Navicular bone osteomyelitis and navicular bursitis with associated fistula diagnosed with magnetic resonance fistulography in the horse

Abstract

A 7-year-old Quarter Horse gelding was referred for magnetic resonance (MR) imaging due to chronic left hindlimb lameness localised to the foot. On presentation, a previously undiagnosed draining tract was identified at the plantar aspect of the pastern. Radiographs revealed severe osteolysis of the navicular bone. Positive contrast MR fistulography was performed using a gadolinium based contrast agent following conventional MR imaging of the left hind foot. Fistulography allowed characterisation of a fistulous tract, which was closely associated with the deep digital flexor tendon, navicular bursa and osteomyelitis of the navicular bone. History and clinical findingsA 7-year-old Quarter Horse gelding was referred for magnetic resonance imaging (MRI) of the left hind foot for the investigation of intermittent lameness of 3 months' duration. Recurrent subsolar and coronary band abscesses were diagnosed by the referring veterinarian. Treatment prior to referral included debridement of devitalised tissue from both the sole and coronary band, oral administration of nonsteroidal anti-inflammatory medication, oral administration of antibiotics, and administration of antibiotics by regional limb perfusion.At presentation, the horse was grade 4-5 out of 5 lame using the AAEP lameness scale on the left hindlimb (Anon 1999). A draining tract not previously reported by the referring veterinarian was identified at the plantar aspect of the pastern. A low 4-point nerve block and a dorsal ring block performed proximal to the metatarsophalangeal joint resulted in marked decrease in the degree of lameness. Imaging RadiographyRadiography of the left hind foot revealed severe navicular bone osteolysis of the distal half of the flexor cortex extending into the medullary cavity (Fig 1). Moderate concentric soft tissue swelling was evident from the metatarsophalangeal joint to the level of the coronary band. The findings were most consistent with infectious osteomyelitis. Magnetic resonance imagingThe horse was placed under general anaesthesia using a standard anaesthetic protocol. Magnetic resonance imaging was performed using a 1.5 T magnet (Echelon) 1 with the horse in left lateral recumbency. Sagittal proton density (PD) at 3 mm slice thickness, T2-weighted fast spin echo (T2W FSE) at 4 mm slice thickness, fast inversion recovery (FIR) at 4 mm slice thickness, transverse PD and T2W FSE both at 3 mm slice thickness, and a dorsal PD sequence at 3 mm slice thickness sequences were acquired from the tip of the foot to the midpoint of the proximal phalanx. A transverse 3D T2* sequence was acquired and reconstructed in 1 mm thick slices in the sagittal plane.The distal aspect of the navicular bone flexor cortex showed a large ill-defined zone of hyperintensity on PD, T2* and FIR sequences (Fig 2). Multifocal, 1-2 mm diameter Fig 1: Lateromedial radiograph of foot of left pelvic limb. The distal aspect of the flexor cortex is lytic and irregularly bordered with extension of lysis into the adjacent medullary region. The distal interphala...

Magnetic resonance imaging assisted management in five cases of suspected quittor

“…Magnetic resonance imaging (MRI) is a well-described imaging modality for use in assessment of lameness localized to the equine foot. The use of MRI in cases of foot penetration and for surgical planning in conditions such as keratoma and osteomyelitis of the navicular bone has also been described (7)(8)(9)(10)(11). Here we present a case series utilizing MRI for treatment planning in cases of suspected quittor.…”

A practical approach to localization of a suppurative cavity and resolution of a chronic draining tract in a horse

“…2 Fistulography is useful for identifying the direction of a chronic draining tract, determining the number and location of foreign bodies or establishing the relationship between draining tracts and suppurative cavities. 2,[8][9][10][11][12][13] A fistulogram is produced when radiographs are taken of contrast media that has been forced through a Foley catheter placed into a chronic draining tract. 2,10,11 Fistulograms aid in localizing foreign bodies and determining communication between chronic draining tracts and suppurative cavities.…”

The use of magnetic resonance imaging for the diagnosis of osteomyelitis

“…The case presented in this issue by Garcia et al . () demonstrates the use of magnetic resonance imaging (MRI) positive contrast fistulography in a horse with a penetrating foot wound and associated osseous and soft tissue injury. Based on the history, and clinical and imaging examinations, infectious osteomyelitis was strongly suspected.…”

“…The case presented in this issue by Garcia et al . () demonstrates the use of positive contrast fistulography in a horse with a suspected penetrating wound. Clear signs of osteomyelitis were present in this case.…”