1 Principles topenlarge
The distal third of the humerus is flattened in the coronal plane and curves anteriorly.
Sometimes, the olecranon fossa and the opposing coronoid fossa communicate through an opening, the supratrochlear foramen.
Stability of the distal third of the humerus depends on the lateral and medial supracondylar columns linked distally, as a trianlge. by the condylar mass. Any rotation causing loss of bony contact decreases fracture stability.
Distal articular surface
The medial part of the trochlea is bigger than the lateral part and the capitellum, resulting a valgus humero-antebrachial geometry ("carrying angle") of long axis of the humerus passes through the centre of the trochlera about 6° in the coronal plane.
During elbow flexion the forearm moves on a plane such that the hand goes directly towards the mouth. Any changes in the valgus position after the reduction will strongly distort the original plane of movement. Adjustment to the distortion has been blamed for causing secondary shoulder problems.
Tendency to malalignment
There is a tendency to malalignment and to secondary anterior displacement after reduction.
Similarly, there is the risk of rotation and rotational malposition of the fragments. Reduction is made more difficult by the weight of the forearm acting on the fracture site.
Healing with any deformity (angulation, malrotation, and / or shortening) will usually cause significant elbow dysfunction. The restoration of normal elbow anatomy (anatomical reduction) is of high importance.
Nerves around the distal third of the humerus
Nerves on both sides of the distal humerus run very closely to the bone, especially the ulnar nerve, which perforates the medial intermuscular septum runs and then in its sulcus behind the medial epicondyle. It can be directly compressed in distal humeral fractures. The radial nerve perforates the lateral intermuscular septum as it loares the spiral groove on the humerus, torun anteriorly and distally. At the level of the radial head it divides into its deep and superficial branches.
The median nerve crosses the anterior capsule of the elbow joint, running into the forearm between the two heads of the pronator teres muscle.
2 Reduction topenlarge
Reduction of fracture fragment
The reduction is performed under general anesthesia, or using an axillary block. The arm is pulled with one hand and the fracture fragment is palpated with the other hand. Reduction of the fracture fragment is obtained pushing it into its appropriate position.
Flexion of the elbow
Flex the elbow up to 90° whilst maintaining the reduction, and apply the posterior splint.
3 Fracture splint management topenlarge
Apply cast padding
With the patient sitting, if possible, cast padding should be wrapped around the upper arm, elbow, forearm and hand, down as far as the transverse crease of the hand (leave the MP joints free). Keeps the elbow in 90° flexion and the forearm in neutral rotation. Make sure that the epicondyles of the humerus and the antecubital area are well padded.
A splint of fiberglass, or plaster, is applied on the posterior aspect of the arm and forearm. It should be wide enough to cover more than half of the circumference of the arm and forearm. It is secured with an elastic bandage that should not be too tight.
The injured arm is supported in a sling.
Analgesia will be required. The patient is usually more comfortable in a sitting or semireclining position, with the elbow elerated on pillows at least for the first few weeks. Fragment motion and crepitus may well be perceived, and the patient should be reassured that this is normal, stimulates healing, and will gradually settle.