Os carpi ulnare (Cu)
The ulnar carpal bone is the lateral bone of the proximal row of the carpus (excluding the accessory). It articulates proximally with the lateral styloid process of the radius, medially with the intermediate carpal bone, distally with the fourth carpal bone, and caudally (palmar) with the accessory carpal bone. It is part of the complex carpal joint that absorbs concussion and transfers weight.
Isolated injury is uncommon. Relevant in evaluations of carpal fractures or chip fractures that may involve adjacent bones. Diagnosis is radiographic.
## Overview Less common fractures occur in bones or locations that are infrequently injured. They still require accurate imaging and individualized treatment. Prognosis is determined by the specific
## Overview Periarticular new bone formation is the growth of extra bone around a joint, usually as a response to osteoarthritis, instability, or previous injury. It appears on radiographs as osteoph
## Overview Degenerative joint disease, also called osteoarthritis, is the progressive loss of articular cartilage accompanied by changes in the underlying bone and joint capsule. It is one of the mo
Carpal swelling or lameness after fast work should be evaluated promptly.
## Overview Less common fractures occur in bones or locations that are infrequently injured. They still require accurate imaging and individualized treatment. Prognosis is determined by the specific fracture rather than its rarity. ## Causes Unusual trauma or loading. ## Diagnosis Radiographs and, when needed, computed tomography. ## Treatment Conservative or surgical according to stability and location. ## Recovery and Prognosis Case-dependent. ## Prevention General trauma reduction. Signs include: lameness or pain localized to an uncommon site; imaging confirmation
## Overview Periarticular new bone formation is the growth of extra bone around a joint, usually as a response to osteoarthritis, instability, or previous injury. It appears on radiographs as osteophytes or enthesophytes and may or may not cause clinical lameness depending on size and location. ## Causes Joint instability, chronic inflammation, or trauma. ## Diagnosis Radiographs correlated with clinical signs. ## Treatment Manage the underlying joint disease. The new bone itself is not removed unless it is mechanically interfering. ## Recovery and Prognosis Depends on the joint and degree of osteoarthritis. ## Prevention Early treatment of joint inflammation and instability. Signs include: radiographic osteophytes around a joint; variable lameness; joint stiffness
## Overview Degenerative joint disease, also called osteoarthritis, is the progressive loss of articular cartilage accompanied by changes in the underlying bone and joint capsule. It is one of the most common causes of chronic lameness in horses and can affect any joint, though certain joints (hock, coffin, fetlock, stifle) are frequently involved in performance horses. ## Causes Repetitive loading, prior trauma, conformational faults, or developmental joint disease. Inflammation and mechanical stress drive the progression. ## Diagnosis Lameness examination, flexion tests, diagnostic analgesia, and imaging (radiographs show osteophytes and joint-space changes; advanced imaging assesses cartilage). ## Treatment Intra-articular medications (corticosteroids, biologics, viscosupplements), systemic anti-inflammatories, shoeing or trimming adjustments, and workload modification. Management rather than cure is the goal. ## Recovery and Prognosis Many horses remain comfortable and useful for years with appropriate management. Advanced disease eventually limits athletic career length. ## Prevention Early treatment of joint inflammation, balanced shoeing, and sensible training programs. Signs include: progressive lameness worse with work; joint effusion; stiffness after rest; reduced range of motion; muscle atrophy in chronic cases
Isolated injury is uncommon. Relevant in evaluations of carpal fractures or chip fractures that may involve adjacent bones. Diagnosis is radiographic.
Carpal swelling or lameness after fast work should be evaluated promptly.
See the Ulnar Carpal Bone (Left) on our interactive 3D horse model. Open 3D Model