1. Equine Proximal Sesamoiditis Accession # 70753 Christina Copple, DVM Radiology Resident NCSU CVM-VTH

2. Sesamoid Bones: embedded within a tendon and protect it Equine Metacarpo-/Metatarsophalangeal Joints = function to provide a frictionless surface along the flexor aspect Sesamoiditis – ischemic disease of the proximal sesamoid bones resulting in lameness usually after hard exercise and pain on deep palpation of the abaxial surface of the proximal sesamoids

3. Anatomy • Proximal Sesamoid Bones are 3-sided pyramids with an apex, body, and base • Dorsal surface • Abaxial surface • Palmar surface

4. Sesamoidean Ligaments Collateral sesamoidean Intersesamoidean Superficial (straight) Middle (oblique) Deep (cruciate) Palmar annular ligament Anatomy

5. Anatomy

6. Anatomy Palmarolateral View

7. Anatomy Palmar View

8. Views Lateromedial (standing & flexed) Dorsopalmar/-plantar (standing & flexed) 45 degree DLPM/DMPL obliques Findings Marginal osteophytosis Abaxial enthesophytosis Enlarged vascular channels Focal osteolysis Radiography

9. Accession # 70753Blackis 15 yr old MC Walking HorseChronic left hindlimb 4/5 lameness, marked swelling palpable over metatarsophalangeal joint

10. Accession # 70753

11. References • Pasquini, Chris, D.V.M, V. Krishna Reddy, B.V.Sc., Ph.D., Marc H. Ratzlaff, D.V.M., Ph.D. Atlas of Equine Anatomy. 2nd ed. Sudz Publishing. Eureka, CA, 1983. • Dyce, K. M., D.V.M. &S., B.Sc., M.R.C.V.S., W.O. Sack, D.V.M., Ph.D., Dr. med. Vet., C. J. G. Wensing, D.V.M., Ph.D., Textbook of Veterinary Anatomy. 2nd ed. W.B. Saunders. Philadelphia, PA, 1996. • Ross, Mike W., DVM, 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, DACVR. Textbook of Veterinary Diagnostic Radiology. 5th ed. Saunders. St. Louis, MO, 2007. • Butler et al. Clinical Radiology of the Horse. 2nd ed. Blackwell Science. Onsey Mead, Oxford, 2000. • Denoix, J.-M. The Equine Distal Limb Atlas of Clinical Anatomy and Comparative Imaging. Iowa State University Press. Ames, IA, 2000.