Equis ISSN 2398-2977

PIP joint: osteoarthritis

Synonym(s): Ringbone

Contributor(s): Dallas Goble, Graham Munroe, Vetstream Ltd, Chris Whitton


  • Cause: trauma, osteochondrosis, biomechanical wear and tear on a high load, low motion joint; 'ringbone' describes the development of peri-articular new bone which may precede or follow development of osteoarthritis.
  • Signs: mainly presents as an insidious, chronic lameness   Musculoskeletal: gait evaluation  , but occasionally there may be a sudden acute onset +/- firm swelling associated with joint and/or attachment of ligaments around the joint   Middle phalanx: osteoarthritis 02 - ringbone  ; pain in response to flexion   Musculoskeletal: manipulative tests  , positive flexion test, worse when turning.
  • Diagnosis: palpation, positive response to nerve and intra-articular analgesia   Forelimb: perineural analgesia  , radiography   Forelimb: radiography    Hindlimb: radiography  .
  • Treatment: conservative - rest, NSAIDs, intra-articular medication, corrective shoeing; surgery - arthrodesis pastern joint   PIP joint: arthrodesis  .
  • Prognosis: depends on degree of osteoarthritic changes but always guarded.
  • See Musculoskeletal: osteoarthritis (joint disease)   Musculoskeletal: osteoarthritis (joint disease)  .
Print off the Owner factsheet on Osteoarthritis - the facts to give to your clients.



  • Trauma:
    • Wear and tear trauma to the joint and associated cartilage. This depends on the type and extent of work, limb and foot conformation, shoeing, size of animal, and age.
    • Articular fractures of the middle   Middle phalanx: fracture  or proximal phalanx   Proximal phalanx: fracture  .
    • Other intra-articular pathology such as osteochondrosis or infection (wounds, penetrations, injections).

Predisposing factors

  • Osteochondrosis   Bone: osteochondrosis  .
  • Horses that jump and perform dressage may be over represented.



  • High load low motion joint.
  • Area of maximal weight bearing is nearly stationary   →   forces concentrated on a small surface area.
  • Focal excess weight bearing   →   necrosis of bone and cartilage.
  • Secondary joint capsule fibrosis   →   decreased joint movement   →   exacerbates cycle of degenerative joint disease   Musculoskeletal: osteoarthritis (joint disease)  .

Articular ringbone

  • Severe degenerative joint disease can lead to excessive osteophytic formation and enthesopathy/periosteal proliferation which used to be termed articular ringbone.
  • Further cartilage loss and joint collapse with increasing fibrotic and bony periarticular formation can eventually lead to partial or complete joint ankylosis.

Non-articular ringbone

  • Chronic pulling of collateral ligaments, joint capsule attachments, extensor tendon attachments, direct trauma   →   periostitis   →   new bone formation outside of the margins of the joint.
  • See Musculoskeletal: osteoarthritis (joint disease)   Musculoskeletal: osteoarthritis (joint disease)  .


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Caston S et al (2013) Retrospective evaluation of facilitated pastern ankylosis using intra-articular ethanol injections: 34 cases (2006-2012). Equine Vet J 45 (4), 442-447 PubMed.
  • Carpenter R & Baxter G (2011) The equine pastern. Comp Cont Ed Vet 33(4), E3 PubMed.
  • Poore L E et al (2011) Comparison of three methods of injecting the proximal interphalangeal joint in horses. Vet Rec 168 (11), 302 PubMed.
  • Jones P et al (2009) A limited surgical approach for pastern arthrodesis in horses with severe osteoarthritis. Vet Comp Orthop Traumatol 22 (4), 303-308 PubMed.
  • Wolker R R et al (2009) Arthrodesis of the equine proximal interphalangeal joint: a biomechanical comparison of two parallel headless, tapered, variable-pitched, titanium compression screws and two parallel 5.5 cm stainless steel cortical screws. Vet Surg 38 (7), 861-867 PubMed.
  • Garvican E & Clegg P (2007) Clinical aspects of the equine proximal interphalangeal (pastern) joint. UK Vet 12 (6), 11-16 VetMedResource.
  • Knox P M & Watkins J P (2006) Proximal interphalangeal joint arthrodesis using a combination plate-screw technique in 53 horses (1994-2003). Equine Vet J 38 (6), 538-542 PubMed.
  • Kidd J A, Fuller C & Barr A R S (2001) Osteoarthritis in the horse. Equine Vet Educ 13 (3), 160-168 VetMedResource.