How Mini-Rail Fixators Can Be Beneficial For Jones Fractures
A Jones fracture is a fracture of the metaphyseal-diaphyseal junction of the fifth metatarsal base. Fractures in this area are known to have difficulty healing due to the tenuous blood supply to this area.
To that end, one may treat these fractures with strict non-weightbearing for a minimum of six weeks or explore surgical options.
The traditional surgery includes intramedullary screw fixation. One can perform this percutaneously under fluoroscopy guidance. Even though the outcomes of intramedullary screw fixation are very good, I choose a simpler procedure that affords immediate weightbearing for the patient. I go with mini-rail external fixation.
When intramedullary screw fixation of a Jones fracture fails, it fails miserably. If compression fails, then the threads of the screw keep the fracture “gapped.” The screw often will break, making it difficult to retrieve the distal threaded portion. Studies have proven that outcomes are better with screws that have a diameter of larger than 4.0 mm.1 Therefore, surgeons need a large screw, which can be a problem with soft tissue irritation from the head of the screw.
External fixation may seem complicated if you do not have experience with it. However, using mini-rail fixators is as easy as inserting K-wires.
A Step-By-Step Guide To The Surgical Procedure
Once the patient is under sedation or general anesthesia, I will use fluoroscopy to mark the fracture line on the foot. I will use a Freer elevator and a skin scribe. Remember to mark your fracture line after visualizing it from anteroposterior and lateral views.
Next, I will make a guide hole in the bone with a 0.045 K-wire distal to the fracture line. Remember that the pins will be dorsolateral on the foot, not lateral. You want your pins to be perpendicular to the bone and engaged in both cortices. After confirming the pins are in good position, I will take another 0.045 K-wire and insert that proximal to the fracture line. I use the first pin as a guide so I can make sure it will be perfectly parallel and in the same spatial plane. Again, confirm this on fluoroscopy.
If the position is good, I will replace one K-wire with a tapered half pin, making sure both cortices are engaged. You should have at least two to three threads past the far cortex. Remember that these half pins are tapered, so if you back up the half pin, then you will lose bone purchase. If you have inserted the half pin too far, say four to five threads past the far cortex, you are better off leaving it as is or you will need to start a new hole.
Then place the second half pin, making sure it is parallel to the first half pin. Once both half pins are in place, place the rail over the two half pins and drive a K-wire through the open slot on each side of the inserted half pins. This acts as a jig so you can be certain the additional two half pins will be placed at appropriate distances from the inserted half pins. Once both K-wires are in the bone, one can remove the rail and the half pins can replace each K-wire.
Perform a final check with fluoroscopy and, if acceptable, place the rail on the four half pins and tighten the rail. Proceed to compress the fracture until you meet resistance. You can appreciate compression of the fracture on fluoroscopy.
Finally, I use antibiotic ointment around the pins, use xeroform gauze and place 4x4 gauze between the rail and skin to keep swelling down. Cover the foot with roll gauze and an elastic bandage. I will place the foot in a fracture boot and weightbearing can per patient tolerance.
Pertinent Pearls On Post-Op Care And Rail Removal
On the first postoperative visit in one week, I will check to make sure the rail is tight and may add more compression if needed. Typically, the rail stays on for a minimum of six weeks and up to eight weeks depending on radiographic findings. More common than not, the rail comes off in six weeks.
I have yet to have a Jones fracture not heal using this method. Pin tract infections are rare with appropriate pin care maintenance. I allow showering with the device on after one week. I give patients instructions to clean around each pin site with alcohol, use a subsequent antibiotic ointment (not cream) and stuff gauze under the rail.
I remove the rail in the office without the need for anesthesia. Surprisingly, there is no pain upon taking off the rail and removing the pins. After removing the pins, I will use antibiotic ointment in each pin site hole and a light dressing. Usually, the four pin tract sites scab over in a few days. One can allow the return to regular shoes at that time.
This is my preferred course of surgical treatment for the Jones fracture. With external fixation, I have no concerns about non-union, hardware irritation or broken hardware. Moreover, I have the luxury of adjusting compression postoperatively.
1.Reese K, Litsky A, Kaeding C, Pedroza A, Shah N. Cannulated screw fixation of Jones fractures: a clinical and biomechanical study. Am J Sports Med. 2004; 32(7):1736-42.