Page 344 - Canine Lameness

316 19 Stifle Region

with diagnostic imaging). Patellar fractures have also been reported to occur in up to 2% of dogs
after tibial plateau leveling osteotomy (TPLO); however, these fractures generally do not require
surgical treatment (Rutherford et al. 2012).

19.3.2 Salter-Harris Fractures
Proximal tibia and distal femur fractures most frequently affect the physes and therefore are most
commonly observed in immature animals. Dogs of any breed with open physes may be affected.
Physes of domestic dogs are fragile and very little trauma can result in a Salter-Harris (SH) fracture.
Typical causes of these fractures include collision with humans or bigger dogs during play, falls off
furniture or down stairs, and jump-down injuries out of an owner’s arms, out of vehicles, or other
mild-to-moderate heights.
SH fractures of the proximal tibia and distal femur are most commonly Type I or II and therefore
do not involve the articular surface (see Chapter 13 for description of SH fractures). The proximal
tibial growth plate rarely fractures on its own and, more commonly, fractures in conjunction with
the tibial apophyseal growth plate (Figure 19.4C, D). The epiphysis generally rocks back (i.e.
caudolateral displacement) and failure to repair these fractures results in an excessive tibial pla-
teau which can cause CCL strain and tearing in the long term. The distal physis of the femur con-
STIFLE REGION radiographically (Figure 19.3). Similar to proximal tibial physeal fractures, the distal femoral epi-
sists of four pyramidal grooves and corresponding pegs that result in the classis “W-shape” seen

physis commonly rocks back (i.e. caudolateral displacement) but failure to repair these fractures
results in excessive distal femoral procurvatum. Type III and IV fractures are rare and can be chal-
lenging to identify radiographically if displacement is minimal (Figure 19.4). Oblique radiographs
in addition to flexed and extended views can be used to identify minimal displacement.
Tibial tuberosity avulsion fractures may present in various degrees of severity ranging from a severely
displaced, palpable fracture with non-weight-bearing lameness to a minimally displaced fracture
with only mild clinical signs. Severely displaced fractures are best treated with surgical fixation that
ideally permits continued growth of the physis, if the patient has significant growth potential left.
Radiographs while fully flexing the stifle can exacerbate the displacement of these fractures and aid
in decision-making if displacement is minimal. It is important to note that the growth plate of the
tibial tuberosity apophysis (i.e. the site of the patellar ligament attachment) closes late during devel-
opment and the ossification may be irregular (von Pfeil et al. 2009). As such, interpretation of radio-
graphic changes to the area should be made with caution. Comparison to the non-affected limb is
advised before making a diagnosis. Based on these observations, a condition termed minimally dis-
placed tibial tuberosity avulsion fractures (MDTTAF) has been described (von Pfeil et al. 2012). Dogs
affected with MDTTAF show secondary remodeling of the physis with no or mild displacement of
the tibial tuberosity, while the most caudoproximal aspect of the tibial tuberosity always remains
attached to the proximal tibial epiphysis. Patients present with mild-moderate lameness and pain
when pressure is applied to the tibial tuberosity. Nonsurgical treatment is generally successful. In
people, a condition similar to MDTTAF is known as “Osgood-Schlatter disease”; however, since this
condition does not involve the physis, this terminology should not be used for dogs with MDTTAF.

19.4 Cranial Cruciate Ligament Disease

CCLD is the term used to describe any disruption of the CCL. This includes rare conditions such
as avulsion fractures and traumatic ruptures but generally CCLD refers to chronic degeneration of
the ligament. The latter is by far most commonly encountered and represents one of the most