History
A 10-week-old Thoroughbred foal was evaluated for acute (grade 3/5) lameness in the right hind limb seen when trotting alongside the mare. The owners first noticed the lameness when the foal was brought in from the pasture with the mare. Physical examination of the right metatarsophalangeal joint revealed soft tissue swelling and edema, and palpation of the joint elicited signs of pain. Radiographs of the right metatarsophalangeal joint were obtained (Figure 1).
Lateral (A) and dorsoplantar (B) radiographic views of the right metatarsophalangeal joint of a 10-week-old Thoroughbred foal evaluated because of lameness (grade 3/5) in the right hind limb.
Citation: Journal of the American Veterinary Medical Association 228, 3; 10.2460/javma.228.3.353
Radiographic Findings and Interpretation
A midsagittal nondisplaced Salter-Harris type III fracture of the proximal phalanx of the right hind limb is evident (Figure 2).
Same dorsoplantar radiographic view as in Figure 1. Notice the sagittal fracture line (arrow) extending from the joint space distally into the physis of the proximal phalanx.
Citation: Journal of the American Veterinary Medical Association 228, 3; 10.2460/javma.228.3.353
Comments
Salter-Harris type III fractures are rare in foals, especially in this location. Salter-Harris type III fractures are most often seen in locations in which the growth plates are closing while the horse is beginning training.1 The fracture is initiated at the articular surface, crosses the epiphysis, enters the physis, and is propagated through the hypertrophic zone of the physis. This type of fracture is caused by torsion at the articular surface during weight bearing or by the propagation of shear forces through the articular surface into the epiphysis2 and is similar to the more common short incomplete midsagittal fractures of the proximal phalanx in racehorses.
To the authors’ knowledge, there are no previous reports of Salter-Harris type III fractures in the metacarpo- or metatarsophalangeal joints in foals. The fracture can be managed with consideration of the treatment of short incomplete midsagittal fractures or Salter-Harris type II and IV fractures in the proximal phalanx and type III fractures in other locations. Treatment options include conservative management with stall rest and external coaptation, or internal fixation with screws placed in lag fashion. Bone plating is not a viable option because of the small size and proximal location of the fracture fragment. The plate would also retard physeal growth and would need to be removed as soon as the fracture healed.1
In the foal of this report, the affected limb was placed in a semirigid bandage. The foal was confined in a stall for 6 weeks and received flunixin meglumine for pain and omeprazole prophylactically for gastric ulcers. External coaptation with bandages or casts that permit the foot to bear weight should only be necessary for 4 to 6 weeks because foals heal quickly.3 Casts should be changed at 2-week intervals. Casts that enclose the foot may cause severe osteopenia, soft tissue injury, and laxity of the flexor tendons and suspensory ligaments that support the metatarsophalangeal joint.4
One serious complication of physeal injury is angular limb deformity caused by transphyseal callus formation if the metaphysis and epiphysis are malaligned.2 Degenerative joint disease may also develop because of the intra-articular component of the fracture. Reduction and stabilization minimize this potential complication.5
Within 5 days, the foal's lameness improved, compared with the initial examination. Treatment progressed without complications; the bandage support was maintained until no lameness was observed and radiographic evidence of a fracture line was not detected (6 weeks after initial examination; Figure 3). Radiographs of the joint were obtained at monthly intervals for 3 months after resolution of the fracture to look for radiographic changes of osteoarthritis; no changes were seen.
Dorsoplantar radiographic view of the right metatarsophalangeal joint of the foal in Figure 1 six weeks after the initial radiographs were obtained. Notice that the fracture line is no longer evident, indicating healing of the fracture.
Citation: Journal of the American Veterinary Medical Association 228, 3; 10.2460/javma.228.3.353
- 2↑
Watkins JP. Physeal injuries. In: Colahan PT, Merritt AM, Moore JN, et al, eds. Equine medicine and surgery. Vol 2. 5th ed. St Louis: Mosby, 1999;1356–1357.
- 3↑
Richardson DW. Diseases with physical causes—fractures of the proximal phalanx. In: Colahan PT, Merritt AM, Moore JN, et al, eds. Equine medicine and surgery. Vol 2. 5th ed. St Louis: Mosby, 1999;1558–1565.
- 4↑
Nunamaker DM. Diseases with physical causes—fractures of the third metacarpal and third metatarsal bones. In: Colahan PT, Merritt AM, Moore JN, et al, eds. Equine medicine and surgery. Vol 2. 5th ed. St Louis: Mosby, 1999;1587–1594.
- 5↑
DeBowes RM, Grand BD, Modransky PD. Lag screw stabilization of a Salter type IV femoral fracture in a young horse. J Am Vet Med Assoc 1983; 182: 1123–1125.
