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Unstable PIP Fracture-Dislocations

Purpose: Multiple techniques exist as part of the armamentarium for the management of Proximal Interphalangeal (PIP) joint fracture-dislocations. Of these, unstable lesions with hard reduction are the most complicated to handle. This study aims to compare the biomechanical results obtained with volar plate arthroplasty (VPA) and the hemihamate arthroplasty (HHA). Materials and Methods: We used 20 fingers from 8 cadaveric hands. We created a 50% defect on the base of the middle phalanges to simulate an unstable fracture-dislocation. The 2 techniques were assigned randomly to the different fingers (10 for each technique). A biomechanical harness was used to carry all PIP joints from extension to complete flexion. The amount of dorsal translation of the subluxation was recorded digitally at full extension. We recorded the angle at which subluxation occurred for each specimen. Results: The average of dorsal displacement of the middle phalanx did not show statistical significant difference (0.02 mm for the HHA and 0.01 mm for the VPA). All the fingers with VPA coursed with flexion contracture as opposed to the HHA. Conclusions: The VPA and the HHA are current techniques used for the management of unstable PIP fracture-dislocations. The 2 procedures manage to maintain reduction throughout the range of flexo-extension. Surgeons must choose between a little more invasive technique with double incision, hamate block bone graft with potential discomfort in the donor area and screw fixation on the recipient middle phalanx not leading to flexion contracture (HHA); versus a single surgical approach technique -dorsal or ventral- which provides stability but may course with certain flexion contracture.