Total Disc Arthroplasty: Associated Complications

Chapter 167 Total Disc Arthroplasty

Associated Complications

Surgical management of chronic low back pain remains challenging. Although lumbar fusion remains the gold standard, novel motion-sparing technologies are now available that offer several theoretical advantages over lumbar fusion. The use of intervertebral disc prostheses as an alternative to spinal fusion has been advocated to preserve segmental motion and prevent adjacent degeneration. As with any new technology, safety is a primary outcome measure.

Total disc replacement (TDR) is a relatively new procedure and thus reported complication rates are highly variable. Complications associated with TDR can be divided into three distinct groups. The first group involves surgical approach–related complications. These include vascular injuries, injuries to nerve roots, and retrograde ejaculation due to injury to the presacral sympathetic plexus. In general, the incidence of surgical approach–related complications ranges from 2.1% to 18.7%.¹ The second group includes implant-related complications. These may be divided further into short- and long-tem complications. Short-term complications include implant subsidence, migration, and displacement and vertebral end-plate fractures. There is a paucity of long-term data on the performance of TDR implants. In addition, these data reflect the first generation of implants that have since been replaced by newer, improved discs. Hence, many long-term complications are not well documented. These may include the effect of wear debris and of increased range of motion of the facet joint and adjacent segment. The overall incidence of short-term implant-related complications ranges from 2.9% to 39.3%.¹ The third group represents general complications such as infection, wound complications, persistent pain, and other adverse events related to surgical treatment. The incidence of these complications ranges from 1% to 14%.¹ Another method to assess the safety of the new procedure is to determine reoperation rates at the index level. Available literature suggests that reoperation rates for TDR range from 1% to 28.6%.¹

The results of several randomized controlled trials have been published recently. In the Charité trial, Blumenthal et al. reported overall 2-year complication rates for patients undergoing TDR or fusion of 29.1% and 50.2%, respectively.² The authors also reported that 11 patients (5.4%) in the TDR group and 9 patients (9.1%) in the fusion group underwent reoperation at the index level. McAfee et al. reported similar findings for the Charité TDR. In their report, 6.3% of TDR patients and 10.1% of fusion patients required reoperation at the index level.³ Van den Eerenbeemt et al. compared reported complication rates from Charité TDR studies with U.S. Food and Drug Administration (FDA) reports.¹ They found significant discrepancies in reported rates. In their report, 16 Charité patients (9.1%) experienced an approach-related complication (retrograde ejaculation), 8 patients (3.9%) had implant-related complications, and 33 patients (16.1%) had general surgery–related complications. In the fusion group, 9 patients (12.8%) reported retrograde ejaculation, 10 patients (10.1%) had implant-related complications, and 27 patients (27.2%) had general surgery–related complications. Geisler et al. analyzed a subgroup of patients from a Charité investigational device exemption study,⁴ focusing on patients with neurologic complications. The incidence of neurologic complications was no higher in patients with the Charité TDR (16.6%) than in patients with Bagby and Kuslich (BAK) fusion (17.2%; P = .3). Zigler et al. reported the FDA randomized trial comparing the ProDisc-L artificial disc with circumferential fusion.⁵ In this study, the overall complication rates were 7.3% for the ProDisc-L group and 6.3% for the circumferential fusion group. Reoperation at the index level was necessary for 3.7% of ProDisc-L patients and 5.4% of fusion patients. Van den Eerenbeemt et al. also analyzed the ProDisc-L trial and FDA reports.¹ Their findings suggest that 2.4% of ProDisc-L recipients experienced retrograde ejaculation, 3.1% reported implant-related complications, and 1.8% had general surgical complications. In the fusion group, two patients (2.5%) had retrograde ejaculation; there were no implant- or approach-related complications. Three patients (3.8%) reported general surgery–related complications. Most recently, Sasso et al. reported initial results from the FlexiCore randomized study. They reported an overall rate of complications of 22.7% in the TDR group and 43.5% in the fusion group.⁶ Of 44 FlexiCore patients, 5 (11.4%) required reoperation. In the control group, 6 of 23 patients (26.1%) required reoperation.