3T Magnetic resonance imaging and computed tomography of the bovine carpus.

BACKGROUND: Lameness in cattle is a major health problem and causes great economic losses. Carpal injury is a common cause of forelimb lameness in cattle. Radiography and/or ultrasonography of the carpus is a challenge due to complex anatomy of the joint. Additional imaging using computed tomography (CT) or magnetic resonance imaging (MRI) may be indispensable for reaching a decisive diagnosis. Precise evaluation of the clinical CT and MRI images necessitates an in-depth knowledge of the normal CT and MRI tissue variants. Therefore, our purpose was to provide a detailed description of the normal CT and MRI appearance of the osseous and soft tissue structures of twelve cadaveric bovine carpi using CT and 3 Tesla MRI. Carpi were frozen, transected in sagittal, dorsal and transverse planes then adjoined to their corresponding CT and MRI images. RESULTS: The clinically significant articular and peri-articular structures of the bovine carpus were identified and characterized on the CT and MRI images. CT images provided a remarkable delineation of the cortical, subchondral, and cancellous bone. The high-field 3 Tesla MRI offered high definition and distinction of the delicate soft tissues of the bovine carpus. CONCLUSIONS: 3 Tesla high-field MRI offers new opportunities in soft tissue tomography but cannot be compared with CT in terms of bone imaging. Clinicians have to determine whether CT, MRI or both imaging techniques are required in clinical situations.

Radiographic assessment of carpal conformation in the horse: Technique development and validation of the consistency of measurements.

Carpal conformation is often considered as a contributory factor to performance and lameness in the horse; however, few attempts have been made to objectively measure radiographic variations of carpal conformation in horses due to insufficient measurable carpal parameters. This pilot study used carpal radiographic images acquired from 10 cadaveric equine forelimbs transected at the antebrachial midshaft from 7 adult horses (7.2 ± 2.6 years), positioned at 'zero lateromedial' (ZLM) and 'zero dorsopalmar' (ZDP) views, to investigate the anatomy of the equine carpus and develop parameters that could be objectively used to assess carpal conformation in horses. Dorsal carpal angle (DCA: 176.61 ± 0.66º), distal radial slope carpal angle (DRSCA: 145.59 ± 2.19º), intermediate carpal bone proximal tuberosity-radial angle (CiPxTRA: 115.69 ± 3.15º) and third carpal bone palmar facet angle (C3PalFCA: 84.43 ± 1.13º) were all developed from the ZLM view while medial carpal angle (MCA: 183.34 ± 1.02º), disto-dorsal slope angle of the third carpal bone (C3DDSA: 8.27 ± 0.92º) and width ratio of distal radius to proximal metacarpus (WDR:WPM = 1.13±0.03) were 3 of the 10 parameters developed from the ZDP view. Easy to identify and measurable parameters will help to provide quantitative assessment of carpal conformation in the horse with potential of eliminating subjective observational variation errors between clinicians. These newly developed parameters will be useful in further studies to measure variations in the conformation of the equine carpus in live horses and comparison between subjective visual assessment and objective radiographic evaluation methods.

Kinematics of the Feline Antebrachiocarpal Joint from Supination to Pronation.

OBJECTIVE: Cats rely on their forelimb mobility for everyday activities including climbing and grooming. Supination and pronation of the forelimb in cats are considered to primarily involve the antebrachium, rather than the carpus. Therefore, our null hypothesis was that there would be no movement of the carpal bones (radial carpal bone, ulnar carpal bone and accessory carpal bone) relative to the ulna during supination and pronation. STUDY DESIGN: Eight feline cadaveric forelimbs were rotated from supination to pronation in a jig and computed tomography was performed in the neutral, supinated and pronated positions. The individual carpal bones were segmented from computed tomography images of the supinated and pronated scans in each of the eight specimens. A feline ulna coordinate system was established and used to quantify the translations and rotations between bones of the proximal carpal row and antebrachium. RESULTS: After the carpus was rotated from the initial supinated position into pronation, there was significant translation (x, y and z axes) and rotation (x and y axes) of the proximal row of carpal bones based on absolute magnitude values. Given the differences in translations and rotations of the proximal row of carpal bones, our null hypothesis was rejected. CONCLUSION: The proximal row of carpal bones translate and rotate independently from the ulna in the cat during pronation of the antebrachium. This may have future implications in the diagnosis and management of feline carpal injuries involving the antebrachiocarpal joint.

Comparison between high-field 3 Tesla MRI and computed tomography with and without arthrography for visualization of canine carpal ligaments: A cadaveric study.

OBJECTIVE: To compare the quality of visualization of canine carpal ligaments by using computed tomography (CT), MRI, CT arthrography (CTA), and magnetic resonance arthrography (MRA). STUDY DESIGN: Prospective descriptive study. STUDY POPULATION: Cadavers from dogs weighing more than 20 kg. METHODS: A 16-slice CT scanner and a 3 Tesla MRI were used for the investigation. A dilute contrast medium was injected into the middle carpal and radiocarpal joints under fluoroscopic control, and CTA and MRA images were acquired. To evaluate the difference between imaging modalities, 3 observers graded carpal ligaments of clinical interest using a scale from 0 to 4 for their quality of visualization. Data were analyzed by using a random-effect ordinal logistic regression with Bonferroni adjustment. The interobserver agreement was calculated by using the weighted Cohen's κ. RESULTS: Normal carpal joints (n = 9) were investigated. Magnetic resonance arthrography improved visualization of the majority of carpal ligaments compared with MRI (P < .05) and offered the best visualization overall. Magnetic resonance imaging and MRA offered better visualization compared with both CT and CTA (P < .05). There was no difference between CT and CTA. Interobserver agreement was discrete (0.2 < κ ≤ 0.4) for all observers. CONCLUSION: Arthrography improved the capabilities of MRI but not of CT for visualization of the canine carpal ligaments. Magnetic resonance arthrography was particularly useful for evaluation of the stabilizers of the antebrachiocarpal joint. CLINICAL SIGNIFICANCE: 3 Tesla MRA and MRI allow excellent visualization of the ligamentous morphology and may be helpful in the diagnostic process of carpal sprains in dogs.

The lesser anteater (Tamandua tetradactyla) is not tetradactyla, but pentadactyla.

The name of the species tetradactyla means "four digits." In the literature, the hand of the lesser anteater (Tamandua tetradactyla) is described as having four digits (I, II, III and IV) with the absence of a fifth digit. The purpose of this study was to carry out an update adequately proposing an anatomical description of the T. tetradactyla hand. The present findings were analysed on the validation of Morse's law for this species. In total, seven male cadavers were radiographed and dissected. We observed that the hand of the T. tetradactyla was formed by a carpus containing four bones in the proximal row, which in the medium lateral direction was the radial, intermediate, ulnar and accessory bones of the carpus, and the distal row was formed by carpal bones I, II, III and IV. There were five metacarpal bones (I, II, III, IV and V). The presence of five digits was verified but not confirmed with the literature. Digit I had two phalanges, the proximal and distal; digits II, III and IV had three phalanges: proximal, middle and distal. Digit five had only one phalanx, the proximal, but it was not externally visible. According to the findings of this study, the presence of the fifth digit raises the question of whether the term tetradactyla is the most appropriate to describe this species. This rudimentary fifth digit and the presence of a functional first digit show that the Morse's law does not applies for the T. tetradactyla species.

A novel radiographic projection for the detection of sagittal plane slab fracture of the equine third carpal bone.

BACKGROUND: Some sagittal plane fractures of the equine third carpal bone are difficult to detect with conventional radiographic projections. OBJECTIVES: To describe a novel radiographic projection for the detection of sagittal plane slab fractures of the equine third carpal bone. STUDY DESIGN: Retrospective study of radiological records. METHODS: From a first opinion Thoroughbred racehorse caseload, cases were included for analysis if sagittal fracture of the third carpal bone was evident on a dorsoproximal lateral-palmarodistal medial oblique (DPrL-PDiMO) projection of the distal row of carpal bones and not visible on the standard dorsoproximal-dorsodistal oblique (DPr-DDiO) projection. RESULTS: Eight cases in which radiological identification of fracture was dependent on the DPrL-PDiMO projection were identified from August 2013 to August 2017. MAIN LIMITATIONS: Unblinded study. CONCLUSIONS: Conventional radiographic projections can fail to detect some serious fractures of the equine third carpal bone. The DPrL-PDiMO projection has a role in the investigation of suspected carpal injury in racehorses.

Nonarticular osseous cyst-like lesions of the intermedioradial carpal bone may be incidental magnetic resonance imaging findings in dogs.

As magnetic resonance imaging (MRI) becomes more readily available and more frequently utilized in the assessment of canine carpal lameness, both normal variations and early pathologic conditions must be recognized to optimize patient care and provide accurate diagnosis. On cross sectional studies of the canine carpus, cyst-like lesions have been detected at the dorsolateral aspect of the intermedioradial carpal bone. The cross-sectional imaging and histologic properties of these lesions have not been described. The purpose of this observational study is to evaluate the MRI and histologic features of these cyst-like lesions in a cohort of clinically sound dogs. It was hypothesized that the lesions would show features similar to intraosseous ganglion cysts of the human wrist. Twenty-five cadaveric canine carpi were obtained and a total of 13 lesions were detected on MRI. Based on MRI, six carpi with lesions of varying size and one normal carpus were submitted for histological evaluation. Five of the abnormal carpi had nonarticular cyst-like lesions; one specimen with a positive magnetic resonance image for a cyst-like lesion had no cyst-like lesion on histology. Conspicuity of a medium-size lesion as evaluated on radiographs was poor. Given the presence of these nonarticular cyst-like lesions in a population of clinically sound patients, their clinical importance is uncertain. The development of these lesions may relate to altered mechanics or genetic predispositions, requiring additional study.

Pancarpal and partial carpal arthrodesis with 3 locking compression plates in 6 horses.

OBJECTIVE: To report the outcome of horses after pancarpal or partial carpal arthrodesis with 3 locking compression plates (LCP). STUDY DESIGN: Case series. ANIMALS: Six horses ranging in age from 8 months to 16 years and weighing 227-580 kg with severe carpal pathology including acute fractures, chronic osteoarthritis, and chronic angular limb deformity. METHODS: Pancarpal or partial carpal arthrodesis was performed with 3 LCP. Autologous cancellous bone grafts were used in 5 of 6 cases to facilitate joint arthrodesis. RESULTS: External coaptation was maintained for 4 to 6 weeks after surgery. Radiographic follow-up was available in all 6 cases, all of which reached arthrodesis and pasture soundness by 4-5 months postoperatively. One case required implant removal at 6 months because of implant exposure through the skin but returned to pasture soundness after removal. CONCLUSION: Carpal instability due to acute fractures or chronic disease was successfully stabilized with 3 short LCP, leading to pasture soundness in all 6 horses. CLINICAL SIGNIFICANCE: The use of 3 short LCP should be considered as a strategy to facilitate pancarpal or partial carpal arthrodesis by providing superior stability without placement of implants in the diaphysis of the radius and third metacarpus.

Three-dimensional kinematics of the canine carpal bones imaged with computed tomography after ex vivo axial limb loading and palmar ligament transection.

OBJECTIVE: To describe normal antebrachiocarpal joint kinematic motion during axial loading and to describe the effect of palmar radiocarpal ligament (PRL) and palmar ulnocarpal ligament (PUL) transection on this motion. SAMPLE POPULATION: Ten forelimbs from 5 adult greyhound cadavers. METHODS: Limbs were placed in a custom jig and computed tomography images of limbs were obtained in neutral and extended positions. The translation and rotation of the intermedioradiocarpal bone (RCB), ulnar carpal bone, and accessory carpal bone were described relative to the radius through rigid body motion analysis. Kinematic and load analysis was repeated after sequential transection of the PRL and the PUL. RESULTS: Sagittal plane extension with a lesser component of valgus motion was found in all evaluated carpal bones. RCB supination was also detected during extension. Compared with the normal intact limb, transection of either or both the PRL and the PUL did not influence mean translation or rotation data or limb load. However, the transection of the PRL and the PUL increased the variance in rotation data compared with intact limb. CONCLUSION: This study describes normal antebrachiocarpal kinematics as a foundation for determining carpal functional units. During axial loading, the PRL and the PUL may function to guide consistent motion in extension and flexion as well as pronation and supination. CLINICAL SIGNIFICANCE: Three-dimensional carpal kinematic analyses may improve our understanding of carpal injury and facilitate the development of novel treatments techniques.

Morphology of the thoracic limb of goat as evidenced by gross osteology and radiology.

The objective of this study was to provide the detailed normal gross osteology and radiographic anatomy of the thoracic limb in goats as a reference for clinical use and in biomedical research. Radiography of the thoracic limb was performed in five small East African goats. Radiographic findings were correlated with bone specimens from four adult small East African goats. The scapula was narrow. The major tubercle was large and extended proximally above the head of the humerus. The lateral supracondylar crest was less prominent. The lateral and medial epicondyles of the humerus were almost of the same size. The lateral surface of the lateral condyle of the humerus presented a prominent depression for the origin of extensors of the carpus and digits. The cranially located radial notch was deep seated and the radial tuberosity was represented by a rough area located nearer to the head of the radius. The fifth metacarpal bone was seen in all animals. The morphology of the thoracic limb of small East African goats indicated the presence of powerful extensor muscles and is restricted to forward and backward movements as an adaptation to terrestrial lifestyle.

MAGNETIC RESONANCE IMAGING SCORING OF AN EXPERIMENTAL MODEL OF POST-TRAUMATIC OSTEOARTHRITIS IN THE EQUINE CARPUS.

Magnetic resonance imaging (MRI) is the most sensitive imaging modality to detect the early changes of osteoarthritis. Currently, there is no quantifiable method to tract these pathological changes over time in the horse. The objective of this experimental study was to characterize the progression of MRI changes in an equine model of post-traumatic osteoarthritis using a semiquantitative scoring system for whole-organ evaluation of the middle carpal joint. On day 0, an osteochondral fragment was created in one middle carpal joint (OCI) and the contralateral joint (CON) was sham-operated in 10 horses. On day 14, study horses resumed exercise on a high-speed treadmill until the completion of the study (day 98). High-field MRI examinations were performed on days 0 (preosteochondral fragmentation), 14, and 98 and scored by three blinded observers using consensus agreement. Images were scored based on 15 independent articular features, and scores were compared between and within-groups. On days 14 and 98, OCI joints had significantly (P ≤ 0.05) higher whole-organ median scores (29.0 and 31.5, respectively), compared to CON joints (21.5 and 20.0, respectively). On day 14, OCI joints showed significant increases in high-signal bone lesion scores, and osteochondral fragment number and size. On day 98, high-signal bone lesion, low-signal bone lesion, osteophyte formation, cartilage signal abnormality, subchondral bone irregularity, joint effusion, and synovial thickening scores were significantly increased in OCI joints. Study results suggest that the MRI whole-organ scoring system reported here may be used to identify onset and progression of pathological changes following osteochondral injury.

Computed tomographic arthrography of the normal dromedary camel carpus.

The aim of this prospective cadaveric study was to provide a detailed computed tomographic (CT) reference of the carpal joint in healthy dromedary camels. Twelve forelimbs of six apparently healthy camels were used. Computed tomographic imaging of 12 normal cadaveric camel carpal joints was performed before and after intra-articular administration of iodinated contrast medium. Transverse CT images were reconstructed in dorsal and parasagittal planes. The six carpal bones, the radial trochlea, and the proximal articular surface of the metacarpal bones were clearly visible on CT images with the bone setting window. Radiocarpal, carpometacarpal, transverse intercarpal, medial and lateral palmer intercarpal, middle intercarpal, accessory carpoulnar and medial and lateral collateral ligaments, carpal canal, joint capsule, and the extensor and flexor tendons were identified on CT images with the soft-tissue setting window. Postcontrast CT images provided better delineation of intercarpal ligaments, the capsular compartments and recesses. Results indicated that the osseous and the clinically important soft tissue structures of the dromedary camel carpal joint could be identified using CT and CT arthrography. The CT data of this study will serve as a basis for diagnosis of carpal problems in camels.

Improvement in Bilateral Carpal Valgus Deviation in 9 Foals After Unilateral Distolateral Radial Periosteal Transection and Elevation.

OBJECTIVES: To evaluate the effect of periosteal transection and elevation in foals with naturally occurring carpal valgus deviation. STUDY DESIGN: Prospective clinical study. ANIMALS: Foals (n = 9) with bilateral carpal valgus. METHODS: Foals with bilateral carpal valgus had distolateral radial periosteal transection and elevation (PE) including distal ulnar transection on 1 limb. Foals were stall confined until the skin incisions healed, and then allowed free exercise in a small paddock or round pen. Dorsopalmar carpal radiographs were obtained at 14 day intervals to determine the carpal valgus angle (CVA) until it was <5°. RESULTS: All limbs had a reduction in CVA and there was no significant difference in total carpal valgus angular correction or the rate at which the correction occurred between the surgical and control limb. CONCLUSIONS: Unilateral distolateral radial PE had no effect on carpal angulation in 9 foals with naturally occurring bilateral carpal valgus deviation when performed between 19 and 43 days.

Ultrasonographic findings in 38 horses with septic arthritis/tenosynovitis.

Septic arthritis/tenosynovitis in the horse can have life-threatening consequences. The purpose of this cross-sectional retrospective study was to describe ultrasound characteristics of septic arthritis/tenosynovitis in a group of horses. Diagnosis of septic arthritis/tenosynovitis was based on historical and clinical findings as well as the results of the synovial fluid analysis and/or positive synovial culture. Ultrasonographic findings recorded were degree of joint/sheath effusion, degree of synovial membrane thickening, echogenicity of the synovial fluid, and presence of hyperechogenic spots and fibrinous loculations. Ultrasonographic findings were tested for dependence on the cause of sepsis, time between admission and beginning of clinical signs, and the white blood cell counts in the synovial fluid. Thirty-eight horses with confirmed septic arthritis/tenosynovitis of 43 joints/sheaths were included. Degree of effusion was marked in 81.4% of cases, mild in 16.3%, and absent in 2.3%. Synovial thickening was mild in 30.9% of cases and moderate/severe in 69.1%. Synovial fluid was anechogenic in 45.2% of cases and echogenic in 54.8%. Hyperechogenic spots were identified in 32.5% of structures and fibrinous loculations in 64.3%. Relationships between the degree of synovial effusion, degree of the synovial thickening, presence of fibrinous loculations, and the time between admission and beginning of clinical signs were identified, as well as between the presence of fibrinous loculations and the cause of sepsis (P ≤ 0.05). Findings indicated that ultrasonographic findings of septic arthritis/tenosynovitis may vary in horses, and may be influenced by time between admission and beginning of clinical signs.

Thoracic Limb Morphology of the Ring-tailed Lemur (Lemur catta) Evidenced by Gross Osteology and Radiography.

There is limited information available on the morphology of the thoracic limb of the ring-tailed lemur (Lemur catta). This study describes the morphology of the thoracic limb of captive ring-tailed lemurs evidenced by gross osteology and radiography as a guide for clinical use. Radiographic findings of 12 captive ring-tailed lemurs are correlated with bone specimens of three adult animals. The clavicle is well developed. The scapula has a large area for the origin of the m. teres major. The coracoid and hamate processes are well developed. The lateral supracondylar crest and medial epicondyle are prominent. The metacarpal bones are widely spread, and the radial tuberosity is prominent. These features indicate the presence of strong flexor muscles and flexibility of thoracic limb joints, which are important in arboreal quadrupedal locomotion. Furthermore, an ovoid ossicle is always seen at the inter-phalangeal joint of the first digit. Areas of increased soft tissue opacity are superimposed over the proximal half of the humerus and distal half of the antebrachium in male animals as a result of the scent gland. Knowledge of the morphology of the thoracic limb of individual species is important for accurate interpretation and diagnosis of musculoskeletal diseases.

Carpal valgus in llamas and alpacas: Retrospective evaluation of patient characteristics, radiographic features and outcomes following surgical treatment.

This study evaluated outcomes of surgical treatment for carpal valgus in New World camelids and correlated successful outcome (absence of carpal valgus determined by a veterinarian) with patient characteristics and radiographic features. Univariable and multivariable analyses of retrospective case data in 19 camelids (33 limbs) treated for carpal valgus between 1987 and 2010 revealed that procedures incorporating a distal radial transphyseal bridge were more likely (P = 0.03) to result in success after a single surgical procedure. A greater degree of angulation (> 19°, P = 0.02) and younger age at surgery (< 4 months, P = 0.03) were associated with unsuccessful outcome. Overall, 74% of limbs straightened, 15% overcorrected, and 11% had persistent valgus following surgical intervention. To straighten, 22% of limbs required multiple procedures, not including implant removal. According to owners, valgus returned following implant removal in 4 limbs that had straightened after surgery.

Valgus carpien chez les lamas et les alpagas : évaluation rétrospective des caractéristiques des patients, des radiographies et des résultats après un traitement chirurgical. Cette étude a évalué les résultats du traitement chirurgical pour le valgus carpien chez des camélidés du nouveau monde et a établi une corrélation entre les résultats fructueux (absence de valgus carpien déterminée par un vétérinaire) et les caractéristiques du patient et des radiographies. Des analyses à variable unique et à variables multiples des données de cas rétrospectifs chez 19 camélidés (33 jambes) traités pour le valgus carpien entre 1987 et 2010 ont révélé que les procédures intégrant un pont radial distal transphyséal présentaient une plus grande probabilité de succès (P = 0,03) après une seule intervention chirurgicale. Une déviation supérieure (> 19°, P = 0,02) et un jeune âge à la chirurgie (< 4 mois, P = 0,03) étaient associés à des échecs. Dans l'ensemble, 74 % des jambes ont été redressés, 15 % ont été corrigées et 11 % présentaient un valgus persistant après l'intervention chirurgicale. Pour le redressement, 22 % des jambes ont nécessité des procédures multiples, ce qui n'incluait pas l'enlèvement de l'implant. Selon les propriétaires, le valgus est réapparu après l'enlèvement de l'implant dans 4 jambes qui avaient été redressées après la chirurgie.(Traduit par Isabelle Vallières).

Management of carpal hyperextension injury in a cat using combined temporary transarticular internal and external skeletal fixation.

This report describes the successful management of a carpal hyperextension injury in a cat using combined temporary transarticular internal and external skeletal fixation, without performing an arthrodesis. To our knowledge, there have been no previous reports of management of feline carpal hyperextension injuries in this fashion.

Frontal plane fractures of the accessory carpal bone and implications for the carpal sheath of the digital flexor tendons.

REASONS FOR PERFORMING STUDY: Accurate radiological and ultrasonographic descriptions of frontal plane fractures of the accessory carpal bone (ACB) are lacking, and implications of these fractures for the carpal sheath and its contents have not previously been reported. OBJECTIVES: Aims were as follows: 1) to describe the location and radiological features of frontal plane fractures of the ACB; 2) to document communication of displaced fractures with the carpal sheath and consequent injury to the deep digital flexor tendon (DDFT); 3) to describe ultrasonographic identification of lesions; and 4) to report tenoscopic evaluation and treatment. STUDY DESIGN: Retrospective case series. METHODS: Analysis of frontal plane fractures of the ACB referred to a single hospital between 2006 and 2012, including review of radiographic, ultrasonographic and tenoscopic images. RESULTS: Nine fractures were identified, of which 8 displaced fractures all communicated with the carpal sheath. Comminuted fragments and/or protruding fracture margins lacerated the lateral margin of the enclosed DDFT. This was identifiable ultrasonographically and confirmed at tenoscopy in 7 cases. Treatment in these horses consisted of removal of torn tendon tissue together with fragmentation and protuberant fracture edges, and 7 of 7 cases returned to work. One horse with a nondisplaced fracture was managed with immobilisation; the fracture healed, and the horse returned to work. One horse with a displaced fracture was retired to stud. CONCLUSIONS: Frontal plane fractures of the ACB occur palmar to the groove in its lateral margin for the tendon of insertion of ulnaris lateralis. Comminuted fragments can displace distally within the carpal sheath to a mid-metacarpal level or abaxially to lie extrathecally, lateral to the parent bone. Displaced fractures communicate with the carpal sheath and traumatise the DDFT.

An assessment of intra- and interobserver agreement of reporting orthopaedic findings on presale radiographs of Thoroughbred yearlings.

REASONS FOR PERFORMING STUDY: Radiography is commonly used in clinical practice but agreement of reporting of radiographically detected orthopaedic findings in horses has rarely been studied. OBJECTIVES: To assess agreement within and between observers for reporting of orthopaedic findings on presale radiographs of Thoroughbred yearlings. STUDY DESIGN: Retrospective analysis of archived radiographs. METHODS: Four veterinary radiology specialists each twice examined 167 sets of radiographs for orthopaedic findings in the fore feet, fore and hind fetlocks, carpi, tarsi and stifles. There were 27 findings analysed for agreement. Kappa statistic (κ), percentage of positive agreement (Ppos) and percentage of negative agreement are reported. RESULTS: An excellent percentage of negative agreement was observed for all findings, with the exception of regular vascular channels of the proximal sesamoid bones. Ppos and κ results were variable. The presence of extra carpal bones, osseous cyst-like lesions of the ulnar carpal bone, sagittal ridge defects of the third metacarpus, fracture of the fore and hind proximal sesamoid bones, regular vascular channels in the hind proximal sesamoids, osteochondrosis lesions of the distal intermediate ridge and/or medial malleoli of the tibia, and osseous cyst-like lesions in the medial femoral condyle was consistently observed with an intra- and interagreement κ≥0.5 and Ppos≥50%. Lucency within the proximal sesamoids consistently had an observed intra- and interagreement κ<0.4 and Ppos<40%. CONCLUSIONS: Observation of orthopaedic findings on yearling repository radiographs showed generally excellent agreement on the absence of findings, but variable agreement on the presence of findings. Agreement was good for larger and easy to categorise radiographic findings. More accurate definitions and training need to be developed to improve agreement within and between observers for orthopaedic findings with poor or fair to good agreement.