[RC] feeling depressed about underrun heels.... - Mary Krauss
We're on week 8 of a 12 week rehab program for my 6 yr. old gelding's underrun heels. ?After his first ride out on the trail (flat, open, easy 7 miles), he came up so lame he didn't know which foot to limp on. ?Our vet (Dr. Bryant who came highly recommended by a bunch of you ridecampers) prescribed wedges and pads, but my farrier, who comes highly recommended by Dr. Bryant, says wedges and pads are a bad idea. ?What's the rider/trainer to do when caught between two competent professionals? ?
I've been reading like crazy and can't find a definitive answer. ?Any ideas out there?
Mary K.?
From an article in Anvil Magazine by Kent M. Thompson, PhD:
For this study, each leg was trimmed to a constant angle (55 degrees). Heel wedge pads were then added to create the following toe angles: 58 degrees, 61 degrees, 64 degrees, 67 degrees, 70 degrees, and 78 degrees.Strain on the deep flexor tendon was reduced with increases in toe angle. The reduction in strain followed a linear pattern with the increasing toe angle at two locations on the deep flexor tendon. Deep digital flexor tendon strains decreased from 2.49 for the 55 degree toe angle to 1.42% and 1.02% for the 70 degree and 78 degree toe angles, respectively. This represented a 59% decrease in tendon strain between the 55 degree and 78 degree treatments. Strain decreased in a similar fashion at the interphalangeal site, as there was a 64% decrease between the 55 degree and 78 degree angles. Strain measured in the superficial flexor tendon was not affected by an increase in toe angle. Within the range of toe angle used in this study, there was no change in strain on the superficial flexor tendon. Initial strain for the control treatment was 2.90% and varied very little with the increase in toe angle. This is similar to that observed by others. The suspensory ligament acted very similarly to the superficial flexor tendon; there was not any change in suspensory ligament strain with the addition of the toe wedges. Strain in the suspensory ligament had a small numerical increase in strain as the toe angle was increased, but the change was not significant. However, a large increase was noted for the extensor branch of the suspensory ligament. There was very little strain present on the extensor branches with the 55 degree, 58 degree, 61 degree and 64 degree toe angles. However, when the toe angle was increased to 67 degrees, extensor branch strain increased dramatically. At the 55 degree toe angle, strain on the extensor branches was .02% and when toe angle was increased to 78 degrees, strain increased to 1.40%.Strains on the surface of the hoof wall remained in compression during loading and the magnitude of compression increased on the medial and lateral walls with increases in toe angle, and decreased on the dorsal hoof wall. A similar but opposite trend was observed for the dorsal hoof wall as strain decreased 52.8% as toe angle increased. Strain on the medial hoof wall followed the same pattern as the lateral hoof wall. The trend in this case was for a higher strain on the hoof wall as toe angle increased. The difference was noted between the 78 degree toe angle and the 58 degree and 55 degree toe angles.Heel wedges had no effect on reducing strain in the superficial flexor tendon and suspensory ligament. However, heel wedges are recommended in cases where reduction of strain on the deep flexor tendon is needed, such as laminitis and tendon flexor tendon injury. One other effect noted with the addition of a heel wedge is the large increase in strain of the extensor branch of the suspensory ligament. This may be of particular interest in the treatment of laminitic horses, as reduction of deep flexor tendon strain and increased extensor branch strain both occur with heel wedges and will work concurrently to stabilize the coffin bone in normal and laminitic horses. Heel wedges also raised compressive strains on the surface of the hoof wall at both the medial and lateral quarters, which may affect the occurrence and treatment of quarter cracks.Thus, heel wedges have a great influence on redirecting the forces that are generated by the tendon and ligament structures in the lower limb. The use of heel wedges will be of great benefit in treating laminitic horses, due to their effect on reducing strain in the deep flexor tendon and increasing strain in the extensor branch of the suspensory ligament.
