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PIP joint: diseases – overview
Synonym(s): Proximal interphalangeal joint disease, pastern joint disease
Introduction
- Incidence: the proximal interphalangeal joint is less commonly associated with lameness than more mobile joints such as the carpus or fetlock, or the foot.
- Cause: acute or chronic trauma → conditions such as osteoarthritis, luxation or fracture.
- Signs: varies from mild lameness to non-weightbearing. Peri-articular ringbone may be asymptomatic.
- Diagnosis: clinical examination, radiography Forelimb: radiography Hindlimb: radiography and intra-articular anesthesia Forelimb: joint anesthesia Hindlimb: joint anesthesia are often sufficient.
- Treatment: depends on cause.
- Prognosis: depends on cause.
Presenting signs
- Forelimb or hindlimb lameness, unilateral or bilateral.
- Localized signs of inflammation.
Age predisposition
- Osteochondrosis lesions in young horses <4 years old.
- Flexural deformities in young foals 4 weeks to 4 months old or fast-growing yearlings and weanlings.
- Osteoarthritis in older working horses, or younger horses secondary to osteochondrosis.
Breed/Species predisposition
- Incomplete fractures of the proximal articular margin of the proximal phalanx are most commonly seen Standardbred Standardbred and Thoroughbred Thoroughbred racehorses.
- Horses used for jumping, dressage and Western-type activities are more prone to osteoarthritis.
Pathogenesis
Etiology
Trauma
- Acute injury to collateral ligaments, joint capsule, the attachment of the extensor tendon, joint or other soft tissues PIP joint: osteoarthritis .
- Luxation or subluxation: uncommon and usually secondary to damage to supporting structures, eg distal sesamoidean ligaments, SDFT branch PIP joint: luxation .
- Fractures: may be comminuted, chip (uncommon) or involve the caudal eminence of the middle phalanx Proximal phalanx: fracture Middle phalanx: fracture .
- Wounds to pastern joint.
- Degnerative joint disease (DJD) Musculoskeletal: osteoarthritis (joint disease) .
- Osteoarthritis ('high ringbone') PIP joint: osteoarthritis ; may also be secondary to articular fractures, infection or osteochondrosis Bone: osteochondrosis .
Multifactoral
- Osteochondrosis Bone: osteochondrosis +/- osseous fragmentation.
- Subchondral bone cysts Bone: subchondral cysts .
Infectious
- Penetrating wounds → septic arthritis Joint: septic arthritis - adult .
- Occasionally hematogenous spread of infection in foals → septic arthritis Joint: septic arthritis - foal .
Congenital and perinatal conditions
- Conformational defects/deformities Musculoskeletal: angular deformity .
Predisposing factors
General- Poor conformation Musculoskeletal: conformation may predispose to increasing the stresses placed on the soft tissue structures and cartilage of the joint.
- Septic conditions:
- Failure of transfer of passive immunity in the foal Foal: failure of passive transfer (IgG) , placentitis Placenta: placentitis or endometritis Uterus: endometritis - bacterial .
- Poor hygiene.
Pathophysiology
- The proximal interphalangeal (PIP) joint is the articulation between the distal aspect of the proximal phalanx and the proximal aspect of the middle phalanx.
- Collateral ligaments, abaxial and axial ligaments provide stability to the joint.
- Several ligaments and tendons course over the pastern region, including the superficial digital flexor tendon (SDFT) and deep digital flexor tendon (DDFT).
- Proximity to the ground, paucity of soft tissue cover dorsally and laterally, the degree of flexion occurring at this site and important soft tissue structures (SDFT, DDFT) on its palmar/plantar surface all contribute to this region being vulnerable to injury.
- Depends on the individual joint disease.
- See also Joint: synovial pathobiology Joint: synovial pathobiology .
Timecourse
- Acute onset for fractures, luxations and traumatic lesions.
- Chronic and insidious onset for osteoarthritis, bone cysts, DJD.
Diagnosis
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Treatment
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Prevention
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Outcomes
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Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
- Garvican E & Clegg P (2007) Clinical aspects of the equine proximal interphalangeal (pastern) joint. UK Vet 12 (6), 11-16 VetMedResource.
Other sources of information
- Ruggles A J (2003) The Proximal and Middle Phalanges and Proximal Interphalangeal Joint. In: Diagnosis & Management of Lameness in the Horse. Eds: Ross M W & Dyson S J. Saunders, USA. pp 342-348.