Proximal phalanx, comminuted fractures: description and preoperative considerations
Dean W. Richardson
This text is taken from G.E. Fackelman, J.A. Auer, D.M. Nunamaker: AO Principles of Equine Osteosynthesis.
Comminuted fractures of the proximal phalanx occur most commonly in racehorses working at high speeds, although they are also seen in animals at pasture. They rarely afflict horses under 2 years of age. In racehorses the forelimbs are affected twice as often as the hindlimbs but there appears to be no significant predilection for the left or right side.
Accurate radiographic interpretation is essential for a complete understanding of the extent of the fracture. A minimum of four views must be taken in every horse with a proximal phalangeal fracture. Overlooking a fracture line in a frontal or oblique plane could thwart an attempt to treat an assumed simple sagittal fracture and prove disastrous.
Internal fixation of these fractures should only be undertaken if there is a reasonable expectation that reconstruction will result in a column of bone that will sustain weight bearing forces within a short limb cast. Many fractures of the proximal phalanx are so severe that internal fixation with screws alone, or even with plates, is unlikely to succeed. As a general rule, surgical reconstruction should not be attempted unless there is a single intact strut of bone that extends from joint to joint. This allows the comminuted fragments to be reattached accurately enough to the large piece, and to each olher, so that the reconstructed cortices will not collapse. In some instances, there may be a simple transverse fracture in the strut that still allows reconstruction. If internal fixation is not feasible, some form of external skeletal fixation (pins incorporated in a fibreglass cast or an appropriate sized external fixator) must be considered. Obviously, the major advantage of internal fixation is that better function of the fet lock joint can be expected and limb length can be reliably preserved.
3. Preoperative considerations
As soon as the diagnosis is made, the limb should be protected with a cast or commercial boot that encloses the hoof and extends to the proximal metacarpus, or with one or another variety of splint that aligns the dorsum of the cannon bone with that of the pastern and the hoof wall.
Horses should receive broad spectrum antibiotics and non-steroidal an anti-inflammatory drugs as soon as possible. Horses in intense pain may benefit from stronger analgesics and sedatives such as butorphanol or xylazine, but care should be taken not to make the horse ataxic. If there is profuse sweating and flu d loss, replacement fluids and electrolytes should be given intravenously. Induction of general anesthesia should be performed with an appro riate splint or cast in place and preferably with a sling or table side technique.
 Markel MD, Richardson DW, Nunamaker DM (1985) Comminuted first phalanx fractures in 30 horses: Surgical vs. non-surgical treatments. Vet Surg; 114: 135.
 Ellis DR, Simpson DJ, Greenwood RE, et al. (1987) Observations and management of fractures of the proximal phalanx in young Thoroughbreds. Equine Vet J; 19:43-49.
 Richardson DW, Nunamaker DM, Ross MW (1992) Management of comminuted fractures of the proximal phalanx in 37 horses. Proc Am Assoc Equine Pract; 38: 156.