Radiographic evaluation of BFX acetabular component position in dogs

Objective: To assess the reliability of radiographic measurement of angle of lateral opening (ALO) and angle of version of BFX acetabular cups. Study Design: In vitro radiographic study. Sample Population: BFX cups (24, 28, and 32 mm). Methods: Total hip replacement constructs (cups, 17 mm femoral head and a #7 CFX stem) were mounted on an inclinometer. Ventrodorsal radiographs were obtained with ALO varying between 21° and 70° and inclination set at 0°, 10°, 20°, and 30°. Radiographs were randomized using a random sequence generator. Three observers blinded to the radiograph order assessed ALO using 3 methods: (1) an ellipse method based on trigonometry; (2) using a measurement from the center of the femoral head to the truncated surface of the cup; (3) by visual estimation using a reference chart. Version was measured by assessing the ventral edge of the truncated surface. Results: ALO methods 2 and 3 were accurate and precise to within 10° and were significantly more accurate and precise than method 1 (P<.001). All methods were significantly less accurate with increasing inclination. Version measurement was accurate and precise to within 7° with 0–20° of inclination, but significantly less accurate with 30° of inclination. Conclusions: Methods 2 and 3, but not method 1, were sufficiently accurate and precise to be clinically useful. Version measurement was clinically useful when inclination was ≤20°.     

Radiographic evaluation of the Zurich cementless total hip acetabular component

OBJECTIVE: To radiographically evaluate the Zurich cementless total hip (ZCTH) cup and correlate lucency with clinical signs of implant instability, time since surgery, and implant generation, using zonal analysis. STUDY DESIGN: Retrospective study. ANIMALS: Client-owned dogs (n = 53). METHODS: Radiographs of dogs that had ZCTH arthroplasty (>1 year) were evaluated using zonal analysis, for lucency surrounding the cup-bone interface (number of zones, length, area). Dogs were examined for clinical signs of implant instability (lameness, hip pain). Lucency was correlated with lameness, time after surgery, and implant generation. RESULTS: Radiographs of 68 implants (18 generation I, 50 generation II) were evaluated. Eight dogs were lame (11.8%). Dogs with lameness were more likely to have lucency in > or =2 zones of analysis (per view), have >2 times the average curvilinear length of lucency, and have >4 times the average area of lucency surrounding the implant compared with non-lame dogs. A weak relationship was observed between time after surgery and implant generation; however, there was no relationship between time after surgery and lucency. CONCLUSIONS: Dogs with lameness after ZCTH arthroplasty were more likely to have lucency at the cup-bone interface. Lucency was better evaluated by radiographic projection than zonal analysis. Temporal progression of lucency was weakly correlated with implant generation. CLINICAL RELEVANCE: Dogs with lucency in > or =2 zones of analysis should be evaluated more frequently for clinical signs of implant loosening. Further investigation of serial radiographs after ZCTH arthroplasty is warranted.     

Radiographic evaluation of nonanesthetized and nonsedated dogs for hip dysplasia

The use of chemical or gas restraint was unnecessary in most large breed dogs being evaluated radiographically for hip dysplasia. Of 100 large-breed dogs, 97 were successfully radiographed for hip dysplasia evaluation without the use of sedation or anesthesia.     

Radiographic assessment of liver volume in dogs

In a group of 65 dogs, radiographic liver length, the length of the axis from the most cranial part of the diaphragm to the apex of the liver tip, was correlated significantly (P less than 0.000001) with real liver volume. Within this group, radiographic liver length, compared with the length of the eleventh thoracic vertebra, was correlated with liver volume per kilogram of body weight. In a group of 30 dogs, with histologically normal liver, this measurement was not affected by thoracic conformation. These findings suggest that radiographic liver length is a reliable measurement for estimating liver volume in dogs and that it is not influenced by thoracic conformation. For 60 of the 65 dogs, a method of assessment of liver volume was formulated that required 2 measurements to be made on the lateral abdominal radiograph and 1 to be made on the dog itself.     

Radiographic evaluation of positional atelectasis in sedated dogs breathing room air versus 100% oxygen

This study documents the degree of positional atelectasis in sedated dogs receiving 100% oxygen (O₂) versus room air. Initial lateral recumbency was determined by an orthopedic study and initial treatment (O₂ or room air) was randomized. Each dog was maintained in lateral recumbency for 15 min, at which time ventrodorsal (VD) and opposite lateral thoracic radiographs were obtained. Each dog was then maintained in the opposite lateral recumbency and received the other treatment for 15 min, followed by a VD and opposite lateral radiograph. Radiographs were scored for severity of pulmonary pattern and mediastinal shift by 3 radiologists. Dogs breathing O₂ had significantly higher scores than dogs breathing room air. If radiographically detectable dependent atelectasis is present, repeat thoracic images following manual positive ventilation and/or position change to the opposite lateral recumbency should be made to rule out the effect of O₂ positional atelectasis and avoid misdiagnosis.     

Radiographic findings in induced bacterial pyelonephritis in dogs

Unilateral bacterial pyelonephritis was induced in nine dogs. The upper urinary tracts of these and six control dogs were evaluated by excretory urography prior to and 9 to 10 days following experimental manipulations. Two of the dogs with unilateral pyelonephritis and one control dog were evaluated at intervals throughout a 58-day period. At necropsy, all nine inoculated kidneys were infected, one experimental dog had bilateral pyelonephritis, and one control dog had unilateral pyelonephritis. Most of the infected kidneys had abnormal radiographic changes 9 to 10 days after induction of infection. There was no statistically significant radiographic change in size of infected kidneys at 9 to 10 days. Seven of the 11 infected kidneys and 7 of the 9 inoculated kidneys had renal pelvic and ureteral dilatation. Of the nine dogs with unilateral pyelonephritis, six had decreased opacity of contrast medium in the collecting system and of the vascular nephrogram on the infected side. The size of infected kidneys decreased progressively during the 58-day period. In one of the two dogs evaluated throughout the period, the collecting system of the infected kidney remained dilated; in the other, it returned toward normal size.     

Radiographic and functional evaluation of dogs at least 1 year after tibial plateau leveling osteotomy

The progression of osteoarthritis and clinical function in 29 dogs at least 1 year after tibial plateau leveling osteotomy was evaluated. A previously reported radiographic scoring system was used by 3 investigators to evaluate preoperative and postoperative radiographs for evidence of stifle osteoarthritis. The combined scores were then used to evaluate the progression of osteoarthritis. The difference between the preoperative scores, derived from radiographs taken at the time of surgery, and the postoperative scores based on radiographs taken at least 1 year later was modest but statistically significant. Despite this finding, client satisfaction was very good. Clinical function was assessed by using a previously reported client questionnaire. According to owner assessment at least 1 year after surgery, there was a significant improvement in function after tibial plateau leveling osteotomy when compared with the preoperative status. Improvement in function as measured by the client questionnaire did not significantly predict the radiographic osteoarthritis score.     

Orthogonal view analysis for evaluating the femoral component position of total hip implants in dogs using postoperative radiographs

OBJECTIVE: To show the ability to obtain repeatable, accurate, quantitative data to assess the position of the femoral component of canine total hip implants using postoperative radiographs. STUDY DESIGN: Cadaveric study and clinical trial. ANIMALS: Five cadaveric canine femurs and 4 patients. METHODS: Femoral implants were placed into 5 cadaveric canine femurs in predetermined locations. Orthogonal radiographs were taken of each femur at 10 degrees intervals as they were moved through a natural range of hip motion. An assessment of implant position was made with each set of radiographs and analyzed to observe significant inconsistencies in the values obtained when the femur was repositioned. Three investigators positioned and radiographed the hips of 4 client-owned dogs that had total hip arthroplasty (THA). Each investigator obtained a set of orthogonal radiographic views from which implant position was measured. The measurements obtained from each investigator's set of radiographs were statistically analyzed to evaluate for interobserver differences. RESULTS: The methods described indicate that consistent data regarding femoral implant placement can be obtained from postoperative radiographs of THA patients. Under most circumstances, change in position of the femur did not significantly affect femoral implant measurements. There were no significant differences noted among values obtained by different investigators. CONCLUSIONS: Measurements based on the femoral and implant axes obtained from orthogonal radiographic views of the femur provide a means for obtaining accurate and consistent quantitative data regarding femoral implant position using postoperative radiographs of canine THA patients. CLINICAL RELEVANCE: Acquisition of quantitative information about femoral implant position using postoperative radiographs will facilitate development of a readily available data source. This information, attainable in a clinical setting, may help identify elements of implant position that are important in determining the clinical outcome of THA in dogs.     

Radiographic findings in 16 dogs infected with Angiostrongylus vasorum

Thoracic radiographs of 16 dogs infected naturally with Angiostrongylus vasorum showed signs of bronchial thickening, an interstitial pattern and a multifocal and/or peripheral alveolar pattern. In dogs treated with fenbendazole, follow-up radiographs showed that the alveolar pattern had resolved and a mild, hazy interstitial pattern had developed. In contrast with dogs with heartworm (Dirofilaria immitis), no pulmonary vascular lesions were identified.     

Evaluation of four interfragmentary Kirschner wire configurations as a component of screw/wire/polymethylmethacrylate fixation for acetabular fractures in dogs

The biomechanical contribution of the interfragmentary Kirschner wire as a component of composite fixation for acetabular fracture repair was subjectively and objectively evaluated. Acetabular osteotomies were repaired using the screw/wire/polymethylmethacrylate (SWP) composite fixation with or without one of three configurations of Kirschner wire in 32 hemipelves obtained from 16 dogs. Reduction, assessed objectively and subjectively, was unaffected by Kirschner wire placement. Hemipelves repaired with Kirschner wire(s) were subjectively more stable prior to application of polymethylmethacrylate when manually assessed in multiple planes. Consistent incremental increases in stiffness, yield load, and maximum load sustained that were observed during biomechanical testing were not significant, with the exception that hemipelves repaired with two Kirschner wires had significantly greater yield loads than hemipelves repaired without Kirschner wires. The subjective results of this study support the use of at least one interfragmentary Kirschner wire to maintain reduction prior to polymethylmethacrylate application; however, fracture configuration and location may dictate the number and pattern of interfragmentary Kirschner wires used to maintain reduction prior to application of the polymethylmethacrylate. The objective results and observations made during biomechanical testing suggest that use of one or more interfragmentary Kirschner wires may enhance stability after polymethylmethacrylate application.     

Radiographic study of the maxillary canine tooth in mesaticephalic dogs

Radiology is the most important diagnostic technique for evaluation of the radicular structure of the tooth and adjacent areas. However, superimposition of other oral or nasal structures often creates difficulties when interpreting radiographic images. The purpose of this study was to identify and locate any anatomical structures that may be superimposed over the root of the maxillary canine tooth in radiographs of dogs. Results showed that the nasal conchae minimally interfere with the visualization of the tooth. The vomer bone and maxillary structures (the conchal crest, the line of conjunction between the maxillary body and the palatine process, and the palatine sulcus) are visible as linear radiopacities, and were found to be responsible for most of the radiographic features in this area. The incisivomaxillary canal and the palatine fissure caused radiolucent images. The incisivomaxillary suture and the nasoincisive suture may appear as radiolucent images in young skulls and linear radiopacities in older skulls. It appears from this study that a compromise between minimal superimposition of dental and non-dental structures and small image distortion is needed to obtain diagnostic radiographic views of the maxillary canine tooth in mesaticephalic dogs. The relative positions of the conchal crest, the line of conjunction between the vertical body of the maxilla and its palatine process, the incisivomaxillary canal, and the tooth, cannot be changed radiographically because of the close anatomic position of these structures.     

Definition and determination of acetabular component orientation in cemented total hip arthroplasty

OBJECTIVE: To describe the spatial orientation of the cemented acetabular component in cemented total hip arthroplasty, based on a ventrodorsal and lateral radiographic projection of the pelvis. METHODS: Equations were derived by using trigonometric relationships that describe the radiographic rotation about the longitudinal pelvic axis (alpha), transverse pelvic axis (beta), acetabular inclination (phi), acetabular inclination corrected for longitudinal pelvic rotation, version (phiC), acetabular version (theta), acetabular version corrected for longitudinal pelvic rotation (thetaC), acetabular inclination corrected for transverse pelvic rotation (phi(beta)), and acetabular version corrected for transverse pelvic rotation (theta(beta)) RESULTS: Alpha was calculated by using the equation alpha = sin(-1) (x/y) where x is the transverse distance between the dorsal spinous processes and the center of the pubis on a ventrodorsal radiograph and y is the distance from the pubis to the dorsal aspect of the first coccygeal vertebra perpendicular to the long axis of the pelvis on a lateral radiograph. Phi was calculated from the long axis (LA) and short axis (SA) of the ellipse formed by the radiopaque acetabular marker ring by using the equation phi = sin(-1) (SA/LA). phiC was calculated by using the equation phiC = phi +/- (alpha - tan(-1) (tan alpha cos thetaC)). Theta was determined as previously described. ThetaC was calculated by using the equation thetaC = tan(-1) (tan theta cos alpha). Theta(beta) and theta(beta) were calculated with the equations phi(beta) = tan(-1) (tan theta cos beta) and theta(beta) = theta - tan(-1) (sin beta), respectively. Beta could not be accurately determined from ventrodorsal and lateral pelvic radiographs. CONCLUSIONS AND CLINICAL RELEVANCE: These techniques allow for more accurate postoperative radiographic assessment of acetabular component positioning. This information can then be used in retrospective or prospective analyses examining that effects of implant positioning on clinical outcome.     

Use of reconstruction plates for repair of acetabular fractures in 16 dogs

Acetabular fractures in 16 dogs were repaired using reconstruction plates. Notches cut into the plate permitted contouring in three planes to facilitate accurate articular reconstruction. There were three cranial, seven central, one caudal and five comminuted acetabular fractures. These acetabular fractures were invariably associated with multiple pelvic fractures. Repair of nonacetabular fracture/luxation was indicated in 10 cases. Follow-up information was available for 15 dogs, of which 12 (80 per cent) had an excellent or good outcome. Fracture configuration and the presence of multiple fractures did not influence prognosis. Two dogs died suddenly, late in convalescence, but the cause of death was not established.     

Radiographic diagnosis and surgical management of fragmented medial coronoid process in dogs

The diagnosis of fragmented (ununited) medial coronoid process was made in 21 dogs, with 10 dogs having bilateral lesions. Ten of these dogs were presented to surgery. The diagnosis of fragmented medial coronoid process was made in young and middle-aged large- and giant-breed dogs with a history of intermittent or persistent lameness. Diagnosis was based on history as well as results of clinical examination and radiographic study of both elbows. Concomitant elbow lesions seen with fragmented medial coronoid processes were ununited anconeal process and osteochondritis dissecans of the medial humeral condyle. Avulsion of the medial epicondyle and posteromedial supracondylar ridge of the humerus were thought not to have occurred in these cases. Instead, dystrophic ossification of the synovial membrane and periosteal proliferation on the medial epicondyle and posteromedial supracondylar ridge had taken place. It was concluded that, with a questionable radiographic diagnosis of fragmented medial coronoid process, exploratory arthrotomy may be necessary to confirm the diagnosis. Without surgery, the eventual outcome of fragmented coronoid process is degenerative joint disease. Even with degenerative joint disease, however, clinical improvement was seen following removal of the fragment of the medial coronoid process.