Lumbar spinal fusion: when it is used, risks and recovery

The lumbar spine is the lower back, made of bones called vertebrae separated by discs and linked by small joints. According to the Lancashire Teaching Hospitals leaflet, spinal fusion involves fusing the small joints and bones of the spine to prevent movement of the affected area. Sometimes it also involves removing some bone, disc and soft tissue to relieve pressure on one or more nerves, which can cause pain, numbness, tingling and burning in the leg and foot.

At operation the surgeon makes a cut on the back, may remove bone or disc from around the nerve root and spinal cord, and uses screws, rods and sometimes cages to strengthen and stabilise the spine. Bone, often taken from the back in areas where it is not needed and mixed with donor bone, is packed into the small joints, and eventually this heals and becomes solid, fusing the spine.

The Lancashire leaflet lists conditions for which fusion is performed: spondylolisthesis, where a bone at the base of the spine has slipped forward causing pressure on a nerve; back pain after all other treatment has failed; previous spinal surgery where more extensive surgery is required; instability due to weakness of the joints and muscles; scoliosis; fractures; and tumour.

The national guidance is cautious about back pain on its own. NICE guideline NG59 on low back pain and sciatica says not to offer spinal fusion for people with low back pain unless as part of a randomised controlled trial. The NHS says back pain usually improves within a few weeks, and that when it is caused by a medical condition such as a slipped disc and other treatments have not helped, surgery may be an option. Treatments before surgery include exercise and physiotherapy, manual therapy and cognitive behavioural therapy.

The NHS says to call 999 or go to A&E if you have back pain together with pain, tingling, weakness or numbness in both legs, loss of feeling around the genitals or anus, or changes in bladder or bowel function, such as difficulty peeing or peeing or pooing yourself, or if the pain started after a serious accident. It advises an urgent GP appointment or NHS 111 if back pain is severe and starts suddenly or is getting worse quickly, or if you feel hot, cold, shivery or generally unwell.

These warning signs apply before and after surgery. Someone who has had a spinal operation and develops new leg weakness, numbness or bladder or bowel changes should contact the surgical team or emergency services at once.

The Lancashire leaflet quotes a 60 to 70% chance that fusion significantly improves back pain, and says that after surgery 75% of people have considerable improvement in symptoms, 20% show improvement but have some persisting symptoms, and 5% are not helped at all and in some cases may be worse than before. It notes that decompression, relieving pressure on nerves, is done for leg pain, and that numbness and weakness may or may not improve.

These figures come from one hospital's information and differ between surgeons and conditions, so ask your own surgeon what result to expect for your diagnosis.

General risks listed in the leaflet include problems with the anaesthetic, blood loss needing transfusion, deep vein thrombosis, pulmonary embolism and wound infection. Risks specific to fusion include no improvement in back or leg pain, nerve damage causing pain, weakness or sensory change that may be as bad as or worse than before, numbness of the buttocks or genitals, a dural tear causing a leak of spinal fluid and severe headaches, which it says occurs in 3 to 5% of cases and is more likely in repeat operations, bladder and bowel problems, scarring around the nerve, failure of the bone graft to unite, breakage of screws and rods, and the need for further surgery at the same or other levels of the spine.

It describes serious complications such as paralysis or death as rare. Smoking increases risk, and the leaflet advises stopping before the operation because it increases the risk of complications such as anaesthetic problems and blood clots and reduces oxygen reaching muscles and skin.

The Lancashire leaflet says physiotherapists teach log-rolling in bed, how to get in and out of bed, sit and walk safely, and simple exercises. People are normally discharged between 3 and 10 days after the operation and seen in outpatients at 4 to 8 weeks. Increased back pain after the operation is expected because muscles and nerves have been moved, and difficulty passing urine, if it occurs, is usually due to irritation of the nerve and should resolve over time.

Advice after discharge includes staying active and walking each day, taking regular pain relief at first, not driving for the first 6 weeks and resuming when you can safely do an emergency stop, avoiding baths for 2 to 4 weeks, avoiding excessive bending or lifting for the first 6 to 8 weeks, and starting to exercise again after 3 months, avoiding contact sports for the first 6 months. Generally, most people return to clerical work at 4 to 6 weeks, light manual work at 6 to 12 weeks and heavy manual work after 12 weeks, ideally with a phased return. The leaflet explains that the packed bone eventually heals and becomes solid, so the fused segment strengthens over time.

Spinal fusion is performed by orthopaedic or neurosurgical spinal surgeons in NHS and private hospitals. Because national guidance does not support fusion for ordinary low back pain, it is sensible to expect other measures such as exercise and physiotherapy to have been tried first. Whichever route you take, it is reasonable to ask why fusion rather than decompression alone is advised for you, what the realistic benefit is and what the alternatives are.