Bennett fracture: Anatomy, Treatment Simplified

A Bennett fracture occurs at the base of the first metacarpal bone. It’s an intra-articular joint fracture and dislocation that also involves the articular surface. Therefore, accurate reduction is crucial. Otherwise, it can lead to osteoarthritis as a secondary complication. 

So, without further ado, let’s learn its clinical features and available treatment options. 

Bennett fracture dislocation

So, let’s understand the definition of Bennett fracture dislocation. It’s an oblique intra-articular fracture at the base of the thumb metacarpal with subluxation and dislocation of the metacarpal. 

So why is it called a Bennett fracture? It’s called a Bennett fracture because Edward H. Bennett documented its pattern at the metacarpal joint and how joint tendons slip out of place. Edward H. Bennett was a doctor, a surgeon, and he documented it. So, this Bennett fracture is named after him. 

Observe the X-ray and graphic illustration of the base of the first metacarpal. Observe that the fracture segment has broken apart, and the articular surface is also involved.

Mechanism of injury

This fracture occurs due to a longitudinal force in the direction of the thumb (compressive force) in a partially flexed thumb¹. Suppose we fall, or for some reason, a longitudinal force falls on it. This can happen to workers while working in a factory. It can happen to anyone.

Clinical feature

What are its clinical features? 

1. Its clinical features are pain. 
2. There will be swelling, 
3. Tenderness, and 
4. Restriction of movement at the base of the thumb. If you ask them to move the thumb there, they will complain of pain. 

Treatment

In this fracture, the articular surface is involved, so there’s a chance of osteoarthritis. So, accurate reduction is necessary to prevent this. That’s why surgeons take great precautions to ensure accurate reduction so there’s no mismatch in the articular surface.

So, it can be reduced using two techniques: closed reduction and open reduction.

In closed reduction, after the reduction, percutaneous wire fixation is performed. 

In open reduction, too, a wire or screw is used to fix the reduced fracture segment. 

Closed reduction

In closed reduction, the surgeon first applies a longitudinal force. An outward longitudinal force. Second, the thumb is moved slightly toward radial deviation. Finally, the surgeon reduces the fracture segment by pushing the base of the first metacarpal inward with their thumb . 

After reduction, a percutaneous K-wire is inserted. That means the K wire is inserted through the skin. That’s why it’s called a percutaneous K wire. 

Surgical reduction

In the surgical treatment, the fracture is reduced and fixed surgically using a screw.

In the above image:

• (A) Radiograph of Bennett fracture of the right wrist treated by screw fixation.
• (B) An intraoperative view shows the location of the short incision created for screw introduction, relative to the 1-ulnar (1U) portal (black arrow) and 1-radial (1R) portal (white arrow), which were used for arthroscopic assisted reduction of the joint surface.
• (C) The postoperative artist’s rendering
• (D) and radiograph show anatomic reduction and screw fixation of the volar fragment (white dashed line). The yellow dotted line shows congruent articulation between the first metacarpal (M1) and trapezium (T).

Bennett fracture FAQ

Sunit. S. Ekka

The author is a physiotherapist who has been practising for the last 17 years. He holds a Bachelor's in Physiotherapy (BPT) from SVNIRTAR (Swami Vivekananda National Institute of Rehabilitation and Research), one of the prestigious physiotherapy schools in India.

Whatever he learns dealing with his patient, he shares it with the world through blogs and e-books. He also owns a YouTube channel, "Sunit Physiotherapist" with over 8 lakh active subscribers. Here, he shares everything he gets to learn serving the patient.