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 extends more distally than the lateral part and the capitellum, resulting in a valgus humero-antebrachial geometry ("carrying angle"). With the elbow extended, the long axis of the forearm makes an angle of approximately 6° to the long axis of the humerus 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.
Requirement for splinting
In compliant patients with minimally displaced fractures it may be reasonable to support the limb in a sling without applying a splint. If it is felt that the patient or the fracture need s any protection, it is sensible to apply a splint.
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 follows the spiral groove on the humerus, to run anteriorly and distally. At the level of the radial head it divides into its deep and superficial branches.
Note The median nerve crosses the anterior capsule of the elbow joint, running into the forearm between the two heads of the pronator teres muscle.
The majority of displaced fractures would be treated operatively. If a displaced fracture is to be treated nonoperatively, attempts should be made to reduce the fracture.
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
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 elevated 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.
The arm is immobilized in a splint for comfort with the elbow at 90° of flexion. Active exercises of the elbow should be initiated as soon as possible, as the elbow is prone to stiffness.
Avoidance of shoulder abduction will limit varus elbow stress. Shoulder mobility should be maintained by gravity-assisted pendulum exercises in the sling.
Active assisted elbow motion exercises are performed by having the patient bend the elbow as much as possible using his/her muscles, while simultaneously using the opposite arm to push the arm gently into further flexion. This effort should be sustained for several minutes, the longer the better.
Next, a similar exercise is done for extension.
Load bearing No load-bearing or strengthening exercises are allowed until early fracture healing is established, a minimum of 6-8 weeks after the fracture. Weight bearing on the arm should be avoided until bony union is assured.
Follow up The patient should be seen weekly for follow-up examination and x-rays for 4 weeks, and thereafter every 4-6 weeks, until union is secure and full functional range of motion and strength have returned.