Equis ISSN 2398-2977

Foot: lateral cartilage calcification (sidebone)

Contributor(s): Gordon Baker, Olin Balch, Simon Curtis, Graham Munroe, Vetstream Ltd

Introduction

  • Commonly an incidental finding during a detailed physical examination.
  • A rare cause of lameness.
  • Cause: ossification of the collateral cartilages, usually found in the forefeet. Frequency increases in aged horses.
  • Uncommon in Thoroughbreds   Thoroughbred  .
  • Signs: none   →   lameness (often an indicator of another underlying cause); gait changes more usual.
  • Diagnosis: lameness evaluation, including gait   Musculoskeletal: gait evaluation  , manipulation   Musculoskeletal: manipulative tests  and foot and shoe examination   Foot / shoe: examination  ; perineural analgesia   Forelimb: perineural analgesia  ; radiography   Forelimb: radiography  - usually unilateral, with abaxial cartilage involved.
  • Treatment: farriery plus treatment of any other underlying causes if lameness is present.
  • Prognosis: depends on concurrent conditions and resolution of conformational or weightbearing abnormalities.
Print off the Owner factsheet on Sidebone to give to your clients.

Pathogenesis

Etiology

  • Some authorities believe there is an hereditary component to the condition.
  • Abnormal weight-bearing stress is believed to be the reason for the ossification of the cartilage asymmetrically.

Predisposing factors

General
  • Poor conformation   Musculoskeletal: conformation  - toe-in conformation - unilateral sidebone.
  • Poor shoeing can upset the mediolateral balance of weight-bearing and increase concussion.
  • Significantly associated with injuries to the collateral ligaments of the DIP joint or distal phalanx.

Pathophysiology

  • Some authorities view it as a normal aging process in the horse.
  • Poor or inaccurate shoeing, especially shoeing with weighted shoes and long hooves to exaggerate the gait of certain horse breeds, upsets the balance of the foot and causes increased concussion and abnormal stresses on the collateral cartilages.
  • The physiologic response to this is ossification of cartilage.
  • May be produced by traumatic lesions such as wire cuts that damage the cartilage.
  • Trauma to the area locally induces pain, swelling and increased blood flow to the area.
  • Lameness due to inflammation will subside when damage is repaired.
  • Ongoing predisposing factors such as shoeing with large heel calks and unbalanced feet, will precipitate future lesions unless addressed.

Timecourse

  • Gradual onset.

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.
  • Boerma S, Back W & Sloet van Oldruitenborgh-Oosterbaan M M (2012)The Friesian horse breed: A clinical challenge to the equine veterinarian?Equine Vet Educ24(2), 66-71 VetMedResource.
  • Cullimore A & Booth T (2010)Clinical aspects of the equine foot. Part 6: The collateral cartilages.UK Vet15(8), 9-12 VetMedResource.
  • Dyson S, Brown V, Collins S & Murray R (2010)Is there an association between ossification of the cartilages of the foot and collateral desmopathy of the distal interphalangeal joint or distal phalanx injury?Equine Vet J42(6), 504-511 PubMed.
  • Dakin S G, Robson K E & Dyson S J (2006)Fractures of ossified cartilages of the foot: 10 cases.Equine Vet Educ18(3), 130-136 VetMedResource.
  • Sherlock C E & Mair T S (2006)The enigma of sidebone as a cause of lameness in the horse.Equine Vet Educ18(3), 136-138 VetMedResource.
  • Ruohoniemi Met al(1997)Evaluation of the variably ossified collateral cartilages of the distal phalanx and adjacent anatomic structures in the Finnhorse with computed tomography and magnetic resonance imaging.Vet Radiol Ultrasound38(5), 344-351 PubMed.
  • Ruohoniemi Met al(1997)Relationship between ossification of the cartilages of the foot and conformation and radiographic measurements of the front feet in Finnhorses.Equine Vet J29(1), 44-48 PubMed.
  • Ruohoniemi M, Tulamo R M & Hackzell M (1993)Radiographic evaluation of ossification of the collateral cartilages of the third phalanx in Finnhorses.Equine Vet J25(5), 453-455 PubMed.
  • Reeves M Jet al(1989)Miscellaneous conditions of the equine foot.Vet Clin North Am Equine Pract5(1), 221-242 PubMed.


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