Page 182 - Canine Lameness

154 12 Distal Limb Region

12.4 Fractures of the Distal Limb Region
DISTAL LIMB REGION 12.4.1 Metacarpal and Metatarsal Fractures

Fractures of these bones usually occur following a traumatic event. In racing Greyhounds, they are
considered stress/fatigue fractures and most commonly involve metacarpal II of the right limb and
metacarpal V of the left. In these dogs (and possibly other working dogs where the bones are
exposed to cyclical injury and have not had enough time to adaptively remodel), bone injury is
common and manifests as an ill-defined continuum of periostitis, stress fracture, and finally, com-
plete fracture. In racing Greyhounds, a single bone is most commonly fractured (Boemo 1998). In
contrast, traumatic fractures in pets frequently involve multiple bones (Kornmayer et al. 2014).
Clinical signs can range in severity depending on the extent of the force, number of bones
affected, degree of injury, and the size of the animal. There is usually some adjacent swelling and
there may be associated cutaneous injuries. Palpation will reveal pain, swelling, crepitus, and pos-
sibly topographical deformity of the region.
Diagnostic confirmation and fracture details are generally provided through orthogonal radio-
graphs. Lateral views give confusing superimposition of the bones, which may be resolved through
oblique projections and/or gentle elevation or depression of an individual bone to assist with orien-
tation. CT can be useful to elucidate comminuted fractures, especially those that involve the joints.
Numerous surgical and nonsurgical treatments (e.g. external coaptation) have been described to
treat these fractures but there is no evidence-based consensus as to the best treatment. Factors
influencing the choice of treatment include the age and mass of the dog, intended activity of the
dog, which bones are fractured, number of bone fractures, site of the fractures, extent of fragment
displacement, and concurrent local and distant injuries.

12.4.2 Digit Fractures and Luxations
Digit fractures most commonly occur as a result of trauma and frequently involve only a single digit.
The clinical signs and diagnostic approach are similar to those described for metacarpal/metatarsal
fractures. Due to the complexity of this region, careful evaluation of radiographs is necessary for the
diagnosis of minimally displaced fractures (Figure 12.6). There is also no clear consensus on treat-
ment, with both surgical and nonsurgical treatment described. Most frequently these fractures are
managed nonsurgically; however, because of the difficulty in adequately immobilizing the region,
delayed unions and exuberant callus are common. Surgical repair of shaft fractures has been recom-
mended in performance dogs, although there are no studies to support this (Eaton-Wells 1998).
Luxations or subluxations can occur at any level but are reportedly more common at the distal
interphalangeal joints, especially in athletic dogs (DeCamp et al. 2016). These injuries are due to a
strain injury of the associated collateral and/or sesamoid ligaments and usually involve a single
joint. Dogs with this injury are often not lame at the walk but may show lameness during faster
gaits. There is often no, or minimal pain (luxations of the metacarpophalangeal joints are reported
to be more painful than those of the distal joints), swelling, nor crepitation (Blythe et al. 2007).
With complete luxation, the phalanx is displaced laterally or medially (Figure 12.6).
Instability is palpated by gently opening the joints laterally or medially and performing a dorso-
palmar/plantar “drawer” movement. Diagnosis is confirmed with orthogonal radiographs, but stress
radiographs may be necessary to establish the diagnosis. Small avulsion fractures associated with the
collateral ligaments are often seen. Ultrasound may be useful to identify ligamentous injuries or con-
current tendon injury, in larger dogs. Although reduction and nonsurgical treatments are frequently
successful in the author’s experience, surgical treatment is described for athletic dogs (Guilliard 2003).