SURGERY
Article sponsored by Petcam ®
Extra-articular repair techniques utilise synthetic
materials to traverse and stabilise the stifle joint.
The most commonly performed techniques include
the lateral fabellar suture, bone anchor techniques
and the Tightrope technique. In all cases, material is
anchored at relative isometric points outside the joint
on the distal femur and proximal tibia. Given that there
are no true isometric points in the stifle due to the
cam-shaped femoral condyles, the synthetic material
is subjected to cyclic loading that eventually results
in implant fatigue and failure. The goal of these repair
options is to stabilise the stifle long enough to allow for
periarticular fibrotic tissue to develop and mature over
a 16-week period. This periarticular fibrosis becomes
the long-term stabiliser of the stifle joint. The main
complications of these techniques include implant
infection along with premature implant failure. 8
Biomechanical techniques, also known as osteotomy
procedures, involve cutting and manipulating the tibia
in various ways that result in biomechanical neutralis
ation of cranial tibial thrust in the CCL-deficient stifle.
The most common procedures used today are the
tibial plateau leveling osteotomy (TPLO), the tibial
tuberosity advancement (TTA) and, more recently, the
center of rotation angulation (CORA)-based leveling
osteotomy (CBLO). Of these, the TPLO is probably the
most widely used osteotomy technique.
With the TPLO procedure (Figure 2) the 90-degree
flexed lateral radiograph of the tibia (including stifle
and hock) allows for measurement of the tibial
mechanical axis, and a bisecting joint line of the stifle
allows for measurement of the needed tibial plateau
angle (TPA). Average TPAs in dogs range from 25 to
30 degrees (see text box). 9 Once the patient’s TPA is
measured, a dome osteotomy of the proximal tibia is
performed and the proximal tibial fragment is rotated
a predetermined distance based on the patient’s
specific TPA. This results in a reduction of the tibia
slope to approximately five degrees, thus neutralising
cranial tibial thrust. A bone plate with screws is then
used to bridge and stabilise the fracture on the medial
tibia. The patient is then limited in activity over the next
six to eight weeks while the osteotomy heals.
The TTA (Figure 3) is a technique that involves a linear
cut in the tibial tuberosity and advancement (cranial
displacement) of the tibial tuberosity fragment in a
cranial direction to achieve and maintain a patellar
tendon angle of approximately 90 degrees with respect
Editor: There are specific radiographic positioning techniques to obtain the image and measurements are made
from very specific points on the radiographs. In essence the vertical line is drawn connecting the tibial bony
attachment of the cruciate down to the middle of the tibio-talar joint. The horizontal line is drawn perpendicular
to the vertical line. The tibial plateau angle (TPA) is determined by drawing a line through the intersection of these
two lines which runs parallel to the tibial plateau. The angle thus created is the TPA.
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Issue 03 | JULY 2018 | 8