Complications of artificial disc replacement: a report of 27 patients with the SB Charité disc.

Disc prosthesis surgery is rapidly becoming an option in treating patients with symptomatic degenerative disc disease. Only short-term and midterm results are described in the literature. Most operated patients belong to the age group of 30-50 years. In these active patients, complications can be expected to increase with longer follow-up, similar to total joint replacements in the extremities. Reported here is a series of 27 patients from another institution, who presented with unsatisfactory results or complications after SB Charité disc replacement. The objective of this work was to describe the possible short- and long-term unsatisfactory results of disc prosthesis surgery. Twenty-seven patients were seen in a tertiary university referral center with persisting back and leg complaints after having received a Charité disc prosthesis. All patients were operated on in a neighboring hospital. Most patients were operated on at the L4-L5 and /or the L5-S1 vertebral levels. The patients were evaluated with plain radiography, some with flexion-extension x-rays, and most of them with computed tomography scans. The group consisted of 15 women and 12 men. Their mean age was 40 years (range 30-67 years) at the time of operation. The patients presented to us a mean of 53 months (range 11-127 months) following disc replacement surgery. In two patients, an early removal of a prosthesis was required and in two patients a late removal. In 11 patients, a second spinal reconstructive salvage procedure was performed. Mean follow-up for 26 patients with mid- and long-term evaluation was 91 months (range 15-157 months). Early complications were the following: In one patient, an anterior luxation of the prosthesis after 1 week necessitated removal and cage insertion, which failed to unite. In another patient with prostheses at L4-L5 and L5-S1, the prosthesis at L5-S1 dislocated anteriorly after 3 months and was removed after 12 months. Abdominal wall hematoma occurred in four cases. Retrograde ejaculation with loss of libido was seen in one case and erection weakness in another case. A temporary benefit was experienced by 12 patients, while 14 patients reported no benefit at all. Main causes of persistent complaints were degeneration at another level in 14, subsidence of the prosthesis in 16, and facet joint arthrosis in 11. A combination of pathologies was often present. Slow anterior migration was present in two cases, with compression on the iliac vessels in one case. Polyethylene wear was obvious in one patient 12 years after operation. In eight cases, posterior fusion with pedicle screws was required. In two cases, the prosthesis was removed and the segment was circumferentially fused. These procedures resulted in suboptimal long-term results. In this relatively small group of patients operated on with a Charité disc prosthesis, most problems arose from degeneration of other lumbar discs, facet joint arthrosis at the same or other levels, and subsidence of the prosthesis. It is to be expected that many more patients will be seen with late problems some years after this operation as the survivorship will decrease with time.