title: Ex vivo pathomechanics of the canine Pond-Nuki model.
abstract: BACKGROUND
  Transection of the canine cranial cruciate ligament (CCL) is a well-established osteoarthritis (OA) model. The effect of CCL loss on contact pressure and joint alignment has not been quantified for stifle loading in standing. The purposes of the study were to measure femorotibial contact areas and stresses and joint alignment following transection of the CCL in an ex vivo model. We hypothesized that transection of the CCL would lead to abnormal kinematics, as well as alterations in contact mechanics of the femorotibial joint.
  
  
  RESULTS
  Eight canine hindlimbs were tested in a servo-hydraulic materials testing machine using a custom made femoral jig. Contact area and pressure measurements, and femorotibial rotations and translations were measured in the normal and the CCL-deficient stifle in both standing and deep flexion angles. We found that at standing angle, transection of the CCL caused cranial translation and internal rotation of the tibia with a concurrent caudal shift of the contact area, an increase in peak pressure and a decrease in contact area. These changes were not noted in deep flexion. At standing, loss of CCL caused a redistribution of the joint pressure, with the caudal region of the compartment being overloaded and the rest of the joint being underloaded.
  
  
  CONCLUSIONS
  In the Pond-Nuki model alterations in joint alignment are correlated with shifting of the contact points to infrequently loaded areas of the tibial plateau. The results of this study suggest that this cadaveric Pond-Nuki model simulates the biomechanical changes previously reported in the in-vivo Pond-Nuki model.
authors.affiliation: Comparative Orthopaedics Biomechanics Laboratory, Department of Small Animal Clinical Sciences, University of Florida, Gainesville, Florida, United States of America.
authors.forename: Antonio
authors.initials: A
authors.lastname: Pozzi
authors.affiliation: Comparative Orthopaedics Biomechanics Laboratory, Department of Small Animal Clinical Sciences, University of Florida, Gainesville, Florida, United States of America.
authors.forename: Stanley E
authors.initials: SE
authors.lastname: Kim
authors.affiliation: Comparative Orthopaedics Biomechanics Laboratory, Department of Orthopaedics and Rehabilitation, University of Florida, Gainesville, Florida, United States of America.
authors.forename: Bryan P
authors.initials: BP
authors.lastname: Conrad
authors.affiliation: Comparative Orthopaedics Biomechanics Laboratory, Department of Orthopaedics and Rehabilitation, University of Florida, Gainesville, Florida, United States of America.
authors.forename: MaryBeth
authors.initials: M
authors.lastname: Horodyski
authors.affiliation: Comparative Orthopaedics Biomechanics Laboratory, Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, Florida, United States of America.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Banks
mesh_terms: D000818:Animals; D016118:Anterior Cruciate Ligament / Q000502:physiology*; D001696:Biomechanical Phenomena; D004285:Dogs; D010003:Osteoarthritis / Q000503:physiopathology