Olecranon Fracture
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Direct answer
An olecranon fracture is a break of the ulnar process that forms the point of the elbow, and triceps pull displaces the proximal fragment upwards, making fixation necessary when displacement exists. The Mayo classification sorts it into nondisplaced type I, displaced type II and type III with elbow instability. Simple transverse displaced fractures are typically fixed with tension band wiring, while comminuted or unstable patterns need plating.
What you must remember
- Triceps pull: the triceps insertion draws the proximal fragment upwards, so fixation must neutralise this force.
- Mayo classification: type I is nondisplaced, type II is displaced with a stable elbow, and type III is displaced with elbow instability such as fracture dislocation; subtypes vary between books.
- Tension band principle: tensile forces on the dorsal side are converted into compression across the articular surface using parallel wires and a figure-of-eight wire.
- Plating: used for comminuted, oblique or very proximal fragments, where a tension band cannot give adequate stability.
- Ulnar nerve: at risk during exposure, and its symptoms are checked after surgery.
- Nonoperative care: a nondisplaced fracture with an intact extensor mechanism may be managed in a cast.
- Complications: prominent implants that need removal, nonunion, elbow stiffness and ulnar nerve symptoms.
Choosing between wiring and plating
The pathway depends on the fracture pattern and the stability of the elbow. For a simple displaced fracture the tension band technique is the standard, and it proceeds in clear steps.
- Reduce the articular surface: the joint surface and the trochlear notch alignment are restored with reduction forceps.
- Place parallel K-wires: usually two Kirschner wires are inserted from the proximal fragment into the ulnar shaft, parallel to the ulnar axis.
- Build the tension band: a figure-of-eight wire passes around the wire ends and the olecranon, converting triceps tension into compression on the articular surface.
- Check the reduction: lateral and AP fluoroscopy confirm articular congruity and implant position.
- Mobilise early: range of motion starts within a protective splint, with the fixation guarding the healing bone.
- Remove prominent wires later: wires that irritate the skin are often taken out once union is established.
Comminuted or oblique patterns depart from this route, because a tension band cannot resist the forces acting on them. Plates on the dorsal surface then carry the load, and the same early-motion principle applies.
Where the exam tries to catch you
The triceps mechanism looks simple, but the stability question is often the real test.
- Trap: choosing tension band wiring for a comminuted fracture Correct: comminuted or unstable patterns need plate fixation, because the tension band cannot resist those forces.
- Trap: deciding that the triceps pull means the fracture should simply be cast Correct: triceps pull displaces displaced fractures, so they need fixation.
- Trap: forgetting elbow stability in a fracture dislocation Correct: Mayo type III needs assessment of ligament injury and elbow stability, not only fixation of the olecranon.
Frequently asked questions
What is the Mayo classification of olecranon fractures?
The Mayo classification grades olecranon fractures into type I (nondisplaced), type II (displaced with a stable elbow) and type III (displaced with elbow instability, such as fracture dislocation). Its purpose is to help choose between cast treatment and surgery.
Why does the proximal fragment displace in an olecranon fracture?
The triceps tendon inserts into the olecranon and pulls the proximal fragment upwards once the fracture separates the bone. This displacement is why displaced fractures need fixation.
What is tension band wiring used for in olecranon fracture?
Tension band wiring converts the tensile force from the triceps into compression across the fracture surface, using parallel K-wires and a figure-of-eight wire. It is suited to simple transverse displaced fractures.
When is plate fixation preferred over tension band wiring?
Plate fixation is preferred for comminuted, oblique or very proximal fragments, where a tension band cannot give adequate stability. Plates are usually placed on the dorsal surface and allow early elbow motion.