Radiographic evaluation of acetabular component position in dogs.

OBJECTIVE: To assess the usefulness of standard radiographic projections for determining acetabular cup position and to compare 2 radiographic methods for calculation of the angle of lateral opening of the acetabular cup. STUDY DESIGN: In vitro radiographic study. METHODS: Acetabular components were mounted on a custom-built inclinometer. The effect of varying the angles of lateral opening, inclination, version, and centering of the x-ray beam on the radiographic appearance of the cup was investigated. The angle of lateral opening was calculated trigonometrically after direct measurement and by means of computer-aided image analysis. RESULTS: Using a ventrodorsal radiograph, the computer-aided measurement of angle of lateral opening was accurate to within 5 degrees when the true angle of lateral opening was > or = 40 degrees. In the case of direct measurement, the calculated angle was accurate to within 5 degrees only when the true angle was > or = 60 degrees. An increasing angle of inclination was associated with reduced accuracy of calculation of the angles of lateral opening and version. Standard radiographic assessment of acetabular version and inclination was not found to be clinically useful. The displacement of the x-ray beam, which would cause significant error in the determination of lateral opening, is unlikely to be exceeded in practice. Cup size had no significant effect on the accuracy of the results. CONCLUSIONS: Computer-aided image analysis can be used to calculate angles of lateral opening to within 10 degrees throughout the range of acetabular positions seen in practice and is appropriate for postoperative documentation of cup position. The angles of inclination and version should be interpreted with caution.

Premature closure of the proximal physis of the humerus in a dog as a result of harvesting a cancellous bone graft.

A 5-month-old castrated male mixed-breed dog was evaluated because of lameness of the right forelimb. Physical examination revealed pain on manipulation of the right elbow joint, and radiography revealed premature closure of the distal physis of the radius with subluxation of the right elbow joint. Corrective osteotomy of the radius was performed to increase the length of the radius and establish congruity of the elbow joint. Cancellous bone was obtained from the proximal portion of the humerus and used as a graft at the osteotomy site. The dog did well after surgery. Four months after surgery, the dog again was lame on the right forelimb. Physical examination revealed instability of the right shoulder, and manipulation of that area elicited signs of pain. Radiography revealed caudomedial subluxation of the right shoulder as well as deformity of the humeral head and hypoplasia of the greater tubercle. It was presumed that these changes were associated with collection of the cancellous bone graft during the initial surgery, which resulted in premature closure of the proximal physis of the humerus. To our knowledge, this is the first report of premature closure of the proximal physis of the humerus as a result of procurement of a bone graft.

Evaluation of the compressive mechanical properties of endoluminal metal stents.

The mechanical properties of metal stents are important parameters in the consideration of stent design, matched to resist arterial recoil and vascular spasm. The purpose of this study was to develop a system for a standardized quantitative evaluation of the mechanical characteristics of various coronary stents. Several types of stents were compressed by external hydrostatic pressure. The stent diameter was assessed by placing a pair of small ultrasonic sono-crystals on the stent. From pressure-strain diagrams the ultimate strength and radial stiffness for each stent were determined. For all stents, except the MICRO-II and the Wiktor stent, the diameter decreased homogeneously until an ultimate compressive strength was exceeded, causing an abrupt collapse. Expanded to 3 mm, the mechanical behavior of the beStent, the Crown and the Palmaz-Schatz stent (PS153-series) were comparable. The spiral articulated Palmaz-Schatz stent showed twice the strength (1.26 atm) of the PS-153 (0.65 atm). The NIR stent yielded a maximum strength of 1.05 atm. The MICRO-II and the Wiktor stent did not collapse abruptly but rather showed a continuous decline of diameter with increasing external pressure. The Cardiocoil stent behaved in a fully elastic manner and showed the largest radial stiffness. Difference in mechanical properties between stents were documented using a new device specifically developed for that purpose. These mechanical stent parameters may have important clinical implications.

Subdural injection of contrast medium during cervical myelography.

Three patients (1 dog, 2 horses) are described where myelography was complicated, purportedly by injection of contrast medium into the meninges superficial to the subarachnoid space. Contrast medium injected in this location in a cadaver tended to accumulate dorsally within the vertebral canal, deep to the dura mater but superficial to the subarachnoid space. The ventral margin of the pooled contrast medium had a wavy or undulating margin and the dorsal margin was smooth. Pooled contrast medium was believed to be sequestered within the structurally weak dural border cell layer between the dura mater and arachnoid membrane, or the so-called subdural space.

Treatment of dogs with wounds of the limbs caused by shearing forces: 98 cases (1975-1993).

Medical records of 98 dogs with wounds of the limbs caused by shearing forces (shearing wounds) were reviewed. Shearing wounds were reported most often in young dogs of many breeds, and most often resulted from trauma received during an encounter with an automobile. Wounds were located mainly on the distal portion of the limbs, with the most common site being the medial aspect of the tarsus and metatarsus. All injuries resulted in exposure of subcutaneous soft tissues, about three fourths of all injuries resulted in bone or joint exposure, and slightly more than half of the dogs had joint instability. All wounds were lavaged and debrided. Wounds were sutured, using primary closure techniques or methods that allowed the wound to remain partially or totally open to heal by second intention. Bandages were applied in all dogs. Most bandages were reinforced with a splint device. Grafting procedures or internal fixation devices were not used in initial treatment of the injuries. In the study reported here, healing time ranged from 2.0 to 8.7 weeks, depending on the size and depth of the wound and type of closure used. Mean number of anesthetic and surgical procedures was 1.7 per dog, and the mean number of rechecks after discharge from the hospital was 5.5 per dog. Outcome was considered excellent or good in 89 of 98 (91%) dogs; these dogs were clinically normal or had only minor functional abnormalities after their injuries healed. Outcome was poor in 9 of 60 (15%) dogs.

Radiographic anatomy of the medial coronoid process of dogs.

Mediolateral, flexed mediolateral, mediocaudal-laterocranial 15 degrees oblique (extended and supinated mediolateral), and craniolateral-caudomedial 20 degrees to 30 degrees oblique radiographs of 16 elbow-joint specimens were produced to study the radiographic anatomy of the medial coronoid process. On the mediolateral view, the cranial point of the coronoid process was at the level of the distal one-third of the radial epiphysis. Degree of superimposition of the proximal radius and ulna determined how the medial coronoid process was projected on the radiographs. Mediocaudal-laterocranial oblique radiographs best showed the cranial outline of the medial coronoid process with moderate superimposition of the proximal radius and ulna.

Displacement of the tendon of the superficial digital flexor muscle in dogs: 10 cases (1983-1991).

Displacement of the tendon of the superficial digital flexor muscle was diagnosed in 9 dogs (10 tarsi). Four of 10 displacements occurred in Shetland Sheepdogs. All dogs had an acute onset of lameness with swelling over the proximal end of the tuber calcanei. Lateral displacement occurred in 8 tarsi and medial displacement in 2 tarsi. Nonsurgical treatment (exercise restriction, bandaging, and administration of anti-inflammatory medication) was ineffective in the 5 dogs in which it was attempted. Surgical reconstruction of the supporting soft tissues resulted in return to normal function in 9 cases available for follow-up evaluation.

Pelvic osteotomy as a treatment for obstipation in cats with acquired stenosis of the pelvic canal: six cases (1978-1989).

Pelvic osteotomy with removal or repositioning of bone was performed as treatment for obstipation in 6 domestic shorthair cats with stenosis of the pelvic canal. Narrowing of the pelvic canal was the result of pelvic fracture or sacroiliac luxation in all cats. Tenesmus and obstipation began shortly after pelvic injury in 3 cats and 5 to 12 months after injury in the remaining cats. The duration of clinical signs ranged from 36 hours to 36 months. The duration of large intestinal obstruction influenced the outcome of surgery. Surgical widening of the pelvic canal helped eliminate signs of obstruction when signs were of less than 6 months' duration (n = 2). When signs of obstipation had continued for a longer period, and megacolon had developed, such treatment was minimally effective (n = 4).

Complications associated with the use of Steinmann intramedullary pins and cerclage wires for fixation of long-bone fractures.

There is a unique clinical situation created with each fracture. The veterinarian must be able to synthesize an acceptable method of treatment based on the patient, the owner, and the particular fracture with which he or she is confronted. Stable fixation and preservation of blood supply are prerequisites to successful osteosynthesis. Careful consideration of the fracture type and its location will provide an insight to the type and magnitude of forces that caused the fracture and which might disrupt fixation. Understanding the strengths and weaknesses of the particular implant and adhering to the principles of use will limit the number of complication that occur. Proper application of the implant is of utmost importance.

Partial rupture of the cranial cruciate ligament of the stifle in dogs: 25 cases (1982-1988).

Partial rupture of the cranial cruciate ligament was diagnosed in 25 dogs. In all dogs, the primary problem at the time of physical examination was hind limb lameness. The mean time from initial onset of lameness to diagnosis at exploratory surgery was 17 weeks. A cranial drawer sign was detected in 13 of the 25 dogs; in 9, the cranial drawer sign was evident only when the stifle was positioned in flexion. Of the 25 dogs, 12 had no detectable cranial drawer sign in response to manipulation of the involved stifle. In all dogs, lateral stifle arthrotomy was performed in routine manner, and the cranial cruciate ligament was found to be incompletely torn. Lesions identified during arthrotomy were rupture of the craniomedial band (n = 20 dogs), interstitial tear (n = 4 dogs), and rupture of the caudolateral band (n = 1 dog).

Problems associated with the management and treatment of jaw fractures.

Fractures of the mandible and maxilla occur frequently in the dog and cat. Appropriate preoperative, intraoperative, and postoperative management of jaw fractures is imperative for successful results. Various techniques of jaw fracture management, including tape muzzles, circumferential wiring, interarcade wiring, interosseous wiring, interdental wiring, acrylic splints, percutaneous skeletal fixation, intramedullary pinning, bone plating, and partial mandibulectomy, have unique advantages and disadvantages. Selection of the appropriate method of fixation depends on the signalment of the animal, type of fracture, and the veterinarian's experience and expertise with the various types of fixation. Careful postoperative evaluation will result in the early detection of problems and ensure proper postoperative care.

Use of flexible intramedullary rods for fixation of femoral fractures in eight dogs.

High-density, polysulfone rods were used to repair 4 comminuted and 4 short-oblique, mid-diaphyseal femoral fractures in 8 dogs. Bony union was achieved in 2 dogs at 10 and 12 weeks after surgery. In one dog, the femoral fracture was healing when amputation of the limb became necessary because of sciatic nerve damage secondary to an ipsilateral pelvic fracture. In a fourth dog, fracture repair resulted in nonunion, despite normal clinical function at 18 months after surgery. In the remaining 4 dogs (50%), the rods failed at 3.5, 4, 6, and 22 weeks after surgery. These fractures were then stabilized by use of other methods. Although several factors may have contributed to failure of the rods, multiple autoclaving of the thermoplastic implants may have caused embrittlement and subsequent breakage.

Dynamic intramedullary crosspinning technique for repair of distal femoral fractures in dogs and cats: 71 cases (1981-1985)

Dynamic intramedullary crosspinning was used in the surgical treatment of supracondylar and distal physeal fractures of the femur in 129 dogs and cats over a 5-year period; the records of the 44 dogs and 27 cats with follow-up information up to time of bony union were evaluated. The results were good or excellent in 66 of 71 animals (93%). The mean follow-up period was 22 months. Distal pin migration was the major complication (10 animals; 14%). The pin migrated before bony union in 2 animals because of instability and collapse at the fracture site. The pin migrated in 8 animals after bony union and was associated with intermittent lameness. In 5 of these, pin removal was performed and the lameness resolved.

Detection of sacral sparing in acute spinal cord injury.

Sacral dermatomal-evoked responses (DEP) and posterior tibial nerve (PTN) somatosensory-evoked potentials (SSEP) were recorded 28 hours after gunshot injury to the 12th thoracic vertebra of a 17-year-old male. Repeatable responses were obtained from stimulation of the fourth sacral dermatome despite absence of repeatable PTN responses. This suggestion of "sacral sparing" was accompanied by clinical improvement of neural function during the hospital course and 10 months after discharge. This case suggests DEP can make valuable contributions in the diagnosis of sacral sparing in acute spinal cord injury. Considerations regarding the unusual ipsilateral scalp recording location for sacral DEP are discussed.

Peripheral nerve injury associated with fracture or fracture-dislocation of the pelvis in dogs and cats: 34 cases (1978-1982).

Peripheral nerve injury was associated with fracture or fracture-dislocation of the pelvis in 23 dogs and 11 cats. In most cases, peripheral nerve injury resulted from ilial fracture with craniomedial displacement of bone fragments, or from sacroiliac fracture-dislocation with cranial displacement of the ilium. Sciatic nerve injury was associated with fracture of the acetabulum in 2 dogs. A combination of sensory, voluntary motor, and reflex abnormalities were observed in the ipsilateral extremity of affected animals. Signs of severe pain were noticed in 4 of the dogs and in 1 cat. Eight of the animals died or were euthanatized for reasons not directly related to the severity of peripheral nerve injury. Of the remaining 26 animals, 21 (81%) had good or excellent limb function 16 weeks after peripheral nerve injury was sustained. Limb function was lost or self-mutilation occurred in 4 (15%) of the animals.

Osteosarcoma in cats: 22 cases (1974-1984).

Osteosarcoma was diagnosed in 22 cats. Diagnosis was based on results of physical, radiographic, and histologic findings. Fifteen tumors arose from the appendicular skeleton, 4 from the skull, 2 from the pelvis, and 1 from a rib. Radiography revealed that in 14 of 15 cats (93%) with appendicular tumors, the lesion was metaphyseal, primarily lytic, with a "moth-eaten" appearance; absence and presence of periosteal new bone formation were associated with the tumors in 12 and 3 cats, respectively. The remaining 7 cats had axial tumors that were characterized by the presence of periosteal new bone formation in addition to bony lysis. Of the 15 cats with appendicular tumors, 12 were treated by amputation and 3 were euthanatized at the time of diagnosis. Of the cats undergoing amputation for treatment of their appendicular tumors, 6 cats were still alive 64 months after surgery (range, 13 to 64 months); the median survival time of the 5 cats (1 cat was lost to follow-up evaluation) that died was 49.2 months (range, 1 to 122 months). Four of 12 cats (33%) survived greater than or equal to 5 years after diagnosis. Of the cats with axial tumors that were not euthanatized at the time of diagnosis (6 of 7), the median survival time was 5.5 months. Based on these findings, we concluded that cats with appendicular osteosarcoma have a better prognosis than those with axial osteosarcoma, and that amputation is a viable treatment for cats with appendicular osteosarcoma.

Triple osteotomy of the pelvis and trochanteric osteotomy as a treatment for hip dysplasia in the immature dog: the surgical technique and results of 77 consecutive operations.

Triple osteotomy of the pelvis with transplantation of the greater trochanter was performed in 41 immature dogs (77 hips) with hip dysplasia. Before surgery, all hips were moderately to severely subluxated and unstable on palpation. The juxta-acetabular location of the ilial, ischial, and pubic osteotomies allowed repositioning of the acetabulum over the femoral head even when subluxation was severe. The acetabular fragment was rotated 70 degrees to 90 degrees in all hips. After surgery, craniodorsal coverage of the femoral head was increased and each hip was stable on palpation. Bilateral procedures were performed 4 to 7 weeks apart. The functional status of the limb was assessed and physical examination and radiography were performed in 71% (55) of the hips 1.0 to 5.5 years (mean, 2.7 years) after surgery. Functional ability was considered satisfactory in 93% (51) of the limbs, though few dogs had a normal gait. On palpation, all hips were stable and all but one were evaluated as nonpainful. In most instances, contact between the femoral neck and the repositioned acetabular rim resulted in a variable amount of crepitus and restriction of motion when the hip was abducted and rotated externally and internally. Eighty-two percent (45) of the hips had little or no evidence of degenerative joint disease. A satisfactory functional, physical, and radiographic result was obtained in 73% (40) of the hips.

Osteosarcoma of the patella in a dog.

Osteosarcoma of the patella was diagnosed by biopsy in a 9-year-old, male dog of mixed breeding. The dog was originally examined because of intermittent lameness of the left hindlimb; there were minimal palpable abnormalities of the stifle. After the diagnosis, the owner refused further treatment for the dog. The dog was reexamined 13 months later because of a marked swelling of the stifle. The dog was euthanatized and necropsy findings confirmed the diagnosis.

Ulnar fracture and dislocation of the proximal radial epiphysis (Monteggia lesion) in the dog and cat: a review of 28 cases.

Ulnar fracture with dislocation of the proximal epiphysis of the radius (Monteggia lesion) was diagnosed in 16 dogs and 12 cats. The lesions were classified into 4 types on the basis of direction of the dislocation of the radial head and angulation of the ulnar fracture. Cranial dislocation of the radial head, with cranial angulation of the ulnar fracture (type 1 lesion) was the most common. Radial head chip fractures were frequently associated with the lesions. In 25 cases, open reduction and internal fixation were required. The most common postoperative complications were restricted range of motion in the elbow, osteoarthritis, and recurrent dislocation of the radial head. Follow-up evaluations in 16 cases revealed good to excellent results in 10 animals and fair to poor results in 6 animals.