Effect of different full-limb casts on in vitro bone strain in the distal portion of the equine forelimb.

This study investigates how different full-limb cast types affect bone strain on the lower part of an equine forelimb, finding that the full-limb transfixation pin cast offers greater protection to the first phalanx compared to the standard full-limb cast.

Study Design and Methods

• The study was designed to ascertain if a full-limb transfixation pin cast could protect the distal part of the equine forelimb from the pressure of weight-bearing forces.
• The experiment was conducted in vitro (outside a living organism) using six forelimbs from six different horses.
• Three unidirectional metal foil electrical resistant strain gauges were placed on every limb. The placement of gauges was at specific points including the dorsal aspect of the distal portion of the radius, the mid-dorsal portion of the cortex of the third metacarpal bone, and the first phalanx.
• Each limb was subjected to three test conditions: one supported by a transfixation pin cast, another supported by a standard full-limb cast, and finally uncast (without any supporting cast).
• The mechanical testing machine applied axial loads ranging from 100 to 1,000 lb on each limb, and the bone strains at each load level were recorded.

Results

• In comparison to the uncast limb scenario, both the transfixation pin cast and the standard full-limb cast significantly (with a P-value of less than 0.001) lessened bone strain on the distal portion of the radius, the third metacarpal bone, and the first phalanx.
• Comparatively, the transfixation pin cast significantly (P < 0.001) reduced bone strain on the first phalanx more than the standard full-limb cast did.

Conclusion

• The study concluded that when compared to the standard full limb cast, the full-limb transfixation pin cast provides better protection to the first phalanx of the equine forelimb.
• The results of this research could have applications in equine veterinary practice, specifically regarding the treatment and rehabilitation of equine forelimb injuries.