Findings
- Arising from the solar margin of the lateral quarter of the distal phalanx, and reaching the articular surface of the distal interphalangeal joint, a well-defined fractures line is identified (blue arrowheads). Just lateral, another fracture line is seen extending transversely from the lateral quarter of the distal phalanx (white arrowheads).
- Multiple punctate, well-defined, metal opaque structures are present within the nail tracts.
Diagnosis
- Left distal phalangeal articular fracture (type II) with concurrent fissure line.
A little bit more…
- Fractures of distal phalanx are more common in racing Thoroughbreds, Standardbreds and Quarter horses.
- Causes include racing on hard surfaces, falling, kicking hard, foreign body puncture, and immovable objects. They can be predisposed by osteomyelitis, nutritional deficiencies, upright conformation, unbalancing shoe, and laminitis.
- Clinical findings include the presence of lameness at a walk or trot, digital pulses and heat at the coronary band with an acute fracture; and resentment to compression of the sole and wall with hoof testers.
- The differential diagnoses of distal phalanx fractures include sole abscess, bruised sole, pedal osteitis, navicular bone fracture, navicular disease, foreign body penetration, and laminitis.
Radiographic classification if distal phalanx fractures
- Type I: Nonarticular fractures of the palmar/plantar process of the bone
- Type II: Articular fractures that are not midsagittal and extend from the distal interphalangeal joint to the solar margin of the bone.
- Type III: Midsagittal articular fractures that divide the distal phalanx into two approximately equal parts.
- Type IV: Fractures of the extensor process
- Type V: Comminuted fractures involving the body and solar margin of the distal phalanx
- Type VI: Fractures on the solar margin of the distal phalanx
- The most common fracture is the type VI, followed by the type II
- They are more frequent in the forelimb, probably because they bear more weight than hind limb
- The fracture line for all types become wider in the first week until a maximum width seen at 4 to 6 weeks after injury.
- In Racehorses, distal phalanx fractures occur more frequent in the medial aspect of the right front, and the lateral aspect of the left front.
- CT studies allow a better approach for fractures recognition.
- Discrete fractures are not visualized in radiographs but can be achieved with CT.
References
- Honnas, C. et al. Distal phalanx fractures in horses. A survey of 274 horses with radiographic assessment of healing in 36 horses. Veterinary Radiology, vol 29, No. 3, 1988. pp.99-107
- Crijins, C.P., et al. Equine Veterinary Journal 46, 2014. pp.92-96.