RA- BOUTONNIERE DEFORMITY

Question 1

Boutonniere deformity definition

Answer 1

Deformity characterised by

1. Flexion at PIPJ
2. Hyperextension at DIPJ

Question 2

Pathoanatomy of boutonniere deformity in RA

Answer 2

Pathology is at PIPJ = central slip

• Acute rupture/ chronic attenuation of central slip
• Results in PIPJ flexion = FDS unopposed
• Results in attenuation of triangular and transverse retinacular ligaments which stabilise lateral bands
• Results in volar subluxation of lateral bands = volar to axis of rotation of PIPJ and dorsal to axial of rotation of DIPJ
• Results in DIPJ hyperextension
• Chronically fixed deformity results from volar plate, collateral ligament and oblique retinacular ligament contractures

Question 3

Classification of boutonniere deformity in RA

Answer 3

Nalebuff/ Zancolli classification = clinical and radiological classification with 3 stages based on correctability and arthritis
Stage I = correctable deformity
Stage II = fixed deformity
Stage III = PIPJ arthritis

Question 4

Main special test for boutonniere deformity in RA

Answer 4

Elson’s test = test for central slip rupture

Question 5

3 factors to consider in management of boutonniere deformity in RA

Answer 5

1. Acuity
2. Correctability
3. Arthritis

Question 6

Management of acute central slip rupture in RA

Answer 6

1. Soft-tissue avulsion = extension splinting

2. Bony avulsion = repair

Question 7

Management of chronic central slip rupture and boutonniere deformity in RA

Answer 7

Correctable deformity and no arthritis
1. Fowler tenotomy
- tenotomy of terminal extensor tendon over P2
- decreases hyperextension force at DIPJ
- creates a partial mallet deformity to allow grasp
2. Central slip reconstruction (Matev procedure)
- repair of central slip in a shortened position
- transposition of lateral bands dorsally and repair to central slip
Joint arthritis
3. PIPJ arthrodesis
- preferred for border digits (central digits if fixed deformity/ instability/ poor bone stock)
- position = 30 to 45deg from IF to LF
- headless compression screw/ plate/ TBW
- headless compression screws have highest union rate
4. PIPJ silicone arthropasty
- preferred for central digits if no fixed deformity/ instability/ good bone stock
- RCL must be intact to allow pinch
- volar approach = better ROM and lower revision rate