A 6-year-old Quarter Horse gelding used for barrel racing was evaluated for acute onset of non–weight-bearing lameness of the left hind limb following strenuous exercise.
Nuclear scintigraphic imaging revealed focal increased radiopharmaceutical uptake centrally within the left talus. Subsequent standard radiographic and ultrasonographic examinations of the tarsus failed to identify the cause of the increased radiopharmaceutical uptake; however, the lameness was definitively localized to the tarsocrural joint by intra-articular anesthesia. Subsequent MRI sequences of the left tarsus revealed an incomplete fracture of the talus that extended distally from the trochlear groove and evidence of maladaptive stress remodeling of the trochlear groove of the talus and distal intermediate ridge of the tibia.
TREATMENT AND OUTCOME
The horse was treated conservatively, with management consisting of stall confinement, physical rehabilitation, therapeutic laser therapy, and intra-articular autologous conditioned serum administration. The lameness resolved, and the horse was competing at its previous level within 15 months after lameness onset.
Although rare, incomplete fracture of the talus should be considered as a differential diagnosis for horses that develop acute hind limb lameness following strenuous exercise, especially when that exercise involves abrupt changes in direction while the horse is traveling at maximal speed. Acquisition of additional oblique projections during radiographic evaluation of the tarsus might be useful for identification of such fractures, but definitive diagnosis may require advanced diagnostic imaging modalities such as CT and MRI. Horses with incomplete fractures of the talus can be successfully treated with conservative management.
To assess the repeatability of equine 18F–sodium fluoride (18F-NaF) positron emission tomography (PET) findings, and to evaluate the ability of PET to monitor the progression of areas of increased radiopharmaceutical uptake (IRU) in the fetlocks of Thoroughbred racehorses.
25 racehorses with clinical signs related to fetlock injuries.
This study is a prospective, longitudinal clinical study. Twenty-five racehorses (54 fetlocks) underwent three 18F-NaF PET scans 6 weeks apart. The first 18F-NaF PET scan was performed at the start of a 12-week period of rest from racing (lay-up). Areas of IRU in the fetlock joints were quantified using maximal standardized uptake values (SUVmax) and were graded by 2 experienced observers. Statistical comparisons were made between scans to detect changes in IRU grade and SUVmax over time.
Standing PET findings were repeatable, with 131/149 (88%) areas of IRU identified on the initial scans seen again at the 6-week follow-up scan. The palmar/plantar condyles were the sites most commonly presenting with IRU, followed by the proximal sesamoid bones. Overall, 65% of fetlocks demonstrated improvement in IRU grade during the 12-week period of rest from racing. Areas of higher IRU grade took longer to resolve than the lower graded areas.
Standing PET findings in the racehorse fetlock were repeatable. The SUV-based grading system may be helpful when determining appropriate lay-up duration for Thoroughbred racehorses. PET may be used to monitor areas of the fetlock involved in catastrophic breakdown injuries in Thoroughbred racehorses.
To compare osteoarthritis scores assigned through radiographic evaluation of 18 anatomic regions in the elbow joint with scores assigned through evaluation of 3-D maximum intensity projection (MIP), 3-D surface rendering (TSR), and multiplanar reconstructed (MPR) CT images, and to evaluate intraobserver and interobserver agreement of radiographic and CT scoring.
Radiographic and CT images of 39 elbow joints in 20 dogs.
Images were anonymized and graded independently by 5 observers. One observer graded 12 elbow joints 3 times. Intraobserver consistency and repeatability, interobserver agreement, consistency among methods, and bias between methods were calculated.
The most severe changes were observed at the proximal aspect of the anconeal process, and the medial and cranial aspects of the medial coronoid process. Intraobserver consistency was moderate or better for 11/16 regions with MIP images, 11/16 regions with TSR images, 17/18 regions with MPR images, and 14/18 regions with radiographic images. Interobserver agreement was moderate or better for 5/16 regions with MIP images, 9/16 regions with TSR images, 12/18 regions with MPR images, and 6/18 regions with radiographic images. Mean scores from CT-based methods were higher than mean radiographic scores.
Assessments of osteoarthritis severity in the elbow joints of dogs obtained by examining radiographic images were generally consistent with assessments obtained by examining CT scans. MPR scores were more consistent and more comparable to radiographic scores than were MIP or TSR scores.