The cause of foot numbness in lumbar disc herniation is caused by the posterior lateral herniated disc compressing the nerve roots on both sides. Lumbar disc herniation is more common in lumbar 4-5 and lumbar 5 sacral 1, accounting for about 95% or more of lumbar disc herniation. Due to the structure of the disc, the posterior side has a fibrous ring, and the posterior lateral fibrous ring is still weak, so posterior lateral herniation is generally more common. The postero-lateral herniation then compresses the nerve roots on both sides, and if the nerve roots are compressed the pain in the area of nerve root innervation will occur. The lumbar 4-5 disc herniation compresses the lumbar 5 nerve root, which will cause pain and numbness on the dorsal side of the 1st and 2nd toes of the foot, and the lumbar 5 sacral 1 disc herniation compresses the sacral 1 nerve root, which will cause numbness on the outer edge of the foot.