FAQ Category: General Spine

You are quite right on both counts. You have your neurology correct and you’ve come to the right conclusion. A bulging disc pressing against the L5, S1 nerve root wouldn’t cause quadriceps or hamstring muscle weakness.

Leg weakness (specifically around the knees) on both sides can occur when there’s a central bulge at a higher level (around L2 to L4) as you pointed out.

A recent study was done on the status of trunk and leg strength in patients with lumbar disc herniation (LDH). The researchers concluded that pain, not nerve root compression, is the reason weakness occurs.

Muscle strength may also be affected by fear of movement causing pain. The person avoids any movements that might cause pain. Eventually the muscles controlling that movement get flabby and atrophy. Weakness is the natural result. Kudos to you for thinking through this problem!

Back pain can cause muscle weakness of this type. Other illnesses and diseases can also cause muscle weakness. Are you having any other symptoms of any kind? Are you in good overall general health?

The answers to these questions may give you an idea what to do next. If you are more tired than usual or having other symptoms like fever, sweats, or nausea, then a visit to the doctor is in order.

If you’ve had chronic back pain you may be losing strength from the pain. Fear of pain can cause changes in the way you move. You may be avoiding movement to avoid pain. This is called fear avoidance and could be leading to weakness.

Are you having any pain, numbness, or tingling down the legs or arms? Has your back pain ever been diagnosed properly? If you’ve answered ‘yes’ to more than one of these questions, see a medical doctor.

If you think it’s more likely that your weakness is linked to inactivity, see a physical therapist or fitness trainer.

“Hyper” means too much. For example we refer to a child who moves or talks too much as ‘hyper.’ Mobile refers to movement. Too much movement in the spine is called hypermobility.

Not enough or too little motion is the opposite of hypermobility. This is referred to as hypomobility.

It’s not uncommon to have pain in one section of the spine from too much motion (hypermobility). The vertebrae slide or glide too far in one direction or another. This puts a pull or traction on the soft tissues and nerves in the area.

Likewise, a stiff segment that’s hypomobile doesn’t move enough. Pain occurs when the spine tries to move beyond what the joint and soft tissue structures can or will allow.

A problem in one part of the spine frequently causes problems elsewhere. It may be in another section of the spine or it may be in the hip or sacroiliac joint. The body above or below the problem area tries to adapt or adjust to make up the difference.

Surgeons continue to look for ways to perform spinal surgery with the least amount of blood loss and damage to the soft tissue structures.

Spinal fusion can require a large incision if more than one level is fused. Sometimes the type of fusion makes a difference. A larger incision may be needed if the disc and joints are removed and hardware is inserted.

The muscles are pulled out of the way. The surgeon needs enough room to do all those things. More recently doctors in Korea tried using a smaller incision. This is called a minimally invasive operation. They inserted screws from both sides to help hold the area stable.

Short-term results were good. If the long-term outcome is equally good, the minimally invasive approach may be used more often.

Yes, definitely. The spine is made up of many individual units. There can be differences in the amount of motion from one segment to another.

Sometimes a spinal joint or segment with decreased motion will cause the level above or the level below to make up the difference. One or both of the adjacent levels can become hypermobile (too much motion).

This is why osteopaths, chiropractors, and physical therapists who treat the spine usually test for motion at the painful level, above, and below. Treatment may start with one segment and move to the next as the spine adapts and shifts back to normal.

You’re right. The first lumbar disc replacement was done in the 1950s. Since then many trials with various different implants have been done. Most of these were put into cadavers or animals, not live humans.

It wasn’t until the 1980s that an implant designed for humans was tried. There were concerns about the materials so the implants were never put on the public market. Later new materials were tested in cadavers and monkeys.

More recently surgical tools, techniques, and imaging equipment has made it possible to consider artificial discs once again. The Food and Drug Administration (FDA) approved the first one in 2004 for use in humans. Since then centers all over the United States have implanted hundreds of disc replacements with good results.

Compared to spinal fusion disc replacement has a shorter operative time and fewer days in the hospital. That means reduced costs, which is very popular in the health care world. Patients have a faster recovery. More people are able to get back to work sooner. And the best benefit of all is restoring normal motion in the spine, making this a very popular treatment alternative to spinal fusion.

You’re not rare at all. According to a recent review of data from artificial disc replacement (ADR) research, up to 64 percent of patients with an ADR still suffer from painful symptoms. And this group was taking narcotic medication two years after the implant was put in.

Right now it looks like the complication rate after ADR is no different than with a spinal fusion. In fact there’s an increased risk of blood loss because the entire disc is taken out. A large blood vessel goes right through that area. The approach used for most spinal fusions avoids these blood vessels and other important structures.

A good number of implants (17 percent) aren’t put in the best location. That increases the patient’s risk for implant loosening and loss of motion. Even with good placement, not everyone gets his or her spinal motion back at the level of the implant.

Clearly there are some success stories. More research is needed before we’ll really know the final results.

A normal, healthy disc is shiny and free of any tears or damage. The center portion called the nucleus pulposus is a healthy, whitish-gray color and remains separate from the outer layer (the annulus fibrosus).

Early changes occur only in the nucleus. The annulus fibrosus is still clearly separate from the nucleus. Changes occur in both portions of the disc as the degeneration continues. The nucleus is still soft, but it’s starting to become more fibrous and tough.

In advanced disease, there’s no boundary between the nucleus and the anulus. Tears and holes are present in both. The tissue is discolored and thin.

Sometimes, doctors call this a “nerve block.” Cortisone, along with an anesthetic agent such as lidocaine, is injected into the epidural space. This is the space just outside the spinal cord. Here, the nerve root leaves the spinal cord and travels down the low back to the legs.

The steroid acts as an antiinflammatory to reduce swelling. Lidocaine or some other numbing agent stops the pain.

Single steroid injections can be very helpful both to diagnose and to treat problems. In the neck or back, the injection is made by passing a needle through the skin, ligaments, and soft tissues until reaching the epidural space.

The epidural space is right above and around the lining of the brain or spinal cord. Epidural steroid injections (ESI) are a common procedure. ESIs are used for nerve pain, shingles, and some types of headaches. They can also be used before disc surgery to diagnose the problem.

Studies done can give us numbers and percentages, but they don’t tell us exactly which patients will get better and who won’t. One study predicts a 75 per cent chance of a good result.

Important factors include how long the patient is off work due to back pain. The longer the time, the worse the results. Patients with back pain that lasted more than six months have worse healing. Chronic sciatic pain is also linked with a poor outcome.

Back pain is more common in blue-collar workers. Patients with more strenuous jobs often have trouble getting back to work. Many people have to change jobs or work with restrictions on what they can do.

Workers with more active jobs are more likely to change jobs or retire compared to desk workers.

There are many possible uses for a bone substitute. For example, people with weak or brittle bones from osteoporosis or other bone diseases don’t heal well when they fracture. A bone-stimulating substance or bone substitute could be injected into the break and speed up healing.

Spinal fusions have problems because in up to 40 per cent of cases, the two bones form a false joint. This creates movement at a place where no movement is desired. A substance that could fuse stronger than natural bone is needed in these cases.

Harvesting bone for use by the patient is painful, requires a separate operation, and increases the risk of infection. Other problems such as blood loss, numbness, and injury to the nearby blood vessels can occur.

Other uses for bone substitute may become apparent once it’s available for use.

Recombinant bone morphogenetic protein or rh-BMP-2. Recombinant means that DNA from 2 or more sources is combined to make one. In other words, DNA that is artificially made. DNA is the carrier of our genetic information.

This is done in a laboratory. DNA is made up of two chains intertwined with each other. Four substances combine in pairs to make up these chains. A scientist takes a piece of DNA and splits the two chains apart. Then, the pairs are matched up differently to make new chains.

Scientists found the bone proteins in 1965. It’s taken since then to find a way to use this information to make new bone. Studies were done on animals first, then humans. Rh-BMP has been used to treat bone fractures. New studies on spinal fusion are being reported.

Electric current has been used to increase bone growth after fractures for almost 50 years. It’s use after spinal fusion is relatively new. There are several ways to deliver the electric stimulation to the bone. The doctor may implant a device right in the spine at the time of the fusion.

There are external units, too. One device is worn with a brace eight to 10 hours/day for six to eight months. The patient must put the brace on for the electric current to reach the spine.

Another external device uses a small computer-controlled stimulator. The electric current goes through flexible cables to patches placed on either side of the spine. The stimulator is worn 24 hours/day until healing takes place.

There are good points and problems with each type. Implanted devices have batteries that can leak or stop working. Another operation is needed to make repairs. This type doesn’t require patient cooperation to work.

The external units don’t cause infection or a second surgery to make repairs. However, this type only works if the patient wears it every day for many hours. More studies are needed to compare each type before we’ll know which is best for spinal fusion.

Electrical stimulation for bone growth has been used for almost 50 years now. Most of this has been with bone fractures. The use of electric current to stimulate bone after a spinal fusion is a relatively new area of research.

There doesn’t appear to be any strict guidelines about device removal. Generally, these implants are only taken out if the patient has pain or discomfort. Of course, the device is removed if there is a malfunction or other problem with the unit.

Electrical implants do interfere with some imaging studies such as magnetic resonance imaging (MRI). The unit might be removed if there is a great need for MRI and no other imaging study will give the needed information.

A recent study from the Netherlands reviews previous reports on back injuries from lifting unexpected weights. They go on to complete their own study of loads that shift during lifting.

So far, there’s no proof that lifting an unexpectedly heavy load is linked to back injuries. Lifting a load that shifts can increase the risk for injury. The reason for this is within the muscles, not the spine.

While lifting a load that shifts, the muscles may not respond quickly enough. This decreases the overall muscle force. But uneven muscle contraction (more muscle contraction on one side compared to the other) causes the vertebrae to rotate or twist. Rotation combined with increased pressure through the spine may injure ligaments or the disc.

Yes, but no exact values are considered “normal” by age, weight, gender, or range of motion. Instead, a range of values is used, given as ratios.

Some research has provided strength ratios for men compared to women. Researchers using a computer-based device called a dynamometer show that women can exert about 50 percent of their body weight. This force is about 65 to 75 percent in men. All the people in the study had a history of back pain.

More studies of maximum strength are needed both on “normals” (people without back problems) and those with a history of chronic back pain.

Nothing is very simple with the body and especially the spine. Researchers are taking advantage of new computer-generated devices for scientific study. The spine is a major focus of study.

Like many things, the more we understand, the less we know. New research has shown the complex relationship between the spine, nerve messages, muscle control, and posture.

For a long time, scientists believed that pressure on a nerve from a herniated disc caused back and leg pain. Simple. Remove the disc, take the pressure off, and the symptoms are gone. But that doesn’t always happen. It may be that higher centers (for example, the brain) are affected, too.

It seems that information about any damage down below is transmitted to the brain. There may be a feedback loop between brain and muscles previously overlooked. Future studies using functional brain imaging may shed further light on the subject. Improved pain and reduced disability may be all in the head after all!

It very well could be. Chronic low back pain has been linked with poor balance, especially when the eyes are closed. Delayed muscle response has also been reported with chronic back pain. Good balance requires quick reaction time on the part of muscles and the ability to regain an upright posture.

Active rehab seems to improve these functions. You may need to revisit your physical therapist now that you are back on the job. Specific training to restore these skills is possible. The rehab program can be designed to match your required tasks on the job.

You are at increased risk of back injury, whenever there is a muscle imbalance. Contracting the muscles on one side of the back while twisting or turning may put you at risk for damage to the ligaments or discs in the spine.

One way to counteract this problem is to rotate jobs. Either switch to a different task or work on an assembly process with the same motion to the other side. If this isn’t possible, take frequent stretch breaks.

As often as possible, stand up straight and tall. Make sure you twist and/or bend to the opposite side. A regular exercise program outside work is advised. Be sure and include stretching and strengthening exercises for both sides of the spinal muscles.