Spine Instability & Scoliosis

Structure of spina showing the stacked vertebra, the intervening disc and the exiting nerves.

The spine is composed of vertebra stacked one on top of another with a soft disc intervening them. The spinal cord is well protected inside the bony cage of the spine as it comes down from the brain down to the tail bone. Along the way, the spinal cord branches into many nerves each supplying muscles, skin and organs in different areas of the body. These leave the spine and come out through small holes on the side. These holes happen to be located just in front of the disc.

Any wear and tear in the disc, as it happens during age related degeneration, sets off a series of events. The joints at the back of the spine called facet joints take all the load of the body because the disc is not functioning well. Just like any joint, these joints too will degenerate when excess load is placed on them. Ligaments surrounding the joint try to take some load off the joint and in doing so increase in size. Similar to hip and knee joint, arthritis causes pain and stiffness here. Excess bone formation and increase in the size of ligaments results and this causes the hole to become smaller. This results in crunching of the nerve at the hole causing symptoms of low back / leg pain. This is called spinal stenosis.

Showing normal spinal canal on the left with adequate space for the nerve to pass out and a spine with stenosis on the right with narrowed holes and pressure on the nerve due to bone overgrowth.

What are the usual symptoms?

The following symptoms may result:

• Back pain
• Leg pain
• Numbness / Weakness in legs
• Numbess / Pain in legs after walking for sometime
• Patient may feel that the leg feels heavy / the foot wear slips out without knowledge
• In rare cases there may be disturbances of Urinary / Bowel nerves causing loss of control of urine / stools

What are the ways to diagnose this problem?

A mixture of patient examination, x - rays and MRI are usually required to get an accurate diagnosis. The extent of degenerative changes and the pressure on the nerve need to be understood for suggesting treatment.

What are the choices of treatment available?

• Rest and Pain medicines
• Physiotherapy
• Exercise and weight reduction
• Spine steroid injections into the joint or near the nerve
• Spine surgery - to decompress the nerve and to remove excess bone and ligaments around it.

In some cases, after decompression, so much bone would have been removed that the spine may need to be stabilised one on top of another by inserting screws and trying to cause ' fusion' of two or more adjacent bones. This 'fusion' will need the help of metal screws and rod to connect the bones together and press them in place till they join one another. Bone graft will be applied to the bare bone surface to accelerate healing. Fusion will help reduce the movement between the vertebra and lessen the changes that resulted in nerve compression.

What are the risks associated with this surgical procedure?

As with any common surgical procedure, bleeding, infection, blood clots, and reaction to anaesthesia have to be taken into consideration even though the risk is low. The elderly, diabetic and patients with other medical problems understandably stand a higher risk during and after surgery.

Other complications include

• Tear of the tissue covering the nerves due to excess adhesion between the nerves and covering
• Failure of the bones to fuse to one another or breakage of the metal screws
• Nerve injury
• Resurgery
• Failure to relieve symptoms

What is the general outcome of Spine Decompression and Fusion Surgery?

Outcomes are generally good with over 80 % success rates. There is generally good improvement in the leg pain and some improvement in back pain. Most patients get back to a reasonable level of their previous activity level after the surgery. The surgical treatment outcomes have been improved now with better implants and minimally invasive surgery and microsurgery.