a velocity of 25.4 mm/min, and the maximum load was recorded. We used 1-3 K-wires positioned on the medial side, lateral side, neck only, and stem only and tested 3 specimens for each condition.
  
  
  RESULTS
  The control group withstood the highest load. Stainless steel was the strongest material; 3-mm K-wires in the neck and lateral side withstood a higher load. The computed tomography (CT) imaging revealed a cavity between the K-wires and cement. When K-wires were inserted along the whole length, despite cement fractures, continuity was maintained because of the reinforcing materials.
  
  
  CONCLUSIONS
  It is difficult to improve the reinforcing strength of spacers using K-wires; however, K-wires prevented dislocation of cement spacer fragments, which can help prevent contraction and facilitate spacer removal during replacement.
authors.affiliation: Department of Orthopaedic Surgery, Faculty of Medicine, Oita University, Oita, 879-5593, Japan, nobuhiro@oita-u.ac.jp.
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Kaku
authors.forename: Tomonori
authors.initials: T
authors.lastname: Tabata
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tsumura
mesh_terms: D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects; D001843:Bone Cements; D001864:Bone Wires; D002244:Carbon; D019245:Compressive Strength; D006622:Hip Prosthesis / Q000009:adverse effects; D006801:Humans; D008422:Materials Testing; D011474:Prosthesis Design; D011475:Prosthesis Failure; D016459:Prosthesis-Related Infections / Q000209:etiology / Q000601:surgery*; D012086:Reoperation / Q000295:instrumentation; D013193:Stainless Steel; D013314:Stress, Mechanical; D013526:Surgical Mesh; D014025:Titanium
chemical_list: D001843:Bone Cements; D013193:Stainless Steel; D002244:Carbon; D014025:Titanium