Appearance and incidence of sacroiliac joint disease in ventrodorsal radiographs of the canine pelvis

Ventrodorsal (VD) radiographs of cadaveric pelves of large and giant breeds (n = 40) and of the corresponding bone specimens were made. Gross changes seen in the specimens were marked with metal wire or radiopaque paint to relate radiographic changes to the postmortem appearance of degenerative sacroiliac (SI) joint lesions. Two positioning techniques were used, resulting in two radiographs for each specimen. The techniques used were: (1) pulling the pelvic limbs caudally, with gentle traction producing a view of the sacrum in almost parallel alignment between the sacrum and the X-ray film (we have termed this a "central SI view") and (2) pulling the pelvic limbs caudally with greater traction than above, resulting in maximal inclination of the sacrum with respect to the X-ray film (we have termed this an "angled SI view"). Lesions of the supportive soft connective tissue could be imaged on the central and angled SI views, whereas angled SI views allowed better identification of lesions of the synovial SI joint. The insights gained in the above study were then used in a retrospective examination of 145 routine ventrodorsal radiographs of the pelvis (i.e., 290 sacroiliac joints) to determine the incidence of degenerative changes of the SI joint in large dogs. The lesions most commonly observed were calcification of the supportive soft connective tissue (n = 184/290), whereas lesions of the synovial SI joint were less frequent (n = 86/290). The degree of central or angled projection obtained in standard ventrodorsal radiographs was noted to be significantly (P < 0.05) associated with age, body conformation, anesthetic status, and the presence of spondylosis deformans at the lumbosacral junction. In contrast, SI joint disease and the gender of the animal did not affect the SI view achieved in VD radiographs.     

SCINTIGRAPHIC AND RADIOGRAPHIC APPEARANCE OF THE SACROILIAC REGION IN HORSES WITH GAIT ABNORMALITIES OR POOR PERFORMANCE

Nuclear bone scintigraphy is commonly used in the diagnosis of sacroiliac disease in horses. The aim of the present retrospective study was to determine if there was an association between radiopharmaceutical uptake pattern and radiographic appearance of the sacroiliac region in horses. Seventy-nine horses undergoing bone scintigraphy with Tc-99 m-HDP and radiography of the pelvis because of lameness or poor performance were studied. Subjective and semiquantitative methods were used to characterize and compare radiopharmaceutical uptake between horses. Ventrodorsal radiographs of the region were obtained and were evaluated. Subjectively, 70 horses (88.6%) had an abnormal uptake pattern. In nine horses, the sacroiliac region was normal (11.4%). There was no association between subjective evaluation of the scintigraphic images and semiquantitative methods. There was a significant association between radiopharmaceutical uptake and conformation (T- or Y-like form) and shape (butterfly-, wing-, leaf-, or horn-like) of the sacrum. The radiopharmaceutical uptake of the tubera sacralia was significantly higher in males (left side P =0.002, right side P =0.003). In conclusion, the conformation of the sacrum may play an important role in the scintigraphic appearance and may be the cause of increased radiopharmaceutical uptake.     

The gross and radiographic appearance of sacroiliac ankylosis capsularis ossea in the dog

This study was carried out to determine the incidence and to describe the radiographic appearance of ankylosis capsularis ossea at the canine sacroiliac joint, as well as to determine factors, which might cause radiographic misinterpretation of this finding. Bone specimens of 646 pelves of pure-bred dogs were assessed for morphological evidence of ankylosis capsularis ossea. The lesion was most commonly present at the cranioventral aspects of the sacroiliac joint. More than 50% of adult dogs had signs of being at least mildly affected. Among these, large and giant breeds were most commonly involved. Unlike moderate and severe degrees of this disease, smaller osteophytes had not been visualised on radiographs. For radiographic diagnosis, angled views of the sacrum are recommended. In central views of the sacrum, the presence of increased sacral concavity consistent with increased ilial convexity of the caudal aspect of the sacroiliac contact area might simulate the presence of ankylosis capsularis ossea. The clinical importance of the present findings is discussed in context with human literature.     

Use of routine ventrodorsal radiographic views of the pelvis to assess inclination of the wings of the sacrum in dogs

OBJECTIVE: To determine the ratio of ventral-to-dorsal transverse diameters between the wings of the sacrum on ventrodorsal radiographic views of the pelvis in large dogs and to validate the reliability of this morphometric analysis for functional interpretation. SAMPLE POPULATION: Pelvic specimens from 40 large-breed dogs and radiographs of 113 large-breed dogs. PROCEDURE: In an anatomic and radiographic evaluation, the transverse dorsal diameter (TVDS) and transverse ventral diameter (TVV) between the wings of the sacrum were evaluated in sacrum specimens and on corresponding radiographs of the pelvis and sacrum. The ratio between TVV and TVDS (VD ratio) was calculated. Intraobserver reliability was determined by calculation of the coefficient of variation. In a retrospective radiographic evaluation, the VD ratio was determined in Rottweilers, Golden Retrievers, and German Shepherd Dogs. Correlations between VD ratio and breed, age, and sex were tested. RESULTS: The VD ratio was significantly higher in Rottweilers than in Golden Retrievers and German Shepherd Dogs, denoting an oblique alignment of the sacral wings in Rottweilers (ie, the dorsal aspects of the sacral wings were located more medially than the ventral aspects) and an almost sagittal alignment in the other breeds. The VD ratio was significantly associated with age but not with sex. CONCLUSIONS AND CLINICAL RELEVANCE: Sagittal alignment of the wings of the sacrum is considered to be biomechanically less efficient. These results provide a basis for further studies to evaluate radiographic assessment of the sacroiliac joints similar to the evaluation for hip dysplasia.     

RADIOGRAPHIC TECHNIQUE AND ANATOMY OF THE EQUINE SACROILIAC REGION

Radiography is part of evaluating horses with poor performance and pelvic limb lameness; however, the radiographic appearance of the sacroiliac region is poorly described. The goal of the present study was to describe the use of a simple technique to obtain radiographs of the sacroiliac region in the anesthetized horse and to describe the radiographic appearance of this region. Seventy-nine horses underwent radiography of the pelvis under general anesthesia in dorsal recumbency. During a 5s exposure time the horse was actively ventilated to blur the abdominal viscera, which allowed assessment of individual bone structures in 77 horses. A large variation in the shape of the sacral wings, their articulation with the transverse processes of L6, and the relation of the sacrum to the ilium were observed. Females had significantly narrower width of the sacral wings. Broad sacral wings and bony proliferations at the caudal aspect were commonly observed features and their size was highly correlated with gender. In males, caudal osteophytes were significantly larger than in females. Five horses had transitional or hemitransitional vertebrae. Radiography with the ventilation-induced blurring technique is a simple approach that results in diagnostic quality radiographs and delineation of the highly variable bone structures of the sacroiliac region.     

SCINTIGRAPHY OF THE SACROILIAC JOINT REGION IN ASYMPTOMATIC RIDING HORSES: SCINTIGRAPHIC APPEARANCE AND EVALUATION OF METHOD

The sacroiliac region in 33 clinically normal riding horses was examined with scintigraphy to determine the normal scintigraphic appearance, to evaluate a semiquantitative method used to calculate a sacroiliac joint (SI joint) ratio, and to identify factors that affect the scintigraphic appearance of the pelvis. The scintigraphic examination included dorsal views of each SI joint region and one lateral view of the urinary bladder. Two predefined areas (the SI joint and the area between the tuber sacrale and the SI joint) were evaluated subjectively by comparing the intensity in each area to the intensity in the tuber sacrale, and a semiquantitative method was applied on the images to calculate an SI joint ratio. The thickness of the muscle mass overlying each SI joint was measured by using ultrasound. A corrected ratio was calculated based on a corrected pixel count for each SI joint. Of 29 evaluated horses, 28 had normal radiotracer uptake in the SI joints and 10 horses had symmetric normal radiotracer uptake in the area between the tuber sacrale and the SI joint. The mean SI joint ratio was 0.53 on both the left and right sides, and the mean corrected SI joint ratio was 2.15 on the left side and 2.13 on the right side. Factors that affect the scintigraphic appearance of the pelvis were identified and included attenuation, radioactive urine, and muscle symmetry. The muscle thickness ranged from 8-11 cm, causing 71-82% attenuation. Radioactive urine in the urinary bladder was located ventral to the SI joint region in 16 horses, and four of these were excluded from further evaluation because of risk of misinterpretation. A visual assessment of symmetry of the horses' gluteal muscle mass was compared with the ultrasound measurements. Fourteen horses (14/33) were regarded symmetric by both techniques. Soft tissue attenuation was found to severely compromise the result and indicated that only lesions in the SI joint with severely increased radiotracer uptake can be detected with scintigraphy. Knowledge about presence of radioactive urine ventral to the SI joint region and assessment of muscle symmetry is essential for a correct subjective evaluation. Any situation with difference in muscle mass between the left and right side of the pelvis will give a false impression of increased radiotracer uptake on the side with lesser muscle mass.     

A radiographic stress technique for evaluation of coxofemoral joint laxity in dogs

OBJECTIVE: To develop a radiographic stress technique to quantify hip joint laxity in dogs. STUDY DESIGN: Prospective study on client-owned dogs presented for hip dysplasia screening. ANIMAL POPULATION: 302 nonselected dogs (63 breeds). METHODS: Dogs were sedated and placed in dorsal recumbency. During pelvic radiography, the femoral heads were displaced manually in a craniodorsal direction. On these stress radiographs, the degree of lateral displacement of the femoral heads was assessed in terms of a subluxation index (SI) and compared with the degree of femoral head subluxation and the severity of hip dysplasia found on conventional extended hindlimb radiographs. RESULTS: The degree of subluxation on stress radiographs was significantly greater than on conventional radiographs. Correlation between the severity of canine hip dysplasia (CHD), graded according to conventional techniques, and the degree of subluxation, induced by radiographic stress technique, was positive (r = .57; P<.0001). Two critical SI values were noted. Of the dogs with an SI value of 0.3 or less, 99% were classified as CHD grade normal, borderline, or mildly dysplastic. In dogs with an SI value between 0.3 and 0.5, CHD grading ranged from normal to severely dysplastic. Of the dogs with an SI value greater than 0.5, 95% had dysplastic hip joints. CONCLUSIONS: Hip joint laxity cannot be quantified precisely on standard position radiographs. The proposed stress technique yields significantly higher degrees of femoral head subluxation than the standard position.     

Evaluation of Closed Reduction and Screw Fixation in Lag Fashion of Sacroiliac Fracture‐Luxations

Objective— To evaluate outcome by radiographic assessment after closed reduction and percutaneous screw fixation in lag fashion of sacroiliac fracture‐luxations in dogs. Study Design— Retrospective study. Animals— Dogs (n=24) with sacroiliac fracture‐luxations. Methods— Medical records (1999–2006) and radiographs of 24 dogs (29 fracture‐luxations) that had stabilization of sacroiliac fracture‐luxation by fluoroscopic‐guided closed reduction and percutaneous screw fixation in lag fashion were reviewed. Signalment, body weight, number, and location of all concurrent injuries and implants used for repair were recorded. Radiographs were used to evaluate the accuracy of screw placement in the sacral body, screw depth/sacral width ratio, reduction of the sacroiliac joint, pelvic canal diameter, and hemipelvic canal width. Radiographic re‐examination (range, 4 to >8 weeks postoperatively) was available for evaluation. Results— Mean screw depth/sacral width ratio on immediate postoperative and re‐examination radiographs was 64% and 61%, respectively. Mean percentage reduction of the sacroiliac joint on immediate postoperative and re‐examination radiographs were 91% and 87%, respectively. Pelvic canal diameter ratio demonstrated successful restoration of the pelvic canal. Hemipelvic canal width ratio documented successful closed reduction repair independent of concurrent pelvic injuries. Conclusion— Successful repair of sacroiliac fracture‐luxations, determined by radiographic assessment, can be achieved by fluoroscopic‐guided closed reduction and percutaneous screw fixation in lag fashion. Clinical Relevance— Fluoroscopic‐guided closed reduction and percutaneous screw fixation in lag fashion of sacroiliac fracture‐luxations is a minimally invasive technique that restores and maintains pelvic canal dimensions and should be considered as an alternative to open reduction or nonsurgical management of sacroiliac fracture‐luxations.     

Development and validation of a periarticular injection technique of the sacroiliac joint in horses

REASONS FOR PERFORMING STUDY: Sacroiliac joint osteoarthritis has been recognised as a significant cause of poor performance in competition and racehorses. Reliable diagnostic tools are currently lacking. The diagnosis has been based typically on exclusion of other possible causes of poor performance, back pain and hindlimb lameness. OBJECTIVES: To develop a safe, reliable and minimally invasive periarticular or intra-articular injection technique of potential use for diagnosis and therapy of sacroiliac joint disease in horses. METHODS: Twenty-six horses were used to develop and assess a medial approach to the sacroiliac joint with a 15 gauge, 25 cm long spinal needle. In Part I, the cadaveric study, the spinal needle was introduced cranial to the contralateral tuber sacrale and advanced along the medial aspect of the ipsilateral iliac wing until the dorsal surface of the sacrum was encountered. One ml methylene blue (MB) was injected in both sacroiliac joint regions of the sacropelvic specimens. The location of MB-stained tissues relative to the sacroiliac joints was recorded after dissection and disarticulation of the sacroiliac joint. In Part II, the in vivo study, 18 horses were used to validate the in vivo application of the sacroiliac joint injection technique. Horses were restrained in stocks and sedated in preparation for needle placement. One ml MB was injected bilaterally prior to euthanasia. Stained tissues were identified and recorded at necropsy. Successful joint injections were characterised as having MB located intra-articularly or < or = 2 cm periarticularly from the sacroiliac joint margin and localised to the middle or caudal third of the sacroiliac joint. RESULTS: Intra-articular MB was not observed in any specimen. However, MB-stained tissue was identified periarticularly in all injection sites (n = 48). Based on the predetermined success criteria, 96% of the methylene blue depots were located at the middle or caudal third of the sacroiliac joint. Dye-stained tissue was located < or = 2 cm from the sacroiliac joint margins in 88% of the specimens. Median distance of the MB from the sacroiliac joint margins was 1.0 cm (range 0.2-3.8 cm). The overall success rate considering both location and distance of the MB-stained tissue relative to sacroiliac joint margins was 83% (40 of 48 joints). CONCLUSIONS: The injection technique provides a reliable, easy to perform and consistent access to the medial periarticular aspect of the sacroiliac joint. POTENTIAL RELEVANCE: The described injection technique has the potential for both diagnostic and therapeutic applications in the medical management of equine sacroiliac joint disease. Further investigation is necessary to evaluate clinical efficacy and potential adverse effects.     

CHANGES IN THE CANINE FEMOROPATELLAR JOINT SPACE IN THE POSTSURGICAL, CRUCIATE-DEFICIENT STIFLE JOINT

In this study, we investigate the factors that influence changes in articular cartilage thickness in naturally occurring osteoarthritis of the canine stifle joint. Fifty-eight dogs with QA secondary to cranial cruciate ligament deficiency were examined radiographically at 0, 7, and 13 months using 90 degree flexed mediolateral radiographs of both stifle joints. The femoropatellar joint space widths were measured using a computer-assisted video image analysis system. The femoropatellar joint space widths were found to be significantly increased in index joints as compared to contralateral joints. In addition, there was a significant increase in femoropatellar joint space (FPJS) width over the course of the study, particularly between entry and 7 months. Factors that might influence the degree of femoropatellar joint space increase (bodyweight, age, sex, disease duration, radiographic score) were investigated using regression analysis. Body weight at baseline showed a moderate to strong relationship with change in FPJS between 0 and 7 months (Pearson's partial correlation r = 0.417, p = .006). This relationship was less strong for change in femoropatellar joint space between 7 and 13 months (r = 0.324, p = .036).     

Retrospective evaluation of fixation complications of 49 pelvic osteotomies in 36 dogs

Thirty-six dogs undergoing 49 pelvic osteotomies (POs) stabilised either by manually twisted dynamic compression plates (DCPS; n= 29) or canine pelvic osteotomy plates (CPOPS; n = 20) were retrospectively reviewed. Postoperative radiographs were available for all POs and 36 had additional radiographic follow-up. Pelvic osteotomies with CPOPs were more likely to have three screws placed in the sacrum while DCPs were associated with none, one or two screws in the sacrum. There was no difference in the postoperative sagittal alignment of the acetabular segments for POs with DCPs or CPOPs. Screw loosening was the most common complication (n = 13/36, 36 per cent), usually involving screws in the ilial segment. On follow-up radiographs, medial displacement of the acetabular segment was most frequently associated with screw loosening and plate bending. Medial displacement of the acetabular segment caused apparent pelvic narrowing on radiographs, more pronounced in dogs with bilateral POs, but clinical problems were not reported.     

RADIOGRAPHIC EVALUATION OF FELINE APPENDICULAR DEGENERATIVE JOINT DISEASE VS. MACROSCOPIC APPEARANCE OF ARTICULAR CARTILAGE

Degenerative joint disease (DJD) is common in domesticated cats. Our purpose was to describe how radiographic findings thought to indicate feline DJD relate to macroscopic cartilage degeneration in appendicular joints. Thirty adult cats euthanized for reasons unrelated to this study were evaluated. Orthogonal digital radiographs of the elbow, tarsus, stifle, and coxofemoral joints were evaluated for the presence of DJD. The same joints were dissected for visual inspection of changes indicative of DJD and macroscopic cartilage damage was graded using a Total Cartilage Damage Score. When considering all joints, there was statistically significant fair correlation between cartilage damage and the presence of osteophytes and joint‐associated mineralizations, and the subjective radiographic DJD score. Most correlations were statistically significant when looking at the different joints individually, but only the correlation between the presence of osteophytes and the subjective radiographic DJD score with the presence of cartilage damage in the elbow and coxofemoral joints had a value above 0.4 (moderate correlation). The joints most likely to have cartilage damage without radiographic evidence of DJD are the stifle (71% of radiographically normal joints) followed by the coxofemoral joint (57%), elbow (57%), and tarsal joint (46%). Our data support radiographic findings not relating well to cartilage degeneration, and that other modalities should be evaluated to aid in making a diagnosis of feline DJD.     

Deformation of the equine pelvis in response to in vitro 3D sacroiliac joint loading

Reasons for performing study: Sacroiliac joint injuries can cause poor performance; however, the interaction between pelvic mechanics and the sacroiliac joint is poorly understood. Objective: To measure pelvic displacement during 3D sacroiliac joint loading. Methods: Nine reflective triads were attached rigidly to bony prominences in sacropelvic specimens harvested from 14 horses for stereophotogrammetric analysis of triad displacements and joint kinematics. The sacrum was coupled to a load cell and mounted vertically within a material testing system (MTS). A pneumatic actuator was used to apply 90 Nm moments to the ischial arch to simulate nutation‐counternutation and left and right lateral bending of the sacroiliac joints. Axial rotation of the sacrum was induced by torsion of the upper MTS fixture. Vectors of marker displacement within orthogonal planes of motion were measured during loading of the sacropelvic specimens. Comparisons in the magnitude and direction of triad displacements were made between paired left‐right markers and paired loading conditions. Results: Nutation‐counternutation of the sacroiliac joint caused vertical displacement of the ischial tuberosities and cranial‐caudal displacement of the wings of the ilium. Lateral bending induced rotational displacement within the horizontal plane of all pelvic landmarks, relative to the sacrum. Axial rotation of the sacrum caused elevation of the wing of the ilium ipsilateral to the direction of sacral rotation and depression of the contralateral ilial wing. Significant paired left‐right differences occurred during most sacroiliac joint loading conditions. Comparable magnitudes of pelvic displacement were measured during nutation‐counternutation, left and right lateral bending, and left and right axial rotation. Conclusions: The equine pelvis is not a rigid structure and asymmetric pelvic deformation occurs during most sacroiliac joint movements. Clinical relevance: Bony pelvic deformation should be considered a normal response to any sacroiliac joint movement.     

Stabilization of Sacroiliac Luxation in 40 Cats Using Screws Inserted in Lag Fashion

Objective: To (1) identify prognostic indicators for stability after stabilization of sacroiliac luxation with screws inserted in lag fashion and (2) report dorsoventral dimensions of the sacrum in cats. Study Design: Multicenter retrospective study. Sample Population: Cats (n=40) with sacroiliac luxation. Methods: Case records and radiographs of cats presented at the Queen's Veterinary School Hospital Cambridge and the Royal Veterinary College Hatfield for screw fixation of sacroiliac luxation were reviewed. Dorsoventral dimensions of 15 feline cadaveric sacral bodies were measured to identify the appropriate implant size for use in fixation with screws inserted in lag fashion. Results: Of 40 cats, 13 had left, 14 right, and 13 bilateral sacroiliac luxations. Of 48 screws analyzed, 42 (87.5%) were placed within the sacral body or exited ventrally and 6 (12.5%) were considered malpositioned. Screw purchase within the sacrum was statistically different between unstable and stable repairs (P=.001). Using confidence intervals for screw length within the sacrum and effect on stability, the lowest screw depth that contained 95% of the screws that did not loosen was ∼60% of the sacral width. Mean dorsoventral sacral dimension at its narrowest point was 5.9±1.14 mm. There was no significant difference in the incidence of implant loosening between those luxations that were 100% reduced and those that were <100% reduced (P=.7837). Conclusions: Screw purchase within the feline sacrum of at least 60% of the sacral width significantly reduces the risk of loosening. Clinical Relevance: Screw placement to a depth of 60% of the width of the feline sacrum is recommended.     

The sacroiliac joints: evaluation using nuclear scintigraphy. Part 1: The normal horse

REASONS FOR PERFORMING STUDY: Sacroiliac (SI) disease is recognised as a cause of poor hindlimb action but differential diagnosis is often difficult. HYPOTHESES: That in clinically normal horses there would be a significant difference in the ratio of radiopharmaceutical uptake (RU) between the fifth lumbar vertebra (L5) and each tuber sacrale (TS) and between L5 and each SI joint; and that these ratios would alter with age, but ratios would be bilaterally symmetrical. METHODS: Dorsal scintigraphic images of the SI region of 15 horses, selected randomly from the clinic database, were analysed by 2 of the authors, comparing noncorrected and motion-corrected images. To determine scintigraphic anatomy, the scintigraphic images of 10 Thoroughbred horses were superimposed over a ventrodorsal radiographic image of an isolated pelvis. Dorsal scintigraphic images of 40 clinically normal horses age 3-16 years were evaluated using subjective examination, profile analysis and quantification using regions of interest. RESULTS: The tubera sacrale were seen as 2 well-defined oval regions immediately to the left and right of the midline, abaxial to which were larger, approximately oval areas with less RU, representing uptake in the SI joints. The definition between the SI region and the TS was more obvious in younger horses. Nonmotion-corrected images were often not of diagnostic quality or could be misinterpreted as abnormal. There were significant differences in RU between the TS and SI joints compared to L5, and decreased RU in the tubera sacrale with increasing age, but no change of uptake in the SI joint region and no effect of gender on RU. There was a high degree of left-right symmetry of the TS and SI joint regions. CONCLUSIONS AND POTENTIAL RELEVANCE: The scintigraphic images of horses with suspected sacroiliac joint disease should be compared with images of normal horses of comparable age. In normal horses, there was a high degree of symmetry; therefore, marked left-right asymmetry is likely to be abnormal.     

The sacroiliac joints: evaluation using nuclear scintigraphy. Part 2: Lame horses

REASONS FOR PERFORMING STUDY: Sacroiliac (SI) joint disease is difficult to diagnose definitively on clinical grounds. HYPOTHESES: Lameness not attributable to SI joint pain may result in asymmetrical uptake of radiopharmaceutical in the tubera sacrale and SI joints; and that horses with clinical signs suggestive of sacroiliac joint disease would have differences in the ratios of radiopharmaceutical uptake between the fifth lumbar vertebra (L5) and either the tubera sacrale or SI joints compared with normal horses. OBJECTIVES: To determine whether differences in radiopharmaceutical activity could identify individuals with presumed SI joint region pain. METHODS: The scintigraphic appearance of the pelvic region of 234 horses (Group I) with lameness unrelated to the SI joints was compared with that for 40 normal horses (Group N) in full work and that for 41 horses with suspected SI joint disease (Group II). The effect of age, sex, lame limb and discipline were assessed in Group I. Motion-corrected scintigraphic images were assessed grossly, using profile analysis and by comparing ratios of uptake of mean count per pixel between L5 and each of the left (L) tuber sacrale (TS), right (R) TS, LSI and RSI joints. Left-right symmetry was compared. RESULTS: Lame horses (Group I) had greater asymmetry of radiopharmaceutical uptake in the tubera sacrale compared with normal horses. Horses with right hindlimb lameness had a larger RSI/LSI ratio compared to normal horses. In Group I L5/LTS, L5/RTS and L5/RSI increased with age, and there was a trend for L5/LSI to increase with age. In horses with presumed sacroiliac joint disease (Group II), L5/LTS, L5/RTS and L5/RSI were all greater compared with normal horses. Detection of marked left-right asymmetry by quantitative analysis or profile analysis was helpful in discriminating between those horses with clinical signs compatible with SI joint disease and either normal horses or those lame due to another cause. CONCLUSIONS AND POTENTIAL RELEVANCE: Scintigraphic evaluation of the SI region is useful to identify SI joint disease in combination with other clinical signs supportive of the diagnosis. However, diagnosis should not be based on this alone because of some degree of overlap in the range of radiopharmaceutical uptake between horses with SI joint disease and both normal horses and those with other causes of lameness.     

COMPARISON OF THE ULTRASONOGRAPHIC APPEARANCE OF OSTEOCHONDROSIS LESIONS IN THE CANINE SHOULDER WITH RADIOGRAPHY, ARTHROGRAPHY, AND ARTHROSCOPY

Osteochondrosis lesions in 29 shoulder joints (from 20 dogs) were evaluated with ultrasound (US) and the results were compared with survey radiography, arthrography, and arthroscopy. US was performed with a 7-12 MHz linear matrix transducer which was placed in cranio-caudal direction just distally to the acromion while the joint was adducted and maximally endorotated to visualize the caudal aspect of the humeral head. With US, the subchondral defect was completely visible in 21 joints and partially visible in 8 joints. The length of the subchondral defect measured on US was comparable with the length measured on survey radiographs. In two joints, the cartilage flap was mineralized and thus already visible on survey radiographs. The mineralized flap was visible on US as a straight hyperechoic line above the subchondral defect. In the other joints, survey radiographs could not assess the status of the articular cartilage. In 17 joints, the presence of a cartilage flap or cartilage fissuring was suspected based on the presence of a second hyperechoic line at the base of the subchondral defect, and this suspicion was confirmed by arthroscopic examination in 16 joints and also by arthrographic examination in 15 joints. One joint that was suspected of having a cartilage flap on US was normal on arthroscopy and arthrography. When US revealed only focal thickening of the anechoic cartilage layer (5 joints), the joints appeared normal on arthroscopic and arthrographic examination. Of the four joints where the subchondral defect was irregular and covered by heteroechogeneous material on US, arthroseopy revealed the presence of a lesion resembling chondromalacia in two joints, the presence of a small cartilage flap in one joint and the presence of scar tissue underneath the flap at the level of the subchondral defect in one joint. In conclusion, US is a helpful imaging modality in the identification of osteochondritic lesions in the canine shoulder joint. US also appears to be a satisfactory imaging tool for identifying lesions such as joint mice, joint effusion, and distinct new bone formation.     

THE EFFECT OF ANESTHESIA ON THE RADIOGRAPHIC APPEARANCE OF THE COXOFEMORAL JOINTS

The effect of anesthesia on the radiographic appearance of the coxofemoral joints was evaluated by taking pelvic radiographs of thirty dogs. Each dog was radiographed twice, once under general anesthesia and once without anesthesia. The radiographs were submitted to the Orthopedic Foundation for Animals independently of one another to be evaluated for signs of hip dysplasia. Results suggest there was no statistical difference between the two groups of dogs. Twenty five dogs received the same reading. Three dogs received readings that were worse by one grade while under anesthesia and two dogs received readings that were one grade better while under anesthesia. This study failed to demonstrate any changes due to anesthesia on the radiographic appearance of the coxofemoral joints. Anesthesia may, however, be beneficial for proper positioning and to decrease unnecessary patient, and personnel exposure to radiation.     

THE ACCURACY OF THE DORSOPROXIMAL-DORSODISTAL PROJECTION IN ASSESSING THIRD CARPAL BONE SCLEROSIS IN STANDARDBRED TROTTERS

Thirty-five carpal joints from 20 standardbred trotters, age 1 to 7 years, all euthanized for nonorthopedic reasons, were examined to investigate the correlation between assessments of subchondral bone sclerosis in the third carpal bone from radiographs in the dorsoproximal-dorsodistal (DPr-DDi) projection and histomorphometric bone volume density measurements. The agreement between assessments of sclerosis from antemortem versus postmortem radiographs was also evaluated. Bones graded as sclerotic in the DPr-DDi projection had significantly higher bone volume density values for all areas of measurement than nonsclerotic bones. For sclerotic bones, grading of sclerosis was significantly associated with volume density measurements in the central cancellous bone only. There was a good agreement ( k _w =0.71) between assessments of radiographic bone sclerosis from antemortem versus postmortem radiographs.     

COMPARISON OF COMPUTED TOMOGRAPHY, TANGENTIAL VIEW RADIOGRAPHY, AND CONVENTIONAL RADIOGRAPHY IN EVALUATION OF CANINE PELVIC TRAUMA

Thirteen dogs with fractures requiring surgical repair were evaluated by standard two-view (i.e., lateral and ventrodorsal) radiography, tangential view (ventro 20 degrees cranial-dorsocaudal [inlet] and ventro 20 degrees caudal-dorsocranial [outlet]) radiography, and computed tomography (CT). Radiographic and CT examinations were reviewed independently by the three authors, and specific anatomic sites were graded for the presence or possibility of lesions. The results of radiographic interpretations were compared to CT scan interpretations. Eighty-one percent of skeletal lesions detected by CT scans were diagnosed definitively radiographically. Differences between the interpretation of CT and radiographic examinations included abnormalities associated with soft-tissue structures (P < 0.0001), the sacroiliac joints (P = 0.02), and the acetabula (P = 0.04). Interpretation of the lateral/ventrodorsal and inlet/outlet radiographic series were not statistically different, although inlet views may be complimentary to the standard radiographic examination. Its use deserves further study. Reader variation was less on evaluation of CT examinations than radiographic examinations. CT multiplaner reformations and three-dimensional reconstructions were useful for surgical planning in seven dogs. CT scanning is superior to survey radiography in assessing skeletal and soft-tissue injuries in dogs with pelvic trauma, although all clinically significant surgical lesions were described accurately radiographically. Based on this small series, the routine CT examination of dogs with pelvic trauma may not be justifiable for diagnosis but may be advantageous for surgical planning, especially if acetabular fractures are suspected on radiographs.