Equis ISSN 2398-2977

Tarsus: osteochondrosis

Synonym(s): OCD

Contributor(s): Stephen Adams, Graham Munroe, Vetstream Ltd, Chris Whitton

Introduction

  • Cause: developmental orthopedic disease - disorder of cartilage development - may be nutritional, hereditary, toxic factors; affects the distal intermediate ridge of the tibia, medial malleolus of the tibia, medial and lateral trochlear ridges of the talus and the central and third tarsal bones; almost always in non fully weightbearing sites; very common site.
  • Signs: joint effusion (bog spavin), lameness   Musculoskeletal: gait evaluation  .
  • Diagnosis: intrasynovial anesthesia   Hindlimb: joint anesthesia  , radiography   Hindlimb: radiography  , arthroscopy   Joint: arthroscopy - overview  .
  • Treatment: arthroscopic debridement of damaged cartilage and removal of fragments.
  • Prognosis: good to guarded following arthroscopic surgery - dependent on site, duration and severity of lesion, and secondary pathological changes.
  • See also Osteochondrosis: overview   Bone: osteochondrosis  .
Print off the Owner factsheet on Osteochondrosis to give to your clients.

Pathogenesis

Etiology

  • Unknown.
  • Multifactoral: may be a complex interaction of environmental influences and genetic susceptibility.
  • See also Bone: osteochondrosis   Bone: osteochondrosis  .

Specific

  • Genetic factors.
  • Rapid growth rate.
  • Nutrition.
  • Conformation.

Pathophysiology

  • The pathophysiology of osteochondrosis has not been resolved, although it is most commonly regarded as a developmental condition.
  • Hypothesis: a primary failure of endochondral ossification. Disorder in chondrocyte development is the primary 'essential lesion'.
  • See also Bone: osteochondrosis   Bone: osteochondrosis  .
  • Tarsocrural osteochondrosis lesions are almost always in less than complete weightbearing, peripheral sites.
  • In older horses previously incidental lesions may become loose and move in the tarsocrural joint following exercise or trauma.
  • Can be bilateral.

Sites

  • Cranial intermediate ridge of distal tibia   Tarsus: osteochondrosis 04 - DMPaLO radiograph  :
    • The most common site.
    • May be bilateral.
    • ?Significance: present in 65% Dutch Warmbloods at 1 month old   →    80% normal at 1 year old.
    • Adjacent subchondral bone changes seen.
  • Distal aspect of lateral trochlear ridge of talus:
    • Occur less frequently.
    • Can be enormous in size.
    • If displaced may cause substantial effusion and severe lameness.
    • More common in heavy horse breeds, Warmbloods and Standardbreds.
    • Present in 30% of Dutch Warmbloods at 1 month old   →    97% normal at 1 year old.
  • Medial malleolus of tibia:
    • Difficult to see on radiography because always on axial rather than distal (more visible) part of the malleolus.
    • Usually cause more lameness and effusion than intermediate ridge lesions.
  • Medial trochlear ridge of talus:
    • Interpret with caution - most distal lesions do not require treatment and are incidental findings.
    • May be on proximal or distal side of capsular attachment between tarsocrural and proximal intertarsal joints. Fragments wholly within tarsocrural joint are less stable and more likely to cause lameness.
    • Lesions wholly within the tarsocrural joint are usually easy to remove with minimal dissection. Those with capsular attachments require careful sharp dissection (keep to a minimum).
    • Smooth-outlined depressions, more centrally placed, are common in large Draft horses, Draft crosses and Warmbloods. These rarely cause clinical signs or develop osteochondral flaps requiring surgery.
  • Lateral malleolus of tibia:
    • Rarely (c1%) osteochondral lesions (mostly traumatic).
    • Irregular diffuse radiolucency within the malleolus rather than distinctly separated fragment (cf. traumatic).
    • Difficult to debride arthroscopically because of extensive collateral ligament attachements.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Lykkjen Set al(2014)Heritability estimates of tarsocrural osteochondrosis and palmar/plantar first phalanx osteochondral fragments in Standardbred trotters.Equine Vet J46(1), 32-37PubMed.
  • Relave F, Meulyzer M, Alexander K, Beauchamp G & Marcoux M (2009)Comparison of radiography and ulstrasonography to detect osteochondrosis lesions in the tarsocrural joint: a restrospective study.Equine Vet J41, (1), 34-40PubMed.
  • Olstad K, Ytrehus B, Ekman S, Carlson C S & Dolvik N I (2008)Epiphyseal cartilage canal blood supply to the tarsus of foals and relationship to osteochondrosis.Equine Vet J40(1), 30-39PubMed.
  • Clegg P (2006)Conditions of the equine tarsal joints.UK Vet11(7), 6-12 VetMedResource.

Other sources of information

  • Ross M W & Dyson S J (2003) Eds Diagnosis and Management of Lameness in the Horse.Elsevier Science, USA.
  • McIlwraith C W & Trotter G W (1996) EdsJoint Disease in the Horse. W B Saunders, Philadelphia.


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