Equis ISSN 2398-2977

MCP / MTP joint: developmental orthopedic diseases

Synonym(s): Osteochondrosis, osteochondritis dissecans, subchondral cystic lesions

Contributor(s): Steve Adair, Jessica A Kidd-Millar, Vetstream Ltd, Chris Whitton


  • Many conditions of the fetlcok joint are considered to be developmental by some, and traumatic by others.
  • Sagittal ridge OCD   Bone: osteochondrosis   and subchondral cystic lesions   Bone: subchondral cysts  of the distal condyle/proximal P1 are considered to be developmental conditions.
  • Other conditions of debated etiology include:
    • Plantar osteochondral fragmentation (POFs).
    • Type I osteochondral fragmentation - axial and mainly articular.
    • Type II osteochondral fragmentation:
      • Also called ununited palmar/plantar eminence.
      • Largely non-articular.
      • Rarely causes lameness.
    • Palmar osteochondral disease (POD), previously referred to as palmar metacarpal OCD, is not a developmental orthopedic disease and is characterized by palmar/plantar cartilage erosion +/- collapse of the subchondral bone.
    • Osteochondral fragments of the dorsoproximal first phalanx are considered to be developmental by some and traumatic by others.
  • Signs: fetlock joint effusion, lameness   Musculoskeletal: gait evaluation  , pain on flexion.
  • Diagnosis: radiography   Hindlimb: radiography    Forelimb: radiography  .
  • Treatment: conservative (rest), medical treatment or arthroscopic removal   Joint: arthroscopy - overview  of fragment or debridement.
  • Prognosis: variable.
  • See also Bone: osteochondrosis   Bone: osteochondrosis  .



  • Flattening and fragmentation of the sagittal ridge of distal metacarpus/metatarsus   →   undermining articular cartilage of adjacent condyle.
  • Lesions often arise from the condylar cartilage adjacent to the sagittal ridge and may be termed dorsal parasagittal or dorsal condylar OCD.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Smith R K W, Coumbe A & Schramme M C (1995) Bilateral synovial chondromatosis of the metatarsophalangeal joints in a pony. Equine Vet J 27 (3), 234-238 PubMed.
  • Fortier et al (1995) Arthroscopic removal of axial osteochandral fragments of the plantar/palmar proximal aspect of the proximal phalanx in horses; 119 cases (1988-1992). JAVMA 206 (1), 71-74 PubMed.
  • Houttu J (1991) Arthroscopic removal of osteochondral fragments of the palmar/plantar aspects of the metacarpo/metatarsophalangeal joints. Equine Vet J 23 (3), 163-165 VetMedResource.
  • Nixon A J (1990) Osteochondrosis and osteochondritis dissecans of the equine fetlock. Comp Cont Educ Pract Vet 12, 1463 AGRIS FAO.
  • Yovich J V et al (1986) Arthroscopic surgery for osteochondral fractures of the proximal phalanx of the metacarpophalangeal and metatarsophalangeal (fetlock) joints in horses. JAVMA 188 (3), 273-279 PubMed.
  • Yovich J V, McIlwraith C W & Stashak T S (1985) Osteochondrosis dissecans of the sagittal ridge of the third metacarpal and metatarsal bones in horses. JAVMA 186 (11), 1186 PubMed.

Other sources of information

  • Nixon A J (2006) The Phalanges and Metacarpo/Metatarsophalangeal Joint. In: Equine Surgery. Ed: Aver J A & Stick J A. W B Saunders, USA.
  • McIlwraith C W (1996) Fetlock Fractures and Luxations. In: Equine Fracture Repair. Eds: Nixon A J. W B Saunders, USA.