Effect of Tibial Plateau Leveling Osteotomy on Patellar Tendon Angle: A Radiographic Cadaveric Study


  • Presented in part at the Annual Veterinary Orthopaedic Society Conference, Steamboat, CO, March 2009.

Corresponding Author
Dr. Antonio Pozzi, DMV, MS, Diplomate ACVS, Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32610
E-mail: PozziA@vetmed.ufl.edu


Objectives: To determine the effect of tibial plateau leveling osteotomy (TPLO) on patellar tendon angle (PTA) in dogs.

Study Design: Cadaveric radiographic study.

Animals: Pelvic limb pairs (n=5) obtained from skeletally mature dogs, weighing 22–36 kg.

Methods: TPLO was performed using a radiolucent jig that allowed for plateau segment rotation to a tibial plateau angle (TPA) of 15°, 6°, and 0°. Before, and at each of the prescribed rotations, PTA was measured by the tibial plateau (PTATP) and common tangent (PTACT) methods with the stifle positioned at 135° of flexion. Linear regression analysis was performed to evaluate the correlation between TPA and PTA.

Results: At a mean (±SD) TPA of 5.9±0.7°, mean±SD PTATP and PTACT were 94.1±1.6° and 86.8±2.5°, respectively. A linear correlation was observed between TPA and PTATP (r=0.85) and between TPA and PTACT (r=0.61). Based on the regression equation of TPA and PTACT, a TPA of 12° corresponded to a PTACT of ∼90°.

Conclusion: TPLO to a TPA of 6° reduces PTA to values similar to those recommended when performing tibial tuberosity advancement in dogs with cranial cruciate ligament insufficiency.

Clinical Relevance: TPLO may neutralize tibial thrust by modifying PTA as well as decreasing TPA. TPLO to a TPA of 6° may not be necessary to neutralize the cranial tibial thrust according to the plateau rotation based on PTACT measurement.