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.
Fractures of the humerus shaft can display various patterns: transverse, oblique, spiral, and comminuted. In addition they are differentiated depending on whether the fracture is displaced or undisplaced, relative to the loss of bone alignment and closed or open fracture. The AO (Arbeitsgemeinschaft für Osteosynthesefragen) Foundation, an international organisation founded in Switzerland, focussing on research and education for the management of orthopaedic injuries), is one of most used systems available to characterise humerus shaft fractures. According to the AO humerus shaft fractures are divided into their level of comminution:
Type A - No comminution
Type B - Presence of butterfly fragment (wedge-shaped fragment of bone
Type C - Comminution
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: