Equis ISSN 2398-2977

MC/MT 2 and 4: periostitis (splints)

Synonym(s): Splints

Contributor(s): Steve Adair, Graham Munroe, Vetstream Ltd, Chris Whitton

Introduction

  • Cause: interosseous ligament tearing, fracture of metacarpal/metatarsal II or IV, external trauma, eg interference, unknown.
  • Signs: variable, often none or only mild lameness, localized heat, pain and swelling; may be uni or multifocal; most common forelimb especially medial aspect of metacarpus and also lateral metatarsus.
  • Diagnosis: clinical signs and history, palpation, radiography, ultrasonography and local filtration of local anesthetic or regional nerve blocks.
  • Treatment: cold therapy and systemic/topical NSAIDs to reduce inflammation, bandaging, rest, foot care, protective boots or bandages, surgical removal of exostoses and/or splint.
  • Prognosis: guarded to good.

Pathogenesis

Etiology

  • Interosseous ligament tearing.
  • Metacarpal or metatarsal 2 or 4 injury from direct trauma.
  • Metacarpal or metatarsal 2 or 4 fracture   MC / MT 2 and 4: fracture  .
  • Unknown causes in some cases.

Predisposing factors

General
  • Early intense training.
  • Poor conformation   Musculoskeletal: conformation  , eg bench knees or offset carpii (medial forelimb splints); base narrow, toe out (interference).
  • Poor shoeing or foot trimming (interference)   Foot / shoe: examination  .
  • Rapid growth and large body size.
  • Overweight.

Specific

  • Hard ground conditions.

Pathophysiology

  • Injury to interosseous ligament due to instability between MC/MT 2 and 4 and MC/MT 3   →   desmitis and proliferative new bone formation. This is the most popular theory for splint exostoses but in reality many cases are not related to the interosseous ligament or on some occasions not even the splint bones themselves and are associated with MC/MT 3.
  • Injury to splint bone (MC/MT 2 and 4) from direct trauma   →   an inflammatory process, periostitis and new bone formation.
  • Some cases may involve non-displaced fractures of the splint bone.
  • Some cases do not show a clear pathophysiology for the formation of new bone and do not involve the interosseous space, an inflammatory response or evidence of pain/lameness.
  • Second metacarpal bone bears more weight than fourth metacarpal/metatarsal bone and is more prone to the formation of bony swellings or splints.

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.
  • Jenson P W et al (2004) Segmental ostectomy of the second and fourth metacarpal and metatarsal bones in horses: 17 cases (1993-2002). JAVMA 224, 271 PubMed.
  • Du Preez P (1994) Fractures of the small metacarpal and metatarsal bones (splint bones). Equine Vet J (5), 279-283 VetMedResource.
  • Barber S M et al (1987) Surgical removal of metacarpal/metatarsal exostoses. Proc Am Assoc Equine Pract 32, 371-383 VetMedResource.
  • Allen D & White A (1987) Management of fractures and exostosis of the metacarpals and metatarsals II and IV in 25 horses. Equine Vet J 19 (4), 326-330 PubMed.

Other sources of information

  • Jackson M A & Auer J A (2012) Vestigial Metacarpal and Metatarsal Bones. In: Equine Surgery. 4th edn. Eds: Auer J A & Stick J A. W B Saunders Co, USA. pp 1339-1347.


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