Extensor Tendon Injury at the PIP Joint

Aka: Extensor Tendon Injury at the PIP Joint, PIP Central Slip Dislocation, Central Slip Extensor Tendon Injury, Boutonniere Deformity

1. Mechanism
   1. Central slip tears over PIP dorsum
      1. See Hand Anatomy
   2. Commonly occurs with ball striking dorsal finger
      1. Actively extended PIP joint forced into flexion
      2. Common basketball dislocation
   3. May also occur with volar dislocation of pip joint
2. Signs
   1. See Hand Injury
   2. See Hand Exam
   3. PIP joint diffusely tender and swollen
   4. Maximal pain at midline dorsal proximal middle phalanx
   5. Pain on resisted finger extension
      1. Hold the PIP joint at 15-30 degrees flexion
      2. Patient unable to actively extend finger
      3. Passive extension still possible
   6. Assess for associated collateral ligament injury
3. Radiology: XRay finger
   1. Normal in most cases
   2. Small proximal middle phalanx avulsion Fracture
4. Management
   1. Orthopedic referral indications
      1. Avulsion Fracture involving >1/3 of joint
      2. Passive extension of PIP not possible
   2. First 6 weeks
      1. Splint PIP joint in full extension
         1. Aluminum splint (do not use stack splint)
      2. Must maintain PIP extension continuously
         1. If PIP falls into flexion, 6 weeks starts again
      3. Daily passive range of motion of DIP joint
      4. May participate in sports if PIP remains splinted
   3. After 6 weeks
      1. Range of motion of PIP into full flexion
5. Complications: Boutonniere Deformity
   1. Occurs when central slip injury not splinted
      1. Extensor slip lateral bands migrate to volar pip
      2. Develops weeks after initial injury
   2. Characteristics
      1. PIP Flexion contracture
      2. DIP and MCP hyperextension
6. References
   1. Shamseldin (2003) AAFP Board Review, Seattle
   2. Leggit (2006) Am Fam Physician 73(5):810-23