Dynamic Intra-Digital External Fixation for Proximal Interphalangeal Joint Fracture Dislocations

Author:  Alejandro Badia, MD, F.A.C.S.

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Abstract
Many skeletal traction devices have been described to treat fracture-dislocations of the proximal interphalangeal (PIP) joint. Most of these techniques are technically challenging or involve cumbersome frames. A previously described simple dynamic fixator with no rubber bands was applied to seven patients who sustained fracture-dislocations of the PIP joint. The middle finger was involved in 3 patients, the ring in 3 and the small finger in 1. Average age was 28 years old (range: 21-42). Average follow-up was 30 months (range: 7 – 44 months). Immediate active flexion-extension was allowed and the fixator was removed between 3-4 weeks. The average range of motion of the PIP joint at final follow-up was 5∞ – 86∞ (range: 0∞ – 100∞). This excluded one patient who had severe intra-articular comminution and a floating PIP joint indicated for delayed fusion. Two patients developed pin tract infection that resolved with oral antibiotics. Proper reduction and congruency of the joint was noted on final AP and lateral radiographs. Only one patient complained of mild pain with extreme flexion. Although previously described, no further articles were present in the literature substantiating the initial experience. Based on our experience, we recommend this easy technique to treat fracture-dislocations of the PIP joint.

Introduction
Fracture-dislocations of the PIP joint are common injuries that can lead to stiffness, pain and post-traumatic arthritis when treated improperly. Treatment of these lesions is even harder with delayed presentation, when they have been mistaken as a “jammed finger”. Lateral deviation and rotation of this joint are minimized by its characteristic bony architecture 1-5. Soft tissue stability is given by the ulnar and radial collateral ligaments, the volar plate, dorsal capsule, lateral bands, extensor digitorum communis (EDC) and the flexor tendon sheath 4. The typical mechanism of injury for dorsal fracture-dislocations is a direct force applied to the fingertip with hyperextension and axial loading of the PIP joint that causes impaction of the volar articular lip of the middle phalanx against the condyles of the proximal phalanx 6,7. Dorsal fracture-dislocations are more common than volar 1, and are often seen in ball-handling athletes 8. Depending on the severity of the comminution and stability of the PIP joint, there is the option of treatment by closed versus surgical means. Involvement of the articular surface at the base of the middle phalanx is generally less than 40% in stable fractures and more than 40% in unstable injuries 3. Surgical treatment is required in the presence of unstable fracture-dislocations 3. Fractures with significant comminution or displacement of diepunch fragments are also indicated for operative treatment.