Because diaphyseal radial fractures have a tendency to displace and become open, it is important to put a well-padded splint bandage in place. All the muscles are located at the lateral and caudal aspect of the forelimb. Therefore contraction of the muscles following an injury displace the fracture medially potentially inducing skin perforation (left). A simple bandage does not counteract these forces (middle), but a lateral split extending to the shoulder joint does (right).
The splints should therefore be applied on the caudal and lateral aspect of the limb with the caudal splint extending from the ground to the point of the elbow and the lateral splint extending from the ground beyond the proximal extent of the bandage to prevent abduction of the distal limb and displacement of the fracture into the medial soft tissues.
Emergency external coaptation in distal radius fractures can consist of a full limb cast applied all the way up to the elbow joint.
These fractures as well as other simple fractures of the diaphysis are readily repaired and have a good prognosis in foals. In adult horses, distal metaphyseal radial fractures that have a simple configuration and are closed represent the best opportunity for a favorable outcome. However they are not routinely repaired because of the high rate of complications and substantial expense associated with internal fixation in these injuries. Proximal metaphyseal fractures in adults also have a poor prognosis even if they have a simple oblique configuration.
Because of the strong cranial curvature of the radius the cranial surface is the tension band surface and one plate should always be applied to this aspect of the bone.
Because these fractures usually have an oblique component, the fracture can be reduced by using reduction forceps and traction to gradually slip down the obliquity. Because insufficient forces can be applied to the fracture region with the pointed reduction forceps, even in association with traction to facilitate complete reduction, Kern or similar forceps are preferred.
Once anatomic reduction has been achieved, one or two cortex screws are placed across the fracture in lag fashion to hold the reduction and obtain additional interfragmentary compression. Attention has to be given to place the screws so they will not interfere with plate placement.
Plate selection and preparation
In foals, a 4.5 mm broad plate of appropriate length (spanning the entire length of the radius from the proximal to the distal physis) for application on the cranial side and a 4.5 mm narrow plate, which may be a little shorter distally, for application on the lateral side are usually sufficient. LCP, DCP and LC-DCPs have been used successfully. In adult horses, a 5.5 mm broad LCP is proposed cranially and a DCS or other special human plate laterally/medially.
Note: The cranial aspect of the radius has a strong curvature and the plate needs to be bent to match this curvature.
Application of the first plate
First, the plate to the cranial aspect of the radius is applied. Interfragmentary axial compression is achieved by a combination of using the dynamic compression principles of the plate and placing one or two cortex screws in lag fashion through the plate overlaying the fracture plane. The remaining plate holes are left open until the lateral DCS-plate is applied.
Application of the DCS-plate
The DCS-plate is applied to the medial or lateral aspect of the radius as dictated by fracture configuration and soft-tissue limitations. (The separate steps for application are described in detail in distal McIII/MtIII metaphyseal fractures.) The author prefers to place the plate on the lateral aspect of the radius when possible, because there is more soft-tissue coverage and the plate can be applied through the craniolateral approach. (The distal screws may have to be inserted through stab incisions distant from the original incision.) In addition, the soft tissues on the medial aspect of the limb are often damaged by the fracture fragments during the preoperative period and predispose to incisional complications if a medial approach is used to place the plate on the medial aspect of the limb.
Because of the strong curvature of the radius the ends of the lateral plate has to be torqued to allow the screws that are in the mid-portion of the plate to lie on the lateral aspect of the bone. There is a curved human LCP available that closely resembles the curvature of the lateral aspect of the radius.
Left: the curved human femoral LCP was applied to the entire lateral aspect of this radius fracture without needing to apply torque at the proximal aspect.
The plate is attached to the bone by means of the DCS screw and connecting screw between the DCS screw and the plate in addition to a second cortex screw in the distal fragment, one screw in the middle of the plate but proximal to the fracture and one screw towards the proximal end of the plate.
Note: if the screw(s) applied for temporary fixation interfere(s) with plate placement, it/they can be removed or alternatively may be reinserted in lag fashion through the plate.
Insertion of the remaining screws
Ideally at least one locking head screw is placed one either side of the fracture line and near the ends of the cranial plate. For these screws, plate holes are selected where the locking head screws do not interfere with any of the cortex screws already implanted.
After the plate has been securely tightened to the bone, and axial compression achieved if necessary, locking head screws are applied. The remaining empty holes are filled with cortex screws or locking head screws.
It is strongly advised to take radiographs while the horse is still on the table to assure proper insertion of all implants. Any correction needed can at that time be done without much effort.
Antibiotic impregnated polymethylmethacrylate beads are placed around the implants prior to closure. In the depth of the surgical wound the muscle bellies are apposed to obliterate dead space where seroma formation is likely. The deep antebrachial fascia, subcutaneous tissues and skin are closed in separate layers. Some surgeons prefer to use suction drains, but the author does not routinely use them. If they are appropriate for the situation, they must be maintained aseptically, and removed as soon as the amount of drainage begins to decrease significantly. The author usually removes them in the first 48-72 hours postoperatively. An aseptic compression bandage is applied to the wound.
Recovery from anesthesia should be controlled and assisted to minimize risk of catastrophic injury during recovery from anesthesia. If available, a pool recovery system (left) may be advantageous in larger individuals to reduce risk to personnel and the patient injury.
Note: while preoperative casts are indicated, they should not be applied for the recovery period because the cast changes the tension surfaces within the bone to the caudal cortex. As the plates were applied cranially and laterally they are prone to catastrophic failure during recovery.
7. Overview of rehabilitation
The patient is kept in stall rest for a minimum of 60 - 90 days. The first 30 - 45 days hand-grazing only is advised, followed by 30-45 days of hand-walking.
Follow up radiographs are taken at 60 - 90 days. If healing appears to be progressing without complications the patient is gradually transitioned to free paddock exercise. Adult horses are usually kept in stall rest for a minimum of 90 days and re-evaluated radiographically prior to increasing their exercise level.
In general implant removal is not recommended. However, indications for implant removal include complications secondary to infection where chronic drainage persists after the fracture has healed. In these instances the infected implant(s) is/are removed. Another indication may be in horses intended for performance activities. In these cases the cranial plate and its associated screws are removed. If two plates have been used, it is advisable to stagger plate removal with at least 30 days of pasture exercise prior to removal of each plate.