Sacroiliac Joint of the Horse 2. Morphometric features

The sacroiliac joints were collected from 41 horses from late fetal life to 14 years of age. The sacral and iliac articular surfaces were analysed by morphometry with regard to area, length, width and form factor. The body weights of the animals varied from 10 to 550 kg and the sacral articular surface area from 1.0 to 17.8 cm². Highly significant correlations were found between articular surface dimensions and body weights. Accordingly, the relative size of the joints decreased with increasing body weight/age. The sacral and iliac measurements were essentially comparable. No consistent left-right sidedness was found and no significant sex or breed differences were present.     

Sacroiliac Joint of the Horse 3. Histological appearance

To establish a baseline for the histological appearance of the sacroiliac joint of the horse, joint specimens were collected from 41 horses from late fetal life to the age of 14 years. Sagittal sections from the joints were radiographed and sectioned for histological examination.
There was a striking difference in structure between the sacral and iliac articular cartilages, the former being hyaline and the latter predominantly fibrous. Degenerative changes were seen even in young horses and were more markec on the iliac side. The degeneration of the articular cartilage showed a progressive, age-related pattern.     

Transrectal ultrasonographic examination of the sacroiliac joints of the horse: Technique and normal images

Transrectal ultrasonography of the sacroiliac joints is routinely performed for the diagnosis of the cause of low back pain and lack of power in the hindlimbs. As a result of the localisation of these small joints, performing and interpreting ultrasonographic images requires a good anatomical knowledge. This paper describes an ultrasonographic procedure that allows imaging of the ventral aspect of the sacroiliac joints. A complete screening should be done to evaluate the articular margins. Moreover, the shape of sacral and iliac wings can vary among individuals especially depending on the gender.     

双峰驼荐髂关节骨连接的过渡类型

采用大体解剖学方法，对８例成年双峰驼的荐髂关节进行了形态结构研究。结果发现，双峰驼之荐髂关节较其他动物具有以下显著特征：（１）没有围绕两骨接触面边缘附着的荐髂关节囊；（２）没有完整的耳状面；（３）髂骨翼和荐骨翼间无活动性，属不动关节；（４）两骨间的连接以纤维束为主，有２例还伴有骨性融合现象。纤维束中散在着几个关节小区，有的小区有关节囊、关节面、关节腔等关节基本结构，有的小区则不完全具备上述结构。这是一种既具有纤维关节特征同时又具有滑膜关节特征的混合关节，在骨连接分类方面属直接连接和间接连接的过渡类型。     

CT and gross pathology are comparable methods for detecting some degenerative sacroiliac joint lesions in dogs

Degenerative sacroiliac joint disease is a cause of lumbosacral pain in dogs; however, published information on cross‐sectional imaging characteristics is limited. Objectives of this retrospective, secondary analysis, methods‐comparison study were to test hypotheses that CT lesions reported in humans with degenerative sacroiliac joint disease are also present in dogs, and that CT is comparable to gross pathology for detecting these lesions. Matched CT and gross pathology slice images of 30 sacroiliac joints were retrieved from a previous prospective, canine cadaver study. A veterinary radiologist interpreted randomized CT images for each joint based on previously published CT characteristics of lesions in humans with degenerative sacroiliac joint disease. A veterinary pathologist independently interpreted randomized gross pathology images using the same criteria. All joints had at least one CT lesion consistent with degenerative sacroiliac joint disease. A new CT lesion was also identified and termed “subarticular cleft.” The CT and gross pathology methods agreed for detecting joints with subchondral sclerosis, subchondral erosion, and intra‐articular ankylosis lesions (P > .05, McNemar's test), but disagreed for detection of joints with subchondral cyst, para‐articular ankylosis, and subarticular cleft lesions (P ≤ .05). Using gross pathology as the reference standard, CT had 100% sensitivity for detection of subarticular cleft and subchondral cyst lesions, with 56% and 22% specificity, respectively. Para‐articular ankylosis lesions were detected by CT but not by gross pathology. Findings supported the hypothesis that CT lesions reported in humans with degenerative sacroiliac joint disease are also present in dogs, and partially supported the hypothesis that CT is comparable to gross pathology for detecting joints with these lesions.     

Pathologic changes in the lumbosacral vertebrae and pelvis in Thoroughbred racehorses

OBJECTIVE: To describe the prevalence, characteristics, and severity of soft-tissue and osseous lesions in the caudal portion of the thoracic and lumbosacral vertebral column and pelvis in Thoroughbred racehorses. ANIMALS: 36 Thoroughbred racehorses that died or were euthanatized at California racetracks between October 1993 and July 1994. PROCEDURE: Lumbosacral and pelvic specimens were collected and visually examined for soft-tissue and osseous lesions. RESULTS: Acute sacroiliac joint injury was observed in 2 specimens. Signs of chronic laxity or subluxation of the sacroiliac joint were not observed in any specimens. Impingement of the dorsal spinous processes and transverse processes was observed in 92 and 97% of specimens, respectively. Thoracolumbar articular processes had variable degrees of degenerative change in 97% of specimens. Degenerative changes were observed at lumbar intertransverse joints and sacroiliac articulations in all specimens. Some degenerative changes were widespread and severe. CONCLUSIONS: Numerous degenerative changes affected vertebral processes, intervertebral articulations, and sacroiliac joints in these Thoroughbred racehorses. CLINICAL RELEVANCE: Various types of vertebral and pelvic lesions need to be considered during clinical evaluation of the back and pelvis in horses. Undiagnosed vertebral or pelvic lesions could be an important contributor to poor performance and lameness in athletic horses.     

Transrectal ultrasonographic examination of the sacroiliac joints of the horse: Abnormal findings and lesions

Transrectal ultrasonography is a useful technique for the assessment of sacroiliac osteoarthrosis because of the ventral localisation of lesions. Comparison between the right and left side is essential. Due to the deep localisation of the sacroiliac joints, other imaging modalities have limitations for diagnosing osteoarthrosis. A grading system from 1 to 4 is suggested in order to classify the severity of lesions based on the shape of the articular margins and architecture of the ventral sacroiliac ligament. Abnormal ultrasonographic findings should be correlated with clinical manifestations.     

Ultrasound-guided periarticular injections of the sacroiliac region in horses: a cadaveric study

REASON FOR PERFORMING STUDY: The traditional techniques for injection of the sacroiliac (SI) region are based on external landmarks. Because of the depth of the SI joint and pathological modifications, SI injections are sometimes challenging in horses. HYPOTHESIS: An ultrasound-guided techniques would allow placement of the needle without depending on external landmarks. METHODS: Fourteen pelvic specimens were isolated from mature horses. A 20 cm bent spinal needle was positioned with ultrasonographic guidance under both iliac wings aiming for SI joints using 5 approaches: cranial, craniomedial, medial and 2 caudal approaches. The length of needle inserted was recorded and 2 ml of latex injected. The distance from latex to the closest sacral articular margin, the contact between latex and the SI interosseous ligament or the contact with the neurovascular structures emerging from the greater sciatic foramen were recorded at the time of dissection. RESULTS: Latex was identified under the iliac wing in all injections but one. The distance from the latex to the closest sacral articular margin was significantly shorter (P = 0.02) for the 2 caudal approaches compared to the cranial, craniomedial and medial approaches. Contact between latex and the SI interosseous ligament was significantly more frequent (P = 0.01) with the cranial, craniomedial and medial approaches (38/73) compared to the caudal approaches (1/24). Contact between latex and the neurovascular structures was significantly less frequent (P = 0.005) for the cranial and craniomedial approaches (0/47) compared to the medial and caudal approaches (8/60). Four erratic injections were encountered. CONCLUSIONS: Ultrasonographic guidance allowed the needle to engage under the iliac wing without being dependent on external landmarks. The caudal approaches allowed deposition of liquid extremely close to the SI joint although retroperitoneal injections occurred. CLINICAL RELEVANCE: Each approach has advantages/drawbacks that could be favoured for selected purposes, but additional work is required to evaluate them on clinical cases.     

Feasibility and accuracy of ultrasound-guided sacroiliac joint injection in dogs

Frozen cadaver specimens from three dogs were used to create a sectional anatomic atlas of the sacroiliac region. Frozen/thawed cadaver specimens from 12 dogs were used to develop an ultrasound-guided sacroiliac joint injection technique. Accuracy of the technique was tested in 15 additional canine cadaver specimens, using injectate containing blue dye and iodinated contrast medium. Sonoanatomic landmarks for consistently identifying a caudodorsal window into the canine sacroiliac joint space included the L7-S1 articular process joints, ilial wing, sacral wing, sacral lamina, and median sacral crest. Accuracy of ultrasound-guided sacroiliac joint injection was not significantly affected by operator, but was affected by the tissue location targeted and the reference standard used for calculations. Accuracy of the technique was good for placing injectate into either the synchondrosis component, dorsal sacroiliac ligament or ventral sacroiliac ligament; fair to poor for placing injectate into the synovial component; and poor for placing injectate into all four sacroiliac soft tissue structures. Concurrent placement of injectate into extraarticular tissues occurred frequently. We conclude that ultrasound-guided sacroiliac joint injection is feasible for evaluation as a treatment method for lumbosacral region pain in dogs, but is not sufficiently accurate for localizing pain to the sacroiliac joint alone.     

Pathological changes in the lumbar spine of pigs: gross findings.

The lumbar vertebral columns from 60 sows and 30 slaughter weight pigs were examined grossly for pathological changes. Asymmetry of lumbar articular facets and minor periarticular osteophytes were seen in the slaughter weight group. Degeneration of intervertebral discs or vertebral osteophytes were not present. In contrast, 38% of 60 sows had vertebral osteophytes and 40% had degeneration of intervertebral discs. Extensive ankylosing spondylosis was present in two sows. Other vertebral lesions observed in sows include asymmetry and arthrosis of articular facets, fissures and areas of cavitation in the annulus fibrosus and vertebral end plate, and vertebral osteomyelitis and/or vertebral fracture. Extravertebral skeletal lesions, some of which could be related to a clinical history of lameness or posterior paralysis, include sacroiliac arthrosis, pelvic deformity, polyarthritis, femoral osteomyelitis, sacroiliac dislocation and epiphyseolysis involving the femoral head or tuber ischii.     

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.     

Evaluation of a method for experimental induction of osteoarthritis of the hip joints in dogs

OBJECTIVE: To evaluate a method for experimental induction of osteoarthritis in the hip joints of dogs. ANIMALS: 12 mixed-breed dogs. PROCEDURE: A unilateral triple pelvic osteotomy was performed. In 6 dogs, the iliac osteotomy was repaired with 45 degrees of internal rotation, reducing coverage of the femoral head by the acetabulum. In the other 6 dogs, the fragments were repaired in anatomic alignment. Radiography, force plate evaluations, and subjective lameness evaluations were performed before and after surgery. Dogs were euthanatized 7 months after surgery, and samples of cartilage and joint capsule were examined histologically. RESULTS: Subjective lameness scores, radiographic appearance of the hip joints, and Norberg angles were not significantly different between groups; however, force plate evaluations did reveal significant differences in vertical ground reaction forces. Femoral head coverage was significantly decreased with rotation of the acetabulum. Mild inflammatory changes were discernible in the joint capsule and articular cartilage of some dogs in both groups. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that 45 degrees internal rotation of the acetabulum does not consistently induce biologically important osteoarthritic changes in the hip joints of dogs.     

Measurement of articular cartilage stiffness of the femoropatellar, tarsocrural, and metatarsophalangeal joints in horses and comparison with biochemical data

OBJECTIVE: To determine normal cartilage stiffness values in different weight-bearing and non-weight-bearing areas of 3 different equine joints, and to evaluate the relationship between cartilage stiffness and glycosaminoglycan (GAG) and collagen content. STUDY DESIGN: Compressive stiffness of the articular cartilage was measured in 8 horse cadaver femoropatellar (FP), tarsocrural (TC), and metatarsophalangeal (MT) joints. Gross evaluation, collagen content, GAG content, and histologic appearance were assessed for each measurement location. ANIMALS: Eight equine cadavers (4 intact females, 4 castrated males; 7 Quarter Horse or Quarter Horse type, 1 Arabian; aged 4-12 years, weighing 400-550 kg). METHODS: The articular surfaces of 8 equine cadaver FP, TC, and MT joints were grossly evaluated for signs of articular cartilage pathology. Stiffness at preselected sites (FP joint-6 sites; TC joint-3 sites; MT joint-4 sites) was determined using an arthroscopic indentation instrument. Biochemical composition (collagen, GAG content) and histologic evaluation (modified Mankin score) were assessed for each measurement site. RESULTS: All cartilage from all sites evaluated was determined to be normal based on macroscopic and histologic assessments. No significant correlation between Mankin scores and cartilage stiffness values was observed. Site differences in cartilage stiffness were measured in all 3 joints (P<.001). GAG or collagen content had a significant positive correlation with stiffness values in 6 of 13 sites (P<.05, r>0.622, r2>0.387). CONCLUSION: Relative cartilage stiffness values measured in healthy equine joints are site dependent and can be measured using an indentation device intended for arthroscopic application. CLINICAL RELEVANCE: An indentation instrument provided an objective means of determining relative compressive stiffness of articular cartilage. Further research needs to be performed to confirm the site and joint differences observed in this study in clinically normal horses and to determine if the tester can be used clinically to predict articular cartilage pathology.     

Differences in the topographical distribution of articular cartilage degeneration between equine metacarpo- and metatarsophalangeal joints

REASONS FOR PERFORMING STUDY: The equine metacarpophalangeal (MCP) and metatarsophalangeal (MTP) joints, although having virtually the same geometrical appearance, differ in the prevalence of joint pathologies, such as osteochondral fragmentation, and in biomechanical behaviour. The recently developed cartilage degeneration index (CDI) technique offers a possibility to assess quantitatively differences in cartilage degeneration between these joints and to compare these with known differences in biomechanics and clinical observations. OBJECTIVES: To compare the topographical distribution of articular cartilage degeneration across the proximal articular surface of the proximal phalanx (P1) in the equine fore- and hindlimb. METHODS: In 24 distal hindlimbs from 24 horses, articular cartilage degeneration of the proximal articular surface of P1 was quantified using the CDI. Overall CDI value (CDI(P1)) and CDI values of 6 areas of interest were determined: the medial dorsal surface (mds), lateral dorsal surface (lds), medial central fovea (mcf), lateral central fovea (lcf), medial plantar surface (mps) and lateral plantar surface (lps). The joints were divided into 4 equally sized groups of increasing CDI(P1) values. From an existing CDI database of MCP joints, 24 joints were selected with matching CDI(P1) values to the MTP joints and CDI values for the same areas of interest were determined. RESULTS: In both the MCP and MTP joints, highest CDI values were determined at the dorsal articular surfaces. Values were not significantly different between fore- and hindlimbs. In contrast to the MCP joint, CDI values at the plantar joint margin were significantly higher compared to CDI values in the central sites in the MTP joint. CDI values for the plantar surfaces of P1 were significantly higher than those for the palmar surfaces in the forelimb in joints with advanced stages of OA; and values for the central regions of P1 were significantly lower in the hindlimb compared with the forelimb in joints with severe OA. CONCLUSIONS: In both fore- and hindlimbs, initial cartilage degeneration started at the dorsal articular margin of P1. There was a major difference in the spread of cartilage degeneration; in the forelimb both the central and palmar parts are about equally involved, whereas in the hindlimb the plantar parts were significantly more and the central parts significantly less involved. These differences can be linked to differences in biomechanical loading reported elsewhere. POTENTIAL RELEVANCE: This study supports the hypothesis that differences in biokinematics between fore- and hindlimbs are associated with differences in the development of cartilage degeneration and other joint pathologies such as osteochondral fragmentation in the MCP and MTP joints. This information is indispensable for a better understanding of the dynamic nature and progression of these joint disorders and may be of help when monitoring the effects of therapeutic interventions and preventative measures.     

In vivo kinetic study on uptake and distribution of intramuscular tritium-labeled polysulfated glycosaminoglycan in equine body fluid compartments and articular cartilage in an osteochondrial defect model

The uptake and distribution of intramuscularly (IM) administered tritium-labeled polysulfated glycosaminoglycan (³H-PSGAG) in serum, synovial fluid, and articular cartilage of eight horses was quantitated, and hyaluronic acid (HA) concentration of the middle carpal joint was evaluated in a pharmacokinetic study. A full-thickness articular cartilage defect, created on the distal articular surface of the left radial carpal bone of each horse served as an osteochondral defect model. ³H-PSGAG (500 mg) was injected IM, between 14 and 35 days after creation of the defects. Scintillation analysis of serum and synovial fluid, collected from both middle carpal joints at specific predetermined times up to 96 hours post-injection, revealed mean ³H-PSGAG concentrations peaked at 2 hours post-injection. ³H-PSGAG was detected in cartilage and subchondral bone 96 hours post-injection in samples from all eight horses. There were no statistically significant differences in ³H-PSGAG concentration of synovial fluid or cartilage between cartilage defect and control (right middle carpal) joints.

HA assay of synovial fluid revealed concentrations significantly increased at 24, 48, and 96 hours post-injection in both joints. The concentration nearly doubled 48 hours post-injection. However, no statistically significant differences were found between synovial concentrations of HA in cartilage defect and control joints.

³H-PSGAG administered IM to horses, was distributed in the blood, synovial fluid, and articular cartilage. HA concentrations in synovial fluid increased after IM administration of polysulfated glycosaminoglycan.     

Arthroscopic Surgery for the Treatment of Osteochondritis Dissecans in the Equine Femoropatellar Joint

Forty limbs with femoropatellar osteochondritis dissecans in 24 horses were treated with arthroscopic surgery. Lesions were bilateral in 16 horses and unilateral in eight horses. Diagnostic examination and surgical treatment were performed through a single arthroscopic portal; five different instrument portal locations and six instrument approaches were used. Lesions were localized to the lateral trochlear ridge of the femur in 31 affected joints, medial trochlear ridge in two joints, lateral and medial trochlear ridges together in two joints, lateral trochlear ridge plus patella in four joints, and patella alone in one joint. The lesions consisted of subchondral defects containing chondral or osteochondral flaps or fragments, or were seen as dimpling, cracking, fibrillation, or erosion of articular cartilage, or intact cartilage over a subchondral defect. Loose bodies were found in three joints. There was a poor correlation between radiologic and arthroscopic findings. Surgical manipulations included removal of flaps, fragments, and undermined articular cartilage, and debridement of the subchondral defect. Three horses were euthanized: one electively to assess the joint grossly, one because of complications following surgery and salmonellosis, and one because of unrelated forelimb abnormalities. Immediate clinical improvement after surgery was seen in the 22 horses permitted to survive. Long-term follow-up on seven of 10 racehorses revealed that two have raced successfully, two are "ready to race," three are training sound, two are sound at pasture (still in convalescence), and one has been reoperated. Of six horses used for show or pleasure, three are being shown sound, one is sound for pleasure, and two are training sound. The remaining horses are convalescing.     

Effects of polysulfated glycosaminoglycan on chemical and physical defects in equine articular cartilage

The effect of intra-articular polysulfated glycosaminoglycan (PSG) on repair of chemical and physical articular cartilage injuries was evaluated in 8 horses. In each horse, a partial- and a full-thickness articular cartilage defect was made on the distal articular surface of the radial carpal bone. In the contralateral middle carpal joint, a chemical articular cartilage injury was induced by injecting 50 mg of Na monoiodoacetate (MIA). Four of the 8 horses were not treated (controls), and 4 horses were treated by intra-articular injection of 250 mg of PSG into both middle carpal joints once a week for 5 treatments starting 1 week after cartilage injury. Horses were maintained for 8 weeks. There was less joint circumference enlargement in PSG-treated horses in MIA-injected and physical defect carpi, compared with that in controls. In MIA-injected joints, there was less articular cartilage fibrillation and erosion, less chondrocyte death, and greater safranin-O staining for glycosaminoglycans in PSG-treated horses. Evaluation of joints in which physical defects were made revealed no differences between control and PSG-injected joints. None of the partial-thickness defects had healed. Full-thickness defects were repaired with fibrous tissue (which was more vascular and cellular in PSG-injected joints) and occasionally small amounts of fibrocartilage. Seemingly, PSG had chondroprotective properties in a model of chemically induced articular cartilage damage, whereas PSG had no obvious effect in a physical articular cartilage-defect model.     

Freehand magnetic needle guidance technology for intra-articular cervical injection in horses

The use of ultrasound-guided injections is a widely known and well-established procedure in equine medicine not only for intra-articular procedures but also for treating injuries affecting soft tissues. The aim of this study was to compare the conventional ultrasound-guided technique (CUGT) with a modified ultrasound-guided magnetic navigation technique (MUGT) in the articular process joints spaces of the cervical vertebrae. The aforementioned techniques were compared by measuring the degree of difficulty, the time employed and the success of the procedure (injecting blue methylene into the articular process joints spaces of cadavers to allow us to know whether the procedure was successful). Neck specimens from 11 cadavers were used to conduct this study. To compare the two different techniques, the articular process joints spaces of 11 specimens were injected bilaterally using ultrasound guidance, using one technique on each side. One millilitre of methylene blue was injected into the C2-C3, C3-C4, C4-C5 and C5-C6 articular process joints; then, these joints were dissected to verify the success rate of the injections. The results were similar regarding the success rate of the procedure; however, there were differences in the time employed (25.0 s median runtime for MUGT vs. 32.1 s median runtime for CUGT) and the degree of difficulty (1.3 attempts on average for MUGT vs. 2.4 attempts on average for CUGT). According to the results of this study, MUGT involved less difficulty and slightly less time employed to inject the cervical articular processes joints than CUGT; however, further studies in live horses are needed to assess the efficiency of this method, and studies in other joints or soft tissues are needed to validate the method. This new technique could also improve other equine ultrasound-guided procedures, such as nerve blocks, ultrasound-guided tendon/joints treatments or other articular injections.     

MRI features of cervical articular process degenerative joint disease in Great Dane dogs with cervical spondylomyelopathy

Cervical spondylomyelopathy or Wobbler syndrome commonly affects the cervical vertebral column of Great Dane dogs. Degenerative changes affecting the articular process joints are a frequent finding in these patients; however, the correlation between these changes and other features of cervical spondylomyelopathy are uncertain. We described and graded the degenerative changes evident in the cervical articular process joints from 13 Great Danes dogs with cervical spondylomyelopathy using MR imaging, and evaluated the relationship between individual features of cervical articular process joint degeneration and the presence of spinal cord compression, vertebral foraminal stenosis, intramedullary spinal cord changes, and intervertebral disc degenerative changes. Degenerative changes affecting the articular process joints were common, with only 13 of 94 (14%) having no degenerative changes. The most severe changes were evident between C4-C5 and C7-T1 intervertebral spaces. Reduction or loss of the hyperintense synovial fluid signal on T2-weighted MR images was the most frequent feature associated with articular process joint degenerative changes. Degenerative changes of the articular process joints affecting the synovial fluid or articular surface, or causing lateral hypertrophic tissue, were positively correlated with lateral spinal cord compression and vertebral foraminal stenosis. Dorsal hypertrophic tissue was positively correlated with dorsal spinal cord compression. Disc-associated spinal cord compression was recognized less frequently.     

Intra-articular tissue response to analytical grade metrizamide in dogs

The effect of analytical grade metrizamide (AM) injected into the canine stifle, for purposes of arthrography, was studied in 12 adult dogs using saline solution as the control solution injected into the contralateral joints. The AM was used at a concentration of 280 mg of iodine/ml and was administered at the dose of 0.3 ml/cm thickness of the stifle joint. For each joint, arthrocentesis was done before and 7 days after injection of either the contrast medium or saline solution. Physical, biochemical, and cytologic examinations were done on the synovial fluid while the synovial membranes and femoral articular cartilages were sectioned, stained, and examined for histopathologic changes. At the 95% confidence level, significant differences in the total and differential mononuclear cell counts were not seen between the AM- and saline solution-injected joints. However, some subtle changes in the synovial membranes were observed. Intra-articular injection of AM or saline solution initiated a mild inflammatory response, the AM causing slightly more response than the saline solution.