title: Effect of Osteotomy Position and Tibial Plateau Rotation on the Tensile Force Required for Failure of the Canine Quadriceps Mechanism.
abstract: OBJECTIVE
  To measure the tensile force required for failure of the quadriceps mechanism with different tibial tuberosity widths and different degrees of rotation of the tibial plateau after radial osteotomy of the proximal tibia.
  
  
  METHODS
  Ex vivo study, randomized unblocked design
  
  
  METHODS
  Thirty-five hind limbs from 18 adult Greyhound cadavers.
  
  
  METHODS
  Part 1 (15 limbs)--The center of rotation of the proximal tibial radial osteotomy was advanced craniodistally, progressively reducing absolute tibial tuberosity width (ATTW) for 5 different widths. Part 2 (21 limbs)-Tibial plateau rotation was performed at a set ATTW. Rotation was varied as a function of tibial tuberosity position with rotation proximal, level with, or distal to the tuberosity. All 35 limbs were tested with force applied via the quadriceps mechanism until construct failure occurred.
  
  
  RESULTS
  All but 2 limbs failed by fracture of the tibial tuberosity. The tensile force required for failure of the quadriceps mechanism increased linearly with increasing ATTW. Significantly less force (P = .016) was required for failure of the quadriceps mechanism when the rotation of the tibial plateau was distal to the level of the patella tendon (mean 1,877 N) compared to when it was above the level of the patella tendon (mean 2,533 N). Rotation of the tibial plateau distal to the level of the patella tendon insertion point resulted in fracture at the base of the tibial tuberosity, level with the tibial plateau buttress.
  
  
  CONCLUSIONS
  The overwhelming mode of failure of the quadriceps mechanism was by tibial tuberosity fracture, thus this was the weakest part of the construct. Reducing the tibial tuberosity width and rotation of the tibial plateau segment below the patella tendon insertion decreased the force required for tibial tuberosity fracture. These results support the idea of a safe point with the tibial plateau segment providing buttress to the tibial tuberosity.
authors.affiliation: Langford Veterinary Services, University of Bristol, Bristol, United Kingdom.
authors.forename: Katie
authors.initials: K
authors.lastname: Hamilton
authors.forename: John
authors.initials: J
authors.lastname: Tarlton
authors.affiliation: Langford Veterinary Services, University of Bristol, Bristol, United Kingdom.
authors.forename: Kevin
authors.initials: K
authors.lastname: Parsons
authors.affiliation: Matrix Biology Group, School of Clinical Veterinary Science, Bristol, United Kingdom.
authors.forename: Mike
authors.initials: M
authors.lastname: Toscano
authors.affiliation: Langford Veterinary Services, University of Bristol, Bristol, United Kingdom.
authors.forename: Neil
authors.initials: N
authors.lastname: Burton
mesh_terms: D000818:Animals; D002102:Cadaver; D004285:Dogs / Q000601:surgery*; D007719:Knee Joint / Q000502:physiology*; D010027:Osteotomy / Q000379:methods / Q000662:veterinary*; D052097:Quadriceps Muscle / Q000502:physiology*; D012399:Rotation; D013718:Tensile Strength; D013978:Tibial Fractures / Q000601:surgery*