Fractures at the base of the first metacarpal are among the most common thumb injuries. Because the thumb is essential for almost every grip and the thumb carpometacarpal joint is constantly under load, precise classification and the right treatment determine the later strength and mobility of the hand. This overview summarises current knowledge on Bennett, Rolando and Winterstein fractures.
At a glance
- Winterstein fracture: fracture of the first metacarpal close to its base without joint involvement.
- Bennett fracture: intra-articular fracture with two fragments; the shaft displaces radially and proximally.
- Rolando fracture: Y- or T-shaped intra-articular fracture with three or more fragments.
- Intra-articular fractures are generally treated surgically to avoid a step in the joint surface and later osteoarthritis of the carpometacarpal joint.
Anatomy: why these fractures displace
The thumb carpometacarpal joint (first carpometacarpal joint, CMC I joint) connects the first metacarpal with the trapezium. Its saddle shape allows opposition of the thumb, i.e. bringing it opposite the fingers. The joint is stabilised mainly by ligaments, in particular the strong ligament at the palmar-ulnar edge of the metacarpal base (anterior oblique ligament, “beak ligament”).
In a fracture, several muscles act as displacing forces:
- The abductor pollicis longus inserts at the base of the first metacarpal and pulls the shaft proximally and radially.
- The adductor pollicis pulls the thumb into adduction and supination.
- In extra-articular fractures, the short thumb muscles frequently cause palmar angulation.
These forces explain why many thumb base fractures do not remain in the correct position in a cast alone.
The three fracture types at a glance
| Fracture type | Joint involvement | Typical appearance | Usual treatment |
|---|---|---|---|
| Winterstein | no (extra-articular) | transverse or oblique fracture near the base, angulation | conservative if displacement is minor, otherwise wires or plate |
| Bennett | yes, two fragments | small fragment remains attached to the ligament, shaft subluxates radially and proximally | usually surgical: wires or screw |
| Rolando | yes, three or more fragments | Y or T shape, often a comminuted zone | surgical: plate, screws, wires, external fixator if comminuted |
Mechanism of injury and symptoms
Typically, a force acts along the axis of the slightly flexed thumb – for example in a fall on the hand, when the thumb gets caught while skiing or playing ball sports, or when punching. Those affected have severe pain at the base of the thumb, swelling and often bruising. Gripping, making a fist and opposing the thumb are painful or barely possible. In intra-articular fractures, a step or malalignment may be palpable.
Diagnosis
- Clinical examination: tenderness, axial alignment and rotational malalignment, assessment of circulation, sensation and tendon function.
- X-ray: images of the thumb in two planes. A true AP projection of the carpometacarpal joint (Robert view) shows the joint surface better.
- Computed tomography: CT is generally useful for intra-articular fractures. It shows the number, size and displacement of the fragments and helps with surgical planning. Rolando fractures in particular are often underestimated on X-ray.
Treatment of Winterstein fractures
Because the carpometacarpal joint is very mobile, minor axial deviations are often compensated well functionally. If the fracture is not displaced or only slightly displaced, immobilisation in a forearm cast including the thumb for about four to six weeks, with regular X-ray checks, is sufficient.
Surgery is performed for greater angulation, shortening, rotational malalignment or secondary displacement. Options include closed reduction with Kirschner wire fixation or open reduction with a small (often locking) plate. Plate fixation often allows earlier exercise therapy but requires a larger incision.
Treatment of Bennett fractures
In a Bennett fracture, the small base fragment remains fixed to the joint via the ligament, while the shaft is pulled out of the joint by muscle traction. The position can usually not be maintained conservatively, so surgery is the rule.
- Closed reduction and wire fixation: under traction, abduction and pronation, the shaft is reduced and fixed with percutaneous Kirschner wires, for example to the trapezium or the second metacarpal.
- Open reduction and screw fixation: with larger fragments, the fragment is reduced directly and fixed with one or two small screws.
The aim is a joint surface that is as step-free as possible; in the literature, a residual step of less than about 1 to 2 mm is regarded as the target. A systematic review found no clear advantage of any one procedure; good restoration of the joint surface is what matters.
Treatment of Rolando fractures
Rolando fractures are less common but more difficult to treat. With large fragments, the joint surface is reconstructed openly and stabilised with a T- or L-shaped plate, screws or wires. If there is marked comminution, an external fixator or a combination of traction and wire fixation may be appropriate, as small fragments cannot be fixed individually.
Aftercare
- Immobilisation for about four to six weeks depending on the procedure, often shorter after stable plate fixation.
- Removal of Kirschner wires usually after four to six weeks.
- Followed by hand therapy to restore mobility and strength. Full loading capacity, e.g. for sport or heavy work, is usually reached after about three months.
Complications
- Post-traumatic osteoarthritis of the thumb carpometacarpal joint (rhizarthrosis): especially after intra-articular fractures with a residual step.
- Malunion: shortening, angulation or rotational malalignment with weakness when gripping.
- Restricted movement and loss of strength.
- Non-union (failure of bone healing), rare.
- Irritation of the superficial branch of the radial nerve from incisions or wires, infections at wire entry sites.
Frequently asked questions
Does a Bennett fracture always need surgery?
In most cases yes, because muscle traction pulls the shaft out of the joint and the position can hardly be maintained in a cast. Only very small, undisplaced fragments can be treated conservatively in individual cases.
How long does healing take?
The bone has usually healed sufficiently to bear load after six to eight weeks. It can take three to six months for mobility and strength to return completely.
Can osteoarthritis develop later?
Yes, particularly after intra-articular fractures. The risk is lower if the joint surface has been well restored but cannot be ruled out completely.
Further reading on Medizin Aktuell
Note: This article is for general information only and does not replace a medical examination and treatment. Last updated: October 2026.
