Mallet finger is a common finger injury that affects the tendon responsible for straightening the tip of the finger. The injury usually occurs after the end of the finger is struck, causing the fingertip to droop and making it impossible to actively straighten the end joint.
Mr Robert Farnell is an experienced specialist Consultant Orthopaedic Hand and Wrist Surgeon who has been working in Leeds for over 25 years. He exclusively treats conditions affecting the adult hand and wrist, including tendon injuries, finger fractures, hand trauma and sports injuries.
What is a mallet finger?
A mallet finger occurs when the tendon that straightens the end joint of the finger is damaged. The injury affects the distal interphalangeal joint (DIP joint), resulting in an inability to actively straighten the fingertip.
Most mallet finger injuries involve a tear of the extensor tendon. In some cases, a small fragment of bone is pulled away from the end of the finger. This is known as a bony mallet finger.
Because the tendon can no longer straighten the fingertip, the end of the finger rests in a bent position.
What causes a mallet finger?
A mallet finger most commonly occurs after the end of the finger is forcibly bent whilst the finger is straight. This frequently happens when the fingertip is struck by a ball during sporting activities, which is why the injury is sometimes known as baseball finger.
It can also occur after stubbing the finger against a hard object or sustaining a direct blow to the fingertip.
Symptoms of a mallet finger
Symptoms usually develop immediately after the injury and commonly include:
- Pain at the end of the finger
- Swelling around the end joint
- Bruising
- Drooping of the fingertip
- Inability to actively straighten the end joint
Although the fingertip cannot be actively straightened, it can usually be gently straightened by the other hand.
How is a mallet finger diagnosed?
Diagnosis is usually straightforward following clinical examination.
An X-ray is routinely performed to determine whether the tendon injury is associated with a fracture of the distal phalanx, which is the end bone of the finger.
Find out what to expect at your outpatient appointment.
Treatment for mallet finger
Non-surgical treatment
The majority of mallet finger injuries can be treated without surgery.
Treatment involves wearing a specially designed plastic splint that keeps the fingertip fully straight whilst the tendon heals.
The splint must usually be worn continuously for six weeks. It is important that the fingertip does not bend during this period, as even brief flexion may disrupt healing and require the treatment period to start again.
Figure 3: A typical mallet finger splint used during treatment.
Surgical treatment
Surgery is recommended in selected patients, particularly where there is:
- A displaced fracture involving the joint surface
- A bony mallet finger with joint subluxation
- An injury that cannot be adequately treated with splinting alone
The operation is usually performed under local anaesthetic as a day case procedure.
The fracture is reduced into its normal position and stabilised using fine wires or a small screw depending upon the fracture pattern.
Recovery after treatment
Once the treatment period has finished, the splint is removed and gentle finger movement begins.
Some patients benefit from hand therapy or physiotherapy, although many recover well with a structured home exercise programme.
Recovery of movement and strength continues over several months.
Read more about post-operative care.
Possible complications
Most mallet fingers heal successfully. Occasionally, however, the tendon heals with slight lengthening or fails to heal completely.
This may leave a small residual droop at the fingertip. In many patients this causes little or no functional problem.
Occasionally the altered tendon balance results in hyperextension of the middle finger joint (the proximal interphalangeal joint). This is known as a swan neck deformity because of the characteristic appearance of the finger.
Treatment is not usually necessary, although surgery can sometimes rebalance the tendon if symptoms are troublesome.
Prognosis
The majority of patients recover excellent finger function following appropriate treatment. Careful splint use is particularly important, as successful healing depends on keeping the fingertip fully straight throughout the treatment period.
Unable to straighten the tip of your finger?
If you have injured your finger and the fingertip is drooping or will not straighten, Mr Robert Farnell can assess your injury and advise whether splint treatment or surgery is the most appropriate option.
Mallet Finger FAQs
What is a mallet finger?
Mallet finger is an injury to the tendon that straightens the tip of the finger, causing the fingertip to droop.
What causes a mallet finger?
It usually occurs after the fingertip is forcibly bent, commonly during sport or after stubbing the finger.
What is a bony mallet finger?
A bony mallet finger occurs when the tendon pulls off a small fragment of bone from the end of the finger.
Do I need an X-ray?
Yes. An X-ray is usually performed to determine whether there is an associated fracture of the distal phalanx.
Can a mallet finger heal without surgery?
Yes. Most mallet finger injuries heal successfully with continuous splinting for approximately six weeks.
Why must the splint stay on all the time?
The fingertip must remain fully straight while the tendon heals. If the finger bends during treatment, healing may be disrupted.
When is surgery recommended?
Surgery may be required for displaced fractures, joint subluxation or injuries that cannot be successfully treated with splinting.
What is a swan neck deformity?
A swan neck deformity occurs when imbalance within the extensor tendon mechanism causes hyperextension of the middle finger joint together with drooping of the fingertip.