Medial Epicondyle Fracture of Humerus
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Direct answer
A medial epicondyle fracture of the humerus is an avulsion injury in which the flexor-pronator mass pulls the medial epicondyle off the distal humerus, most often in boys in the early teen years. It is frequently associated with elbow dislocation, and the displaced fragment may become trapped inside the joint. Ulnar nerve involvement must be examined for, because the nerve runs close to the fracture.
What you must remember
- Mechanism: avulsion by the flexor-pronator mass, typically with valgus stress on the elbow or a fall on the outstretched hand.
- Age and sex: most often boys in the early teen years, when the medial epicondyle is still an open apophysis.
- Association: elbow dislocation is commonly linked, and the reduction may pull the fragment into the joint.
- Entrapment: a displaced fragment lying within the joint blocks reduction and usually needs open removal or fixation.
- Ulnar nerve: the nerve runs in the cubital tunnel behind the medial epicondyle, so its sensation, grip and power are documented before any manipulation.
- Surgical threshold: fixation is commonly advised for displacement of more than about 5 mm, for an entrapped fragment or for elbow instability.
- Imaging: the epicondyle is an apophysis, so the fragment can be missed, and the opposite elbow is useful for comparison.
Choosing between conservative and operative care
A 12-year-old boy has elbow pain and swelling after a fall on the outstretched arm, with tenderness over the medial side. The X-ray shows a fragment near the medial epicondyle, and the decision depends on how far the fragment has moved, whether it lies inside the joint and whether the ulnar nerve is involved.
| Feature | Nonoperative care | Operative care |
|---|---|---|
| Fragment position | Minimal displacement, typically under about 5 mm | Larger displacement, or the fragment is entrapped in the joint |
| Elbow stability | Stable, with no tendency to redislocate | Instability, or a persisting valgus gap |
| Early treatment | Cast or splint for a few weeks, then graded movement | Open reduction and screw or wire fixation, with early mobilisation |
| Ulnar nerve | Examined serially and monitored for change | Explored or transposed if symptomatic |
| Follow-up | Clinical review and radiographs to confirm union | Radiographs for union and a check of joint function |
The table reflects a practical rule: the fragment's position and its effect on the joint matter more than its size alone. A child with an entrapped fragment or an unstable elbow needs prompt surgery, because a delayed operation makes the fragment harder to retrieve and the joint harder to protect.
Viva angles on entrapment and the nerve
Examiners often ask how this fracture differs from an ordinary fracture and what must be checked before treatment.
- Trap: treating the medial epicondyle as a simple bruise because the child walks normally. Correct: an avulsed fragment can be trapped in the joint, so the elbow must be imaged and examined carefully.
- Trap: missing ulnar nerve injury because the fracture looks minor. Correct: the nerve lies close to the fragment, so sensation and grip are checked before any reduction.
- Trap: mistaking the normal medial epicondyle apophysis for a fracture. Correct: the apophysis is a normal growth centre, so the opposite elbow is compared when the fragment is uncertain.
Frequently asked questions
Which muscle group pulls off the medial epicondyle in this fracture?
The flexor-pronator mass, which arises from the medial epicondyle, avulses the fragment when the elbow is stressed. Valgus stress and a fall on the outstretched hand are the usual mechanisms of this avulsion injury.
What is the usual indication for surgery in a medial epicondyle fracture?
Surgery is commonly advised when the fragment is displaced by more than about 5 mm, when it is trapped within the joint, or when the elbow is unstable. Minimally displaced fragments in a stable elbow are usually managed without an operation.
Why must the ulnar nerve be examined in a medial epicondyle fracture?
The ulnar nerve runs in the cubital tunnel close to the medial epicondyle, so it can be injured by the fracture or by the dislocation that often accompanies it. Sensation, grip and power should be recorded before treatment, and symptomatic nerve injury may need exploration.
How is elbow dislocation related to a medial epicondyle fracture?
Elbow dislocation is commonly associated with medial epicondyle fracture, and the displaced fragment can be pulled into the joint during reduction. Entrapment of the fragment is a recognised reason for open surgery in this setting.
What is the typical age for a medial epicondyle fracture?
Medial epicondyle fracture most often affects boys in the early teen years, around the ages when the epicondyle is still an apophysis. The injury is typically seen in active children and adolescents who throw or fall on the outstretched arm.