Joint Pressure in the Foot

Research from the Royal Veterinary College (RVC) in the United Kingdom has advanced hoof balance from a farrier's art form to a measurement of pressure inside the distal interphalangeal (DIP) joint (coffin joint). Someday a horse's ideal balance might be determined by a pressure reading of this type.

Excess intra-articular pressure and/or joint fluid volume of the DIP joint is a common, chronic problem in performance and older horses that can lead to osteoarthritis. Excess joint pressure also might alter blood flow in the hoof capsule and destabilize the joint.

RVC researchers created a protocol to determine the amount of pressure in the DIP joint of "balanced" hooves and what effect imbalance of the hoof would have on the same joint's pressure.

Using cadaver legs and a hydraulic vise, they found that balanced, level hooves had a slightly negative pressure and hypothesized that imbalance would cause an undesired increase in pressure.

Wedging the horse's heels caused a direct (and potentially harmful) increase in joint pressure. Wedged heels have been shown to decrease tension on the deep digital flexor tendon when used as therapy for navicular-type pain, but the study showed that wedges might exacerbate co-existing coffin joint problems in the same foot. The researchers were surprised to find that wedging the toe (or, in effect, lowering the heels) decreased the intra-articular pressure in the DIP joint. Mediolateral (inside or outside quarters and wall) wedging had minimal effect on DIP joint pressure.

Throughout the study, the researchers found that the balanced, level foot was the best guarantee of normal (i.e., slightly negative) DIP joint pressure.

When silicone was injected to create a mold of the joints in the press, the wedged hooves' joint surfaces retained material on the side where the wedge had been, indicating abnormal joint function and an increase in joint surface wear.

The researchers concluded that different shoe designs and materials should--and will--be tested in the future to determine the conditions they are best designed to treat and for which conditions they might be contraindicated.

For those working with lame horses, this research helps explain why shoeing modifications have varying results on different horses--it's because different structures can cause similar-appearing lamenesses, but specific shoeing changes don't affect all of those structures the same way.

Researchers for the study titled "Effect of Foot Balance on the Intra-Articular Pressure in the Distal Interphalangeal Joint in vitro," published in the March 2003 Equine Veterinary Journal, included Mina J. Viitanen, PhD; Alan Wilson, BSc, BVMS, PhD, MRCVS; Stephen May, MA, VetMB, PhD, DVR, DEO, MRCVS, Dipl. ECVS; and others.

About the Author

Fran Jurga

Fran Jurga is the publisher of Hoofcare & Lameness, The Journal of Equine Foot Science, based in Gloucester, Mass., and Hoofcare Online, an electronic newsletter accessible at Her work also includes promoting lameness-related research and information for practical use by farriers, veterinarians, and horse owners. Jurga authored Understanding The Equine Foot, published by Eclipse Press and available at or by calling 800/582-5604.

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