The scaphoid non-union

“When things start looking bad and it doesn’t look like your gonna make it that’s when you gotta get mean, I mean plumb mad dog mean.  Because if you give up and lose your head you neither win nor live, and that’s just the way it is”

Clint Eastwood from “The Outlaw Josey Wales”

The scaphoid is a small bone in the wrist that is very often broken or fractured during activities.  In a previous post I talked about the scaphoid, and ways to diagnose and treat a fractured scaphoid.  Unfortunately it is not all that uncommon for the scaphoid to fail to heal, which produces what surgeons call a non-union, or failure of the bone to heal. This is due to two main factors.  First, it is sometimes hard to tell if the scaphoid is broken or not, and if the break is not treated properly then the bone won’t heal and a non-union will develop.  Second, even if the break is diagnosed and treated properly, the bone can sometimes fail to heal despite proper treatment because of the tenuous blood supply to the bone.

Scaphoid fractures can be classified several ways, but one of the most common ways is to figure out in which part of the bone the scaphoid is broken.  Surgeons look at the scaphoid in thirds, with the distal third being nearest the fingers, the proximal third nearest the wrist, and the middle third in between.  This is important because the blood supply to the scaphoid comes into the bone in the distal and middle thirds.  The proximal third has a limited amount of blood going to it which makes breaks of the scaphoid in this area difficult to get to heal.

If the scaphoid bone has failed to heal, for whatever reason, then the surgeon has to evaluate several things.  First, as I mentioned above, is the location of the fracture.  Second is the size of the gap between the two bone ends.  This can effect the type of surgery needed to get the bone to heal.  And third, it’s important to have a good idea of the blood supply still getting to the bone, especially the proximal third of the bone.  A scaphoid non-union with poor blood flow to the proximal part of the bone can require a very different treatment from a non-union with a good blood supply.

The evaluation of a scaphoid non-union consists initially of x-rays.  Often these are the only tests needed and can provide the surgeon enough information to recommend proper treatment.  Sometimes a CT scan will be needed to show the extent of the non-union.  An MRI may be useful to evaluate the blood supply to the scaphoid.

Once enough information has been obtained to assess the non-union, several treatment options exist.  If there hasn’t been a long time between the time the bone was broken and the development of the non-union, and if the bone ends are close together, then an attempt can be made to avoid surgery and try a bone growth stimulator.  There are two kinds of bone growth stimulators.  One type uses ultrasound, and the other low dose electricity.  Both types seem to work reasonably well.  A cast may or may not be needed.  There are medical reports of healing rates up to 85%, so this is something to consider in the right patient.

If the non-union doesn’t look like it would heal with a bone growth stimulator then surgery is indicated to try and get the bone to heal.  There are a number of different options, but all of them require going in, scrapping out the area where the bone failed to heal, adding bone graft, then stabilizing the bone with screws or pins.  Bone graft is bone obtained from the patient.  In scaphoid surgery we can often use bone from the radius bone, which is right next to the scaphoid.  Sometimes we have to get bone from the pelvis, which I’ll describe in a minute.

There are a number of scenarios that might play out, and this is how I usually go about it.

  1.  Scaphoid non-union, good blood supply, and a small gap without collapse or movement of the scaphoid bone.  In this case I recommend going in and cleaning out the non-union, placing bone graft from the distal radius, and placing a screw in the bone.  I estimate this works 80-85% of the time.
  2. Scaphoid non-union, good blood supply, but a larger gap with collapse of the bone.  In this case I usually recommend getting a wedge of bone from the pelvis in order to strengthen and straighten out the scaphoid.  The bone can then be fixed with either pins or a screw.  This surgery works well but probably has closer to a 75% success rate.
  3. Scaphoid non-union, poor blood supply.  In these cases the bone grafting options above don’t work so well, so I will often do what is called a vascularized bone graft from the distal radius.  There are small arteries about the wrist the connect to areas of the distal radius, and a wedge of bone can be lifted up with the artery attached.  These procedures seem to work pretty well even if the scaphoid has poor blood supply, but I would guess that he success rate is the lowest of these three options, probably closer to 60%.
  4. Scaphoid non-union with arthritis.  If arthritis has already set in then it makes to sense to repair the scaphoid.  Instead, depending on the amount of arthritis, the scaphoid can actually be removed.

The goal of these surgeries is to get the scaphoid to heal and restore use and function to the patient.  It’s hard to get a “normal” wrist, mostly because of stiffness,  but getting the bone to heal can usually get people back to the activities they like to do.  The treatment of scaphoid non-unions is difficulty and requires a lot of patience and good decision making by the surgeon and the patient.

 

 

 

 

 

 

 

 

 

 

 

 

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