Arthrodesis is defined as the irreversible fusion of two or more bones of a joint. This creates an osseous bridge, preventing joint motion, and allows the arthrodesed joint to transmit weight-bearing forces. There are several small tarsal joints that together make up the hock or ankle joint. Fusion of the tarsal joints is often indicated when there is irrevocable traumatic damage to the hock often involving ligament damage.
Hyperextension of the tarsus commonly results when a dog lands heavily on their hind leg(s) from a great height, overstretching and damaging the ligaments that hold the small bones together. Some breeds like Shetland Sheep Dogs are especially prone to spontaneous collapse of the tarsal (or carpal) joints under normal loading due to a degenerative process involving the ligaments. Tarsal arthrodesis is also indicated when the tarsal bones are fractured, or when end-stage degenerative joint disease (arthritis) can no longer be managed medically.
It is important to understand that an arthrodesis is a salvage procedure. This means that the procedure is irreversible once performed. As a result, an arthrodesis is generally performed when conservative management has failed or unlikely to be successful.
Arthrodesis Indications
- Joint instability – Hyperextension injury of the tarsus is the most common indication for performing a pan tarsal arthrodesis (surgical fusion of all of the tarsal joints). The high tensile forces following normal weight bearing make conservative treatment futile.
- Intractable arthritis or joint pain.
- Persistent luxation or instability of the joint
- Non-reconstructable articular fractures of the tarsal bones
- Neurological injury
Pan Tarsal Arthrodesis Surgery
The tarsal joints are opened, and the articular cartilage is removed. Cancellous bone grafts taken from another part of the body (usually the humerus or tibia) are inserted into the joint spaces. Specialised surgical plates are affixed with surgical screws to the tibia, tarsus, and metatarsus as required to rigidly fix or hold the joint in a static position.
A splint bandage may be used to support the leg and joint post-operatively.
All patients will receive pain medications to reduce their post-operative discomfort. Your pet should be kept calm and quiet after surgery to allow for tissue healing. A collar is necessary to prevent the patient interfering with the surgical site. Following the post-operative instructions carefully is essential in order to ensure that the procedure is as successful as possible.