Joint Anatomy

Synovial joints:
The foundation of movement1

Synovial joints are the most common joints in the horse’s body. A synovial joint is an articulation where bony ends are capped with cartilage and glide over each other while contained within a fluid-filled joint capsule, enabling movement and transferring load. External supporting structures include skin, tendons and ligaments. For a joint to stay healthy, the synovial joint must remain stable. Instability exerts abnormal forces on the joint and can result in injury.

Adequan Equine Horse Running Joint Anatomy
Adequan Equine horse healthy joint graphic solo

Each component serves its purpose1

Joint capsule with two layers

  • Encloses and protects the joint

Outer fibrous layer

  • Provides mechanical stability
  • Contains nerve endings that provide information to the brain on joint position

Inner synovial membrane

  • Filters blood, excluding the protein and adding hyaluronic acid to form synovial (joint) fluid

Articular cartilage

  • Allows bones to glide over each other smoothly
  • Distributes loads evenly into subchondral bone
  • Cushions against bone-on-bone impact

Subchondral bone

  • Contains blood vessels and nerve endings
  • Carries away waste from the joint
Adequan Equine horse healthy joint graphic solo

The importance of preserving cartilage1

Articular cartilage is a highly specialized connective tissue of synovial joints. Unlike most tissues, it contains no blood vessels, lymphatics or nerves. This unique and complex structure of articular cartilage gives it a limited capacity for intrinsic healing and repair. Cartilage is also subjected to the harsh biomechanical environment, the daily “wear and tear” of every movement. Damage to cartilage is associated with significant musculoskeletal disease. Maintaining the health of articular cartilage is paramount to joint health.

Once cartilage is
eroded, subchondral bone is exposed to abnormal wear, and
pain occurs.

Adequan Equine healthy cartilage rendering

Healthy cartilage

Adequan Equine degraded cartilage rendering

Damaged cartilage

How are canine joints similar?

INDICATIONS Adequan® i.m. (polysulfated glycosaminoglycan) is recommended for the intramuscular treatment of non-infectious degenerative and/or traumatic joint dysfunction and associated lameness of the carpal and hock joints in horses.
IMPORTANT SAFETY INFORMATION There are no known contraindications to the use of intramuscular Polysulfated Glycosaminoglycan. Studies have not been conducted to establish safety in breeding horses. WARNING: Do not use in horses intended for human consumption. Not for use in humans. Keep this and all medications out of the reach of children. CAUTION: Federal law restricts this drug to use by or on the order of a licensed veterinarian. For full prescribing information, click here .
1. McIlwraith CW, Frisbie DD, Kawcak CE, van Weeren PR. Joint Disease in the Horse. St. Louis, MO: Elsevier, 2016; 33-48.

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