Os tarsi centrale
The central tarsal bone sits in the middle of the hock between the talus (above) and the third tarsal bone (below). It articulates laterally with the fourth tarsal bone. Together with the third and fourth tarsal bones it forms the distal intertarsal and tarsometatarsal joints: the joints most often affected by bone spavin (osteoarthritis of the distal hock). Because these joints have limited motion, osteoarthritis here produces a characteristic gait and can be managed with joint injections, shoeing changes, or, in advanced cases, surgical arthrodesis. The central tarsal bone itself can also develop fractures or osteochondral lesions, though less commonly than the distal joints.
Bone spavin is one of the most common hind-limb lamenesses. Radiographs show joint-space narrowing, bone proliferation, and sclerosis. Diagnostic anesthesia of the distal hock joints confirms the source of pain. Fractures of the central tarsal bone are less frequent but can occur with trauma.
## 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
## Overview Bone spavin is osteoarthritis (degenerative joint disease) of the distal tarsal joints, principally the distal intertarsal and tarsometatarsal joints. Repeated compression and rotation da
## Overview Fractures of the central tarsal bone are uncommon slab or sagittal fractures, most often seen in racehorses and occasionally in sport horses. They typically run in a dorsomedial to planta
A hind limb that is stiff at the start of work, improves with exercise, or shows a shortened stride and reduced hock flexion may have distal hock arthritis. Have a veterinarian evaluate it; early management often keeps horses comfortable.
## 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
## Overview Bone spavin is osteoarthritis (degenerative joint disease) of the distal tarsal joints, principally the distal intertarsal and tarsometatarsal joints. Repeated compression and rotation damage cartilage, narrow the joint spaces, and stimulate new bone formation. The result is progressive hind-limb lameness that is one of the most common causes of performance limitation in sport horses. ## Causes Repetitive concussion, conformational faults (straight or sickle hocks), and athletic activities that heavily load the hocks (jumping, dressage, western performance) are the main drivers. Mineral imbalances have been suggested but evidence is limited. ## Diagnosis History of gradual hind-limb lameness that may warm out of, positive flexion tests, and a characteristic “stabbing” or short stride are suggestive. Radiographs show joint-space narrowing, sclerosis, and periarticular new bone. Diagnostic analgesia of the distal tarsal joints confirms the source of pain. ## Treatment Non-steroidal anti-inflammatory drugs, intra-articular corticosteroids, corrective shoeing, and workload modification are first-line measures. Chemical or surgical arthrodesis (facilitated ankylosis) can be considered when medical management fails and the goal is pain-free fusion of the low-motion joints. ## Recovery and Prognosis Many horses remain useful with medical management. Complete fusion, whether spontaneous or surgical, can restore comfort. Advanced bilateral disease may ultimately limit athletic career length. ## Prevention Selection for good hock conformation, balanced shoeing, and sensible training progression reduce risk but cannot eliminate it in high-level athletes. Signs include: gradual hindlimb lameness; shortened stride or toe dragging; positive hock flexion test; bony enlargement on the medial lower hock in advanced cases; stiffness after rest
## Overview Fractures of the central tarsal bone are uncommon slab or sagittal fractures, most often seen in racehorses and occasionally in sport horses. They typically run in a dorsomedial to plantarolateral orientation and may be complete or incomplete. Acute hind-limb lameness after fast work is the usual presentation. ## Causes Repetitive high-speed loading and conformational factors (including wedge-shaped third tarsal bones) predispose to fracture. Previous distal tarsal arthrodesis can also alter loading. ## Diagnosis Acute lameness localized to the hock, positive flexion, and radiographic demonstration of the fracture line are typical. Standing magnetic resonance imaging is particularly useful for incomplete fractures that are difficult to see on plain films. ## Treatment Lag-screw fixation is preferred for displaced or complete fractures when osteoarthritis is absent. Selected nondisplaced incomplete fractures may heal with conservative management, although surgical repair generally yields higher return-to-performance rates. ## Recovery and Prognosis Outcomes vary with fracture configuration and treatment. Concurrent osteoarthritis worsens the outlook. ## Prevention No specific prevention is established beyond sensible training progression in at-risk horses. Signs include: acute hindlimb lameness after fast work; positive hock flexion; pain on palpation of the distal tarsus; radiographic fracture line
Bone spavin is one of the most common hind-limb lamenesses. Radiographs show joint-space narrowing, bone proliferation, and sclerosis. Diagnostic anesthesia of the distal hock joints confirms the source of pain. Fractures of the central tarsal bone are less frequent but can occur with trauma.
A hind limb that is stiff at the start of work, improves with exercise, or shows a shortened stride and reduced hock flexion may have distal hock arthritis. Have a veterinarian evaluate it; early management often keeps horses comfortable.
See the Central Tarsal Bone (Left) on our interactive 3D horse model. Open 3D Model