Introduction
Instabilities of the carp and tarsus in animals, particularly dogs and cats, represent a major clinical challenge. These complex joints play an essential role in limb mobility and stability. Injuries, whether traumatic or degenerative, can lead to pain, lameness and joint dysfunction. This article describes in detail the pathophysiologydiagnostic diagnosis and treatment treatment options of carpal and tarsal instabilities.
Anatomy and Joints of the Carpus and Tarsus
Carpe
The carpus is made up of 7 bones divided into two rows. The proximal row comprises the radial, ulnar and accessory bones, while the distal row is made up of bones numbered I to IV. The main articulations are :
- Antebrachio-carpal Connects the radius and ulna to the proximal row.
- Middle carpal Connects the proximal and distal rows.
- Metacarpophalangeal Connects the distal row to the metacarpals.
The carpal stabilizers include the joint capsule, intra- and extra-articular ligaments, palmar fibrocartilage and tendons.
Tarsus
The tarsus consists of 7 bones organized in three rows. The main joints are :
- Tarsocrural (talocrural): Responsible for 90% of tarsal mobility.
- Talo-Calcanean and Centro-distal : Inter-tarsal joints. The tarsal stabilizers are the joint capsule, collateral ligaments, plantar ligaments and muscles.
Pathophysiology of Carpal and Tarsal lesions
Hyperextension lesions of the carpus
Hyperextension lesions of the carpus are common in animals following trauma such as a fall or jump. They cause swelling, pain and loss of joint function. Associated fractures are often intra-articular, requiring rapid surgical intervention.
Treatment Complete arthrodesis is often indicated in severe cases, while partial arthrodesis may suffice in more moderate cases.
Calcaneum and Talus fractures
Fractures of the calcaneus and talus are rare but serious. They affect the extension function of the hind limbs, with often intra-articular fractures requiring surgical fixation (plates, rods and bracing).
Plantar and dorsal instability of the tarsus
Plantar and dorsal instabilities are often observed in breeds such as the Shetland or the Collie. Plantar hyperextension is frequent, with subluxation if the animal presses on the paw.
Treatment : Calcaneo-quartal arthrodesis is an effective treatment option, with a good prognosis if carried out correctly.
Diagnosis of Carpal and Tarsal Instabilities
Diagnosis is based on several complementary examinations, including :
- Standard and stress radiographs Used to assess instability and fractures.
- Computed tomography (CT Scan) Particularly useful for visualizing complex fractures.
- Orthopedic examination Check for lameness, asymmetry, swelling and joint instability.
Instability tests should be performed in the frontal, sagittal and transverse planes, to identify dysfunctions specific to each joint.
Processing options
- Conservative treatment In 1st degreewhere few ligament fibers are involved, rapid healing can be achieved with minimal treatment.
- Surgical treatment Sprains of 2nd and 3rd degree require rapid surgical repair to avoid permanent loss of joint function.
Arthrodesis Used in cases of non-repairable fractures or severe osteoarthritis. It involves surgically fusing a joint to eliminate pain and restore function.
Conclusion
Instabilities of the carp and tarsus require precise diagnosis and treatment to limit the loss of joint function in companion animals. As front-line veterinarians, it is essential to fully understand the complexity of these joints and to propose appropriate solutions, ranging from conservative treatment to surgery. Early diagnosis and appropriate management can restore optimal mobility and minimize long-term complications.
