A Boxer’s fracture refers to a fracture involving the neck of the 5th metacarpal. It typically results from a punching mechanism. A significant force can result in the bone ending up multiple pieces (comminuted) or become significantly displaced resulting in a deformity.
Any laceration overlying, or associated with, a fracture is referred to as a compound fracture. This typically occurs in boxer’s fractures when the fist strikes a tooth. Even though the laceration is often no more than a small puncture wound, these are at very high risk of developing an infection including septic arthritis and should be treated aggressively.
The forces required to fracture a bone also act on the surrounding soft tissues. Therefore, significant soft tissue trauma also occurs with its resultant swelling. This swelling is magnified by the bleeding that occurs from the bone ends at the site of the fracture. Overall, swelling occurs at the site of the fracture and often affects the whole hand. This swelling can cause stiffness to the hand and fingers.
If a fracture involves the joint surface then arthritis may develop later in life.
In general, Boxer’s fractures are extremely common and usually do not require surgery and cause no functional compromise. However, they will result in a loss of prominence of the little finger knuckle.
The degree to which the fracture has displaced determines the type of complications that can arise with these fractures. The fracture can result in the head of the 5th metacarpal (MCP joint) experiencing significant volar (flexor/forward) angulation and/or rotation at the fracture site. This can cause two of the potential problems associated with these fractures:
Volar angulation can cause an inability to fully straighten the little finger (extensor lag). This is common finding initially in most of these fractures but it usually resolves. Significant angulation will cause a permanent lag.
Little finger rotation can occur such that it overlaps the ring finger when one makes a fist. This can cause significant functional compromise to the hand.
In general, the above two potential issues are the key reasons why surgery would be offered to people with these fractures.
This fracture usually does not involve the joint surface and so arthritis in later life is unusual after this fracture.
NON-SURGICAL
Ice packs – first 24 hours
Elevation – wearing an arm sling
Splint to immobilise – usually the little and ring fingers
Pain killers
Splint is usually required for no more than 2-3 weeks. However, protective splinting should be continued for a further 2-3 during times when the patient is at risk of further injury (eg. work, sleeping)
When splint is removed after 2-3 weeks, simple Coban dressing can be worn. This serves as a constant reminder to the patient and those around them that their hand has a significant injury.
Most Boxer’s fractures are stable and therefore early mobilization is important. Thus, removing the splint at 2-3 weeks post-injury is important. However, the patient must be made aware that his fracture has not yet healed and they should not be cleared for normal activities…….hence the use of “protective splinting” for a further 2-3 weeks.
The major indications to operate on a Boxer’s fracture are if the little finger is rotated or if there is significant extensor lag.
Surgery involves anatomical reduction of the fracture and this can be performed. This can be done “Closed” in which no cut is made and a plaster or splint is applied or “Open” where an incision is made and the bones are directly repositioned.
A closed reduction alone is rarely performed for a Boxer’s fracture because it is unstable once the bone has been realigned. It may be combined with the insertion of wires through the skin.
An open reduction usually requires the use of wires or plates and screws. Such fixation allows immediate movement of the finger after the surgery which is desirable to prevent stiffness.
Loss of prominence of the 5th knuckle – This occurs in patients who have non-surgical treatment of their fractures. This is because a large degree of volar angulation at the fracture site can be tolerated without affecting hand function. These patients will have a loss of prominence of the little finger knuckle.
A bony lump – may appear at the fracture site as the bone heals and is known as “fracture callus”. This is a normal part of the healing process and usually resolves over 6–12 months.
Extensor lag / little finger droop – it often takes 6-8 weeks for the little finger to fully straighten.
Pain – the hand often aches for up to 12 months after the fracture even though it has healed.
As a guide, it takes 6 weeks for a hand fracture to heal and a further 6 weeks to reach near normal strength. Therefore very heavy lifting and contact sport should be avoided until the fracture has solidly healed (up to 12 weeks).
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