A lumbar disc herniation is occurs when a small piece of lumbar disc material breaks off and herniates from it’s normal location and compresses the nerve or the thecal sac. The most common areas for disc herniation are the lower two disc spaces, L4-5 and L5-S1. L4 and L5 are the superior and inferior bones with disc in between called the L4-5 disc; the same notation for L5-S1 and any other disc. If the disc herniates laterally, it will compress a nerve usually causing unilateral leg pain; if the disc herniates centrally, it causes back and sometimes bilateral leg pain. When there is a disc herniation at L4-5 to one side or the other, a patient can develop a foot drop from compression of the L5 nerve root. A foot drop occurs when you lose the ability lift your foot up while taking a step and the foot then drags as you walk. An L4-5 disc herniation can cause severe leg pain starting in the buttock radiating to the top of the foot with or without a foot drop. An L5-S1 herniation can cause severe leg pain starting in the buttock radiating to the bottom of the foot with or without weakness when stepping down. A herniated disc at L3-4 will cause thigh pain and a herniated disk at L2-3 will cause groin pain. Most symptomatic disc herniations resolve on their own, over time. It is estimated that only 10 – 15% of patients who present with a symptomatic disc herniation will need surgery.