Disc replacement surgery is implantation of a “mobile” device in intervertebral disc space after discectomy. It maintains motion at operated level unlike spine fusion surgery which eliminates motion. Loss of motion can lead to decreased flexibility of spine. Also, fusion can increase stress on next spine level causing accelerated degeneration of that segment (Adjacent Segment Degeneration/ ASD). ASD is one of the major cause of revision spine surgeries. These problems are further increased in multi-level fusions. Disc replacement avoids these problems.

Disc replacement is used for both cervical and lumbar spine; however, results are more encouraging in cervical spine in carefully selected patients.

Indications:

• Spondylosis: A mild to moderate spondylosis can be treated by disc replacement. It will eliminate pain of disc degeneration while maintaining motion.
• Cervical Disc Prolapse: A younger patient with cervical disc herniation is ideal case.
•  Multilevel Cervical Instrumentation Surgery: Cervical disc replacement can be combined at the end of construct in a multilevel cervical disc disease instrumentation. While the middle levels are fused, disc is replaced at both ends. This will preserve some spinal movements  and also reduce stress on adjacent levels reducing ASD.

Advantages:

• Spine Flexibility: Maintains spinal motion and patients flexibility.
• Prevention of Adjacent Segment Degeneration: Due to decreased stress on adjacent level.

Disadvantages:

• Disc replacement device is costlier that fusion devices.
• It may not provide adequate motion in patients with advanced spondylosis.
• Pain of facetal arthritis will persist in severe spondylosis cases as only disc is replaced.
• It requires precise surgical technique and better surgical expertise.
• Disc replacement requires very carefully selected patient for best results.

Contra-indication:

• Severe Spondylosis: Severe spondylosis causes facetal arthritis along with disc degeneration. These patients will not benefit from disc replacement surgery as pain from arthritic facet joints will continue to trouble the patient. If there is significant disc space collapse, it is unlikely that movements will be restored at that level. For these patients, a spine fusion surgery is more beneficial as it will eliminate motion and will cure facetal arthritis pain also.
• Spine Instability: Mobile disc will not provide sufficient stability to treat an unstable spinal segment. Spine fusion surgery is recommended in these cases.
• Spine Infection: An infective process can cause failure of disc replacement surgery. Infection can loosen the device from bone. Disc implant will act as a foreign body and halt infection healing process.
• Vertebral Body Destruction: Vertebral destruction requires spinal fusion and reconstruction surgery.