Boutonnière Deformity of the Thumb

Pathophysiology and Presentation

Boutonnière deformity in the thumb commonly develops as a consequence of advanced thumb base osteoarthritis, creating a characteristic zigzag collapse pattern, according to the American College of Rheumatology 1
The deformity is more common in erosive hand OA, which shows worse clinical and structural outcomes than non-erosive forms, as reported by the American College of Rheumatology 1, 4

The deformity significantly impacts hand function, with functional impairment potentially as severe as that seen in rheumatoid arthritis, as stated by the American College of Rheumatology 2

Hypermobility has been reported as a risk factor for thumb base OA, according to the American College of Rheumatology 3

Clinical diagnosis is based on the characteristic appearance of the thumb with outward angling of the distal portion, as described by the American College of Rheumatology 2
Radiographic assessment with at least 2 views (PA and lateral) is essential to evaluate the extent of arthritic changes and joint displacement, as recommended by the American Academy of Orthopaedic Surgeons 5
Plain radiographs remain the gold standard for morphological assessment, showing joint space narrowing, osteophytes, and subchondral bone sclerosis, as stated by the American College of Rheumatology 2

Orthoses (splints) should be considered as first-line treatment for symptom relief, with long-term use advocated, as recommended by the American Academy of Orthopaedic Surgeons 6, 7, 8
Custom-made thermoplast or neoprene orthoses have shown beneficial effects on pain and function when used for at least 3 months, according to the American College of Rheumatology 7
Hand exercises to improve joint mobility, muscle strength, and thumb base stability should be considered for every patient, as recommended by the American College of Rheumatology 6, 7
Topical NSAIDs are recommended as first-line pharmacological treatment due to their favorable safety profile, as stated by the American College of Rheumatology 8

Orthoses that are not well-fitted or custom-made may lead to poor patient compliance and reduced effectiveness, as reported by the American College of Rheumatology 7
Exercises alone without addressing joint stability through orthoses may not provide sustainable improvement, according to the American College of Rheumatology 6, 7
The long-term functional outcome for erosive OA appears worse than for nodal OA, requiring more aggressive management, as stated by the American College of Rheumatology 3