Equis ISSN 2398-2977

Peroneus tertius: rupture

Synonym(s): Fibularis tertius rupture

Contributor(s): Ron Genovese, Graham Munroe, Chris Whitton

Introduction

  • Cause: sudden overextension of tarsus.
  • Signs: tarsus can extend while stifle is flexed   Hindlimb: peroneus tertius rupture 01  ; lameness, gait abnormality; acute swelling along dorsal and dorsolateral aspect of tibia.
  • Diagnosis: signs   Hindlimb: peroneus tertius rupture 02    Hindlimb: peroneus tertius rupture 03  , ultrasonography   Ultrasonography: flexor tendon  .
  • Treatment: conservative - stall rest for 2-3 months, then limited and incrementally increasing exercise over following 2-3 months.
  • Prognosis: good.
  • See also Flexor tendon: trauma   Flexor tendon: trauma  .

Pathogenesis

Etiology

  • Trauma resulting in hyperextension of the limb, eg leg caught on jump/stable door, slips with leg extended backwards.
  • Dorsal tarsus laceration    →   tendon transection.
  • Avulsion of origin of tendon in foals (rare).

Predisposing factors

General
  • If a horse goes down with the leg extended backwards with a full hindlimb cast/splint in place, rupture can occur.

Pathophysiology

  • Tendinous muscle extends from extensor fossa of lateral distal femur along craniolateral surface of the tibia then splits to insert on dorsoproximal aspect of MT3 and the calcaneus, T3 and T4; it maintains synchronous movement of tarsus and stifle, and forms part of stay apparatus.
  • Usually ruptures in the middle of the crus but occasionally more distad.
  • Partial tearing at level of tarsocrural joint may occur.
  • Reciprocal apparatus may be partially disrupted.

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.
  • Denoix J M (2007) Peroneus tertius anatomy and lesions. Equine Vet Educ 19 (8), 416-418 VetMedResource.
  • Dyson S (1997) An approach to hindlimb lameness 2. Gait assessment, flexion tests and what to do next. In Pract, 14-20 VetMedResource.
  • Leveille R et al (1993) Ultrasonographic appearance of ruptured peroneus tertius in a horse. JAVMA 202 (12), 1981-1982 PubMed.
  • Trout D R et al (1981) Anatomy and therapeutic resection of the peroneus tertius muscle in a foal. JAVMA 179 (3), 247-251 PubMed.

Other sources of information

  • Dyson S J (2003) Rupture of Fibularis (Peroneus) Tertius. In: Diagnosis & Management of Lameness in the HorseEds: Ross M W & Dyson S J. Saunders, USA. pp 708-709.


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