Artificial Disc Placement for Spondylotic Cervical Myelopathy

History
This 45-year-old man has had increasing difficulty walking and using his hands. He also noted numbness in both hands and on neck flexion occasionally had electric shock-like symptoms through his whole body. He is a non-smoker. On examination he had evidence of a moderately severe cervical myelopathy, with hypertonia, hyperreflexia, positive Hoffman's signs bilaterally, upgoing toes and poor fine-finger movements. There was no weakness. Neck movements were within normal limits. His initial preoperative imaging is shown below (Figures 1-3):

Figure 1: Sagittal T2-weighted

Figure 2: Axial T2-weighted MRI at the C5-6 level

Figure 3: CT Scan at the C5-6 level

All images confirm severe compression predominantly from anterior osteophyte and disc causing cord flattening with signal changes in the spinal cord. Cervical lordosis is reasonable. The adjacent levels appear reasonable.

In view of the symptomatic myelopathy with signal change surgical intervention was recommended.

Operative Details
Initial surgical positioning was similar to that for a standard anterior cervical decompression and fusion. A roll was placed behind the shoulders and the head placed on a foam donut. The neck was extended slightly to facilitate exposure and an image intensifier was draped into the field. A transverse cervical incision was made in the neck over the C5-6 disc space and a standard extensile exposure of the C5-6 disc space was performed. Similarly routine diskectomy was performed. The Bryan Cervical Disc System was utilized. The size of the implant (14 mm) and angle of the disc space was calculated precisely prior to placement of the implant. Using custom drill bits, and a milling wheel, a reciprocal concavity was cut into the endplates of C5 and C6. This is shown in Figures 4 and 5.

Figure 4
Figure 4: Shows intraoperative fluoroscopic images during surgery. Distraction pins are in place and a depth gauge is measuring the maximal depth of milling.

Figure 5
Figure 5: A view of the decompression prior to insertion of the prosthesis. A total discectomy has been affected and a trough approximately 10 mm in height created. A larger decompression is attained through endplate milling than through a standard anterior cervical decompression for disc.

After the endplates were precisely drilled and the decompression effected, the correct size prosthesis was placed into the defect (see Figure 6-9).

Figure 6
Figure 6: Shows the artificial disc prosthesis being primed with saline prior to insertion.

Figure 7
Figure 7: Shows the implant on the implant holder prior to insertion into the disc space.

Figure 8
Figure 8: Shows intraoperative fluoroscopic images during surgery after implantation of the prosthesis into the disc space.

Figure 9
Figure 9: Shows a "surgeon's eye" view of the anterior surface of the prosthesis as it appears placed.

At the completion of this stage closure was affected over a suction drain. The patient was transferred to the intensive care unit and extubated uneventfully.