Intervertebral disc replacement for cervical degenerative disease -: clinical results and functional outcome at two years in patients implanted with the Bryan® cervical disc prosthesis

Background. This is a prospective study of patients with degenerative cervical disease who underwent ventral discectomy and disc replacement with the Bryan(R) cervical disc prosthesis. The objective was to investigate clinical outcome at 2 years of patients implanted with the Bryan(R) disc and to evaluate function of the implant itself. Methods. Fifty-four consecutive patients with cervical disc herniation and/or spondylosis with preserved mobility in the affected spinal segments were enrolled. Patients presented clinically with cervical radiculopathy and/or myelopathy with or without neck pain. A standard anterior cervical discectomy was carried out and a Bryan(R) disc was implanted in the affected levels. A total of 59 prosthetic discs were implanted, in 49 patients at a single level and in 5 at two adjacent levels. The neurological status was evaluated pre-operatively and at one and two years thereafter. Plain X-rays, CT, and MRI were used for pre-operative diagnostics. Post-operative follow-up was done by X-rays. Findings. All patients had an excellent or good neurological outcome according to the Odom criteria. Loss of function (motion range < 3 degrees) was found in 7 (12%) out of 59 Bryan(R) discs at two years after surgery. Heterotopic ossification (HO) of the McAffee grades 1-4 was seen in a total of 17 (29%) segments. There were no implant dislocations or migrations. Conclusions. Implantation of the Bryan(R) disc resulted in excellent or good neurological outcome in all patients. The surgical technique was safe and without complications. Twelve percent of the implanted Bryan(R) discs lost mobility at two years, mainly due to HO. A trend was seen towards development of HO in the operated segments. Further investigations with longer follow-up periods and with a control group (e.g. fusion with intervertebral cage) will be necessary for a definitive assessment of the long-term functionality and benefits of artificial cervical discs.