Dorsal Subluxation of the Distal Interphalangeal Joint
Cause
Dorsal subluxation of the DIP joint results from hyperextension injury causing volar plate avulsion with or without a volar base fracture of the distal phalanx, leading to dorsal displacement of the distal phalanx relative to the middle phalanx. 1, 2
The mechanism involves:
- Forced hyperextension that tears the volar plate from its insertion at the base of the distal phalanx 3, 4
- Volar comminution and impaction of the distal phalanx base with associated dorsal subluxation 2
- Avulsion fractures involving the volar base of the distal phalanx (Type 3 FDP avulsion/"Jersey finger") 1
In irreducible cases, the volar plate becomes interposed between the joint surfaces, or the flexor digitorum profundus tendon becomes entrapped behind the middle phalanx head, preventing closed reduction 4.
Initial Diagnostic Workup
Obtain at least 3-view radiographs immediately to assess fracture pattern, displacement, and articular involvement. 5, 6
Key radiographic findings to identify:
- Volar base fracture fragments of the distal phalanx 1
- Degree of dorsal subluxation of the DIP joint 2
- Articular surface involvement (≥1/3 involvement indicates surgery) 7, 6
- Interfragmentary gap (>3mm indicates surgery) 6
MRI is indicated if flexor tendon avulsion is suspected, with 92-100% sensitivity for detecting tendon injuries and level of retraction 6. Dynamic ultrasound can directly visualize DIP joint malalignment in the absence of fracture 8.
Treatment Algorithm
Acute Injuries (≤2 weeks)
Attempt closed reduction first for simple dislocations without large fracture fragments:
- Apply ice-water mixture for 10-20 minutes with thin towel barrier 7
- Never attempt manual straightening before proper evaluation 7
- Splint in position found until definitive treatment 7
Surgical indications requiring immediate referral: 7, 6
- Avulsion fractures involving ≥1/3 of articular surface
- Interfragmentary gap >3mm
- Displacement >3mm
- Palmar subluxation of distal phalanx with irreducible subluxation
- Open injuries
- Failed closed reduction (irreducible dislocation)
Chronic Injuries (>2 weeks to 4 months)
Volar plate advancement arthroplasty is the definitive treatment for chronic dorsal fracture-subluxation of the DIP joint. 2
Surgical technique:
- Volar approach provides better wound healing, easier release of entrapped structures, and allows volar plate/collateral ligament repair 4
- Volar plate advancement to the base of the distal phalanx 2, 3
- K-wire fixation of the reduced joint for 4 weeks 2
- For recurrent instability, reinforce with ulnar half of flexor digitorum profundus tendon 3
- Alternative: umbrella handle technique using 0.9mm hooked K-wire for FDP avulsion fractures 1
Post-Operative Management
Rigid immobilization for 3-6 weeks followed by aggressive early motion is mandatory. 6
Critical rehabilitation steps:
- Remove K-wire at 4-5 weeks when fracture union is confirmed 1, 2
- Begin active finger motion exercises immediately after immobilization to prevent stiffness (the most functionally disabling complication) 8, 6
- Home exercise programs moving fingers through complete range of motion are effective 6
- Uninterrupted immobilization is essential—even brief splint removal restarts the healing timeline 7
Expected Outcomes
Realistic functional expectations after volar plate arthroplasty: 2
- Average DIP arc of motion: 42° for fingers, 51° for thumb
- Residual flexion contracture: average 12° (range 6-25°)
- Full flexion typically achievable without extension lag 1
Critical Follow-Up Red Flags
Unremitting pain during follow-up warrants immediate re-evaluation for: 6
- Inadequate fixation
- Pulley system injury
- Tendon adhesions or re-rupture
Arthrodesis is the recommended salvage procedure for failed DIP joint reconstruction, as arthroplasty is reserved for PIP joints 8.