Introduction:
Each of our hands is made up of 14 bones. Each finger consists of three bones: the distal, middle, and proximal (close to the palm) phalanges; interestingly, the thumb has only two phalanges. The finger's structure and function involve several tendons, ligaments, and joints.
Knowing about the finger's joints is essential to understanding Boutonniere's deformity.
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The metacarpophalangeal joint (MCP) is present at the finger's base.
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The proximal interphalangeal joint (PIP) is in the finger's middle part.
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Distal interphalangeal joint (DIP) - Present near the fingertip.
What Is Boutonniere Deformity?
In Boutonniere deformity, the finger middle joint (PIP) is bent, and the fingertip is flexed upwards. It occurs due to a direct injury to the middle joint's tendon (central slip). The central slip is the portion of the extensor tendon that assists in straightening the finger's middle joint. Therefore, damage to the central slip will result in Boutonniere's deformity.
What Causes Boutonniere Deformity?
As mentioned above, the injury to the middle joint's tendon leads to the finger's flexion. In addition, a slit occurs on the tendon, which may appear as a button-hole in the surgical examination. The deformity derives its name from the French word- boutonniere, meaning a button-hole.
The common causes of Boutonniere deformity are listed below:
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It may occur due to an injury that causes a cut in the extensor tendon of the middle joint.
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Sports-related trauma (football, basketball, etc.) is the main reason.
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A burn injury might also lead to tendon rupture.
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An inflammatory condition of joints called rheumatoid arthritis might lead to joint deformities.
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By-birth defect.
What Are the Symptoms?
Individuals with Boutonniere deformity may feel:
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Inability to straighten the middle joint of the affected finger or toe.
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Pain and swelling in the affected finger.
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The affected fingertip flexes upwards.
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The finger joints become stiff, which worsens over time, and the finger joint may lose its function.
How to Diagnose Boutonniere Deformity?
The Boutonniere deformity is usually diagnosed several weeks later. In cases of severe injury or laceration (cut) of the finger, the doctor may examine the joint's tendon for any rupture.
The techniques that aid in diagnosing Boutonniere deformity and its associated conditions are as follows:
Elson’s Test - The doctor might ask the patient to place the affected finger at a 90-degree angle to the table's surface. Then, pressure is exerted on the middle phalanx (center bone of the finger), and the patient is asked to extend the finger at the PIP joint. The doctor confirms it as a positive result if the patient cannot extend the finger at the middle joint; also, upward flexion of the fingertip is noted.
Radiographic Investigation - The degree of flexion of joints in the affected finger is noticed in a plain radiograph. The specialist also checks for associated fractures in cases of severe injury.
Other Investigations - Studies show that about 50 percent of individuals affected by rheumatoid arthritis may develop Boutonniere deformities. In such cases, the doctor may inquire about the degree and severity of symptoms and medications during the physical examination.
What Are the Related Conditions?
PIP Joint Dislocation - Due to specific sports-related injuries, the PIP joint in the finger may get dislocated from its original position. As a result, it causes pain, swelling, and stiffness in the affected finger. The specialist’s knowledge is essential in diagnosing the condition correctly and advising appropriate management.
Skin Contracture - The skin is damaged and tightened due to a severe burn on the finger. It eventually leads to decreased finger movements by affecting the tendons and joints.
How to Fix the Boutonniere Deformity?
1) Non-surgical Management:
Splinting - The specialist advises a splint that supports the affected joints, relieves pain and inflammation, and straightens the flexed joint. Maintaining it for six weeks in young patients and three weeks in older adults is recommended. After the recommended period, it is advisable to wear it at night.
Exercise - Following specific stretching exercises the specialist suggests to improve joint flexibility is crucial.
Protection - Even after the splints are removed, wearing protective taping or splints is essential to prevent the joints from re-injuring.
2) Surgical Management is preferred in the following cases:
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Severe injury to the tendon.
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Lack of improvement with splinting.
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Displacement of bone fragments from their original position.
However, a deformity lasting more than three weeks is difficult to treat.
Surgical Joint Fusion - The surgeon fuses two joints of the affected digit to improve stability, relieve pain, and control complications. Splints are suggested after the surgical treatment to stabilize the straightened joint.
Joint Replacement Surgery - The surgeon may remove and replace the severely damaged joint with an artificial joint to improve its function.
3) Other Management: If Boutonniere deformity occurs due to rheumatoid arthritis, the doctor may suggest the following:
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Disease-modifying anti-rheumatic drugs (DMARDs) like Methotrexate and Hydroxychloroquine aid in relieving symptoms like pain, swelling, and stiffness of joints.
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Biologic response modifiers - Drugs like Adalimumab are responsible for inhibiting certain immune system factors that trigger inflammation. Thus, in patients with rheumatoid arthritis, the symptoms are relieved by biological response modifiers.
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Glucocorticoids aid in reducing the swelling of joints caused by rheumatoid arthritis.
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Non-steroidal anti-inflammatory drugs (NSAIDs) help reduce pain and swelling; however, they do not control the disease progression.
What Are the Associated Complications?
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Long-term joint stiffness and swelling.
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Post-traumatic arthritis - The untreated joint injury may accumulate fluid around it, causing pain, swelling, and limited movements.
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Decrease in finger mobility.
How Can One Prevent Boutonnière Deformity?
Wear protection gear like gloves when engaging in activities that could cause harm to an individual's hands. This is especially important for jobs that could harm or impair the fingertips. Use caution when lifting heavy objects or performing tasks requiring repetitive finger bending.
To reduce unnecessary stress on the finger joints, distribute the weight throughout the hand equally. Regularly stretch and work on the hands to maintain strong, flexible finger joints. Speak with a physical therapist or other healthcare provider for advice on suitable exercises. When engaging in repetitive hand movements, use good technique.
Ensure the approach is ergonomic when performing tasks like typing or playing an instrument to reduce finger strain. If an individual has a finger injury, get medical help right away. If injuries like fractures or dislocations are not properly treated, they may lead to the development of boutonnière deformity.
Acquire knowledge of and utilize joint protection techniques, particularly if people suffer from a disease like rheumatoid arthritis that raises the possibility of joint abnormalities. This could entail changing how one can complete specific chores or using assistive technology.
What Is the Difference Between Boutonniere Deformity and Swan-Neck Deformity?
Boutonnière Deformity:
Visualize the finger as a double-jointed tube. The boutonnière deformity is characterized by the fingertip joint (DIP joint) bending backward and the middle joint (PIP joint) bending down, giving the impression of a buttonhole. This may occur due to an injury or damage to the extensor mechanism of the middle joint, such as a fracture or tendon injury.
Swan-Neck Deformity:
Think about the finger once more. The fingertip joint (DIP joint) bends forward, and the middle joint (PIP joint) bends backward in swan-neck deformity, giving the finger the appearance of a swan's neck. Disorders such as rheumatoid arthritis or trauma to the supporting tissues of the finger joints can cause this deformity.
Conclusion:
Boutonniere deformity is more commonly seen in individuals engaged in outdoor sports, especially basketball and football. Therefore, it is the responsibility of the healthcare specialist to educate such individuals about the injury or trauma to the finger joints and the development of complications if left untreated. In addition, the early diagnosis and management of Boutonniere deformity are essential to avoid loss of mobility.
