Boutonniere deformity

Background

• Extensor Zone III Injury over the PIP joint.
• Most commonly central tendon is injured, causing FDS to be unopposed, thus causing flexion of PIP
  • Disruption of central tendon causes lateral bands to be displaced volarly, causing them to act like flexors
• FDP still intact

Clinical Features

• History of trauma to digit and painful PIP.
• Forced flexion of actively extended finger
• Direct blow to PIP
• Jamming
• Laceration distal to PIP can injure central tendon
• On exam, will see hyperflexion of PIP w/ hyperextension of DIP and MP joints.

Differential Diagnosis

• Rheumatoid Arthritis
• Volar PIP dislocation
• Flexion contracture of PIP joint

Diagnosis

• Elson’s test: bend PIP 90 deg over edge of table, extend middle phalanx against resistance. Should have weak PIP extension and DIP goes rigid as lateral bands have to work.
  • Positive test indicated rupture of central tnedon slip.

Management

• XR to assess for avulsion fracture of middle phalanx
• If open or with displaced avulsion fracture: operative repair
• Closed: splint in extension (Both DIP and PIP) for up to 6 weeks, refer to hand surgeon. NO flexion of DP permitted for duration of splinting, including during cleaning. Repair extensor tendon if injured.

Disposition

• Hand specialist follow up if closed injury
• Immediate consult if deformity is caused by open injury

See Also

• Hand_and_finger_diagnoses
• Jammed_finger
• Hand_Tendon_Injuries

References

• Tintinalli
• Rosen's