“Pin Under Plate” Technique for Distal Radius Fractures
By Dr. Orrin Franko

Distal radius fractures are quite fun to treat, often because of the great variety of “tips and tricks” available to surgeons in the procedure.  Personally, one of my favorite tricks us to use 0.35 K-wires held beneath a volar plate to capture and provide stability to small or challenging fragments that would otherwise be difficult to stabilize with a screw.  I cannot take credit for this technique, rather it has been published by Dennison & Moore in 2014 in a small series.  However, my preferred technique varies somewhat from their recommendation based on experience with over 30 fractures.  I have highlighted my tips and tricks below, with example images.

The concept is simple: fracture fragments that are either too small or too distal to be securely fixed with a traditional locking screw can be stabilized with a K-wire.  That k-wire can be subsequently secured beneath a traditional plate.  Together, a rigid construct has been created to secure the fragment.  Conceptually, this is similar to TriMed’s “pin-plate” implants.  However, the technique described below uses smaller wires (0.35 compared to TriMed’s 0.45) and can be used with any plating system.

My technique varies from Dennison’s technique, shown in Figure, in a few ways.  First, it should be noted that this can be performed volarly through the standard FCR approach, or through an volar/ulnar approach for isolated volar lunate facet fractures.  I have also performed this on dorsal fragments to reduce plate prominence, and radial styloid fragments for the same reason.

Step 1) I approach the distal radius as I would for any fracture.  When small or distal fragments are encountered and I decide to use this technique, I begin by driving a few 0.35 K-wires from the volar lip of the fragment into the radial metaphysis.  Unlike Dennison’s recommendation, I do not believe capturing the dorsal cortex is important, and rather has the potential to result in a long wire that protrudes dorsally and may cause extensor tendon rupture (don’t ask me how I know).  Typically I only drive the K-wire about 10-15mm.

Step 2) I use needle drivers to bend the K-wire down to closely match the radial volar cortical slope.  Unlike Dennison, I do not spend time getting a “perfect” bend.  I have found the plate will easily bend the wires when it is lagged to the bone, so only an approximate bend is necessary.  Of note, it is important to cut the wires short before completing the bend, as the length of the wire will prevent you from bending it down enough to sit on the bone.  Only enough wire to extend proximal to the plate’s distal screw holes is required, typically not more than 15mm.  Often I will place 2, 3, or even 4 wires depending on the fracture pattern and my confidence in the wires.

Step 3) With the fragment stabilized and with the wires cut and bent, I then “tap” the wires in to ensure they are seated down to bone.  Typically this causes them to “disappear” because they are deep to the volar ligaments.  Flouro is then used here and I carefully check a few areas.  On the lateral: confirm the “bend” is seated down to bone volarly, and confirm the dorsal extension of the wire does not extend beyond the dorsal cortex.  On the AP view, confirm the wires do not entire the DRUJ.

Step 4) Position your plate on to the bone.  It will not seat perfectly due to the wires…. but don’t worry about it.  Ensure that the exposed wires are rotated so they are “captured” within the margins of the ulnar and radial screw holes in the plate.  In other words, once the screws are inserted, the wires will not be able to “rotate out” from beneath the plate.  I typically will start by drilling the oblong hole in the plate shaft once I like the position.

Step 5) My first screw is typically an intentionally-long, non-locking screw to lag the plate down the bone.  This maneuver will help bend the wires as well.  Occasionally if I am concerned about bone quality and losing fixation with the screw, I will place a second non-locking screw and sequentially screw them down to reduce the plate to bone.

Step 6) Next I place locking screws across the distal row, and replace any non-locking screws with locking screws.  At this point all wires are “captured” beneath the plate, sandwiched between bone and metal, and “trapped” between the screws so they cannot rotate out.

Done!  With practice, I find that this technique adds only about 3-5 minutes to the case.  Once you get the hang of Steps 2 and 3, it proceeds as a normal case.  Below are series of cases where I have used this technique in various forms.