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Nov 14, 2023

Practice Perfect 887
An Easy K-Wire Technique Tip -
The Mallet Method

  Jarrod Shapiro, DPM, FACFAS, FACPM

PRACTICE PERFECT   November 14, 2023

This is a quick technique tip for all of you budding surgeons. I would have thought this technique was too remedial to publish, but during a recent surgery no one in the room was aware of it, so maybe not everyone knows about it. This technique is an easy way to drive a K-wire down the shaft of a metatarsal without running it out the cortex by accident.

Before we come to the technique tip itself, I can’t help but digress just a little down the annals of medical history and talk about the K-wire itself. The “Kirschner” is named after German physician and surgeon Martin Kirschner (1879 – 1942) who invented the original Kirschner nail in response to infection complications with – you guessed it – the Steinmann pin (invented by Fritz Steinmann). Initially, the Steinmann pin was thicker, which increased the risk of infection. As a result, Steinmann began predrilling the hole to insert the pin. But this led to a pin that would not hold well. In response to this need, Kirschner invented an accordion-like device that would drive his nail percutaneously through skin and bone without the need to predrill. This lack of predrilling also allowed the nail to sit tight within the bone without loosening (at least during the initial postoperative period). Over time, modifications to the nail were made, including constructing it out of corrosion resistant metals, offering both a diamond (the original shape) and trochar points, and thinning the metal to create wires that could be used in the hand during WWII.1

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Ok, with that digression aside, let’s get to the technique. You may want to run the wire down the shaft of a metatarsal, for example during hammertoe surgery or fixating a metatarsal fracture, or placing the guidewire for a beam screw in Charcot realignment, where the pin is guided down the shaft of the metatarsal. It’s fast to just run the wire using the wire driver, but it’s common to inadvertently run the wire obliquely out one of the sides of the metatarsal shaft, or even out the dorsal or plantar cortex.

Instead, place the wire at the head of the metatarsal where you would like it to enter. Line up your angle in the sagittal and transverse planes. For an intramedullary screw, as for Charcot reconstructions, or when fixating a metatarsal fracture, the wire is placed into the head from a plantar approach. This may also be done during hammertoe surgery where the wire is retrograded across the toe. See Figure 1. Run the wire driver for just a second to mount the wire into the subchondral bone so it doesn’t fall out. Then use a mallet to tap on the end of the wire. By tapping the wire, it will run slowly down the medullary cavity and will bounce off the internal cortical surface of the bone rather than running out of it. Once the wire runs down the shaft, you will feel a satisfying slide as the wire progresses proximally with little resistance.

Figure 1. Mallet technique to drive a wire down the center of a metatarsal.

Now, I can’t take any credit for inventing this technique. The first time I learned this was during residency while placing skinny wires for ring external fixation. This mallet method is commonly used because it eliminates heat generation from the rapid spinning of the wire and decreases the risk that nerves or other important structures will inadvertently wrap themselves around a spinning wire. Safe zones, people! Safe zones!


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This mallet method is commonly used because it eliminates heat generation from the rapid spinning of the wire and decreases the risk that nerves or other important structures will inadvertently wrap themselves around a spinning wire.

Interestingly, it was actually Dr Kirschner himself who seems to have invented the tapping method for the express purpose of eliminating heat necrosis. In fact, in 1909 when Kirschner invented the original Kirschner nail, the hole for the nail was predrilled and then the K-nail (it wasn’t a wire yet) was hammered into the guide hole. Can you imagine predrilling a K-wire today?

Desert Foot 2023

Give the mallet technique a try next time you’re planning to insert a Kirschner wire and remember the creative doctor that invented this powerful instrument.

Best wishes.

Jarrod Shapiro, DPM
PRESENT Practice Perfect Editor
[email protected]


References
  1. Franssen BB, Schuurman AH, Van der Molen AM, Kon M. One century of Kirschner wires and Kirschner wire insertion techniques: a historical review. Acta Orthop Belg. 2010 Feb;76(1):1-6.
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