Treatment of Metacarpal and Phalangeal Fractures: Intramedullary Screw Technique.

Background: Metacarpal and phalangeal fractures are among the most common fractures that upper-extremity surgeons encounter, accounting for 30% of all hand fractures Description: Metacarpal fractures can be treated with 3.6 or 4.0-mm intramedullary screws according to the canal diameter. The fracture is reduced by closed means or a limited open reduction. With the metacarpophalangeal joint flexed, the guidewire is inserted into the dorsal third of the metacarpal head through the articular cartilage and driven past the fracture site to the desired depth. A small stab incision is made, and the depth gauge is placed against the metacarpal head. The cannulated drill is placed over the guidewire, and the canal is drilled on the oscillate setting. A screw of the appropriate diameter and length is then placed over the wire, and its position is confirmed under fluoroscopy. Phalangeal fractures are treated with one or two 2-mm screws, inserted antegrade or retrograde according to the fracture location and orientation. The fracture is reduced, and the dual-diameter guidewire is passed through the long axis of the canal to the level of the far cortex (typically at the phalangeal base). A stab incision is made, and the depth gauge is inserted down to bone. The dual-diameter guidepin measures 1.6 mm in diameter on one half and 0.8 mm on the other half. The 1.6-mm portion of the guidewire is then driven out of the far cortex such that the smaller-diameter segment spans the fracture site and remains in the bone. The screw is then placed over the guidewire. A second screw may be placed in a V or X pattern with use of a similar technique. Alternatives: Alternatives to this procedure include nonoperative treatment, Kirschner wire fixation, plate-and-screw constructs, interfragmentary compression screws, and intramedullary headless compression screws. Expected Outcomes: Although many metacarpal and phalangeal fractures may be treated by closed means, a number of fractures require surgical fixation. Melone discussed that 10% of phalangeal and metacarpal fractures are either irreducible by closed means or unsuitable for percutaneous pinning Important Tips: Preoperative evaluation of canal diameter is helpful to determine the appropriate screw diameter. The ring finger metacarpal typically has the narrowest canal, and a 3.6-mm screw is thus typically utilized. Most other fingers can accommodate a 4.0-mm screw. Anatomy can vary, however.Ensure that the depth gauge is flush against the bone, confirmed on fluoroscopy. We typically subtract 5 mm from the measured length; however, this is dependent on fracture location.Prior to drilling, advance the guidewire into the far cortex in order to avoid guidewire pullout when the cannulated drill is removed.In some cases, tight isthmal fit of the screw can make screw progression difficult. If excessive torque is encountered, back out the implant 2 to 3 turns before continuing (similar to tapping).Ensure that the screw is buried under the articular surface. This is especially important in more distal fractures, in which purchase in subchondral bone is important in avoiding subsidence. In these fractures, a larger incision is often made in order to directly visualize the screw position.When attempting to place crossed screws into a proximal phalanx, sequential advancement of the screws (i.e., alternating screw progression across the isthmus of the canal) can allow for easier screw passage when both guidewires are across the fracture site.To gauge the stability of phalangeal shaft fractures, we apply varus/valgus and flexion/extension stress while using dynamic fluoroscopy after the first screw is inserted. If unstable, a second screw is inserted according to the previously described technique. Acronyms and Abbreviations: K-wire = Kirschner wireMCP = metacarpophalangealAP = anteroposteriorCMC = carpometacarpal.