Equis ISSN 2398-2977

Middle phalanx: fracture

Contributor(s): Jeffrey Watkins, Chris Whitton

Introduction

Pathogenesis

Etiology

  • Polo games.
  • Stock work.
  • Free paddock exercise.

Pathophysiology

  • Proximal interphalangeal joint (pastern) is high load, low motion joint.
  • Distal articulation with distal phalanx and navicular bone (coffin joint) is high motion joint.
  • Hyperextension of the proximal interphalangeal joint   →   insertions of the superficial digital flexor tendon, superficial distal sesamoidean ligament, and palmar and plantar ligaments of the pastern joint   →   tensile forces on palmar and plantar eminences   →   eminence fractures - may be large enough for internal fixation.
  • Also, sudden pastern extension, eg sliding stops   →   distal displacement of the proximal phalanx   →   axial compression focused on the palmar or plantar aspect of the eminences   →   shear forces contribute to fracture.
  • Axial compression, bending and torsion forces at the same time, eg hoof fixed relative to digit   →   comminuted fracture.
  • Extension of the proximal interphalangeal joint   →   partial avulsion with fibrous tissue attachments   →   osteochondral chip fractures.
  • Uni-axial fractures   →   no compromise of proximal interphalangeal joint stability.
  • Bi-axial fractures or complete avulsion of fibrous tissue attachments   →   instability   →   subluxation or luxation of proximal interphalangeal joint   PIP joint: luxation  .

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.
  • Galuppo L D, Stover S M & Willits N H (2000)A biomechanical comparison of double-plate and Y-plate fixation for comminuted equine second phalangeal fractures.Vet Surgery29, 152-162 PubMed.
  • Schneider R Ket al(1994)Arthroscopic removal of osteochondral fragments from the proximal interphalangeal joint of the pelvic limbs in three horses.JAVMA205, 79-82 PubMed.
  • Welch R D & Watkins J P (1991)Osteochondral fracture of the proximal palmar middle phalanx in a Thoroughbred.Equine Vet J23, 67-69 PubMed.

Other sources of information

  • Watkins J P (1996)Fractures of the middle phalanx.In:Equine Fracture Repair.Ed. A J Nixon. Philadelphia: W B Saunders. ISBN 0-7216-6754-6.


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