PIP joint: arthrodesis in Horses (Equis) | Vetlexicon
equis - Articles

PIP joint: arthrodesis

ISSN 2398-2977

Contributor(s) :


  • The proximal interphalangeal joint is a low-motion joint amenable to fusion to overcome lameness and pain associated with degenerative joint disease   Musculoskeletal: osteoarthritis (joint disease)  .
  • Arthrodesis provides a rapid resolution of the problem affording an earlier return to exercise.




  • Change in biomechanics following surgery, particularly in the forelimb, may predispose to osteoarthritis in the distal interphalangeal joint.

Decision taking

Criteria for choosing test

  • Radiographic assessment of the joint   Forelimb: radiography  .
  • Degree of degenerative change.
  • Amenability of fractures to more physiologic repair methods.


Materials required

Minimum equipment

Ideal equipment

  • Screw set.
  • Dynamic compression plates   Bone: internal fixation - plates  .
  • Y-plate specifically designed for comminuted P2 fractures:
    • Designed to compress the PIP joint with screws in proximal portion.
    • Three screws can be placed in the proximal P2.
    • Palmar eminence fragments can be engaged (abaxial screw holes are widened so that screws can be placed at increased angles to improve engagement of medial and lateral palmar eminences).
    • The distal end of the plate is beveled and concave to avoid impinging DIP capsule and extensor process of P3.
    • Increased cross-sectional area over the PIP joint - increased resistance to bending.



Site preparation

  • Dorsal or lateral recumbency.
  • Clip and scrub pastern aseptically.
  • Barrier draping from coronary band to fetlock.




Step 1 - Expose the pastern joint

  • Make an inverted T-skin incision over the dorsal aspect of the proximal interphalangeal joint.
  • Make an inverted - V incision in the extensor tendon.
  • Elevate the extensor tendon and joint capsule.
  • Transect (partial or complete) the collateral ligaments to allow dorsal subluxation of the pastern joint.
  • May need to resect periosteal new bone on dorsum of phalanges.

Exposure will be more difficult in chronic osteoarthritis cases

Step 2 - Debride the joint

  • Debride the articular cartilage.
  • Perform osteostixis on joint surfaces.

Core procedure


Step 1 - Apply internal fixation

  • Insert a 5.5 mm cortex screw in lag fashion from dorsal distal end of the proximal phalanx in to the proximal palmar/plantar aspect of the middle phalanx, if the latter is sufficiently stable to support screw, ie no fractures   PIP joint: arthrodesis 01 - screws - LM radiograph  .
  • Apply a five hole plate dorsolaterally   PIP joint: arthrodesis 02 - LM radiograph    PIP joint: arthrodesis 03 - DP radiograph  .

A plate applied on the dorsal midline may interfere with the extensor process of the distal phalanx.

Step 2 - Insert more lag screws

  • Can use three 5.5 mm cortical screws across the pastern joint as lag screws.
  • These screws have increased strength and can generate substantial compression across the joint.
  • Additional plates may be used at the surgeon's discretion.
  • A 4.5 mm narrow DCP can be applied axially to increase stability of the fixation.
  • Consider use of bone grafts   Bone: grafting  or bone replacement (tricalcium phosphate hydroxyapatite).



Step 1 - Close the joint and skin



Immediate Aftercare


Antimicrobial therapy

Long term Aftercare

Follow up

  • Maintain cast until radiographic evidence that the articulation has been bridged, 4-8 weeks, if use only lag screws, or with plate fixation of fractures.
  • Arthrodesis with a dorsal plate for stable conditions (DJD, uniaxial eminence fracture without subluxation) provides adequate stability for cast removal 2 weeks post-operatively.




  • Good - for athletic use if performed in the hindlimbs.
  • Guarded - for forelimbs.
  • Horse may be only useful for breeding.

Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Levine D G & Richardson D W (2007) Clinical use of the locking compression plate (LCP) in horses: a retrospective study of 31 cases (2004-2006). Equine Vet J 39 (5), 401-406 PubMed.
  • Watts A E, Fortier L A & Caldwell F J (2007) Proximal interphalangeal joint arthrodesis in a one-mouth-old foal for superficial digital flexor tendon and straight sesamoidean ligament disruption. Equine Vet Educ 19 (8), 407-412 WileyOnline.
  • 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.
  • 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 Surgery 29, 152-162 PubMed.
  • Crabill M R et al (1995) Double-plate fixation of comminuted fractures of the 2nd phalanx in horses - 10 cases (1985-1993). JAVMA 207 (11), 1458 PubMed.
  • Caron J P et al (1990) Proximal interphalangeal arthrodesis in the horse. A retrospective study and a modified screw technique. Vet Surg 19 (3), 196-202 PubMed.
  • Shiroma J T et al (1989) Dorsal subluxation of the proximal interphalangeal joint in the pelvic limb of three horses. JAVMA 195 (6), 777-779 PubMed.

Other sources of information

  • Watkins J P (1996) Fractures of the middle phalanx. In: Equine Fracture Repair. Ed: A J Nixon. W B Saunders, USA.