title: Locked plating of distal femur fractures leads to inconsistent and asymmetric callus formation.
abstract: OBJECTIVE
  Locked plating constructs may be too stiff to reliably promote secondary bone healing. This study used a novel imaging technique to quantify periosteal callus formation of distal femur fractures stabilized with locking plates. It investigated the effects of cortex-to-plate distance, bridging span, and implant material on periosteal callus formation.
  
  
  METHODS
  Retrospective cohort study.
  
  
  METHODS
  One Level I and one Level II trauma center.
  
  
  METHODS
  Sixty-four consecutive patients with distal femur fractures (AO types 32A, 33A-C) stabilized with periarticular locking plates.
  
  
  METHODS
  Osteosynthesis using indirect reduction and bridge plating with periarticular locking plates.
  
  
  METHODS
  Periosteal callus size on lateral and anteroposterior radiographs.
  
  
  RESULTS
  Callus size varied from 0 to 650 mm2. Deficient callus (20 mm2 or less) formed in 52%, 47%, and 37% of fractures at 6, 12, and 24 weeks postsurgery, respectively. Callus formation was asymmetric, whereby the medial cortex had on average 64% more callus (P=0.001) than the anterior or posterior cortices. A longer bridge span correlated minimally with an increased callus size at Week 6 (P=0.02), but no correlation was found at Weeks 12 and 24 postsurgery. Compared with stainless steel plates, titanium plates had 76%, 71%, and 56% more callus at Week 6 (P=0.04), Week 12 (P=0.03), and Week 24 (P=0.09), respectively.
  
  
  CONCLUSIONS
  Stabilization of distal femur fractures with periarticular locking plates can cause inconsistent and asymmetric formation of periosteal callus. A larger bridge span only minimally improves callus formation. The more flexible titanium plates enhanced callus formation compared with stainless steel plates.
authors.affiliation: Biomechanics Laboratory, Legacy Research & Technology Center, Portland, OR 97215, USA.
authors.forename: Trevor J
authors.initials: TJ
authors.lastname: Lujan
authors.forename: Chris E
authors.initials: CE
authors.lastname: Henderson
authors.forename: Steven M
authors.initials: SM
authors.lastname: Madey
authors.forename: Dan C
authors.initials: DC
authors.lastname: Fitzpatrick
authors.forename: J Lawrence
authors.initials: JL
authors.lastname: Marsh
authors.forename: Michael
authors.initials: M
authors.lastname: Bottlang
mesh_terms: D001860:Bone Plates; D002146:Bony Callus / Q000000981:diagnostic imaging / Q000502:physiology*; D015331:Cohort Studies; D005260:Female; D005264:Femoral Fractures / Q000000981:diagnostic imaging / Q000601:surgery*; D005593:Fracture Fixation, Internal / Q000295:instrumentation / Q000379:methods*; D017102:Fracture Healing / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011859:Radiography; D012189:Retrospective Studies; D013193:Stainless Steel; D014025:Titanium
chemical_list: D013193:Stainless Steel; D014025:Titanium