Volar plate avulsion injuries are a type of avulsion injury. The volar plate of the proximal interphalangeal (PIP) joint is vulnerable hyperextension injury as either an ligamentous or intra-articular fracture.
The volar plate forms the floor of PIP joint separating the joint space from the flexor tendon sheath. The volar plate has a ligamentous origin on the proximal phalanx with a capsular insertion onto the middle phalanx.
Hyperextension injury involving the PIP of finger can avulse the volar plate which is commonly associated with a volar avulsion fracture at the base of the middle phalanx.
When the volar avulsion fracture involves a significant portion of the articular surface, instability and dorsal dislocation of middle phalanx can occur. This is because greater portion of the stabilising collateral ligaments are attached to the avulsed fragment.
Knowledge of the orthopaedic Eaton classification is practical when reporting volar plate injury as it influence decision on management 3. Treatment is dependent on the following factors:
- size of the fragment (<40% of articular segment)
- degree of impaction
- direction of the dislocation
- Eaton type I: hyperextension mechanism of injury with an avulsion of the volar plate and a longitudinal tear of the collateral ligaments; the opposing joint surface remain congruent
- Eaton type II: dorsal dislocation of the PIP joint with avulsion of the volar plate; there is complete tear of the collateral ligament
Eaton type III
Eaton type IIIa
- fracture dislocation with an avulsed small fragment <40% of articular surface
- dorsal aspect of the collateral ligament remains attached to the middle phalanx
Eaton type IIIb
- fracture dislocation with fracture or impaction of the articular surface of more than 40%
- Eaton type IIIa
Another classification which is considered useful in management is Keifhaber-Stern classification.
Small fragment of bone is avulsed from volar base of middle phalanx. If there is significant involvement of the articular surface involved this maybe associated with dorsal dislocation of the middle phalanx.
Treatment and prognosis
Overall small fragment involving <40% of articular segment and/or reducible fracture with <30 degrees of flexion is usually managed conservatively with finger splinting. Large fragment or >30 degrees of flexion to reduce the fragment and malalignment post closed reduction are indicators for operative treatment.
Wrist and hand fractures
- wrist and hand fractures (Amsterdam wrist rules)
- distal radial fracture (Frykman classification)
- distal ulna fractures
- fracture dislocations of the radius and ulna
- carpal fractures
- metacarpal fractures
- phalanx fractures
- 1. Nance EP, Kaye JJ, Milek MA. Volar plate fractures. Radiology. 1979;133 (1): 61-4. Pubmed citation
- 2. Emergency Radiology: Imaging and Intervention. Springer. ISBN:354026227X. Read it at Google Books - Find it at Amazon
- 3. Eaton RG, Malerich MM. Volar plate arthroplasty of the proximal interphalangeal joint: a review of ten years' experience. J Hand Surg Am. 1980;5 (3): 260-8.