Equis ISSN 2398-2977

MC / MT 3: fracture - condylar

Contributor(s): Stephen Adams, Andy Bathe, Graham Munroe, Vetstream Ltd

Introduction

  • Cause: fatigue failure of bone from repetitive loading; common racing injury especially Thoroughbred forelimb, Standardbred fore and hindlimbs.
  • Signs: acute lameness after hard exercise   Musculoskeletal: gait evaluation  , joint effusion, pain on flexion   Musculoskeletal: manipulative tests  .
  • Diagnosis: physical examination, radiography.
  • Treatment: surgery.
  • Prognosis: good for incomplete fractures; guarded for more serious injuries.

Pathogenesis

Etiology

  • Repetitive high loading of condyle, ie race training.

Pathophysiology

  • Unbalanced loading of limbs during racing on circular tracks   →   forces concentrated on a condyle   →   accumulation of concussive injury   →   fatigue failure of bone   →   fracture.
  • Intense remodeling activity has been observed at the fracture site. Unknown whether this contributes to fracture propagation.
  • Other injuries may occur simultaneously, eg axial sesamoid fracture   Proximal sesamoid: fracture  , soft tissue structures supporting the metacarpophalangeal joint, eg collateral ligaments    →   arthritis   Musculoskeletal: osteoarthritis (joint disease)  .
  • Lateral condylar fractures are the most common in the foreleg; they rarely spiral and may extend a variable distance from the joint surface.
  • Sagittal ridge and medial condylar fractures tend to extend proximally into diaphysis, spiralling or dividing into a Y-shape, increasing risk of a complete fracture.
  • Many MT3 fractures are located medially and have a tendency to spiral.
  • Sub-clinical, pre-existing abnormal bone modeling (presumably stress-related) commonly results in incomplete proximal palmar cortical fatigue fractures of MC3, often bilateral, in horses >4 years entering racing, eg National Hunt or point-to-point, for the first time.
  • See Musculoskeletal: fracture   Musculoskeletal: fracture  .

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Whitton R C et al (2010) Third metacarpal condylar fatigue fractures in equine athletes occur within previously modelled subchondral bone. Bone 47 (4), 826-831 PubMed.
  • Smith L C, Greet T R & Bathe A P (2009) A lateral approach for screw repair in lag fashion of spiral third metacarpal and metatarsal medial condylar fractures in horses. Vet Surg 38 (6), 681-688 PubMed.
  • Wright I M & Smith M R W (2009) A lateral approach to the repair of propagating fractures of the medial condyle of the third metacarpal and metatarsal bone in 18 racehorses. Vet Surg 38 (6), 689-695 PubMed.
  • Zekas L J, Bramlage L R, Embertson R M & Hance S R (1999) Characterisation of the type and location of fractures of the third metacarpal/metatarsal condyles in 135 horses in central Kentucky (1986-1994). Equine Vet J 31 (4),304-308 PubMed.
  • Zekas L J, Bramlage L R, Embertson R M & Hance S R (1999) Results of treatment of 145 fractures of the third metacarpal/metatarsal condyles in 135 horses (1986-1994). Equine Vet J 31 (4),309-313 PubMed.

Other sources of information

  • Richardson D W & Dyson S J (2011) The Metacarpophalangeal Joint. In: Lameness in the Horse. 2nd edn. Eds: Ross W R & Dyson S J. Elsevier, USA. pp 408-409. ISBN: 978-1-4160-6069-7.
  • Nixon A J (1996) Ed. Equine Fracture Repair.W B Saunders, USA.


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