Page 374 - The Veterinary Care of the Horse

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Figure 8.12 Sites of articular ringbone

CAUSES

Trauma leading to inflammation of the soft tissues surrounding this low-motion joint is
considered to be the initiating factor. These tissues repair by fibrosis and this reduces the

range of movement further and subjects the articular cartilage to abnormal stresses. Small
areas of the joint surface bear an increased load and damage to the cartilage occurs.

Injuries leading to osteoarthritis of the PIP joint include:

• direct blows to the bone

• a sprain causing tearing of the periosteal attachments of:

– the collateral ligaments

– the distal sesamoiden ligaments
– the extensor tendon

– the joint capsule

• puncture wounds and wire cuts that damage the periosteum or collateral ligaments