What is carpal hyperextension?
The carpal (wrist) joint consists of the radius, ulna, and carpal bones. The bones are held together by ligaments and tendons. Laxity can occur between any of the bones in the joint, causing the joint to collapse. This can be due to an acute injury to the tendons or ligaments, congenital abnormalities, degeneration of the joint, or chronic steroid use. The degree of collapse may vary and can include flattening of the toes as well. There also may be increased movement on the inside or outside of the joint causing the joint to appear bowed or collapsed in.
How is carpal hyperextension diagnosed?
Carpal hyperextension can be detected by a physical exam that assesses the standing angle of the carpus and the integrity of the tendons and ligaments. Stress radiographs, ultrasound, or advanced imaging may also be performed to determine the extent of injury.
How do we treat carpal hyperextension?
Rehabilitation for carpal hyperextension first focuses on stabilizing the joint. This can be accomplished through a custom Orthopets brace or an off the shelf carpal wrap if surgery is not needed. The type of brace a dog requires depends on the severity of the injury and other individual factors. Utilizing a custom brace or soft carpal wrap will stabilize the wrist from the outside. Any time the dog is bearing weight though the carpus, the brace will need to be on. The length of time a dog will need to be in a brace is dependent on the extent of the injury. Patients with severe injuries may need to be in the brace the rest of their life.
After we stabilize the joint, we then focus on treatments to help decrease inflammation and pain and promote healing. This generally includes modalities and hands on work. We then address any flexibility restrictions and range of motion. Finally, we incrementally progress strengthening around the carpal joint to help stabilize it.
Sometimes, surgery may be needed to address a severe carpal hyperextension injury. Surgery typically consists of a partial or full pan arthrodesis where the joint is fused with a plate. Although this prevents range of motion of the carpal joint, it does provide permanent stability.