Front Matter

Chapter 14 Disorders of the Pelvic Limb: Diagnosis and Treatment 377

Trochleoplasties

Wedge or block trochlear recession can be
performed to deepen the sulcus and so pro­
vide more effective buttressing to the patella
(Johnson et al., 2001; L’Eplattenier & Montavon,
2002b) (Figure 14.28). However, there are no
good studies detailing what the trochlear depth
should be (as a guideline, the surgeon should
aim to have one third of the height of the patella
and two thirds the length of the patella in
the  groove) and both techniques involve
some degree of violation to the joint surface.
Techniques that do not preserve the articular
cartilage such as abrasion arthroplasty should
be avoided.

Tibial tuberosity transposition

Deepening the trochlear sulcus will do nothing
to realign the quadriceps mechanism and so
some form of tibial or femoral osteotomy is also
required. Internal rotation of the tibia is com­
mon in dogs with MPL (external rotation with
lateral patellar luxation). Transposition of
the tibial tuberosity by several millimeters
has been shown to significantly decrease the
incidence of reluxation following surgical
correction (Arthurs & Langley‐Hobbs, 2006).
This procedure involves an osteotomy of the

tibial tuberosity and placement of orthopedic

implants (K‐wires ± cerclage wire) to secure

the tuberosity in the transposed location

(L’Eplattenier & Montavon, 2002b) (Figure 14.29).

Rates of reluxation can be high after tibial

tubercle transposition, especially in grades

III and IV (Arthurs & Langley‐Hobbs, 2006;

Cashmore et al., 2014), and often the anatomic

distal femoral lateral angle (aDFLA) will be

exaggerated (excessive femoral varus). Tibial

osteotomy does not address this primary cause,

so consideration should be given to femoral

osteotomy in cases of excessive femoral varus

(aDFLA of greater than 104 degrees) (Barnes

et al., 2015).

Distal femoral osteotomy

The normal range of aDFLA is between 94 and

98 degrees (Barnes et al., 2015). Patients with

higher grades of luxation (III and IV) with

excessive varus should be treated by distal

femoral osteotomy (DFO). Recent advances in

CT and the better assessment of femoral torsion

Block

recession

Femoral

condyle

Figure 14.28 Block trochlear recession. Note that the
patella is well‐seated within the surgically deepened
groove. Source: Illustration by Marcia Schlehr.

Figure 14.29 Tibial tuberosity transposition involves an

osteotomy of the tibial tuberosity and placement of

orthopedic implants (K‐wires ± cerclage wire) to secure

the tuberosity in the transposed location.