History
A 4-year-old male Border Terrier was examined because of a right hind limb lameness of 2 days' duration. Immediately prior to the onset of lameness, the dog had fallen from a tabletop while inside a traveling crate.
Dorsoplantar (A) and mediolateral (B) views of the right tarsus of a 4-year-old male Border Terrier with a non–weight-bearing lameness of 2 days' duration.
Citation: Journal of the American Veterinary Medical Association 231, 12; 10.2460/javma.231.12.1809
Dorsoplantar (A) and mediolateral (B) views of the right tarsus of a 4-year-old male Border Terrier with a non–weight-bearing lameness of 2 days' duration.
Citation: Journal of the American Veterinary Medical Association 231, 12; 10.2460/javma.231.12.1809
Dorsoplantar (A) and mediolateral (B) views of the right tarsus of a 4-year-old male Border Terrier with a non–weight-bearing lameness of 2 days' duration.
Citation: Journal of the American Veterinary Medical Association 231, 12; 10.2460/javma.231.12.1809
On physical examination the dog was non–weight bearing on the right hind limb. Extension of the right tarsus induced signs of pain. The initial examination did not reveal any instability in the tarsus. Dorsoplantar and mediolateral radiographic views of the right tarsus were obtained (Figure 1).
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Radiographic Findings and Interpretation
Circumferential soft tissue swelling of the right tarsus is evident. There is a transverse fracture through the body of the first tarsal bone with mild distal and abaxial displacement of the distal segment. A subtle finding is bony fragmentation in the plantar soft tissues adjacent to the first and fourth tarsal bones. Subjectively, the tarsometatarsal joint space appears widened (Figure 2).
Same radiographic views as in Figure 1. Notice the circumferential soft tissue swelling (white arrowheads), transverse fracture of the first tarsal bone (arrow), small bony fragments plantar to the first and fourth tarsal bones (white chevron), and widening of the tarsometatarsal joint space (black arrowheads).
Citation: Journal of the American Veterinary Medical Association 231, 12; 10.2460/javma.231.12.1809
Same radiographic views as in Figure 1. Notice the circumferential soft tissue swelling (white arrowheads), transverse fracture of the first tarsal bone (arrow), small bony fragments plantar to the first and fourth tarsal bones (white chevron), and widening of the tarsometatarsal joint space (black arrowheads).
Citation: Journal of the American Veterinary Medical Association 231, 12; 10.2460/javma.231.12.1809
Same radiographic views as in Figure 1. Notice the circumferential soft tissue swelling (white arrowheads), transverse fracture of the first tarsal bone (arrow), small bony fragments plantar to the first and fourth tarsal bones (white chevron), and widening of the tarsometatarsal joint space (black arrowheads).
Citation: Journal of the American Veterinary Medical Association 231, 12; 10.2460/javma.231.12.1809
Comments
While the dog was sedated for radiography, a more thorough physical examination of the right tarsus was performed. Instability could be appreciated on the medial aspect when a laterally directed force was applied to the foot. A dorsoplantar radiographic view of the tarsus was obtained while applying this lateral force (Figure 3). The fracture can be more easily visualized with exacerbation of the distal and abaxial displacement of the distal segment. Also evident on this view is subluxation of the second, third, and fourth tarsometatarsal joints. This view demonstrates the importance of using stress radiography to fully evaluate tarsal injuries where ligamentous damage is suspected.1,2 Stress radiography is defined as “the application of a controlled force upon a joint in order to show an abnormal spatial relationship between two or more of its components.”2 This technique can be vital to the diagnosis and appropriate treatment of sprain injuries and is probably underutilized in general practice.2 When performing these studies, anesthesia or sedation is recommended to facilitate accurate positioning and minimize patient discomfort. Force is manually applied to the joint in such a way that instability consistent with damage to supporting soft tissue structures can be appreciated radiographically. Various objects may be used as a fulcrum to help stabilize the area under investigation and direct the force correctly.2 In the dog of this report, the limb was positioned as it would be to obtain a dorsoplantar radiographic view of the tarsus and stabilized by grasping the limb just distal to the stifle. Nonporous tape was wrapped around the metatarsal bones and was used to pull the foot laterally, revealing the medial instability (Figure 3).
Stressed dorsoplantar radiographic view of the right tarsus. Notice the distal and abaxial displacement of the distal segment of the fractured first tarsal bone (white arrow) and subluxation of the second, third, and fourth tarsometatarsal joints (black arrowheads).
Citation: Journal of the American Veterinary Medical Association 231, 12; 10.2460/javma.231.12.1809
Stressed dorsoplantar radiographic view of the right tarsus. Notice the distal and abaxial displacement of the distal segment of the fractured first tarsal bone (white arrow) and subluxation of the second, third, and fourth tarsometatarsal joints (black arrowheads).
Citation: Journal of the American Veterinary Medical Association 231, 12; 10.2460/javma.231.12.1809
Stressed dorsoplantar radiographic view of the right tarsus. Notice the distal and abaxial displacement of the distal segment of the fractured first tarsal bone (white arrow) and subluxation of the second, third, and fourth tarsometatarsal joints (black arrowheads).
Citation: Journal of the American Veterinary Medical Association 231, 12; 10.2460/javma.231.12.1809
By considering the regional anatomy, it is possible to hypothesize about the pathologic lesions underlying the radiographic findings.3 The long and short components of the medial collateral ligament have an attachment to the first tarsal bone. The fracture may represent an avulsion of these attachments resulting in medial instability. Subluxation of tarsometatarsal joints 2, 3, and 4 is suggestive of damage to the small dorsal tarsometatarsal ligaments traversing these joint spaces. The soft tissue swelling probably had articular (attributable to stretching and tearing of the joint capsule) and extra-articular components (secondary to the fracture and ligamentous damage).
Tarsometatarsal subluxation is most commonly caused by traumatic injury to the support structures of the tarsus, and various degrees of plantar, mediolateral, and dorsal instability may be appreciated.4 Subluxation may be accompanied by fracture of tarsal or metatarsal bones,5 although to the authors' knowledge, concurrent fracture of the first tarsal bone has not been reported. Various methods of partial tarsal arthrodesis have been used to successfully treat these subluxations.5
The instability was mild in the dog of this report; therefore, external coaptation (lateral splint) was used on a trial basis. After 2 weeks, the joint was more stable on palpation. Coaptation for an additional month was successful in allowing the fractured first tarsal bone to heal and in restoring stability to the tarsometatarsal joint. The dog returned to normal function.
References
- 1.
Dee JF. Tarsal injuries. In: Bloomberg MS, Dee JF, Taylor RA, eds. Canine sports medicine and surgery. Philadelphia: WB Saunders Co, 1998;120–137.
- 2.↑
Farrow CS. Stress radiography: applications in small animal practice. J Am Vet Med Assoc 1982;181:777–784.
- 3.↑
Evans HE. Tarsal joints. In: Evans HE, ed. Miller's anatomy of the dog. 3rd ed. Philadelphia: WB Saunders Co, 1993;252–256.
- 4.↑
Piermattei DL, Flo GL, DeCamp CE. The metatarsus, phalanges and sesamoids. In: Piermattei DL, Flo GL, DeCamp CE, eds. Brinker, Piermattei and Flo's handbook of small animal orthopedics and fracture repair. 4th ed. St Louis: Elsevier Inc, 2006;707–713.
- 5.↑
Muir P, Norris JL. Tarsometatarsal subluxation in dogs: partial arthrodesis by plate fixation. J Am Anim Hosp Assoc 1999;35:155–162.
