Serious Problems Can Occur After Surgery for Odontoid FracturesYou probably don't give it much thought but the head sits on a stack of little, tiny bones called the cervical spine. Kids fall and bonk their heads, get up and keep going. They seem practically made of rubber. But in our older years, a fall even while at ground level can fracture one of those upper cervical vertebrae and cause serious problems. The treatment of odontoid fractures of the upper cervical spine is the subject of this article.
At the very top of the cervical spine is the atlas bone labeled C1. Directly underneath the atlas (C1) is the axis bone, also known as C2. The axis (C2) has a knob sticking straight up from it called the dens or odontoid process. The dens pokes up through the opening of the atlas. A series of complex ligaments holds the skull on top of the atlas. You can nod, shake, tilt, and turn your head -- all done as the skull moves around the pivot point of the upper cervical spine.
A fracture of the odontoid process (dens) can create instability of the head on the spine. A type II odontoid fracture extends through the base of the dens. It is the most common type of fracture in this area. Without treatment, difficulty breathing, paralysis, and even death can occur.
What's the best way to secure this broken bone in someone who is 70 years old or older? There are two basic choices: a rigid neck brace that holds the spine still until the fracture heals or surgical fixation. Surgical fixation means that screws are used to hold everything together while the bone knits itself back together.
The bracing option is really more for the younger crowd. Studies have shown that the complication rate is so high for older adults treated this way, it's just not worth it. So that leaves surgical fixation as the best practice. But it's a pretty small area at the top of the spine just under the base of the skull. How many screws are needed? Should the procedure be anterior (done from the front of the spine)? Or is a posterior approach better? Each method has its own problems and potential complications.
To answer these questions, a group of neurosurgeons did a chart review of their patients treated for odontoid fractures over a period of 15 years. Their search turned up 42 patients who were treated and followed long enough to record results of treatment. They were all over age 70. Direct anterior fixation of the odontoid fracture was used with each one of these patients.
The authors say they chose the anterior approach for all of these patients because it helps preserve motion at the C1-C2 segment, decreases the amount of trauma to the surrounding soft-tissues, and doesn't require bone grafting to provide the stability needed. This approach also reduces the time it takes to perform the operation and that's important for this age group. There is also less risk of damage to the nerves and blood vessels compared with the posterior approach.
There are two major downsides to an anterior spinal procedure. And that's the fact that the patient can end up with difficulty swallowing called dysphagia, which can lead to aspiration. Aspiration refers to inhaling food into the lungs. The result can be pneumonia, a potentially life-threatening complication in this age group.
The surgeons hoped that by looking back at how their surgeries were done and the final outcomes, they would be able to see who had the best results and why. This type of information can help shape treatment decisions for future patients who develop odontoid fractures. In order to assess their results, they reviewed patient X-rays, recorded how each surgery was done, and compiled data on postoperative complications.
They found that the patients who were treated with two screws (two-thirds of the patients) did better than those who only had one screw put in place (one-third of the group). The decision about whether to use one or two screws is left up to the surgeon at the time of the operation. If it's possible to connect the broken bone together with one screw, then why disrupt the soft tissue and bone by using two? But the results of this study will bring that approach back under review.
The authors recommend using CT scans before surgery in order to assess the strength of the bones and their ability to hold screws. The procedure should be pre-planned to place the screw(s) through the densest (strongest) portion of the bone. A careful preop review of the patient's anatomy is needed to find the best path for fixation. Sometimes the final decision about surgical methods used can't be made until the surgeon is in the operating room.
And there are some times when surgery just can't be done. The patient may be too fragile medically. Those who have severe dementia and won't be able to follow postoperative directions aren't good candidates for this type of surgery. Sometimes the family or even the patient refuses surgical treatment. In such cases, the surgeon must be prepared to discuss other treatment options. Each case must be reviewed and decided individually based on all patient factors and potential risk factors.
For these patients who did have surgery, there were some serious complications including nine per cent of the patients who died. Heart, lungs, or intestinal issues were reported as the primary cause of death following fixation surgery. One-third of the group had difficulty swallowing after the procedure. This was treated with a soft diet or temporary feeding tube. Quite a few patients (19 per cent) also developed pneumonia.
X-rays with the head bending forward and backward were used to assess stability. Only slightly more than half of the remaining patients (57 per cent) had a stable union of the bone fracture at first. Some of these patients had a second surgery to place a longer screw or fuse the spine. It was observed that over time, the number of patients who fused gradually increased to 76 per cent.
Reflecting back on the results, the surgeons commented that these are complex patients with a serious problem. Surgery to stabilize the C1-C2 spine and prevent neurologic (spinal cord) injury can be very successful. But the transformation of a fibrous union to a bony union takes a long time (months to years) in this age group. Patients must be forewarned about the potential for various complications. Follow-up should continue until the spine is stable with a solid fusion.
Andrew T. Dailey, MD, et al. Anterior Fixation of Odontoid Fractures in an Elderly Population. In Journal of Neurosurgery. January 2010. Vol. 12. No. 1. Pp. 1-8.
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