Cervical Disc Replacement, A Step Beyond Cervical Fusion

written by Dr Chee Chee Pin on 18 June 2013
Aging process results in a decrease in the water content of the nucleous pulposus of the cervical disc resulting in reduced overall deformation, smaller elastic zone and lower threshold for failure. It causes even distribution of the forces to the end plate and may lead to narrowing of the intervertebral forament, facet loading and even compression fracture of the cervical spine. The effect of cervical spine with degeneration is that of overall decreased in cervical mobility usually only sparing the rotation on neck flexion. The resulting pathology includes disc prolapse, cervical spondylosis, spinal stenosis, posterior longitudinal calcification, subluxation and compression fractures.
 
Cervical disc prolapse and spondylosis without severe stenosis usually present with neck pain, radiculopathy and myelopathy. The classical surgical treatment includes discetomy with or without fusion using bone graft, plating or cage and sometimes foraminotomy. Usually discetomy and fusion results in good relief in the symptomsand allow stability. The main concerns are that of accelerated degeneration on the adjacent vertebra and decrease in the mobility of the cervical spine, hence the development of cervical disc replacement prosthesis.
 
Cervical Disc Prolapse
 
The goal of development of the cervical prosthesis is to restore the physiological height of the disc, cervical lordosis and the physiological mobility. The requirement of this cervical prothesis is that the implant is of reliable and durable design, simple and safe in the process of implantation and minimal wear and attrition preferably without a need to replace a new one in one’s life time to maintain the same mobility.
 
Several made of cervical disc prothesis has been used since 2002. These include the Bryan and Prestige by Medtronic, Prodisc C by Synthes and PCM by Cervitech, Mobi-C by LDR Medical and Baguera by Spinart. The made, mobility, advantages and disadvantages of each of the prosthesis are discussed.
 
Recent results indicated that patients who underwent proper cervical replacement adhering to the strict indications of the technique showed excellent results with satisfaction in 97% patients, cervical pain relief more than 80%, radicular pain relief 75% and ease of walking 80%.More than 80% were working at 1 year compared 38% reoperatively. Analgesic usage decreased from 80% to 23%. Radiological study did not show any subluxation, device migration or subsidence. In one series, out of 218 cases only 4 cases had heterotopic calcifications and 1 fusion at 2 years. The range of movement was more than 5% in 84 % of the cases.
 
Cervical Disc Replacement
 
The advantages versus disadvantages of cervical replacements and cervical fusion were discussed and compared. The doctor managing the case should carefully consider the wish of the patients versus other factors including the surgeon’s personal wish and skill and the social and financial condition of the patients.
Recent concept of hybrid solution has been developed combining disc replacement arthoplasty and cervical fusion with cage in many cases especially in considering the fact that many a time cervical spondylosis and disc prolapse involve multiple levels.
 
Extension 6 months after Arthroplasty                                 Flexion 6 months after Arthroplast