Signalment & History
- This patient presents to your clinic for a severe forelimb lameness (grade 4). He has flip and fall 1 month ago.
- You order left fore foot radiographs.
Findings
- There is a fracture line arising from the solar margin of the lateral quarter of the distal phalanx, and reaching the articular surface of the distal interphalangeal joint (blue head arrow).
- Another fracture line is seen arising from the standpoint of the lateral quarter of the distal phalanx (white head arrow).
- Multiple punctate, well-defined, metal opaque structures are present within the nail tracts.
Diagnosis
- This patient is diagnosed with sub-acute, left distal phalangeal articular fracture (type II) with concurrent fissure line.
Fracture of distal phalanx
- Fractures of distal phalanx are more common in racing Thoroughbreds, Standardbreds and Quarter horses.
- Their 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.
The radiographic views to evaluate the third phalanx
- Dorso 65 proximal – palmaro distal oblique (1)
- Dorsopalmar view (2)
- Lateromedial view (3)
- DLPMO or DMPLO (4)
Radiographic classification if distal phalanx fractures
- Type I: Non articular 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.
