Auxiliary osseous findings in fetlocks of non-racing sports horses with sagittal groove disease of the proximal phalanx on low-field magnetic resonance imaging.

BACKGROUND: Sagittal groove disease of the proximal phalanx in equine athletes is commonly considered a bone stress injury. Repetitive hyperextension of the fetlock under high load is thought to contribute to its development. Concurrent changes are often reported in the dorsal sagittal ridge of the third metacarpus/metatarsus (MC3/MT3). OBJECTIVES: To describe the spectrum of associated osseous abnormalities that are present in the fetlock in a large group of horses diagnosed with sagittal groove disease on low-field magnetic resonance imaging (MRI). STUDY DESIGN: Retrospective, cross-sectional. METHODS: MRI images of horses diagnosed with sagittal groove disease at Equitom Equine Clinic between March 2014 and March 2023 were evaluated using semi-quantitative grading schemes and a sagittal groove disease MRI classification system. RESULTS: MRIs of 132 limbs were evaluated, predominantly from warmbloods used for showjumping (n = 83) and dressage (n = 18). Osseous densification and bone oedema-like signal grades were higher in the dorsal sagittal ridge than palmarly/plantarly (p < 0.001 and p < 0.05, respectively). Grades of both osseous densification and bone oedema-like signal in the dorsal sagittal ridge did not significantly differ between the different sagittal groove disease MRI classifications (both p > 0.05). MAIN LIMITATIONS: Inclusion based on original MRI reports, absence of control group, small numbers within some grading groups hindering statistical analyses. CONCLUSIONS: Findings support the aetiological theories of chronic bone-stress due to loaded fetlock hyperextension however the severity of osseous changes of the dorsal sagittal ridge does not appear to be associated with the severity of sagittal groove disease classification.

HISTORIAL: La enfermedad del surco sagital (SGD) de la falange proximal en equinos atletas, es considerada comúnmente como un lesión de hueso por estrés. Se piensa que la hiperextensión repetitiva del nudo bajo alta carga contribuye a su desarrollo. Cambios concurrentes ocurren menudo en la cresta sagital dorsal del tercer metacarpo/metatarso (MC3/MT3). OBJETIVOS: Describir el espectro de anomalías óseas asociadas que están presentes en el nudo en un gran grupo de caballos diagnosticados con SGD por imágenes de resonancia magnética de baja frecuencia (MRI). DISEÑO DEL ESTUDIO: Retrospectivo, transversal. MÉTODOS: Imágenes de MRI de caballos diagnosticados con SGD en la Clínica Equina Equitom de Marzo 2014 a Marzo 2023, fueron evaluadas usando esquemas de graduación semi­cuantitativos y un sistema de clasificación de SGD MRI. RESULTADOS: MRIs de 132 extremidades fueron evaluadas, proveniente principalmente de caballos de sangre caliente (Warmblood) usados para salto (n = 83) y adiestramiento (n = 18). Densificación ósea y los grados de las señales parecidas al edema de hueso, eran mayores en la cresta sagital dorsal que en palmar/plantar (p < 0.001 y p < 0.05, respectivamente). Los grados de tanto la densificación ósea como de la señal parecida al edema óseo en la cresta sagital, no difirieron significativamente entre las clasificaciones SGD MRI (ambos p > 0.05). LIMITACIONES PRINCIPALES: Inclusión basada en los informes de MRI originales, ausencia de grupo de control, numero pequeño dentro de algunos de los grupos por graduación lo que no permitió hacer análisis estadísticos. CONCLUSIONES: Los hallazgos apoyan las teorías etiológicas del estrés óseo crónico debido a la hiperextensión del nudo bajo carga, sin embargo la severidad de los cambios óseos de la cresta sagital dorsal no parecen estar asociada con la severidad de la clasificación SGD.

Low-field magnetic resonance imaging of sagittal groove disease of the proximal phalanx in non-racing sport horses.

BACKGROUND: Injuries of the sagittal groove of the proximal phalanx (P1) in equine athletes are considered to predominantly occur due to chronic bone stress overload. OBJECTIVES: To describe the range of abnormalities that is present in the sagittal groove in a large group of horses diagnosed with sagittal groove disease (SGD) on low-field MRI. STUDY DESIGN: Retrospective, cross-sectional. METHODS: Medical records were searched to identify initial MRI images of horses diagnosed with SGD and these were blindly evaluated using a semi-quantitative grading scheme and novel SGD MRI classification system reflecting potential pathways of pathological progression and severity of stress injury. RESULTS: A total of 132 limbs from 111 horses were included in the study; predominantly warmbloods competing in showjumping (n = 83) and dressage (n = 18). SGD MRI classifications were: 0 (normal, n = 0), 1 (small subchondral defect, n = 2), 2 (osseous densification, n = 28), 3 (subchondral microfissure with osseous densification, n = 7), 4 (bone oedema-like signal within the subchondral ± trabecular bone and ± subchondral microfissure or demineralisation, n = 72), 5 (incomplete macrofissure/fracture, n = 23) and 6 (complete fracture, n = 0). Classification 4c (bone oedema-like signal with demineralisation) and 5 had higher proportions in the plantar third of hindlimbs (3% and 10%, respectively) compared with forelimbs (0% and 0%, respectively). SGD classification and extent of bone oedema-like signal were not significantly different between lame (n = 116) and non-lame limbs (n = 16) (both p > 0.05). Periosteal new bone and oedema-like signal were identified (either confidently or suspected) at the dorsoproximal aspect of P1 in 25% and 39% of limbs, respectively. MAIN LIMITATIONS: Inclusion via diagnoses in original MRI reports, variable clinical history, small size of some classification groups. CONCLUSIONS: The presence or absence of lameness is not a dependable measure of the severity of SGD. The periosteal oedema-like signal of P1 has not previously been described in MRI of SGD and further supports the concept of bone stress injury.

Follow-Up Magnetic Resonance Imaging of Sagittal Groove Disease of the Equine Proximal Phalanx Using a Classification System in 29 Non-Racing Sports Horses.

Evolution of magnetic resonance imaging (MRI) findings in horses with sagittal groove disease (SGD) of the proximal phalanx is relatively sparsely described. This retrospective, descriptive, longitudinal study describes the findings of sequential low-field MRI fetlock examinations in horses with SGD of the proximal phalanx using a classification system. Twenty-nine horses were included, predominantly warmbloods used for show jumping (79%). For 29 limbs re-examined during the initial rehabilitation period, classification remained constant (n = 18), increased (n = 2), decreased (n = 7), and fluctuated (n = 2). Notably, two limbs with initial classification 4b (bone oedema-like signal with subchondral microfissure) and one with 4c (bone oedema-like signal with subchondral demineralisation) progressed to classification 5 (incomplete macrofissure/fracture), highlighting their potential as prodromal or imminent fissure pathology. Following conservative (n = 28) and surgical (n = 1) treatment, 86% of the horses re-entered full training and competition with a mean ± sd recovery time of 9.4 ± 4.4 months. In total, 20% of horses in the study subsequently presented for repeat MRI due to recurrent lameness after resuming full work, with classification that was the same (n = 2), increased (n = 2), or decreased (n = 2) compared with the last scan. This study underscores the variability in progression of SGD MRI findings, emphasising the need for further larger-scale research into patterns of progression.

Evaluation of three approaches for performing ultrasonography-guided anesthetic blockade of the femoral nerve in calves.

OBJECTIVE: To develop a practical ultrasonography-guided injection approach to anesthetic blockade of the femoral nerve in calves and to assess the method's accuracy. ANIMALS: 13 cadavers of 4-week-old male Holstein Friesian calves. PROCEDURES: Detailed topographic and anatomic cross-sectional evaluation of the relevant topography in 3 cadavers was performed to identify optimal injection approaches to the femoral nerve. Three approaches (ventral paravertebral, dorsal paravertebral, and ileal) were evaluated by simulated ultrasonography-guided perineural injection of methylene blue dye in 10 cadavers. Ultrasonographic image quality, number of needle redirections required for correct needle positioning, and injection success as defined through a 3-point grading system were recorded. RESULTS: The dorsal paravertebral approach yielded the best results, compared with the ileal and ventral paravertebral approaches, to properly and adequately stain the targeted nerve. CONCLUSIONS AND CLINICAL RELEVANCE: The dorsal paravertebral injection technique appeared to be the best choice for performing a femoral nerve block in calves, although this technique will need to be further evaluated in live calves to determine its effectiveness and clinical usefulness. Diagnostic perineural anesthesia of the femoral nerve in cattle might be helpful in identifying quadriceps muscle involvement in those with complex spastic paresis.

Ultrasound-guided femoral nerve block as a diagnostic aid in demonstrating quadriceps involvement in bovine spastic paresis.

The aim of this study was to evaluate the clinical effects of a femoral nerve block via a dorsal paralumbar injection in healthy calves and calves suffering from spastic paresis. Based on bony landmarks and using ultrasound guidance, the femoral nerves of eight healthy calves were blocked bilaterally with a 4% procaine solution containing blue dye. In 11/16 nerve blocks, paralysis of the quadriceps muscle was obtained after dorsal paralumbar injection. Paralysis was total in 8/16 cases. The injection site was confirmed by post mortem dissection, and in 12/16 cases, the blue dye was found <2mm from the nerve. Clinical use of the technique was then demonstrated in two cases of atypical bovine spastic paresis. In such calves an objective diagnostic tool is required to identify those calves which are suitable for partial tibial neurectomy. The femoral nerve block used in this study has the potential to be such a method and can be used to establish the involvement of the quadriceps femoris in calves suffering from the quadriceps or mixed presentation form of spastic paresis.