Definition
The olecranon is the upper (proximal) end of the ulna. It represents the starting point of the triceps brachii muscle. The olecranon is part of the elbow joint and articulates here with the joint roll of the humerus (trochlea humeri).
The elbow joint (Articulatio cubiti) is a compound joint consisting of three parts. The ulna and radius form one joint (proximal radioulnar joint), the humerus and radius form another joint (humeroradial joint), and finally the humerus and the olecranon of the ulna articulate in the humeroulnar joint. The latter is a hinge joint, whereby the forearm can be bent or stretched in relation to the upper arm. An olecranon fracture is therefore a fracture of the upper part of the ulna of the forearm.
Causes
Olecranon fractures are usually caused by direct force applied to the elbow, most often in the form of a fall directly onto the elbow or, less frequently, by a blow. In the case of an olecranon fracture, the elbow is massively swollen and bruised. The elbow starts to hurt strongly immediately after the injury.
Due to the attachment of the triceps muscle to the olecranon, the arm can no longer be actively stretched in the elbow joint in the event of a fracture of the elbow. It is also characteristic that the pull of the triceps muscle pulls the broken piece of bone of the olecranon upwards, where it can also be palpated. Likewise, a gap at the elbow can be palpated where the olecranon would otherwise be located.
This typically results in a painful restriction of movement. The medical history (doctor’s consultation) already provides the doctor with initial information about the course of the accident, which can lead to the suspicion of an olecranon fracture. The swelling, blue coloration and painful restriction of movement that becomes apparent during the inspection confirm the suspicion.
During the functional examination, the physician finds a lack of extensibility in the joint as well as a palpable gap. Furthermore, the aborted olecranon fragment is palpated further up by the pull of the triceps muscle. The physician checks the peripheral motor function (strength), sensitivity (sensation) and blood circulation (pulses) on the forearm in order to rule out injuries to nerves or vessels.
Subsequently, the suspicion is confirmed by imaging. First of all, an X-ray is used. The image is always taken in two planes, so that the beam path runs from front to back and then from the side.
If there is a suspicion of an accompanying ligament injury, this can be confirmed with an ultrasound examination or with “held images”. In this special x-ray, the elbow joint is pretensioned laterally in order to detect increased folding due to damage to the stabilizing ligament apparatus. Vascular injuries, on the other hand, can be detected relatively quickly.
Only rarely is it necessary to take an angiography (imaging of the vessels with a contrast medium in X-ray, CT or MRI). All soft tissue injuries are generally most reliably detected by MRI. Accompanying nerve damage can in some cases only be detected after weeks, whereby electro-neurography (ENG) and electro-myography (EMG) have proved particularly effective in diagnosing such damage.
