238 Surgical Treatment
Outcome and complications with
first-generation TTA
The first-generation cage with plate and fork
or screws has been in general use since 2006.
There are many anecdotal reports of good to
excellent results, and a number of early clin-
ical results published (Hoffmannet al. 2006;
Lafaveret al. 2007; Stein & Schmoekel 2008; Voss
et al. 2008; Dymondet al. 2010; Kemperet al.
2011; Steinberget al. 2011; Hirshensonet al. 2012;
Wolfet al. 2012; MacDonaldet al. 2013; Skinner
et al. 2013; Kieferet al. 2015). These reports com-
prise approximately 1600 cases, with an overall
complication rate of∼19.0% to 59%. Major com-
plications represent 2.3% to 26.1%, and minor
complications were 7.6% to 37%, with a reoper-
ation rate of 9.8% (Hoffmannet al. 2006; Stein
& Schmoekel 2008; Vosset al. 2008; Dymond
et al. 2010; Kemperet al. 2011; Steinberget al.
2011; Hirshensonet al. 2012; Wolfet al. 2012;
Kieferet al. 2015). The most common complica-
tions were postliminary meniscal tears and tib-
ial tuberosity fractures with or without implant
failure, infection, medial patella luxation and
tibial fracture. It has been proposed that many
of these complications are related to technical
failures, particularly insufficient advancement
and incorrect osteotomy placement (Botte 2013).
Radiographic healing was reported to
occur by 8–10 weeks postoperatively, and
with reported outcomes generally from 3 to
15 months postoperatively (Hoffmann et al.
2006; Lafaveret al. 2007; Stein & Schmoekel
2008). Good to excellent overall function and
clinical outcome in more than 90% of the dogs
was reported by the owners. The major differ-
ences between all of the reports included the
frequency of meniscal tears and the number of
technical failures reported.
Meniscus
Whether meniscal tears are the result of a
postliminary tear of an intact meniscus, or are
latent tears is unclear. Postliminary tears sug-
gest that a meniscal release might be indicated,
whereas latent tears suggest that thorough joint
evaluation is necessary. Controversy remains
regarding the use of meniscal release. More
recently, persistent instability in the joint after
tibial tuberosity advancement has been sug-
gested (Bottcher ̈ et al. 2013; Skinneret al. 2013),
but whether this is a consequence of the tech-
nique itself or incorrect execution of the TTA is
debated. Under-advancement because of inex-
perience with the technique and lack of aware-
ness of potential pitfalls with preoperative plan-
ning may occur (Etcheparebordeet al. 2011;
Bushet al. 2011; Botte 2013; Boudrieau 2013; Mil-
letet al. 2013; Cadmuset al. 2014). The prob-
lem is reduced by virtual planning. Regard-
less of the reason, insufficient advancement can
result in persistent tibiofemoral shear instabil-
ity and can be expected to result in postlimi-
nary meniscal tears. This may explain the pur-
ported value of meniscal release. Despite these
assertions, it appears that the clinical results
remain satisfactory in the majority of the cases
(Skinneret al. 2013). Given the limited informa-
tion on TTA biomechanics, debate remains as
to whether or not to perform a medial menis-
cal release. It appears there are two opposing
opinions regarding the necessity of meniscal
release at this time with TTA. Further discus-
sion of meniscal release is presented in Chapters
35 and 36. Continued postoperative instability
with confirmation of the amount of advance-
ment and postoperative PTA needs to be docu-
mented to advance any understanding of TTA
clinical outcomes related to surgical planning
and technique.Technical failures
The most common technical failures involve
an osteotomy that is too cranial with a small
tibial tuberosity bone fragment, or too low
adjacent to the level of distal plate screws,
which can create a stress-riser and a tibial
fracture. Tibial tuberosity fracture from inap-
propriate fork/screw placement into the tib-
ial tuberosity bone fragment, most often due
to a small size crest fragment, patellar luxa-
tion from inappropriate realignment of the tib-
ial tuberosity in the sagittal plane; distal patella
displacement because of a tuberosity-based
advancement, as opposed to a patella-based
advancement, are also common. Other miscel-
laneous complications include cage malposi-
tion (too high, too low, angled mediolaterally,
upside down), intra-articular screw placement,