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 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.
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:
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.
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
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)
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 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.
A mallet finger is most common amongst players of ball games such as:
The symptoms arising from a mallet finger are:
Sudden pain at time of injury
Swelling around the DIP joint
Blood accumulation within the nail bed
Inability to completely extend the finger
Typical finger deformity
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.
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:
Administration of NSAIDs
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.
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
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:
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: