Advances in the Canine Cranial Cruciate Ligament, 2nd edition

232 Surgical Treatment

to make a stable construct. In this technique, a
patella-based positioning of the tibial tuberos-
ity is performed, with a slight proximal shift of
the tibial crest segment with the advancement,
so as to not change the patella position. Finally,
a graft is applied within the osteotomy gap and
within the cage (Lafaveret al. 2007). The need
for a graft is controversial (Guerreroet al. 2011;
Boudrieau 2011).
The second-generation method is currently
evolving. Plates are no longer used; instead,
the construct is held in place by a cage only,
but with varying ‘accessories’ or ‘adjunct’ meth-
ods to ensure that the cage remains in place
(Brunelet al. 2013; Samoyet al. 2015; Torring-
ton 2015). One of the major conceptual modifi-
cations is an incomplete distal osteotomy of the
tibial tuberosity, so as to help stabilize the fixa-
tion. This encompasses a distal-based tuberos-
ity advancement. This type of advancement
was not recommended during development of
the first-generation method, where a patella-
based advancement is used. With the second-
generation TTA, the advancement causes some
distal displacement of the patella. The rationale
for the incomplete osteotomy of the distal end
of the tibial tuberosity is that it aids construct
stability and neutralization of the distractive
force of the quadriceps mechanism that were
previously neutralized with a plate. A result
of this modification is some distal patella dis-
placement. The clinical ramifications, if any, of
this change in patella position have yet to be
investigated.

First-generation implants and techniques

The original implants were produced by the
technique inventors (Tepic, Kyon). These
titanium implants have been copied exactly,
although there is controversy as to the quality
of the copies. Other alternate implants that use
different fixation methods to achieve the same
general concept are also available. For example,
stainless steel plates with standard screws
instead of a fork for the tuberosity fixation
(XGEN forkless TTA plates; Securos Surgical,
Boise, ID, USA). Another approach is locking
screw fixation for the tuberosity segment, again
with a similar-appearing stainless steel plate
with a PEEK spacer (DePuy Synthes Vet, West

Chester, PA, USA). Many other similar copies

are available from a variety of manufacturers.

Second-generation implants

and techniques

Three basic concepts are currently marketed.

These include the modified Maquet procedure^1

(MMP; Orthomed, West Yorkshire, UK), TTA

Rapid^2 (Rita Leibinger, DE, USA) and TTA-2^3

(KYON Veterinary Surgical Products, Boston,

MA, USA). These techniques have resulted

in the development of alternative stand-alone

cage designs and techniques to orient the tib-

ial osteotomy a fixed distance along the cra-

nial tibial shaft that corresponds to the degree

of tuberosity advancement and cage width

desired. The specific technical feature of these

approaches, primarily pertain to the location

and length of the osteotomy, and the method

to spread of the incomplete osteotomy and

achieve the tuberosity advancement needed.

These details can be found on the manufac-

turer’s websites.1,2,3

TTA pre-planning and surgery

There are many considerations regarding the

pre-planning of TTA, particularly with regard

to the measurement methods using PTACTor

PTATPA. Additional alternative methods have

also been proposed. Some of the other tech-

niques, such as the MMP procedure, have been

critically assessed; here, the target PTA of 90◦

is often not achieved as current planning meth-

ods may lead to underadvancement of the tibial

tuberosity (Kapleret al. 2015).

The planning methods for first- and second-

generation techniques are similar and aim to

achieve a PTA of 90◦. There are a number of

nuances with both the plan and its execution

to ensure that the TTA does achieve a postop-

erative PTA of 90◦. Unfortunately, minimal data

(^1) MMP see pdf downloads athttp://www.orthomed
.co.uk/
(^2) TTA Rapid,http://tta-rapid.com/
(^3) TTA-2,http://www.kyon.ch/current-products/tibial-
tuberosity-advancement-tta/tta-2-development-
technique