Microdiscectomy vs spinal fusion

People often search for these two together as if they were rival treatments for a bad back. In practice they address different problems. Sciatica occurs when a disc bulge or herniation presses on a nerve, producing leg pain, tingling or weakness. A microdiscectomy relieves that pressure. Low back pain without nerve compression is different, and spinal fusion is not a routine treatment for it.

The right starting question is therefore what exactly is wrong: is a nerve compressed, is a vertebra slipping or unstable, or is the pain non-specific?

Under general anaesthetic, the surgeon makes a small cut in the back, uses a microscope or magnifying loupes to see the nerve root, and removes the fragment of disc pressing on it. Many people go home the same or next day and walk soon afterwards. Leg pain usually improves faster than back pain.

Risks include infection, a tear in the membrane around the nerves (dural tear), nerve injury, and a chance of the disc herniating again. Not everyone is pain-free afterwards, and the operation is best at relieving leg pain with a matching scan finding.

Fusion uses screws, rods or a cage and bone graft to join two or more vertebrae so that they heal as a single block. This removes movement at the painful or unstable level. It is a larger operation with greater blood loss, a longer hospital stay and months of recovery while the bone fuses.

It is used for conditions such as spondylolisthesis (a vertebra slipping forward), certain deformities, fractures and tumours, and after failed decompression in selected cases. Risks include infection, non-union, hardware problems, nerve injury and accelerated wear in adjacent levels. Some people continue to have pain.

NICE NG59 recommends considering spinal decompression for people with sciatica when non-surgical treatment has not worked and imaging findings fit the symptoms, and recommends not offering spinal fusion for low back pain without a trial. The reasoning is that the benefits of fusion for non-specific back pain are unproven while risks are real.

Before surgery, clinicians usually require a period of conservative care such as exercise, physiotherapy and analgesia, and sometimes an epidural injection, unless there is progressive weakness or cauda equina symptoms, which are surgical emergencies.

• Leg pain with a scan showing a disc compressing the matching nerve, not improving after weeks of care: ask about microdiscectomy.

• Mainly back pain with no nerve compression: surgery is rarely the answer, and fusion is not recommended outside trials.

• A slipped vertebra (spondylolisthesis) causing symptoms: a spinal surgeon will discuss decompression with or without fusion.

• Progressive leg weakness: urgent specialist review.

• Loss of bladder or bowel control or saddle numbness: go to A&E or call 999.

Fusion is not a stronger or more permanent fix for a disc problem, and it does not guarantee relief of back pain. Disc surgery also does not "fix the whole back"; it addresses nerve pressure. And a scan showing a disc bulge does not automatically mean surgery is needed.

Another misconception is that all back surgery needs metalwork. Microdiscectomy does not.

• Does the level on my scan match my symptoms and examination?

• What are the realistic chances of relief for leg pain versus back pain?

• What non-surgical options remain, including injections?

• How many of these operations do you perform each year, and what are your complication rates?