Objective—To determine the detailed computed tomography (CT) anatomy of the metacarpophalangeal (MCP) joint in healthy horses.
Sample Population—10 cadaveric forelimbs from 10 adult horses without orthopedic disease.
Procedures—CT of the MCP joint was performed on 4 forelimbs. In 1 of the limbs, CT was also performed after intra-articular injection of 30 mL of contrast medium (40 mg of iodine/mL). Transverse slices 1-mm thick were obtained, and sagittal and dorsal planes were reformatted with a slice thickness of 2 mm. The CT images were matched with corresponding anatomic slices from 6 additional forelimbs.
Results—The third metacarpal bone, proximal sesamoid bones, and proximal phalanx could be clearly visualized. Common digital extensor tendon; accessory digital extensor tendon; lateral digital extensor tendon; superficial digital flexor tendon (including manica flexoria); deep digital flexor tendon; branches of the suspensory ligament (including its attachment); extensor branches of the suspensory ligament; collateral ligaments; straight, oblique, and cruciate distal sesamoidean ligaments; intersesamoidean ligament; annular ligament; and joint capsule could be seen. Collateral sesamoidean ligaments and short distal sesamoidean ligaments could be localized but not at all times clearly identified, whereas the metacarpointersesamoidean ligament could not be identified. The cartilage of the MCP joint could be assessed on the postcontrast sequence.
Conclusions and Clinical Relevance—CT of the equine MCP joint can be of great value when results of radiography and ultrasonography are inconclusive. Images obtained in this study may serve as reference for CT of the equine MCP joint.
Objective—To compare clinical usefulness of ultrasonography versus radiography for detection of fragmentation of the dorsal aspect of the metacarpophalangeal (MCP) and metatarsophalangeal (MTP) joints in horses.
Animals—36 horses with fragmentation of the MCP (n = 19) and MTP (29) joints.
Procedures—In all joints, radiography (4 standard projections) and ultrasonography were performed prior to arthroscopic examination and fragment removal. Number and location of fragments identified radiographically and ultrasonographically were compared with arthroscopic findings.
Results—Radiographic and arthroscopic findings were in agreement with respect to both number and location of fragments in 21 of the 48 (44%) joints. Ultrasonographic and arthroscopic findings were in agreement with respect to number and location of fragments for 46 of the 48 (96%) joints. In the remaining 2 joints, arthroscopy revealed additional fragments that were not identified ultrasonographically. When ultrasonographic findings were compared with radiographic findings, more fragments were seen ultrasonographically in 3 joints and fewer fragments were seen ultrasonographically in 1 joint. Ultrasonographic findings also confirmed the absence (4 joints) or presence (3 joints) of fragmentation at the dorsoproximal aspect of the joint that had been suspected on the basis of radiographic findings. Ultrasonography was also able to determine the location of the fragments in the joints where this was not possible radiographically.
Conclusions and Clinical Relevance—Results of the present study suggested that ultrasonography was a useful method for determining the number and location of fragments in horses with dorsal fragmentation of the MCP or MTP joint.
Objective—To compare computed tomography (CT) images of equine tarsi with cross-sectional anatomic slices and evaluate the potential of CT for imaging pathological tarsal changes in horses.
Sample—6 anatomically normal equine cadaveric hind limbs and 4 tarsi with pathological changes.
Procedures—Precontrast CT was performed on 3 equine tarsi; sagittal and dorsal reconstructions were made. In all limbs, postcontrast CT was performed after intra-articular contrast medium injection of the tarsocrural, centrodistal, and tarsometatarsal joints. Images were matched with corresponding anatomic slices. Four tarsi with pathological changes underwent CT examination.
Results—The tibia, talus, calcaneus, and central, fused first and second, third, and fourth tarsal bones were clearly visualized as well as the long digital extensor, superficial digital flexor, lateral digital flexor (with tarsal flexor retinaculum), gastrocnemius, peroneus tertius, and tibialis cranialis tendons and the long plantar ligament. The lateral digital extensor, medial digital flexor, split peroneus tertius, and tibialis cranialis tendons and collateral ligaments could be located but not always clearly identified. Some small tarsal ligaments were identifiable, including plantar, medial, interosseus, and lateral talocalcaneal ligaments; interosseus talocentral, centrodistal, and tarsometatarsal ligaments; proximal and distal plantar ligaments; and talometatarsal ligament. Parts of the articular cartilage could be assessed on postcontrast images. Lesions were detected in the 4 tarsi with pathological changes.
Conclusions and Clinical Relevance—CT of the tarsus is recommended when radiography and ultrasonography are inconclusive and during preoperative planning for treatment of complex fractures. Images from this study can serve as a CT reference, and CT of pathological changes was useful.
To quantify the degree of dural compression and assess the association between site and direction of compression and articular process (AP) size and degree of dural compression with CT myelography.
26 client-oriented horses with ataxia.
Spinal cord-to-dura and AP-to-cross-sectional area of the C6 body ratios (APBRs) were calculated for each noncompressive site and site that had > 50% compression of the subarachnoid space. Site of maximum compression had the largest spinal cord-to-dura ratio. Fisher exact test and linear regression analyses were used to assess the association between site and direction of compression and mean or maximum APBR and spinal cord-todura ratio, respectively.
Mean ± SD spinal cord-to-dura ratio was 0.31 ± 0.044 (range, 0.20 to 0.41) for noncompressive sites and 0.44 ± 0.078 (0.29 to 0.60) for sites of maximum compression. Sites of maximum compression were intervertebral and extra-dural, most frequently at C6 through 7 (n = 10), followed by C3 through 4 (6). Thirteen horses had dorsolateral and lateral compression at the AP joints, secondary to AP (n = 7) or soft tissue proliferation (6). Site significantly affected direction of compression, and directions of compression from occiput through C4 were primarily ventral and lateral, whereas from C6 through T1 were primarily dorsal and dorsolateral. No linear relationship was identified between mean or maximum APBR and spinal cord-to-dura ratio.
CONCLUSIONS AND CLINICAL RELEVANCE
CT myelography may be useful for examination of horses with suspected cervical compressive myelopathy. Degree of compression can be assessed quantitatively, and site of compression significantly affected direction of compression.
To describe articular process joints (APJs) of the cervical spine in horses on the basis of CT and to determine whether abnormalities were associated with clinical signs.
86 client-owned warmblood horses.
Horses that underwent CT of the cervical spine between January 2015 and January 2017 were eligible for study inclusion. Medical records were reviewed for age, body weight, breed, sex, history, clinical signs, and CT findings. Horses were divided into 3 case groups and 1 control group on the basis of clinical signs.
70 warmblood horses were cases, and 16 were controls. Abnormalities were more frequent from C5 through T1 and were severe in only horses from the case group. Narrowing of the intervertebral foramen was common in horses in the case group (85.7%), often owing to enlarged, misshaped articular processes, followed by degenerative changes, periarticular osteolysis, cyst-like lesions, and fragmentation. High articular process-to-vertebral body (C6) ratio (APBR) and high-grade narrowing of the intervertebral foramen and periarticular osteolysis were noted for horses with forelimb lameness or signs of cervical pain or stiffness. No association was identified between APBR and age or sex. An APBR > 1.5 was found in only horses in the case group, and 32.3% of APJs with APBRs > 1.5 did not have any degenerative changes and periarticular osteolysis.
CONCLUSIONS AND CLINICAL RELEVANCE
CT was useful to identify abnormalities of the APJs of the cervical spine. An association existed between CT findings and clinical signs. The APJs can be enlarged without concurrent degenerative changes.
Objective—To provide a detailed computed tomography (CT) reference of the anatomically normal equine stifle joint.
Sample—16 hind limbs from 8 equine cadavers; no horses had evidence of orthopedic disease of the stifle joints.
Procedures—CT of the stifle joint was performed on 8 hind limbs. In all limbs, CT was also performed after intra-articular injection of 60 mL of contrast material (150 mg of iodine/mL) in the lateral and medial compartments of the femorotibial joint and 80 mL of contrast material in the femoropatellar joint (CT arthrography). Reformatted CT images in the transverse, parasagittal, and dorsal plane were matched with corresponding anatomic slices of the 8 remaining limbs.
Results—The femur, tibia, and patella were clearly visible. The patellar ligaments, common origin of the tendinous portions of the long digital extensor muscle and peroneus tertius muscle, collateral ligaments, tendinous portion of the popliteus muscle, and cranial and caudal cruciate ligaments could also be consistently evaluated. The cruciate ligaments and the meniscotibial ligaments could be completely assessed in the arthrogram sequences. Margins of the meniscofemoral ligament and the lateral and medial femoropatellar ligaments were difficult to visualize on the precontrast and postcontrast images.
Conclusions and Clinical Relevance—CT and CT arthrography were used to accurately identify and characterize osseous and soft tissue structures of the equine stifle joint. This technique may be of value when results from other diagnostic imaging techniques are inconclusive. The images provided will serve as a CT reference for the equine stifle joint.