The Carpenter and the Nail

The Carpenter and the Nail
Subtitled: The Surgeon and the Implanted Biomechanical Device

Following the introduction, in 1989, of the intervertebral titanium cage as a means of spinal stabilization strident debate has raged regarding the safety and efficacy of these devices. While there are surgeons who have achieved remarkably good success with cage use, there are also surgeons who have experienced many serious complications and have left behind them a trail of disappointed patients. This is also true for the use of instrumented flexible and rigid pedicle screw systems as well as other implanted biomechanical devices such as the artificial disc. The following discussion is presented as a means of bringing some clarity to this controversy:

This a a nail, it is used for holding things together just like a titanium cage.

Next to the nail stands a carpenter.

Which is the more important in achieving a good result....the nail, or the carpenter?

As the controversy regarding the use of implantable cages continues to swirl through clinical circles, an important area of disagreement is whether an anterior or posterior surgical approach should be performed. Once again, there should be no mystery regarding this issue.

When the head of the hammer is used to engage a nail, optimum utilization and efficiency is achieved. When titanium cages are placed through a posterior interbody approach (PLIF) the greatest immediate stability can also be accomplished.

When the butt of the hammer is used to engage the nail the results are usually less than satisfactory than using the hammer head. When titanium cages are placed through a anterior interbody approach (ALIF) poor immediate stability is achieved for a number of reasons, including the fragmentation of the intact anterior disc annulus. This approach is, however, sometimes considered to be "easier for the surgeon".

PLIF is said to be a more dangerous procedure because the dura and nerves are directly in the surgeon's path. It must be pointed out that in the ALIF the great blood vessels (aorta, common iliac arteries and veins), ureters, lymph channels and some important nerves are also directly in the surgeon's path. A good "carpenter" learns how to avoid these pitfalls. National organizations dedicated to certifying spine surgeons such as the American Board of Spine Surgery have been created to promote better "carpenters."

All of this leads back to the original question as to which is more important.....the carpenter or the nail?