Equis ISSN 2398-2977

Proximal sesamoid: sesamoiditis

Contributor(s): Graham Munroe

Introduction

  • Local inflammation of the proximal sesamoid bones at the site of ligament attachment in racing horses.
  • Two forms of the disease have been described.
  • Signs: can present as an acute, or more usually chronic, forelimb lameness in horses in race training with swelling of the palmar fetlock and palpable pain.
  • Diagnosis: regional anesthesia, radiography and ultrasonography are essential.
  • Treatment: involves rest, modification of work programmes, cold therapy, support bandaging and topical/systemic anti-inflammatory medications.
  • Prognosis: guarded.

Pathogenesis

Predisposing factors

General
  • Hard training or racing.
  • Abnormal limb conformation.
  • Previous injury to suspensory apparatus.

Pathophysiology

  • Term used to describe proliferative or degenerative bony changes of the proximal sesamoid bones.
  • Two forms have been described:
    • Periostitis.
    • Osteitis.
  • 2 forms of seamoiditis have been described.

Periostitis form

  • Acute or chronic injury to the suspensory ligament, distal sesamoidean ligaments and/or palmar/plantar annular ligament of fetlock.
  • Leads to damage at bone-ligament interface (entheses) with proximal sesamoid bones.
  • Osseous metaplasia of fibrous scar tissue and periostitis   →   formation of enthesiophytes + changes in bone contour.

Osteitis form

  • Degenerative condition - is sesamoiditis the right term?
  • Arteriosclerosis and thrombosis of nutrient arteries with subsequent local ischemic necrosis has been suggested as causing demineralized vascular channels within sesamoid bones.
  • Others have suggested that they are normal variations in appearance.
  • Enthesiopathy at the insertion site of the suspensory ligament branches between the nutrient foramina may   →   to the impression of radiolucency and enlargement of vascular channels.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references fromPubMedandVetMedResource.
  • McLellan J & Plevin S (2014)Do radiographic signs of sesamoiditis in yearling Thoroughbreds predispose the development of suspensory ligament branch injury?Equine Vet J46(4), 446-450PubMed.
  • Zekas L Jet al(1999)Characterization of the type and location of fractures of the third metacarpal/metatarsal condyles in 135 horses in central Kentucky (1986-1994).Equine Vet J31(4), 304-308PubMed.
  • Trumble T Net al(1995)Clinical relevance of the microvasculature of the equine proximal sesamaoid bone.Am J Vet Res56(6), 720-724PubMed.
  • Reeves M (1991)Sesamoiditis.JAVMA199(6), 682-683PubMed.
  • Hardy Jet al(1991)Clinical relevance of radiographic findings in proximal sesamoid bones of two year-old Standardbreds in their first year of race training.JAVMA198(12), 2089-2094PubMed.
  • Nemeth F (1973)Sesamoiditis in the horse.Tijdschr Diergeneeskd98(20), 988-994PubMed.
  • Nemeth F (1973)The pathology of sesamoiditis.Tijdschr Diergeneeskd98(20), 1003-1021PubMed.


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