Page 708 - Adams and Stashak's Lameness in Horses, 7th Edition

674 Chapter 5

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A

C B

Figure 5.74. Horses with OA of the TC joint can develop chronic demonstrated significant loss of articular cartilage (arrowheads) and
thickening of the joint capsule (A; small arrows) and significant periarticular osteophyte formation (arrow). Proximal is to the left of
enthesophytes of the joint capsular attachments (A and B; large the image.
arrows). The longitudinal US image of the lateral trochlear ridge (C)

talus (Figure 5.74C). Joint capsule thickening, with or costeroids into a chronically effusive TC joint can lead
without metaplasia, is also a common feature of OA. to OA particularly when treatment is instituted without
Diagnostic analgesia is usually not necessary but may an accurate diagnosis. As mentioned earlier, OA of the
be indicated in some horses that have had persistent TC can be seen in conjunction and may be due to exten-
swelling but have only recently started to manifest lame- sion of OA of the DT joints (it is possible that there is a
ness. Intra‐articular analgesia of the TC joint may not causal relationship). Some horses that are diagnosed
effectively eliminate the lameness due to the presence of with TC pain may have concurrent talocalcaneal OA as
an intact articular cartilage and the presence of substan- these two joints freely communicate.
tial subchondral bone pain associated with OA of the Acute onset of a marked to severe weight‐bearing
TC joint. Perineural analgesia of the tibial and peroneal lameness associated with swelling of the TC joint fre-
nerves may be required to improve the lameness. quently indicates a traumatic event. This is often associ-
Most TC disorders have joint distension (bog spavin) ated with joint distension and/or periarticular swelling of
as a component of the clinical presentation. As discussed the tarsus. Intra‐articular fractures or synovial infections
before, not all horses with bog spavin are lame. In addi- are typically easy to localize and demand immediate
tion, the majority of horses with benign effusion of the attention. Penetrating wounds that breach the synovial
TC joint will not have a marked response to proximal membrane of any of the four pouches can lead to signifi-
limb flexion (spavin test). However, the presence of a cant heat, swelling, and pain of the TC joint. Management
bog spavin in a horse manifesting lameness needs more of these types of injuries is discussed later in this section.
careful evaluation of the TC joint. However OA of the The presence of a partially mobile OCD fragment
TC joint can occur as a primary disease but usually such as a DIRT lesion may predispose to OA of the TC
develops due to an underlying problem such as an OC joint. Asymptomatic OCD of the intermediate ridge of
lesion (long‐standing DIRT lesion left in situ is most the tibia is often left alone with the horses placed in
common), or it can be a sequela to some traumatic show regularly. It is not uncommon to have chronic
injury of the joint. Long‐term administration of corti- long‐standing DIRT lesion in a horse that suddenly