Q2 How is IMF Performed?
The operation is performed under regional block with sedation or under general anesthesia. After prep, if rapid reduction cannot be obtained in a closed manner, then an open reduction is performed. A 1.5-cm longitudinal incision is made dorsally over the metacarpal head. The metacarpal head is exposed by splitting the extensor tendon longitudinally. In this patient a bony malunion had to be disrupted and callus removed prior to reduction, so a longer incision was made. Prior to driving the guide wire, the appropriately sized screw is overlaid over the bone and fluoroscopy is used to confirm appropriate sizing. The appropriate guide wire is driven into the dorsal 1/3 of metacarpal head and advanced retrograde to the level of fracture under fluoroscopic guidance. The fracture is reduced, and the K-wire is advanced across the fracture site to the base of metacarpal. The flexion cascade is evaluated for absence of malrotation. The K-wire is then advanced through the carpometacarpal joint to avoid inadvertent removal when reaming over the wire. The metacarpal is drilled just past the fracture site while ensuring that the narrowest part of the canal is reamed in order to accommodate the screw threads. A countersink is used to allow the screw head to be seated in subchondral bone. In order to prevent rotational deformity during screw placement, the fingers are all flexed into the palm to set the appropriate flexion cascade and prevent malrotation. The screw is then hand driven with the fingers flexed. The surgeon should confirm screw placement under fluoroscopy and again check for malrotation. The guidewire is then removed. Extensor tendon and skin are closed.
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