Page 331 - Canine Lameness

18.7 ­ctrF gesrresres ooracgoe ctrf rFesral reg o 303

(A) (C) (E) (G)

(B) (D) (F) (H) TARSAL REGION

Figure 18.12 Other diseases affecting the tarsal region: (A, C, D) idiopathic tarsal hyperextension without
identifiable underlying pathology; (B) tarsal hyperextension secondary to severe stifle disease; (C) standard
lateral radiograph of patient depicted in image (A), note that there are (white arrows) degenerative changes
several joints of the tarsus; (D) stressed image illustrating the hyperextension visualized in image (A); (E, F)
calcification in the (white arrow) deep digital flexor tendon sheath likely representing a migrated OCD flap;
there is another (blue arrow) calcification in the dorsal joint space of unknown origin; and (G, H) tarsal
synovial cell sarcoma not the (white arrows) subtle lysis of the talus and distal tibia.

Tarsal hyperextension does not typically seem to be painful, so it is usually treated conservatively.
Orthoses that allow tarsal flexion while limiting extension may be considered. In calves, shortening
of the fibularis longus tendon seems to be effective in preventing hyperextension (Kilic et al. 2015),
but specific surgical therapy has not been reported for dogs. Once tarsal hyperextension has devel-
oped, it persists even if concurrent orthopedic conditions have been successfully addressed.

18.7.4 Osteochondrosis Fragment Migration into the DDF Tendon Sheath

An unusual manifestation of talar OCD is the migration of osteochondrosis fragments into the
synovial sheath surrounding the DDF tendon. This sheath communicates with the tarsocrural
joint just caudal to the medial malleolus and near the plantar aspect of the talus, making it possible
for free fragments from the medial (and occasionally lateral) talar ridge to become trapped around
the tendon.
These osteochondral fragments can irritate the DDF and restrict its motion within the sheath
(Post et al. 2008). Lameness is intermittent (resembling patellar luxation by causing a “skipping”
pelvic limb lameness) to continuous (particularly if severe arthritis is present due to the primary