Атлас по рентгенологии травмированных собак и кошек / an-atlas-of-radiology-of-the-traumatized-dog-and-cat
.pdf
422 Radiology of Musculoskeletal Trauma and Emergency Cases
4
Case 4.101
Signalment/History: “Smokey” was the name given to a young male cat who had been brought to the clinic as a “stray”. He was lame, but the nature of any trauma was unknown.
Physical examination: The left hip joint palpated abnormally and a fracture was evident in the left distal tibia with severe soft tissue swelling.
Radiographic procedure: Radiographs were made of the distal limb.
Radiographic diagnosis: The distal tibial fracture was badly comminuted with rather large butterfly fragments. A single fracture of the fibula was present. The fragments were impacted and the soft tissue injury was thought to be severe.
Joint disease at the antebrachiocarpal and intercarpal joints was characterized by subchondral bone cysts and periosteal new bone especially on the accessory carpal bone. Cranial rotation of the distal radial fragment had altered the plane of the articular surfaces of that joint contributing to the secondary arthrosis.
The elbow joint was radiographically normal. The soft tissues were thought to be unremarkable
Differential diagnosis: The cause of the trauma was unknown, if it were due to a bite wound, the possibility of secondary infection would have been considered likely.
Treatment/Management: The tibial fracture was treated with a full Kirschner apparatus (Type II splintage). Healing of the tibial fracture was delayed and a cancellous graft was added after two months.
Radiographs made at three months showed the Kirschner apparatus to still be in place. A small strip of bone joined the two major tibial fragments (white arrows). Another pointed “peak” of new bone extended from the distal fragment, but had failed to meet the proximal fragment (black arrows). The fibula had healed with a rather strong appearing union. Both stifle and tarsal joints were still normal in appearance. The tibial malunion was weak and resulted in the problem of deciding how to stage the removal of the external apparatus to permit further strengthening of the healing callus without overstressing it and causing a pathologic fracture.
Malunion fractures 423
Case 4.102 |
|
|
|
|
|
|
|
Signalment/History: |
“Yamo” |
|
|
was a 4-year-old, male German |
|
||
Shepherd mixed breed with a histo- |
|
||
ry of lower bowel obstruction. He |
|
||
had been straining to defecate over |
|
||
the previous three days. |
|
|
|
Physical examination: The dog |
|
||
was depressed and appeared to be |
|
||
uncomfortable. A large firm tubular |
|
||
mass was palpated in the abdomen. |
|
||
Radiographic procedure: Ab- |
4 |
||
dominal studies were made includ- |
|||
ing the pelvic region.
Radiographic diagnosis: A distended colon with an apparent constriction cranial to the pelvis was
filled with inspisated fecal material. A soft tissue mass was positioned between the pelvic rim and the distended colon, and probably represented the prostate gland. The urinary bladder could not be identified.
The badly deformed left hemipelvis resulted in at least a 50 % occlusion of the pelvic inlet. The left femoral head was seated within the malformed acetabulum. A small surgical plate was positioned on the acetabular margin. The small pin in the greater trochanter probably indicated the site of a trochanteric osteotomy. The malformed body of L7 and the heavy spondylosis deformans suggested a malunion fracture in this region.
Treatment/Management: Multiple enemas were administered and resulted in two small “onions” being retrieved in addition to the hard fecal material.
Comments: Later, the owner offered the history that “Yamo” had been struck by a car as a puppy and had had a surgically corrected pelvic fracture. They had not been informed of the LS fracture.
424 Radiology of Musculoskeletal Trauma and Emergency Cases
Case 4.103
4
Malunion fractures 425
Signalment/History: “Rose” was a 1-year-old, female kitten who had been found by the owner three weeks previously. She had been brought to the clinic because the owners thought she was pregnant and in labor. No kittens had been born.
Physical examination: Palpation of the abdomen suggested a gravid uterus and the cat was straining as though in labor.
Radiographic procedure: Radiographs were made of the abdomen and pelvis.
Radiographic diagnosis: Abdominal radiographs showed the gravid uterus with four fully developed fetal skeletons. No abnormal gas accumulation was associated with the skeletons and there was no collapse of the skeletal structures suggesting that the feti were dead.
Malunion fractures of the left ilium and ischium had resulted in the destruction of the acetabulum and a narrowing of the pelvic inlet. A chronic subcapital non-union epiphyseal fracture had lead to a dorsal luxation of the left femoral head. The right femur had a malunion fracture distally resulting in shortening of the bone. The right femoral head was normal and was seated within the acetabulum.
Treatment/Management: The kittens were removed by cesarean section some days after the radiographic examination and were all dead. The surgical incision became infected and because she had been a stray, the owners elected not to continue treatment but to have the cat euthanized. At necropsy, the vaginal stump of the uterus was infected along with the suture line.
Comments: The determination of fetal death on a radiographic study is only accurate after fluid absorption has resulted in collapse of the skeletal structures or if gas accumulation has occurred within the fetus. Ultrasound examination is the technique of choice in evaluation of fetal viability.
4
426 Radiology of Musculoskeletal Trauma and Emergency Cases
4
On presentation
Case 4.104
Signalment/History: A mature female German Shepherd was found and brought to the clinic because of an obvious mechanical lameness in the left pelvic limb.
Physical examination: Shortening of the limb plus the detection of a large firm mass around the midshaft of the femur suggested a healing fracture or a malunion fracture. The lesion was not painful tending to rule out an infectious or malignant lesion.
Radiographic procedure: Radiographs were made of the pelvis and both femurs.
Radiographic diagnosis: On the left, there was a chronic, comminuted, oblique midshaft femoral fracture in a healing phase, with marked separation and over-riding of the fragments. A massive exuberant callus had started to bridge between the two bones. The stifle joint appeared normal; however, the proximal fragment had assumed an anteversion position and caused a partial luxation of the femoral head (arrow). The fracture had the appearance of being more than one month old. Soft tissue atrophy around the affected limb was prominent.
Malunion fractures 427
4
2 months later
Treatment/Management: The dog was treated conservatively. Radiographs made two months later showed healing of the fracture with apposition and alignment of the fragments remaining unchanged. Note the femoral head appeared to be seated deeply, the result of the limb being in partial abduction.
Comments: Often it is important to determine the age of an injury to assist in the determination of treatment. In this dog, the fracture callus and modeling of the fragments suggested a stage of healing that would have made it nearly impossible to attempt a repositioning of the fracture fragments. The possibility of injury to tendon, ligament, or nerve was described to the owner in an explanation of the problems that the dog might have in walking. Note the transitional lumbosacral segment, which is a common congenital anomaly in this breed.
It is more accurate to measure the length of the femur on the lateral view, because it is parallel to the tabletop, than on the VD view in which position the femur may be at an angle to the surface.
428 Radiology of Musculoskeletal Trauma and Emergency Cases
4
Case 4.105
Signalment/History: “Gray Ling Cry” was an adult male cat with a history of a slight lameness in the left pelvic limb. The owners wanted to know more about the injury and its clinical importance.
Physical examination: The cat could walk on the affected limb suggesting a mechanical lameness rather than a lameness due to pain. A comparison of the length of the pelvic limbs indicated that the shortening of the left limb was indicative of a dorsocranial coxofemoral luxation. Movement of that limb produced marked crepitus. Soft tissue atrophy was slight.
Radiographic procedure: Radiographs were made of the pelvis and hip joints.
Radiographic diagnosis: While the lateral radiograph of the pelvis was relatively normal in appearance, the VD view showed an extensive pseudoarthrosis of the left coxofemoral joint. The new acetabular roof extending from the ilium was very prominent. The acetabulum was shallow with the appearance that the dorsocranial acetabular margin had fractured free. The femoral head and neck were severely deformed sug-
gesting that the capital epiphysis had fractured free and had subsequently undergone a malunion healing to the femoral neck. The free bony fragment adjacent to the bony spur attached to the right ilium was probably an avulsion from the greater trochanter. The right hip joint was normal.
Outcome: The owners chose not to consider a femoral head and neck ostectomy that was offered as a way to diminish the lameness and pain.
Comments: The exact explanation of the nature of the original trauma was an academic exercise that played only a minor role in either the clinical condition of the patient at the time of presentation in this case or the expected prognosis. The lesion is definitely post-traumatic with formation of a pseudoarthrosis following injury to the left hip joint.
Malunion fractures 429
Case 4.106 |
|
Signalment/History: “Rhonda” was a 2-year-old, female |
|
German Shepherd undergoing routine radiographs of the |
|
pelvis to determine the status of her hip joints. She had no his- |
|
tory of injury or lameness. |
|
Radiographic procedure: Routine VD studies were made |
|
of the pelvis for a hip dysplasia study. |
|
Radiographic diagnosis: Both hip joints were radiographi- |
|
cally normal with the femoral heads well formed and seated |
|
deeply in well-formed acetabula. A bony lesion involved the |
|
ischiatic tuberosity of the right ischium was characterized by a |
|
loss of the normal trabecular pattern, a displaced cortical seg- |
4 |
ment, and an area of increased bone density. |
Differential diagnosis: The dog was young and had no history of trauma. The diagnosis of a malunion/non-union fracture was considered first as a bone tumor or an osteomyelitis would have been associated with more reactive bone and would be more painful. Also, this lesion had a smooth border which suggested a chronic benign process.
Treatment/Management: Palpation of the tuberosity failed to produce any pain or discomfort and the lesion was not treated.
Comments: The discovery of what is assumed to be a chronic traumatic event is rather common in skeletal radiography. Often the finding is of no clinical importance, but in some patients it explains chronic lameness or may suggest the possibility of future clinical importance.
430 Radiology of Musculoskeletal Trauma and Emergency Cases
Case 4.107
4
Signalment/History: “Freta” was a 5-year-old, female German Shepherd mixed breed who was presented with muscle atrophy in the left pelvic limb.
Physical examination: The left limb lameness was more mechanical than painful. The stifle joint was enlarged but was non-painful and firm on palpation. The right tibia was thickened and deformed with a valgus deformity and slight caudal angulation.
Radiographic procedures: Studies were made of the pelvis and right pelvic limb.
Radiographic diagnosis (pelvis): A malunion left acetabular fracture, malunion pelvic fractures of the left ischium and ilium, and a post-traumatic fusion following a luxated right sacroiliac joint were noted. The severity of the post-traumat- ic arthrosis in the left hip joint was difficult to determine. The subluxation of the right femoral head could have been secondary to hip dysplasia or influenced by the malposition of the pelvis following the trauma. Generalized muscle atrophy was more pronounced on the right.
Malunion fractures 431
Radiographic diagnosis (tibia): A malunion fracture in the midshaft of the right tibia had resulted in a nonanatomic restoration with caudal and lateral angulation of the distal tibia resulting in a valgus deformity. Osteosynthesis of tibia and fibula had occurred. The persistent cavitary pattern (arrows) at the site of malunion suggested a chronic bone infection, whose state of activity could not be determined on the radiographs.
The post-traumatic joint disease in the stifle and tibiotarsal joints was important clinically.
Comments: What was rather confusing on physical examination became apparent through the radiographic studies. The biggest question as to the continued use of the left limb was the degree of severity of the arthrosis in the left hip joint and
what was the resulting limitation of movement of the pelvic 4 limb. The contour of the femoral head appeared near normal
suggesting that a femoral head or neck fracture was not a part of the injury. The question of why the muscle atrophy was more prominent on the right was answered by evaluation of the radiographs of the right tibia. The nature of that malunion fracture was influenced by the presence of chronic osteomyelitis. The original radiographs did not clearly show the severity of the joint injuries, which were possibly a major cause of the dog’s inability to use its limbs normally at the time of examination. A lateral malleolar fracture was suggested as well.
This was a difficult case, since the original injuries involved the left hip joint, the right stifle joint, and the right tibiotarsal joint. The joint injuries had a greater clinical importance at presentation than the malunion pelvic and tibial fractures. Superimposed on these injuries was the suspected chronic bone infection in the tibia.