What is disc replacement ?

An artificial disc replacement in the neck replaces a diseased or damaged disc with a specialized implant that tries to preserve motion in the neck. This procedure is called an Artificial Cervical Disc Replacement, or ACDR. In this procedure discectomy is done 1st in which disease disc was taken out than in place of diseased disc artificial disc was kept. This procedure is also commonly referred to as a Cervical Arthroplasty procedure as it replaces a joint.

Indication of disc replacement:-

This procedure is done to treat the following condition-

• Degenerative disc disease
• Spinal Stenosis
• Disc Herniation
• Radiculopathy

Artificial Cervical Disc Replacement cannot treat spinal instability.

Advantages of disc replacement over fusion:-

• A disc replacement is designed to preserve spinal motion and keep the cervical spine properly aligned.
• A disc replacement is thought to reduce mechanical stress on levels of the spine above and below the replacement when compared to a fusion.

Since degenerative disc disease stems mostly from genetic causes, people with spinal problems are generally more likely to develop more spinal problems in the future. There is debate as to whether a one level fusion surgery increases stress on the discs above and below causing accelerated degeneration. One argument is that fusion of one level is felt to create greater stress on the remaining "movable" joints leading to early failure. Another argument is that those discs are simply predisposed to degeneration. No study to date has proven that a fusion surgery accelerates this process. Regardless, preserving motion in the spine is an ideal outcome. 

• A fusion surgery also keeps the cervical spine properly aligned, but any fusion decreases motion at that level. The first two vertebrae in the neck, C1-C2, contribute 60% of your head's rotation. Approximately 50% of neck bending occurs between the occiput, or skull, and C1 vertebra. Each vertebra after that contributes approximately 7% of forward and backward bending and rotation. Many people with severe pain and spasms from neck problems have very limited motion. This motion will improve after surgery since most of the restriction is not structural, but muscular. Thus, even though a fusion may remove some mobility many people move more after surgery than before because they have less pain and spasms. Because a disc replacement retains motion, the replacement experience stresses. At this point, research does not show the lifespan of an implant; this may need to be replaced in the future by a fusion procedure.

How is the surgery performed:-

This surgery is done under general anesthesia, meaning the patient goes to sleep. During the surgery the patient lies face up on a special surgical bed. The procedure is performed through a small incision on the front of the neck to gain access to the spine, usually in the neck's natural crease. The trachea (windpipe), esophagus (stomach tube), and blood vessels lie in front of the spine and are carefully moved aside. Once the surgeon safely creates a window to see the spine, the damaged disc is removed with surgical tools. This part of the surgery is called a discectomy. The surfaces of the vertebral bodies are prepared to accept the implant. The bones are slightly spread apart to make more room for the disc replacement. This realigns proper curvature and enlarges the openings to relieve pressure off any pinched nerves. The artificial disc is inserted into the space between the vertebrae and carefully secured into place.

Complication of surgery:-

Although they are rare but may be happen after surgery.they are as follow

• Dysphagia due to pharyngeal or esophageal injury(3 %)
• Dysphonia due to recurrent laryngeal nerve injury(3.1%)
• Injury to the treachea(<0.1 %)
• Injury to major vessel-vessel into the carotid sheath( <0.1 %)
• Horners syndrome -Injury to Sympathetic ganglion(0.1 %)
• Dural perforation(0.5 %)
• Wound infection(0.4%)
• Worsening of myelopathy/radiculopathy(0.2%)
• Hematoma formation at surgical site(5.6%) but require surgical intervention only in 2.4 % of cases.
• Instrument backout(0.1%)

Although complication are very rare but can be manage successfully in almost every case.

How is it look like:-