From the Research
Boutonniere deformity is primarily caused by injury to the central slip of the extensor tendon at the middle joint of a finger, often resulting from direct trauma, deep cuts, or chronic inflammation in conditions like rheumatoid arthritis. This condition disrupts the normal balance of forces across the finger joints, leading to the characteristic deformity where the middle joint is bent downward while the fingertip joint is hyperextended 1. The deformity consists of flexion of the proximal interphalangeal joint and hyperextension of the distal interphalangeal joint, as noted in patients with rheumatoid arthritis 1.
Key factors contributing to boutonniere deformity include:
- Direct trauma to the finger when it is bent
- Deep cuts on the top of the middle joint
- Chronic inflammation in conditions like rheumatoid arthritis
- Disruption of the normal balance of forces across the finger joints due to damage to the central slip of the extensor tendon
When the central slip is damaged, the lateral bands of the extensor tendon slip downward, causing the middle joint to flex while the end joint extends abnormally 2. This creates a deformity that can become fixed due to contractures and remodeling of the joint surfaces if left untreated. Early intervention, such as splinting of the middle joint in extension while allowing the end joint to bend freely, is crucial for proper healing and preventing long-term damage. In severe or chronic cases, surgical repair may be necessary to restore normal finger function and alignment, with options including corrective splinting, injections, synovectomy, terminal tenotomy, extensor reconstruction, or salvage surgery (arthrodesis or arthroplasty) 1.