View source for 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
[[File:Boutonniere deformity.jpg|thumb]]

==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 with hyperextension of DIP and MP joints.

==Differential Diagnosis==
*[[Rheumatoid arthritis]]
*Volar [[Proximal interphalangeal dislocation (finger)|PIP dislocation]]
*Flexion contracture of PIP joint

{{Hand and finger injury DDX}}

==Evaluation==
*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 tendon slip.
*XR to assess for avulsion [[phalynx fracture|fracture of middle phalanx]]

==Management==
*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]]

==External Links==


==References==
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[[Category:Orthopedics]]
[[Category:Sports Medicine]]