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Fracture of the first metacarpal: causes, symptoms, diagnosis, treatment
Last reviewed: 07.07.2025
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Particular attention is paid to this bone because the first metacarpal bone is located separately from the others, is very mobile, and is involved in adduction, abduction, and opposition of the first finger. In functional terms, it is equated to the other four fingers.
ICD-10 code
S62.2. Fracture of first metacarpal bone.
Bennett's fracture
Reasons
A Bennett fracture occurs as a result of a blow directed along the axis of the first finger. This causes a dislocation in the carpometacarpal joint with a simultaneous fracture of the base of the first metacarpal bone, which, shifting upward, breaks off a triangular fragment of the ulnar edge of its own base. Thus, a Bennett fracture is more correctly called a fracture-dislocation of the first metacarpal bone.
Symptoms and diagnosis
Complaints of pain at the fracture site, limited hand function. The radial side of the wrist joint is deformed due to the protruding first metacarpal bone and edema. The contours of the "anatomical snuffbox" are smoothed. Palpation of the first carpometacarpal joint and axial load on the first finger are painful. Adduction, abduction and opposition of the first finger are sharply limited. X-ray confirms the diagnosis.
Treatment
Conservative treatment. 5-10 ml of 2% procaine solution is injected into the area of the first carpometacarpal joint. After the onset of anesthesia, the first metacarpal bone is repositioned. This is achieved by axial traction and abduction of the first finger. The limb is fixed with a circular plaster cast from the upper third of the forearm to the metacarpophalangeal joints, capturing the main phalanx of the first finger in the abduction position. A control radiograph is required. If repositioning and reduction have occurred, immobilization is left for 4-6 weeks.
Surgical treatment. If the reduction is unsuccessful, the attempt should be repeated or the patient should be referred to a hospital where skeletal traction or surgical treatment methods can be used.
If attempts at reduction are unsuccessful, skeletal traction or fixation with a Kirschner wire and bone autospike is used.
Approximate period of incapacity. Working capacity is restored in 6-8 weeks.
[ Flexion fracture of the first metacarpal bone
Reasons
A flexion fracture of the first metacarpal bone occurs with a sharp forced flexion of the first metacarpal bone in the palmar-ulnar direction (when hitting a hard object). In this case, unlike the Bennett fracture, the fracture line passes outside the joint, 1-1.5 cm distal to it. The fragments are displaced at an angle open to the palmar side.
Often such fractures occur during fights and in novice boxers who perform side punches incorrectly.
Symptoms and diagnosis
The symptoms and diagnosis are identical to those of a Bennett fracture, except that the carpometacarpal joint is palpated to be undeformed. The difference is also revealed radiographically.
Treatment
Treatment is conservative. Under local anesthesia, manual reposition is performed to eliminate the angular deformity and fixation is carried out in the same way as in the case of a Bennett fracture. The period of immobilization for a fracture of the base and body of the first metacarpal bone is 4-5 weeks. In cases where reposition is unsuccessful, skeletal traction or surgical treatment is used.
Approximate period of disability. Restoration of working capacity occurs in 6-7 weeks.