Bennett’s fracture

Definition/Description

A Bennett fracture is a fracture at the base of the thumb caused by forced abduction of the first metacarpal. It is defined as an intra-articular two-part fracture of the base of the first metacarpal. [1]

• Despite its relatively uncomplicated appearance on radiographs, a Bennett fracture is considered unstable.
• Placing the patient in the thumb extended position (hitchhiker position) should be avoided when evaluating and treating these fractures, as this can displace the fracture further.
• If the fracture fragments are well aligned when immobilized postoperatively, the clinical outcome is usually good. [2]
• Named after Edward Hallaran Bennett (1837-1907), a surgeon from Dublin, Ireland. [1]

Clinically relevant anatomy and pathophysiology

The first CMCJ is unique in that it has only the articulation between the trapezium and the base of the first metacarpal.

• The joints are saddle shaped to allow for greater movement. [3]
• The ligaments in this joint are the anterior (volar) and posterior oblique ligaments, the anterior and posterior intermetacarpal ligaments, and the dorsal radial ligament.
• The anterior oblique ligament is most important for the stability of the carpus metacarpal joint. [4]

The fracture pattern is distinct.

• As the metacarpal ulnar fragment of the first metacarpal is held in place during axial loading by its ligamentous attachment to the trapezium (anterior oblique ligament), the base of the first metacarpal fractures and extends intra-articularly, and the remaining metacarpals move intra-articularly The opposite direction and major fracture line occurs along this weak point.
• As a result of this fracture, the first metacarpal shaft is dorsally proximally and radially subluxed due to pull by the extensor pollicis longus, extensor pollicis longus brevis, and adductor pollicis brevis, which remain attached to the fracture fragment. [2]

Differential Diagnosis

Other common injuries involving the first metacarpal include Rolando fractures, extra-articular fractures, and gamekeepers thumb

The first clue to identification can be found during inspection/palpation of the injured area. A Bennett’s fracture is associated with pain and weakness in pinching the carpus metacarpal joint of the thumb, as well as swelling and ecchymosis. Patient will not be able to perform Functional tasks, such as tying shoelaces or using keys. Possible complications may be infection malunion or nonunion arthritis and contracture stiffness. [5]

Examination

If a Bennett fracture is suspected, the patient’s subjective history should include hand or thumb trauma followed by immediate pain, swelling, or ischemia. [6] The most common mechanism of injury is the axial force (compression) exerted on the thumb during flexion.

On physical examination, a Bennett’s fracture of the first carpus metacarpal joint may present with:

• Visible deformity if the fracture is displaced
• Thumb carpal metacarpal joint pain and swelling +/- ecchymosis
• tenderness to touch
• warmth over the area in acute phase
• Decreased pinch grip and decreased grip strength 13

While x-rays can be used to diagnose this condition, a CT scan should be done to assess the extent of the damage. On these CT scans, a Bennett fracture will appear as an intra-articular fracture and dislocation of the base of the first metacarpal. even if there is a misalignment there It should still be a small piece of the first metacarpal, continuing to connect with the trapezoidal joint.

Medical Management

For stable nondisplaced fractures, 3-4 weeks of non-surgical treatment in a thumb spline cast may be considered.

Surgery is recommended for unstable fracture types and >1 mm intra-articular displacement. Although open reduction and internal fixation with screws or K-wires are both common practice, screws are usually preferred because the K-wires must be removed after engagement.

The treatment algorithm is also influenced by the patient’s age and occupation/hobbies.

Untreated or poorly reduced fractures can lead to secondary osteoarthritis. Osteoarthritis or malunion can cause significant pain and decreased function. [1]

Physical Therapy Management

Typically, hand fractures are treated with a cast or splint, whether surgery or conservative treatment is required.

Physiotherapists and/or occupational therapists are actively involved in creating and adapting these, often in consultation with the treatment team or surgeon.

• Rehabilitation programs must be based on fracture stability and fracture management (operative or nonoperative).
• Following the immobilization period, physical therapists and professional hand therapists are involved to facilitate the return of maximum hand function [7].
• Range of motion exercises can be started 5 to 10 days after screw fixation and 4 weeks after fixation (after pin removal). [2]
• Approaches include cryotherapy combined with mobilization strengthening and flexibility exercises dexterity re-education and special education.
• Exercise intensity and complexity should be increased as appropriate according to the prescribed regimen usually provided by the surgeon. [8] [9]
• Evidence supports the positive impact of early physiotherapy intervention to promote optimal return of function and return to work/sports in fractured hands. [10]

Conclusion

The management of a Bennet’s fracture is complex and is best done by an interprofessional team that includes a hand surgeon/orthopedic surgeon skilled nursing nurse and a physiotherapist.

When emergency physicians and nurse practitioners encounter a fracture, it is important to promptly refer the patient to a hand surgeon.

Inappropriately treated bennet fractures have a very high morbidity. Even with proper treatment, extensive rehabilitation is required.

Results of Bennet’s fracture protected