Surgeons used to fused knees and hips for severe arthritis many years ago. Nowadays, this form of surgery is no longer acceptable. The standard of care now for severe arthritis is joint replacement surgery. The same technology is now available for the spine.

Spondylosis is a common phenomenon that affects everybody. It starts with intervertebral disc dehydration and progresses to loss of disc height, disc bulges and formation of osteophytes. This ultimately leads to compression of the nerve roots or spinal cord resulting in radiculopathy and myelopathy respectively.

The usual course of treatment for this condition is conservative in the first instance. The presence of neurological deficits (weakness or numbness) implies ongoing nerve or cord damage which necessitates surgery.

Surgery removes the constrictive elements to release the nerves or spinal cord. The next step is fusion in most cases. For the older patient, this form of surgery is perfectly acceptable.

For those below 50 years old, loss of motion at the fused level will result in increased stress at the adjacent levels. This accelerates wear and tear at these adjacent disc levels with increased risks of radiculopathy and myelopathy, which has been shown to require surgery at a rate of 2.9% per year. ¹ Repeat surgery in the cervical spine carries an increased morbidity of oesophageal injury and recurrent laryngeal nerve damage.

Cervical spine joint replacement surgery is now available with the Bryan Cervical Disc System. This artificial disc comprises of two titanium outer shells made of rough textured porous coating that allows bony ingrowths into the surface. There is an inner polyurethane nucleus that permits motion between the two outer shells thus preserving motion at the operated segment.

Unlike lumbar disc replacements, these cervical artificial joints do not bear as much weight and hence undergo less deterioration over time. Bryan discs have undergone a custom cervical spine stimulator to over 10,000,000 cycles with minimal deterioration of the components.

The preliminary experience with the use of the Bryan Disc in Europe has recently been published. ² In this analysis, a total of 90 patients had 97 joint replacements in a prospective, concurrently enrolled, multicenter trial. Of these 90 patients, 60 were followed up for 6 months and the remaining 30 for a year. They reported a success (Odom’s criteria of excellent, good and fair) of 86% (of 60 patients) at 6 months and 90% (of 30 patients) at 1 year. At 6 months, 93% demonstrated motion of the device in flexion and extension.

To date, approximately 1000 Bryan discs have been used in Europe with no major complications. ³

Lateral Cervical Spine X-ray of Bryan Disc in action (Neutral)	Lateral Cervical Spine X-ray of Bryan Disc in action (flexion)

Conclusions

By preserving motion at the operated level, premature deterioration of adjacent levels would therefore be averted. Although the cost of the implant is high, there is no donor site morbidity from graft harvesting, hospitalisation period is shortened and future risky repeat spine surgery is avoided.

References

C Wigfield, S Gill, R Nelson, et al. Influence of an Artificial Cervical Joint Compared with Fusion on Adjacent-level Motion in the Treatment of Degenerative Cervical Disc Disease. J Neurosurg (Spine 1) 96:17-21,2002

J Goffin, A Casey, P Kehr, et al. Preliminary Clinical Experience with the Bryan Cervical Disc Prosthesis. Neurosurg 51:840-847,2002