If I have a spinal fusion will I be able to bend my low back?

Hi doctor,

Last week I went to my family doctor for my annual examination.  Once again I complained about how much my low back bothers me most of the time.  He casually reminded me that I have arthritis in my spine.  He said that if I really wanted to end my back pain he could refer me to an orthopedic surgeon for spinal surgery to fuse the two spinal bones together that are at the bottom of my spine. That really scares me.  I do not want to be fused together like that.  I am afraid that if I have a spinal fusion I will never be able to bend normally.  Am I worrying about nothing? 

Thank you for easing my mind with an answer.  If I get your opinion that will let me know I have a second opinion that is unbiased.




Greetings Lucille,

My purpose in offering you my ideas and information about your problem should by no means considered a second opinion; I cannot give you a second opinion.  A valid and true second opinion would only come from a doctor who has examined you personally and reviewed your complete health records and all available examination results.  I cannot do that.  Besides, surgery is not my specialty. For your second opinion about the need and value of spinal surgery you need to make an appointment to actually see another doctor for a complete history and examination.  I am just offering ideas based on the very limited information you offer here, and that is not sufficient to provide you a second opinion.

First I will address your concerns about limited movement of the spine after fusion surgery, and then I will address another aspect and concern I have about spinal fusion that you did not raise.  

As you consider this option your doctor offered for spine surgery in your low back you must understand that most fusions are limited to just two different spinal bones; seldom are three spinal bones fused; with great rarity are four or five lumbar spinal segments fused.  When you bend over to tie your shoes the movement comes not only from the lumbar or low back section of the spine, but both hip joints must pivot and rotate much more than the spine.   Each spinal segment has about a 10° to 15° of total range of motion, and the rest of the bending movement when you try to bend over to touch your toes comes from the hips.  For this reason when fusion takes place between two spinal segments, or as they say “at one spinal level,” the actual limitation of movement is usually very small; some people say they do not even notice much change in their ability to flex their low back forward.  There is a good explanation for this that will be given soon.  However, if your fusion would include three or more spinal bones then the total reduction of spinal movement would be greater.

Toward the end of your email you said, “I am afraid that if I have a spinal fusion I will never be able to bend normally.”   The key words in your sentence are the last two: “bend normally.”  What I have mentioned to you previously is that you would still be able to bend forward at the waist after spinal fusion, but you would do so by means of a complex mechanism of compensation and altered body mechanics that the body will automatically use to keep you moving.  In this sense you will be able to bend your back, but it will certainly not be normal.  It cannot be normal bending.  It must be abnormal bending because after surgery you are not the same person with five lumbar vertebrae moving in your back because you would have essentially four lumbar vertebrae because the fusion changes two smaller spinal bones into one larger spinal bone.    

If the five lumbar spinal bones move a total of 50° to 75° (5 X 10° to 15° each = 50° to 75° total bending movement) and you now have four lumbar spinal bones that move a total of 40° to 60° (4 X 10° to 15° = 40° to 60° total bending movement), something must change within your body to make up for the lost 10° to 15° of movement.  Your hips or the remaining lumbar spinal segments that are not fused must make up in some way for the reduced movement.     

To make up for the lost movement that occurs because of spinal fusion, the body will naturally compensate in a variety of ways to maintain a range of motion that is as full and complete as it can.  What happens is that areas of the spine above and below the fusion will experience stretching and lengthening of tendons, ligaments and joint capsules to allow greater than normal movement, as well as the same thing happening in the hip joints and to a lesser extend in the knee joints.  Those joints that are not fused will have to make up for the lack of movement (hypomobility) of the spine and the surrounding joints by allowing structural changes that result in greater than normal movement (hypermobility) elsewhere.  A joint becoming hypermobile (greater than normal movement) finds itself modifying its structure  and doing abnormal things.  This will sooner or later result in new problems because the excess movement will lead to early wear and tear injuries that accumulate over time.  

If one dog in a team of sled dogs stops running the remaining dogs must work harder.  Those harder working sled dogs will get tired quicker and are far more likely to develop health problems because of their greater work load.   

You must make your decision knowing it is not possible to fuse the spine without involuntary and automatic compensation occurring in several related areas and tissues.  Over time these areas become so stressed by the greater movement and work they are doing that they are not built to perform, that new problems will inevitably arise – back pain in new areas, sciatica, hip pain, knee pain.  Sometimes new or worsening of old complaints can develop in a year or two, and in other cases in might  take many years to come to the surface.  If you have slight arthritis in other parts of your back, it is a good guess these already abnormal areas will have a hard time compensating well and they will soon become aggravated and express new pain complaints.  If you have no arthritis in other parts of your back, it is a good guess that your back will compensate better than average and might take many years to develop a new problem.

If your back is really bothering you a great deal, with easy aggravation of great pain, and delayed recovery time, resulting in a greatly reduced enjoyment of life, and great difficulty  with many small and large things that you cannot do, then you might decide that having spinal surgery is worth the risk of developing new problems sometime in the future. However, if you now reflect and decide that your back is not really all that bad, that it does not hurt you too often or too much, or that you are not really limited in your ability to enjoy life and do important things, then that awareness might help you to decide that you might want to wait a while before having this kind of back surgery.  

A decision about having or not having any kind of surgery is always a matter of trade off and a balance between risks and rewards.  Your decision about fusion surgery can be made easier if you keep these ideas and information in mind.  Seldom do surgeons say anything – usually nothing – about these compensation problems because this honest information discourages people from surgery and business might be lost to them.  This is unfortunate, but true.  Doctors get sued for malpractice because of this omission of information, but they do their best to avoid discussing these things because they want to perform surgery.  

I suggest that you think long and hard about your decision and the short and long term possibilities, and that you get a real second opinion from a really good surgeon.  There is no such thing as a second operation that can totally reverse even the smallest surgery – and spinal surgery is no small surgery by any stretch of the imagination.  Talk to your children, talk to people whose opinion you trust, and try to talk to people who have had spinal fusion surgery at least 3-5 or more years ago.  Someone who had spinal surgery a year or two ago has not had time to develop the full experience of what happens afterward.

Good luck to you.  DL