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.
Figure 4. A stifle specimen. Note the position of the No. 11 scalpel blade for transecting the caudal tibial ligament of the
medial meniscus to release the intact medial meniscus. The proximity of the caudal cruciate ligament (*) should be noted as
it must be identified and preserved during the release procedure. Accidentally lacerating the caudal cruciate ligament negates
the mechanical benefits of the TPLO.
Medial meniscal pathology is often present and can vary from partial-thickness tearing to a full-thickness bucket-handle tear
to a severe crushing injury. The surgeon should excise the pathologic segment of the medial meniscus, using caution to protect
the caudal cruciate ligament in the process. Suction is essential, and headlight illumination is helpful. If the meniscus
is intact, a medial meniscal release can be performed because it has been theorized to decrease the incidence of delayed meniscal
injury (Figure 4). Alternatively, the medial meniscus can be released by transecting it at the midbody level as described later.
Figure 5. A stifle specimen. Note the patellar ligament (*), the medial collateral ligament (#), and the caudal retraction
of the pes anserinus muscle group (+). As an alternative to releasing the intact medial meniscus as shown in Figure 4, the
medial meniscus can be released at the midbody by directing a No. 11 scalpel blade from the caudal margin of the medial collateral
ligament toward the tubercle of Gerdy (at the cranial margin of the extensor groove of the tibia). This procedure is more
difficult to visualize for the novice surgeon.
In preparation for the TPLO, the surgeon takes great care to elevate the muscles from the caudal and lateral surfaces of the
tibia to avoid lacerating the popliteal vessels. If indicated, the medial meniscus can be released at the midbody at this
time (Figure 5). Next, radiopaque-marked gauze sponges are packed around the caudal and lateral tibial surfaces to retract the surrounding
soft tissues (Figure 6).
The jig (TPLO Jig—Slocum Enterprises) maintains alignment of the two bony segments after the osteotomy. Proper positioning
and orientation of the most proximal jig pin are essential because the pin functions as the axis around which the tibial plateau
rotates and as a visual guide for orienting the osteotomy. Improper positioning or orientation of the most proximal jig pin
compromises subsequent aspects of the procedure.
Figure 6. A stifle specimen. Gauze sponges are firmly packed along the caudal and lateral surfaces of the tibia to protect
the surrounding tissues during the osteotomy.