Lumbar disc herniation (LDH) is a common pathological process leading to spinal surgery. Open discectomy used to be a widespread procedure for surgical treatment for symptomatic LDH. Currently, several minimal invasive surgeries have been uesd widely. Percutaneous lumbar discectomy(PLD) and ozone therapy are two widely used minimal invasive treatment, and ozone therapy combined other minimally invasive treatment could improve other minimally invasive treatment's clinical effectiveness. The effectiveness of which has been proved to be comparable to conventional open discectomy.

In this study, a single-blind randomized controlled trial will be performed to evaluate the effectiveness of two minimal invasive discectomy, percutaneous lumbar discectomy combined with ozone and percutaneous lumbar discectomy, for the treatment of symptomatic LDH.

Two groups of patients will be investigated; 1) patients diagnosed with lumbar disc herniation undergoing PLD combined with ozone, and 2) patients diagnosed with lumbar disc herniation undergoing PLD.

The primary endpoints of the study will be changes in in pain and functional status by the Visual Analog Scale (VAS) and functional status as measured by Oswestry Low Back Disability Questionnaire (Oswestry Disability Index,ODI) and Japanese Orthopaedic Association (JOA) as measured at pre- and post-operation, 1 month, 3 months, 6 months. Secondary outcomes include response evaluation by MacNab response evaluation criteria as measured at pre- and post-operation, 1 month, 3 months, 6 months. Treatment effect is defined as the difference in the mean change from baseline between the two groups.

For the first time,the results of this trial will provide scientific evidence as to the relative effectiveness of PLD combined with ozone versus PLD for minimal invasive surgical treatment for symptomatic lumbar disc herniation.

Inclusion Criteria:

• Age older than 18 years.
• 4 or more weeks low back pain and/or lower-limb radiation pain.
• MRI and/or CT test confirm diagnosis lumbar disc herniation and level(s).
• Invalid after Non-steroidal anti-inflammatory medical therapy and physical therapy.
• Pain level（Visual Analog Scale）≥5.

Exclusion Criteria:

• Spinal tumors.
• Spine infections, fractures, slippage(more than I °) and other deformities.
• Combining with spinal stenosis, lateral recess stenosis, yellow ligament hypertrophy.
• Nucleus pulposus herniated too much, dural sac compressed more than 50%;
• Psychological, cognitive disorders which may affect the reliability of the outcome;
• Previous lumbar disc surgery;
• Bleeding tendency or severe cardiovascular disease can not tolerate surgery;
• Don't accept the trial's informed consent;
• Possible pregnancy.