Minor problems after spinal fusion including leg pain and numbness occur in 10 to 15 percent of all patients. Often these symptoms are "transient" meaning temporary. They do go away over time, usually between one to six weeks.
The most common nerve root affected by lumbar fusion is L5 near the bottom of the lumbar spine. The nerve must be moved out of the way during the operation. It can get pinched or stretched during this process.
If your symptoms last more than six months talk to your doctor about treatment options. Another operation may be needed to take pressure off the nerve. Results of this surgery are usually very good.