Boutonniere Deformity vs. Swan Neck Deformity

Attribute	Boutonniere Deformity	Swan Neck Deformity
Cause	Central slip rupture of extensor tendon	Laxity of volar plate or intrinsic muscles
Appearance	Flexion of PIP joint and hyperextension of DIP joint	Hyperextension of PIP joint and flexion of DIP joint
Associated conditions	Rheumatoid arthritis, trauma	Rheumatoid arthritis, trauma
Treatment	Splinting, therapy, surgery	Splinting, therapy, surgery

Introduction

Boutonniere deformity and Swan Neck deformity are two common hand deformities that can affect individuals for various reasons. While both deformities involve changes in the alignment of the fingers, they have distinct characteristics that differentiate them from each other. Understanding the attributes of each deformity is crucial for accurate diagnosis and appropriate treatment.

Causes

Boutonniere deformity is typically caused by an injury to the central slip of the extensor tendon in the finger. This injury can result from trauma, such as a direct blow to the finger or a laceration. On the other hand, Swan Neck deformity is often associated with conditions like rheumatoid arthritis, which can lead to joint laxity and deformity over time. Other causes of Swan Neck deformity include ligament injuries and chronic inflammation.

Symptoms

Individuals with Boutonniere deformity may experience difficulty straightening the affected finger, as well as pain and swelling in the joint. The deformity is characterized by a flexion of the proximal interphalangeal (PIP) joint and hyperextension of the distal interphalangeal (DIP) joint. In contrast, Swan Neck deformity presents with hyperextension of the PIP joint and flexion of the DIP joint. This can result in a "swan-like" appearance of the finger.

Diagnosis

Diagnosing Boutonniere deformity typically involves a physical examination of the affected finger, as well as imaging studies like X-rays to assess the extent of the deformity. In some cases, an MRI may be necessary to evaluate the condition of the extensor tendon. Swan Neck deformity can also be diagnosed through a physical examination and imaging studies. Blood tests may be ordered to rule out underlying conditions like rheumatoid arthritis.

Treatment

Treatment for Boutonniere deformity often involves splinting the affected finger in a straight position to allow the central slip of the extensor tendon to heal. Physical therapy may be recommended to improve range of motion and strength in the finger. In severe cases, surgery may be necessary to repair the damaged tendon. On the other hand, treatment for Swan Neck deformity may include splinting to correct the alignment of the finger joints. In some cases, surgery may be required to stabilize the joints and prevent further deformity.

Prognosis

The prognosis for individuals with Boutonniere deformity is generally good with early diagnosis and appropriate treatment. Most patients can regain full function of the affected finger with splinting and physical therapy. However, if left untreated, Boutonniere deformity can lead to chronic pain and stiffness in the finger joint. Similarly, the prognosis for Swan Neck deformity depends on the underlying cause and severity of the deformity. With proper treatment, individuals can improve the alignment of their finger joints and prevent further complications.