- 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
- History of trauma to digit and painful PIP.
- Forced flexion of actively extended finger
- Direct blow to PIP
- Laceration distal to PIP can injure central tendon
- On exam, will see hyperflexion of PIP with hyperextension of DIP and MP joints.
- Distal finger
- Other finger/thumb
- 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 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.
- Hand specialist follow up if closed injury
- Immediate consult if deformity is caused by open injury