236 Surgical Treatment
(A) (B)25°
43°Figure 28.8 Lateral stifle joint radiographs demonstrating differences in the anatomic shape of the proximal tibia such
that the tibial plateau angle (TPA) is either considered excessive (A) at 43◦, or within normal limits (B) at 25◦.This
conformational deformity of the stifle joint angle in panel (A) places the joint in a relatively hyperextended position,
compared with panel (B). Advancing the tibial tuberosity does not correct this hyperextension as the TPA remains
unaltered. Source: Boudrieau 2009. Reproduced with permission from John Wiley & Sons, Inc.
in the proximal one-third of the medial tibial
surface, which will interfere with subsequent
additional medial plate fixation. Although a
standard plate could be applied over the thin
TTA plate, this is far from ideal and generally
not recommended. With the second-generation
TTA, using a wedge-only technique and no
plate, this issue is ameliorated. However, a sec-
ond osteotomy in the transverse plane is still
required to address these deformities. There-
fore, TTA is generally not recommended under
these circumstances.
Patellar luxation
Patellar luxation requiring tibial tuberosity
transposition combined with cruciate ligament
rupture may be very well suited to TTA, as any
desired transposition may be simultaneously
performed concurrently with the advancement.
In this instance, the TTA plate is slightly over-
bent to conform to the new laterally (or medi-
ally) transposed tibial crest. The alteration in
the surgical technique occurs with cage appli-
cation. For example, in a medial patellar luxa-
tion, where the tibial crest is moved laterally,
either the caudal ‘ear’ of the cage is recessed
into the proximal tibia, or the cranial ‘ear’ of
the cage is elevated above the surface of the tib-
ial tuberosity by interposing some washers, or
both (Figure 28.9). Ancillary fixation generally
is unnecessary. This technique has been briefly
described (2007 Veterinary Symposium – The
Surgical Summit; Pre-Symposium Laboratories:
TTA Laboratory; Chicago, IL, USA) (Boudrieau
2005), and reported in a series of cases (Yeadon
et al. 2011).Patient size
TTA has been performed in dogs as small as
5 kg and as large as 92 kg (Hoffmannet al.
2006; Lafaveret al. 2007). Size limitation is
dependent on the availability of appropriately
sized implants (2- to 8-hole plates, and 3- to
15-mm cage widths, Kyon; Zurich, Switzer- ̈
land). The implants are produced in a variety
of sizes such that they can be used in almost
any sized dog. In some instances, in very tall
dogs such as Great Danes, a limitation of the
TTA may be the large advancement distance
(>15 mm) that is required (Burns & Boudrieau
2008). The widest cage currently available to
support the osteotomy gap is 15 mm, which
became available in early 2009. Whereas the
cage can be moved further distally to increase