navicular syndrome
DESCRIPTION
Navicular Syndrome. Accession numbers 89605 and 89621 Christina Copple, DVM Radiology Resident. Navicular Syndrome. Syndrome = group of symptoms, collectively indicate the presence of an underlying abnormal condition - PowerPoint PPT PresentationTRANSCRIPT
Navicular Syndrome
Accession numbers 89605 and 89621
Christina Copple, DVM
Radiology Resident
Navicular Syndrome
• Syndrome = group of symptoms, collectively indicate the presence of an underlying abnormal condition
• Navicular Syndrome = chronically progressive, intermittent, bilateral forelimb lameness due to pain arising from the navicular apparatus– Can be unilateral and can occur in the hind limb
Navicular Apparatus
• Navicular bone – distal sesamoid bone
• Collateral ligaments
• Distal sesamoidean impar ligament
• Navicular bursa
• Distal digital annular ligament
• Deep digital flexor tendon - major compressive forces
• 4-navicular bone or distal sesamoid bone• 14- deep digital flexor tendon• 8- distal sesamoidean impar ligament• 16- navicular bursa• 15- distal digital annular ligament
• 3- navicular bone or distal sesamoid bone• 8- deep digital flexor tendon• 6- distal sesamoidean impar ligament• 9a/9b- navicular bursa (proximal and distal recesses)• 11- distal digital annular ligament
Risk Factors
• Concave or undulating proximal articular margin
• Degenerative changes of palmar fibrocartilage– Physiologic vs. Non-
physiologic
• Fibrillation of DDFT• Enthesophytosis and
mineralized fragments• Primary navicular bursitis
http://www.portugalweb.com/images/Portuguese-horse-500-1.jpg
History, Clinical Signs and Diagnosis
• Insidious onset, intermittent bilateral forelimb shifting leg lameness
• Usually 7-9 yrs of age• Pain when standing at rest, pointing toe• Lameness more apparent moving in a circle with lame
limb on inside• Usually positive response to palmar digital nerve blocks
and navicular bursa analgesia• * No pathognomic findings• Diagnosis = characteristic gait, palmar foot pain,
radiographic degenerative changes of navicular bone, rule-out other possible causes of lameness
Radiographs
• Proximal border & Extremities– Enthesophytosis of
extremities– Remodeling
• Distal border– Synovial invaginations– Small osseous fragments
• Flexor cortex– Cortical erosions– DDFT mineralization
• Medullary Cavity– Radiolucent cysts– Sclerosis
Nuclear Scintigraphy
• Patterns of increased radiopharmaceutical uptake commonly associated with palmar foot pain– Focal or generalized in navicular
bone– Navicular bone and distal
phalanx at region of insertion of DDFT
– Navicular bone and palmar processes of distal phalanx
– One or both palmar processes of distal phalanx
– Distal phalanx at sites of insertion of DDFT
CT & MRI
• Both more sensitive than radiographs to further characterize structural lesions of navicular bone, primary lesions of DDFT, identify degenerative changes of DIP articular cartilage
• CT: osseous changes and surface contour of lateral wings, evaluate articular flexor surface
• MRI: 3D spoiled gradient echo, 3D T2 gradient echo, STIR and fat-saturated 3D T2*– Soft tissues lesions – fibrocartilage changes,
distension of navicular bursa, DDFT or impar ligament changes, abnormal bone marrow within navicular bone
SNORT
• 16 yr old Quarter horse gelding
• 3yr history of left forelimb lameness
• Previously diagnosed with bilateral navicular “disease”
• PE: right forelimb lame 3/5, positive on flexion tests in both forelimbs
Left Dorsolateral-Palmaromedial oblique
Left Dorsomedial-Palmarolateral oblique
Left palmaroproximal-palmarodistal oblique
Right palmaroproximal-palmarodistal oblique
Right dorsolateral-palmaromedial oblique
Right dorsomedial-palmarolateral oblique
Left STIR Right STIR
References•Ross, Mike W., DVM and Sue J. Dyson, MA, VetMB, PhD, DEO, FRCVS. Diagnosis and Management of Lameness in the Horse. Saunders. Philadelphia, PA. 2003.•Thrall, Donald E., DVM, PhD. Textbook of Veterinary Diagnostic Radiology. 5th ed. Saunders. St. Louis, MO. 2007.•Stashak, Ted S., DVM, MS. Adams’ Lameness In Horses. 5th ed. Lippincott Williams & Wilkins. Philadelphia, PA. 2002.•Denoix, J.-M. The Equine Distal Limb Atlas of Clinical Anatomy and Comparative Imaging. Iowa State University Press. Ames, IA. 2000.•Pasquini, Chris, DVM, MS, Tom Spurgeon, PhD, and Susan Pasquini, DVM. Anatomy of Domestic Animals Systemic and regional approach. 7th ed. Sudz Publishing. Pilot Point, TX. 1996.