Mallet finger
Mallet finger is also known as baseball finger due to the high incidence of the pathology in baseball players

Definition

A mallet finger is the inability to straighten the distal phalange of a finger. This condition may lead to a deformity of the phalange, which remains permanently bent towards the palm.

 

A mallet finger causes the inability to straighten the last phalange of a finger

Pathology

A mallet finger is the result of the rupture of the finger extensor tendon at the distal inter-phalangeal (DIP) joint. This condition is also called baseball finger, as it is common in baseball players. Sometimes the rupture of the finger extensor tendon occurs in combination with a fracture of the distal phalange. Consequently the patient is unable to completely straighten the finger.

 

Colles' fracture with bone displacement seen before (left) and after closed reduction (right) in a cast

Classification

The fractures of the distal radius are defined with various classification systems including the AO (Arbeitsgemeinschaft fuer Osteosynthese) system. They relate to the mechanisms of injury and bone fracture characteristics and provide a guideline towards suitable treatments. The most frequent types of distal radius fracture are:

No 1.

Colles’ fracture is the most common type of fracture in which the distal bone of the radius tilts upwards following an outer bending of the wrist as it happens when falling on the hand

Smith’s fracture or reversed Colles’ fracture occurs when the distal portion of the radius tilts downwards following the inward bending of the wrist

Barton fracture is an intra-articular fracture of the distal radius with dislocation of the radiocarpal joint

Chauffeur fracture is an intra-articular fracture of the radial styloid process, also known as Hutchinson fracture or backfire fracture.

Left: Distal radius intraarticular, displaced fracture; Middle: Older distal radius fracture with callus formation; Right: Distal radius and ulna fracture, extraarticular and displaced

No 2.

Intra-articular fracture extends to the wrist joint (or articulation)

Extra-articular fracture is located outside of the wrist joint

Open fracture when bone fragments perforate the skin

Comminuted fracture when the bone breaks into multiple fragments

Non-displaced when the anatomical alignment of the bone is maintained or displaced when the bone fragments move apart.

Melone’s classification describes the characteristics of intra-articular fractures of the radius:

i    Stable fracture

ii    Unstable "die-punch"

iii   "Spike" fracture

iv Split fracture

v   Explosion injuries

Acetabular fracture of the pelvis

Acetabular fractures

These fractures are divided into:

Anterior pillar (not weight bearing part of joint)

Posterior pillar (often associated with dislocation of the hip including the weight bearing part of joint)

Transverse

Comminuted involving both column type 

Sacral / coccygeal fractures

The sacrum is a triangular-shaped bone formed by 5 fused vertebrae, which provide a posterior wall to the pelvic ring. At each side of the sacrum, the ala structures articulate with the ilium bones forming the sacro-iliac joints. Sacral fractures are usually parallel to the spine and can involve the ala. Less frequently sacral fractures may display an “H” shape, including a transversal fracture uniting both sides of the sacrum. Three zones are described where sacral fractures can occur that are along vertical lines relative to the alignment of the foramina. Sacral fractures may result in sacral instability and require treatment via sacroplasty (injection of bone glue into the fracture). Surgery is necessary in case of associated neurological symptoms.

Fractures of the coccyx involve the tailbone, the terminal portion of the spine situated below the sacrum formed by 3 to 5 fused vertebrae. Coccyx fractures occur when falling on a seated position. They are more common in elderly women and seldom require surgical treatment.

A hard hit of a ball onto the straighten finger can lead to the rupture of the finger extensor tendon

Causes

A mallet finger is more commonly observed in ball sport injuries but can also arise from daily activities that do not require a strong force. It typically ensues when the ball hits the straight finger forcing it to bend forward.

Baseball is one of the ball sports which increases the risk for a mallet finger

Risk factors

A mallet finger is most common amongst players of ball games such as:

Baseball

Basketball

Netball

Football

Rugby

Daily activities

A patient is unable to straighten the index finger

Symptoms

The symptoms arising from a mallet finger are:

Sudden pain at time of injury

Swelling around the DIP joint

Bruising

Blood accumulation within the nail bed

Nail loss

Finger stiffness

Inability to completely extend the finger

Typical finger deformity

X-rays of the hand show a clear deformity of the ring and index fingers at the distal inter-phalangeal joints

Diagnosis

The medical history focuses on the mechanisms of injury leading to mallet finger. Medical examination is usually sufficient for the diagnosis and includes: 

Detection of finger deformity

Palpation to the region of interest

Test changes in the range of movement of the finger distal phalanges, both passively and actively

X-rays in case of suspected avulsion fracture of the phalange.

Treatment

A splint may be used for conservative treatment following an injury to the extensor tendon

Nonoperative treatment

Management of the mallet finger is normally achieved conservatively if no fracture or other complications are present. Conservative treatment includes the immobilisation with a splint to keep the finger in full extension for up to 6 – 8 weeks and another 6 weeks of night use of the splint. Additional treatments include:

Ice pads

Administration of NSAIDs

Painkillers

Surgery may include the fixation of the fractured phalange associated with extensor tendon injury and repair of the rupture tendon by reattaching it to the bone

Surgical treatment

Surgery is employed when the rupture of the extensor tendon is associated with joint misalignment or with the presence of a phalange fracture.

Surgical splinting: is recommended in case of severe deformity or when the patient requires an immediate use of the hand. A metal pin is inserted into the DIP joint to achieve an internal finger immobilisation. This facilitates earlier use of the finger. The pin is kept in situ until the tendon has healed for approximately 6 – 8 weeks.

Extensive surgery is performed when mallet finger occurs concomitant to rupture of the extensor tendon or phalange fractures with the following methods:

Surgical tendon repair: the tendon is sutured or repaired with a tissue graft.

Fracture fixation: internal fixation of the bony fragment with screws and wires is a common approach to repair the fractures of the phalanges associated with extensor tendon rupture.

Finger joint fusion: fusion of the phalanges can be performed as an alternative to internal fixation in both mallet finger and swan neck deformity.

Complications

The most common complications following either conservative or surgical treatment of mallet finger include:

Skin damage due to prolonged splinting

Stiffness at the DIP joint

Infection following surgery

 

Gentle finger stretch exercises help restoring flexibility at the inter-phalangeal joints

Rehabilitation

A physical or occupational therapist guides the patient through an exercise plan to restore flexibility and strength of the finger affected by mallet pathology. Education will inform how to modify activities to avoid recurrent finger injuries. Additional rehabilitative therapy includes:

Joint mobilisation

Stretches

Electrotherapy

Individual finger taping or taping two adjacent fingers together can prevent tendon injuries

Prevention

Prevention of a mallet finger aims at reducing the risk of future injuries to the extensor tendons by protecting fingers during physical activities and sport. Common strategies are:

Finger splinting

Finger taping