Understanding tibial plateau leveling osteotomies in dogs - Veterinary Medicine
  • SEARCH:
Medicine Center
DVM Veterinary Medicine Featuring Information from:

ADVERTISEMENT

Understanding tibial plateau leveling osteotomies in dogs
You've heard a lot about TPLO and have possibly even referred patients for it, but you may still question exactly how it is performed and how it stabilizes the stifle. This surgeon walks you through the procedure so you'll be better equipped to educate your clients about its basis, some of its intricacies, and its potential complications.


VETERINARY MEDICINE


Next, the surgeon extends and flexes the stifle while evaluating the tibia for malalignment. Torsional malalignment is corrected by bending the distal jig pin either cranially or caudally as appropriate. Varus or valgus malalignment is corrected by sliding the jig in or out on the distal jig pin. A detailed discussion of limb alignment strategies is beyond this scope of this article. The edge of the saw blade is used to level out any stairsteps at the osteotomy site in the region of the proposed plate placement.

Bone plate application


Figure 11. A surgical photo showing the TPLO plate holding the desired rotation of the tibial plateau after removal of the jig, temporary Steinmann pin, and Kirschner wire. Stifle stability, limb alignment, and implant placement are assessed.
The bone plate is contoured with bending irons for a precise fit against the medial tibial cortex to avoid inducing tibial malalignment. Cortical screws are placed through the fourth, fifth, and sixth plate holes into the distal tibial segment by using standard insertion methods. Next, cortical or cancellous screws (as appropriate) are placed in the second, third, and first holes, respectively. Provided no limb alignment alterations were made, these screws are inserted in compression mode to compress the osteotomy surfaces. If, however, tibial alignment corrections were made, the screws in the proximal segment are inserted in neutralization mode. Care is used to avoid placing these proximal screws into the stifle joint. The jig and temporary Kirschner wire are removed, and stifle stability, limb alignment, and implant placement are assessed (Figure 11).


Figure 12A. A mediolateral postoperative TPLO radiograph that shows appropriate centering of the osteotomy in the approximate region of the most proximal point of the tibial functional axis. Note also that the proximal jig pin was placed on the tibial functional axis immediately distal to the stifle joint.

12B. A caudocranial postoperative TPLO radiograph that shows proper angling of screws such that intra-articular penetration is avoided.
The surgical field is lavaged thoroughly with lactated Ringer's solution. The joint capsule is apposed routinely with a continuous suture pattern. The popliteus muscle is apposed to the medial collateral ligament. The pes anserinus muscle group is apposed to the insertion remnant left on the medial margin of the tibial crest by using stifle flexion to ease tension during closure. Subcutaneous tissues are closed in one or two layers. Skin is apposed routinely. Mediolateral and caudocranial radiographs are obtained by using the same patient positioning described previously, and the tibial plateau angle is measured (Figures 12A & 12B). The radiographs are also evaluated for proper placement of the temporary jig pins (as evidenced by their pin tracts), osteotomy, and implants.


ADVERTISEMENT

Source: VETERINARY MEDICINE,
Click here