Most cases of equine lameness are treated with a combination of medical and other non-surgical methods. However, there are
a few specific cases in which surgical management is the treatment of choice. The surgical procedures that will be discussed
in this paper include arthroscopy/tenoscopy/bursoscopy, palmar digital neurectomy, plantar fasciotomy with or without neurectomy
of the deep branch of the lateral plantar nerve, pastern arthrodesis, and tarsal arthrodesis.
Arthroscopy involves the surgical exploration of a joint using a small telescope enabling a thorough examination of the joint
without the need for a large surgical approach. Tenoscopy/bursoscopy involves the surgical exploration of tendon sheaths and
bursae using the same surgical method. Using a technique called triangulation, additional small portals can be made that allow
for surgical instruments to be placed within the synovial structure. The most common condition for the utilization of arthroscopy
is for fragment removal. Fragments in equine joints arise from 2 main sources: traumatic injury and osteochodritis dissecans.
The most common instances of traumatically induced osteochondral chip fragmentation are in the carpal and fetlock joints.
Although chip fractures have been frequently considered acute injuries and recognized with acute clinical signs, it has been
suggested that they are a secondary complication affecting joint margins previously altered by subchondral bone disease. Exercise
causes microdamage within the joint which can lead to microcracks, more diffuse microdamage, and subchondral bone sclerosis.
Therefore the ŇacuteÓ chip fracture typically occurs through this abnormal bone.
When accompanied by lameness, joint effusion, and pain upon flexion, the management of intra-articular joint fragments is
relatively straight forward. These types of cases are most common in horses that perform at speed (race horses). In these
cases, arthroscopic fragment removal and joint exploration is indicated. If not treated in a timely fashion, the inflammatory
mediators that are released from the damaged bone and cartilage can lead to further cartilage damage, chronic proliferative
synovitis, and joint capsule fibrosis leading to a decreased range of motion. When the lameness and effusion are significant,
usually there is damage to the joint in addition to the fragmentation seen radiographically. Therefore, a thorough exploration
of the joint should be performed.
In many cases of intra-articular fragmentation, the management may not be straight forward. In my practice, there are many
sound horses with intra-articular chip fragments that are found incidentally on pre-purchase examinations or in lameness examinations
where the lameness is being caused by a different problem. Sometimes it is hard to recommend surgery and the accompanying
down time in an otherwise sound horse that has been competing regularly. Decision making depends on the specific joint involved
or the location of the fragment. I find that chip fragments in low motion joints, such as the pastern joint, rarely cause
lameness problems and therefore are usually left in place, unless diagnostic intra-articular anesthesia confirms that the
lameness is originating from the fragment. In high motion joints, such as the fetlock joint, I feel that location within the
joint is particularly important, in addition to the discipline of the horse. I recommend that dorsal articular chip fragments
within the fetlock joint be removed, even in the absence of clinical disease. These fragments over time can cause articular
surface damage to the adjacent metacarpal condyle leading to osteoarthritis in the athletic horse. They also serve as point
to decline purchase when found on a pre-purchase examination. Despite this recommendation, I have seen several horses with
dorsal fetlock osteochondral fragments that have maintained athletic careers for years in the absence of clinical lameness.
This is particularly true in horses that perform at low speeds (western performance horse). Palmar or plantar osteochondral
fragmentation off of the proximal palmar or plantar eminence of the first phalanx are also common incidental findings in otherwise
sound horses. Again, these are generally removed in horses that perform at speed. However, in horses involved in other disciplines,
particularly those that work at lower speeds, I generally do not recommend surgical removal when there is clinical soundness.
If lameness is present, the palmar/plantar fetlock fragment must be confirmed as the cause of the lameness using intra-articular
anesthesia prior to recommending surgical removal. This is because these fragments are embedded within the distal sesamoidean
ligaments in an area of the joint that is difficult to surgically access. The surgical removal of these fragments can be associated
with some damage to the articular surface as well as to the distal sesamoidean ligaments, resulting in a longer post-operative
convalescent periods. There are many horses in my practice that perform in disciplines at lower speeds that have these palmar/plantar
osteochondral fragments with no apparent lameness or performance problems. Many of these fragments may have been present in
the joint since they were yearlings or even weanlings.