Mallet Finger

Mallet Deformity is an inability to maintain extension of the distal phalanx of the finger at the distal intraphalangeal  joint.

This is usually as a result of forced flexion of the joint whilst trying to maintain extension. It is sometimes known as chambermaids finger – imagine stubbing your finger and flexing it whilst trying to tuck in a sheet – but is commonly seen as a sporting injury, such as catching a cricket ball.

The patient will present with a similar mechanism to this, sudden pain and an inability to extend the finger at the DIPJ.

On examination there will be an obvious droop/flexion, at the DIPJ. Usually to about 45 degrees.

The deformity is caused by one of two specific injuries.

 

Mallet Deformity

Tendon injuries tend to show less swelling/tenderness over DIPJ and should be passively correctable without pain.

Fractures tend to show swelling/bruising over the DIPJ, tenderness and tend not be fully passively correctable and this may or may not illicit pain.

Initially both will be managed in a mallet splint for immobilisation.

However, it important to make a definitive diagnosis with plain x-ray as this affects the onward referral of the patient, and in some cases the definitive management.

Mallet fingers with fracture need referral to fracture clinic.

Mallet fingers without fracture to ED consultant clinic – in 6 weeks.

Mallet Splints

Mallet splints are designed to keep the DP in extension and reduce stress of the injury to promote good healing.

Pictured are the splints we hold locally, “stax” splints, but there are several other varieties available.

Stax type mallet splint

This splint should be close-fitting but not causing compression of the skin. Patients waiting for ED clinic review will need to be advised they may need to attend again for resizing as their swelling eases.

The bottom section of the splint should then be taped to the finger to secure the splint and hold it in place.

Stax Style Mallet Splint - Fitted

Patients should be advised to remove them for about 20 minutes twice a day in order to mitigate the risk of skin maceration or sores developing. Equally, although you can get them wet (for example when bathing) they should be removed and re-taped immediately afterward.

Patients need clearly counselling that when they remove the splint it is important to keep the DP ‏supported, for example by laying the finger on a table. If the finger is lifted and allowed to flex again then this will cause re-injury, longer in splint and if recurrent will eventually build up of scar tissue will prevent the tendon from healing.

Patient advice is available here

PEARLS 

Xray to confirm tendon rupture vs. fracture

Fracture  – Next fracture clinic

Rupture – ED clinic in 6 weeks

Mallet splint in both cases

Ensure patient knows not to let finger flex

In some cases large avulsion fractures may require fixation

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