What is Boutonniere Deformity?
Boutonniere deformity occurs when the central slip tendon, an important portion of the extensor tendon, is damaged near the PIP joint (proximal interphalangeal joint). The central slip normally helps extend the middle phalanx, or middle bone, of the finger.
When the central slip is torn or detached, the lateral bands of the extensor mechanism can shift toward the palm. Over time, these structures can pull the PIP joint into a flexed position. At the same time, changes involving the terminal tendon and supporting soft tissues can cause the DIP joint (distal interphalangeal joint) to become hyperextended. The result is a characteristic deformity involving two joints of the finger.
What Are Common Causes of Boutonniere Deformity?
A jammed finger is a common cause. A forceful impact can injure the central slip without causing a major fracture. A cut or other trauma may also produce extensor tendon injuries.
Other causes include:
- Direct blows to the back of the PIP joint
- Finger dislocations
- Fractures involving the middle phalanx
- Sports-related finger injuries
- Rheumatoid arthritis, which can affect the extensor mechanism and surrounding tissues
Symptoms may not develop immediately, particularly after an apparently minor finger injury.
Signs and Symptoms of a Boutonniere Deformity
The most recognizable sign is difficulty straightening the PIP joint. The affected finger may gradually remain bent at the middle joint while the DIP joint moves into hyperextension.
Other symptoms may include:
- Pain or tenderness around the PIP joint
- Swelling after an injury
- Difficulty fully straightening the finger
- Reduced range of motion
- Stiffness
- Weakness when using the finger
- A visible change in finger alignment
Because the deformity can progress gradually, it is important to have persistent symptoms evaluated.
How is Boutonniere Deformity Diagnosed?
A hand specialist will review the circumstances of the finger injury and examine the affected finger. The doctor may assess active and passive motion, tendon function, swelling, tenderness, and joint alignment.
X-rays can help identify fractures, dislocations, or other bone abnormalities. In some cases, additional imaging may be considered to evaluate the central slip, soft tissues, or other portions of the extensor mechanism.
Treatment for Boutonniere Deformities
Treatment depends on the severity of the injury, how long symptoms have been present, and whether the deformity is flexible or established.
For many acute injuries, nonsurgical treatment may include splinting the PIP joint in an appropriate straightened position while allowing controlled DIP joint movement. A hand therapist can help guide exercises and splint adjustments during recovery.
Depending on the underlying cause, oral medications or corticosteroid injections may sometimes be considered to reduce pain or inflammation, particularly when inflammatory conditions such as rheumatoid arthritis contribute to symptoms.
The goal is to protect the injured central slip while maintaining as much safe finger motion as possible.
When is Surgery Needed?
Surgical treatment may be considered when there is a significant tendon injury, fracture or dislocation that cannot be adequately treated without surgery, or a persistent deformity that does not respond to appropriate nonsurgical care.
For chronic injuries, surgical intervention may involve repairing or reconstructing damaged portions of the extensor mechanism and addressing related soft-tissue changes.
Recovery and Hand Therapy
Recovery varies according to the severity of the injury and the treatment provided. Following splinting or surgery, hand therapy plays an important role in gradually restoring motion while protecting healing tissues.
A therapist may provide a customized splint and exercises designed to improve PIP joint extension, maintain DIP joint movement, and gradually restore strength. The lumbrical and interosseous muscles also contribute to coordinated finger movement and may be addressed during rehabilitation.
Following the recommended treatment plan is important because returning to demanding hand activities too quickly can interfere with healing.
Protecting Your Finger Function
If you are experiencing finger pain, stiffness, or difficulty straightening a finger, Georgia Hand, Shoulder & Elbow can evaluate your condition and discuss an appropriate treatment plan. Schedule an appointment with our office in Marietta or Atlanta, Georgia, to get expert care for your hand and finger concerns.
