258 Surgical Treatment
without any loss of bone apposition at the TPLO
(arrows in Figure 30.3) (Wehet al. 2011). In
cases with patella alta, the closing wedge can be
used to position the patella more distally in the
trochlear groove; the amount of change in patel-
lar position is roughly equivalent to the distance
of cranial tibial cortex that is removed with the
CCWO (Talaatet al. 2006). Thus, the angle of the
CCWO can be adjusted to provide the necessary
change in patellar position, and the rotation at
the TPLO can be adjusted to provide the balance
of the tibial plateau leveling required achiev-
ing a postoperative TPA of 5◦, without rotating
beyond the safe point.
Surgical technique
Slocum & Slocum (1993) were the first to
describe the TPLO/CCWO procedure utilizing
two radial osteotomies.^2 However, this tech-
nique was shown to result in unpredictable
and inaccurate correction (Talaatet al. 2006),
and consequently it was modified to use linear
osteotomies at the CCWO (Talaatet al. 2006).
This was found to make preoperative plan-
ning and intraoperative execution more precise.
Once the radial osteotomy for the TPLO is made
partially through the tibia, the proximal limb
of the CCWO is scored on the medial cortex,
such that it intersects the radial osteotomy of
the TPLO at the caudal cortex of the tibia. The
CCWO can be accurately executed intraopera-
tively by using a sterile angle template, a ster-
ile goniometer, or a simple geometric method.
If the geometric method is used, the proximal
limb of the CCWO must be placed such that it
is perpendicular to the cranial tibial cortex (Fig-
ure 30.1C). The length of the proximal limb of
the CCWO (base of a right-triangle) is measured
and the length of the opposite limb of the right-
triangle (the limb of the triangle along cranial
border of the tibia) is calculated (Figure 30.1C),
determining the appropriate position of the dis-
tal limb of the CCWO (hypotenuse of the tri-
angle), which is then scored. The TPLO is com-
pleted, the tibial plateau segment is rotated, and
(^2) Seminars entitled “Tibial Plateau Leveling Osteotomy
for Cranial Cruciate Ligament Repair,” Slocum Enter-
prises, Inc.
two holding Kirschner wires are placed from
proximal to the patellar tendon attachment at
the tibial tuberosity into the tibial plateau seg-
ment. It should be noted that the plateau is not
leveled to 5◦at this stage, and care must be taken
to ensure that the Kirschner wires do not pen-
etrate the joint surface. These Kirschner wires
remain as part of the permanent fixation. The
CCWO is completed, reduced, and a holding
Kirschner wire is placed from craniodistal to
caudoproximal, avoiding the articular surface
(Figure 30.1D). Two large-gauge tension band
wires are applied to achieve cranial compres-
sion and apposition of the tibial closing wedge
osteotomy. The bone plate(s) are then applied in
compression to complete the stabilization (Fig-
ure 30.1D,E). Application of the implants in this
order seems to improve osteotomy apposition
and healing (Wehet al. 2011).
The CCWO wedge can be morselized and
placed as autogenous corticocancellous bone
graft at the osteotomy sites, particularly at the
CCWO site, as this is generally the area that
heals most slowly (Figure 30.1D,E). Torsional
correction at the CCWO (arrows in Figure 30.3)
and/or lateral translation of the tibial tuberos-
ity segment can be accomplished before apply-
ing the fixation, facilitating limb alignment cor-
rection in complex cases, such as severe tibial
torsion or medial patellar luxation with cruci-
ate ligament rupture in which tibial tuberosity
transposition is required.
Rigid fixation is required in cases treated with
TPLO/CCWO to mitigate the risk of implant
loosening, fixation failure, or prolonged heal-
ing. In particular, fixation of the cranial tibial
tuberosity segment must be rigid, since the dis-
tractive force of the patellar tendon is consider-
able. Therefore, in all cases, the Kirschner wires
placed to stabilize the TPLO and CCWO dur-
ing the procedure are maintained as permanent
fixation, and two figure-of-eight tension band
wires are placed to counteract this strong dis-
tractive force. The Kirschner wires and tension
band wires should be of a suitably large gauge
(1/16′′or 3/32′′Kirschner wires/pins and 18-g
or 16-g cerclage wire in most patients), tight-
ened adequately, and anchored in bone tunnels
as illustrated (Figure 30.1D,E). Double plate fix-
ation is recommended if the tibial size is suffi-
cient to place a second bone plate. In patients
weighing 30–40 kg an additional 2.4-mm or