The success rate for artificial disc replacement surgery is not as straight forward as listing a series of spine surgery statistics. Success is judged on many subjective and objective measures. The artificial disc operation is usually judged successful if the patient's pain is dramatically reduced, mobility is restored and there is no lingering complication. Please note here that we did not say that the pain was completely eliminated, only that was dramatically reduced. If a patient has experienced back pain for many years from degenerative disc disease, changes due to calcification and thickening of the ligaments of the spine, the spinal processes and nerves may still cause pain after the artificial disc is inserted. Nerve changes may cause phantom pain, which is pain that is no longer caused by the initial mechanical force on the nerve. So while the doctor from an objective point of view considers the artificial disc operation a success, the patient may not, because pain is still present. This is why we hear success rates varing between 70% and 96%.