5 Most Common Limb Issues Identified by The Equina Standing CT
Since the Equina Standing CT’s first installation at the UW School of Veterinary Medicine in Madison, there are now five Equina® installations around the world, located in the USA and Australia, with several more planned. Together these locations have scanned over 2,000 patients for diagnostic and screening purposes of all sizes and breeds. We went through our archives to display the five most common limb injuries and diseases identified by the Equina.
The 1st most common limb issue identified by the Equina is Navicular Syndrome
How is the Equina Useful in these cases?
Image 1: Two-centimeter defect on the flexor cortex with distal border fragments
Navicular syndrome is commonly described as a syndrome of lameness problems caused by inflammation or degeneration of the navicular bone and its surrounding tissue. The Equina can be a valuable imaging modality since bone changes as well as a significant soft tissue changes (with and without contrast) can be observed. The soft tissue window can show tendon/ligament lesions and calcifications in tendons in the caudal heel region of the foot. Although tendon calcifications can be seen on radiographs, CT gives us more detail in that region. The bone window can detect differences in mineralization of the navicular bone due to navicular syndrome as well as distal border fragmentation, bone lucencies, enlarged synovial invaginations, pathological fractures and other bone defects.
Navicular Case Study
Image 2: Three-dimensional images show a large spot of erosion on the navicular bone and two distal border fragments.
“This 13-year-old Quarter Horse had intermittent bilateral front limb lameness and was sensitive to hoof testers. Left front limb was a grade 3 out of 5 AAEP scale lameness, right front limb was grade 2 out of 5 AAEP scale lameness. The horse went sound after a palmar digital nerve block on both front feet. CT images show a large 2cm defect on the flexor cortex with other lesions in the navicular bone and distal border fragments (image 1). Three-dimensional images show a large spot of erosion on the navicular bone and two distal border fragments (image 2). For treatment, the horse received rocker-rail shoes, NSAID’s, and Osphos injection.” -Dr. Diego De Gasperi
The 2nd most common limb issue identified by the Equina is Lesions of Lysis and Sclerosis
How is the Equina Useful in these cases?
Lesions of lysis with surrounding sclerosis are identified by a translucent middle (lysis) and concentrated edges (sclerosis) on CT images. Irregular bone remodeling and resorption can happen in all bones of the horse, particularly in bones in the fetlock, carpus, and tarsus. The Equina has become a great tool to diagnose this pathology and determine what could potentially lead to a fracture. Its capabilities have been useful to researchers developing new analytical methods to evaluate CT images with this pathology.
Sclerosis running into the Parasagittal Grove Case Study
Image 3: The white arch shows sclerosis leaning across into the parasagittal grove. This type of sclerosis orientation is common for potential condylar fractures in the condylar parasagittal grove The red arch is the typical orientation of a condyle POD lesion with sclerosis.
“This 5-year-old Thoroughbred had radiographs of the right front limb. Some linear lucent areas were observed in the lateral parasagittal grove. The horse was sent for a CT to determine if it could continue performing. CT images show focal lysis with surrounding sclerosis and a small fissure at the surface. Sclerosis was shown leaning across into the parasagittal grove, meaning the area was under strain (image 3). This type of sclerosis is typical for growing condylar fractures in the condylar parasagittal grove. It was recommended to back off this horse” -Dr. Chris Whitton
The 3rd most common limb issue identified by the Equina is Palmar/Plantar Osteochondral Disease (POD)
How is the Equina Useful in these cases?
“Palmar/Plantar Osteochondral Disease (POD) is a fatigue injury of the subchondral bone of the metacarpal/metatarsal condyle [cannon bone]. This disease has a variety of alterations in bone remodeling. Cystic lesion in the subchondral bone could be one of the changes seen” (Dr. Sabrina Brounts, DVM, MS, PhD, Asto CT clinical advisor). CT is excellent for detecting these changes due its sensitivity and three-dimensional capabilities. To use a loaf of bread analogy, you can slice the loaf, take out a slice and look at it. Then you can put that slice back, slice the bread in different directions, and take those slices out individually (image 4). These three-dimensional capabilities make the Equina a great diagnostic technique for detecting POD.
POD Case Study
Image 4: The white line shows the oblique dorsal plane, this plane allows veterinarians to see lysis and sclerosis where heavy action occurs.
“This is a seven-year-old Thoroughbred that came in with a right hind lameness and swapped to left hind lameness with a low four-point block. CT images show lysis in the lateral and medial condyle surrounded by sclerosis. The red circles (image 4) show bi-axial subchondral bone resorption with surrounding sclerosis that doesn’t extend into the parasagittal grove. Diagnosis was bi-axial POD with no articular surface collapse.” -Dr. Chris Whitton
The 4th most common limb issue identified by the Equina is Fractures
How is the Equina Useful in these cases?
There is a wide variety of fractures that occur in equine patients. Complete, incomplete, comminuted, compound, fracture fragments, spiraling fracture, articular, non-articular; fractures are diverse in how they occur. Usually, fractures can be identified on radiographs, however, with CT veterinarians are able to get a more detailed assessment. Fractures that are severe or complex may need more surgical planning before repair. CT can be a very useful imaging modality in those circumstances. The Equina is able to show these details which provide veterinarians with the knowledge to prepare a specific treatment plan for each individual horse.
Complete Comminuted Fracture with Bone Sequestrum Case Study
Image 5: Axial fracture of proximal MTIV of right rear limb of a 2-year-old QH; Undetectable by radiograph.
“This horse came in with an open complete comminuted fracture of the lateral splint bone in the right hind limb. A partial ostectomy was performed, removing the bone just above the fracture site. A few days after surgery, discharge was noticed in several wound bandages. Radiographs were taken and nothing conclusive was found. CT images showed a bone sequestrum fragment on the axial aspect of the splint bone (image 5). Once the fragment was removed the horse healed up nicely. The sequestrum found in CT images was not able to be seen in radiographs.” - Dr. Diego De Gasperi
The 5th most common limb issue identified by the Equina is Osteoarthritis
How is the Equina useful in these cases?
Image 6: Cyst-like lesions in the tarsal bones.
Osteoarthritis (OA), is a painful degeneration of the cartilage lining the ends of long bones inside joints, causing symptoms such as pain, stiffness, loss of flexibility, swelling due to soft tissue inflammation. OA can affect any joint where two cartilage-covered bones meet, most commonly the carpus, fetlock, distal tarsal bones and distal interphalangeal joints. Imaging osteoarthritis with the Equina can be beneficial since cartilage and soft tissue is not visible on X-rays. The use of contrast can help to outline structures in the joint such as cartilage. Usually OA is bilateral (affecting both limbs), this is where Equina’s dual limb scanning is beneficial for clinicians. In one scan their able to compare both legs under the same circumstances with no superimposition.
Osteoarthritis in the Hocks Case Study
“This horse had a history of hock arthritis and lameness which was managed conservatively. CT images show several cyst-like lesions in the third tarsal bone and the proximal aspect of the third metatarsal bone (image 6). The arthritis was noticed mostly in the right hind but also in the left hind with narrowing in the joint space. The client continued to treat with less aggressive treatment.” - Dr. Diego De Gasperi
If you have any questions regarding Standing CT or the Equina please visit our website www.AstoCT.com or email us at information@astoct.com. Like us on Linked In, Facebook, and Twitter to stay up to date on our latest releases.