History
A 6-month-old male American Staffordshire Terrier was evaluated because of a 2-day history of moderate-to-severe left hind limb lameness. The owner first noticed the lameness after the dog was left in the backyard unsupervised. The dog had been previously healthy.
On physical examination, the dog had a non–weight-bearing lameness of the left hind limb. Signs of severe discomfort were evident on manipulation of the left hip joint. The remainder of the physical examination findings were unremarkable. Packed cell volume, total protein concentration, and BUN concentration were measured, and results were within reference ranges. Radiographs of the pelvis were obtained (Figure 1).
Right lateral (A) and ventrodorsal (B) radiographic views of the pelvis of a 6-month-old male American Staffordshire Terrier with a 2-day history of left hind limb lameness.
Citation: Journal of the American Veterinary Medical Association 245, 11; 10.2460/javma.245.11.1225
Determine whether additional imaging studies are required, or make your diagnosis from Figure 1—then turn the page →
Diagnostic Imaging Findings and Interpretation
On the ventrodorsal radiographic image (Figure 2), a well-defined, 12-mm-long, concave defect and a decrease in opacity of the medial portion of the femoral head are evident. Radiopacity of the proximal aspect of the femoral neck is increased and the physis is ill-defined. On the lateral radiographic image, a well-defined, 15-mm-long, oval bone opacity is seen immediately cranial to the acetabula.
Same radiographic images as in Figure 1. A well-defined, 12-mm-long, concave defect is evident (arrows). The medial portion of the femoral head has an area of decreased radiopacity. Notice the well-defined, 15-mm-long, oval bone opacity immediately cranial to the acetabula (arrowheads).
Citation: Journal of the American Veterinary Medical Association 245, 11; 10.2460/javma.245.11.1225
A ventrodorsal view of the pelvis with the hind limbs flexed was obtained (Figure 3). A fracture of the capital physis associated with the left femur that extended through the craniomedial aspect of the femoral head was observed. The epiphyseal fracture fragment was sharply margined and displaced cranially and distally. These findings were consistent with an acute Salter-Harris type III fracture of the left femoral capital physis.
Ventrodorsal view of the pelvis with the hind limbs flexed of the same dog as in Figure 1. A fracture of the capital physis associated with the left femur that extends through the craniomedial aspect of the femoral head is evident. The epiphyseal fracture fragment is sharply margined and is displaced cranially and distally (arrow).
Citation: Journal of the American Veterinary Medical Association 245, 11; 10.2460/javma.245.11.1225
A CT scan of the pelvis with multiplanar and 3-D reformatted images of the pelvis and left femur was performed to better evaluate the fracture conformation (Figure 4). Computed tomography revealed a comminuted Salter-Harris type III fracture of the left femoral capital physis involving the craniomedial aspect of the epiphysis. Two large displaced epiphyseal fracture fragments were displaced cranially and distally, and the largest fragment measured 9 × 12 × 5 mm.
Three-dimensional CT reconstruction of the craniomedial proximal portion of the left femur (A) and transverse CT image of the pelvis at the level of the hip joints (B; slice thickness, 1 mm; bone standard algorithm) of the same dog as in Figure 1. Notice the comminuted Salter-Harris type III fracture of the left femoral capital physis involving the craniomedial aspect of the epiphysis. Two large displaced epiphyseal fracture fragments (medial fragment [white arrows] and cranial fragment [black arrows]) are displaced cranially and distally.
Citation: Journal of the American Veterinary Medical Association 245, 11; 10.2460/javma.245.11.1225
Treatment and Outcome
The dog underwent surgery for open reduction and internal fixation of the fractures. A ventromedial approach to the left hip joint was performed. Two osteochondral fragments were identified: one smaller distally displaced avulsion fragment attached to the round ligament and another larger cranially and distally displaced fragment attached to part of the joint capsule. The fragments were anatomically reduced and stabilized with a combination of Kirschner wires and lag screws. Implants were countersunk to below the level of the articular cartilage. Reduction, implant size, and implant positioning were considered to be excellent on radiographs obtained immediately after surgery.
The dog continued to be non–weight bearing lame on its left hind limb after surgery. Radiographs obtained 6 weeks after surgery revealed resorption of the craniomedial aspect of the left femoral head, subluxation of the left hip joint, and subsequent left hip joint osteoarthritis. A total hip joint replacement surgery or femoral head and neck ostectomy was recommended.
Comments
Fractures of the capital femoral physis in immature dogs are usually Salter-Harris type I or II. Salter-Harris type III (as seen in this case) and IV fractures are rare.1 Salter-Harris type III fractures are usually avulsion fractures with no comminution, where the round ligament remains attached to the small epiphyseal fragment.1
Standard pelvic radiography may not allow for detection of fractures involving the hip joint because of superimposition of osseous structures or inadequate x-ray beam orientation through the fracture site. In addition to the typical lateral and ventrodorsal views, addition of a ventrodorsal view of the pelvis with the hind limbs flexed helps in the assessment of femoral head and femoral neck traumatic lesions.2 In this case, the ventrodorsal image with the hind limbs flexed better delineated one of the fracture fragments, compared with the standard orthogonal pelvic views. Computed tomography was further able to aid in the characterization of the fracture. One recent clinical study3 of pelvic fractures demonstrated that CT was superior to radiography for the characterization of acetabular fracture configurations.
An accurate understanding of the precise fracture configuration before surgery is often crucial for selecting the best surgical treatment option. In hindsight, it could be argued that this dog should have been treated with a femoral head and neck ostectomy or total hip joint replacement because of the multifragmentary nature of the fracture and associated guarded prognosis.4
1. Vernon FF, Olmstead ML. Femoral head fractures resulting in epiphyseal fragmentation: results of repair in 5 dogs. Vet Surg 1983; 12: 123–126.
2. Rendano VT, Quick CB, Allen GS, et al. Radiographic evaluation of femoral head and neck fractures: the value of the flexed ventrodorsal and oblique projections in diagnosis. J Am Anim Hosp Assoc 1980; 16: 485–491.
3. Draffan D, Clements D, Farrell M, et al. The role of computed tomography in the classification and management of pelvic fractures. Vet Comp Orthop Traumatol 2009; 22: 190–197.
4. Gibson KL, vanEe RT, Pechman RD. Femoral capital physeal fractures in dogs: 34 cases (1979–1989). J Am Vet Med Assoc 1991; 198: 886–890.
