Extensor hand injuries can occur by a variety of different mechanisms. The location of the disruption of the tendon is important for diagnosis and treatment decisions. The farther from the finger tip the injury is located, the more joints that are disabled. These injuries can lead to severe disability due to the inability to straighten the fingers. Most injuries do well if treated promptly by an orthopedic surgeon or hand surgery specialist.
Mallet Finger
A mallet finger is the term for an injury to the extensor tendon over the joint closest to the finger nail known as the distal interphalangeal joint. The injury can occur with either blunt trauma or by a laceration. The finger is unable to be actively straightened at the distal interphalangeal joint. Treatment for blunt trauma injuries is generally with splinting for six to eight weeks, according to the AAOS Comprehensive Orthopaedic Review.
Boutonniere Deformity
The Boutonniere deformity refers to the the distal interphalangeal joint being hyperextended while the proximal interphalangeal joint is bent or flexed. This gives the appearance of a boutonniere. The proximal interphalangeal joint is the joint in the middle of the finger. The injury can occur from either blunt trauma or by a laceration to the central slip that lies over the proximal interphalangeal joint. Treatment for laceration injuries is with surgically pinning the joint in extension or straight. Treatment for blunt injuries may be with a trial of splinting for a few months to try to allow structures to heal with the finger in extension.
Fight Bite
According to Dr. James Daniels of Southern Illinois University School of Medicine, a "fight bite" occurs when a clenched fist hits another person's mouth and the tooth penetrates the top of the hand over the metacarpophalangeal joint. The metacarpophalangeal joint is the finger joint closest to the palm of the hand. The resulting injury can be an acute tear of the sagittal band portion of the extensor mechanism of the finger. A "fight bite" leading to tendon damage is known also as a sagittal band disruption. The sagittal band can also be stretched in rheumatoid arthritis. Any lengthening or tearing of the sagittal band will lead to the inability to straighten the finger at this joint. Treatment of this injury is with antibiotics if there is a human or animal bite. Treatment of the torn sagittal band may be by splinting. If no improvement is seen with non-operative splinting, surgery can be performed to correct the injury.
References
- "AAOS Comprehensive Orthopaedic Review"; Dr. Jay Lieberman (ed); 2008
- American Family Physician: Hand and Wrist Injuries: Part II Emergent Evaluation
