Influence of the Initial Sagittal Lumbar Alignment on Clinical and Radiological Outcomes of Single-Level Lumbar Total Disc Replacements at a Minimum 2-Year Follow-up

Study Design. Retrospective cohort study Objective. To analyze the clinical and radiographic outcomes of patients undergoing a one-level lumbar total disc replacement (TDR), according to the initial sagittal alignment of the spine. Summary of Background Data. No authors have highlighted correlation between the initial spinopelvic parameters and the postoperative outcome after a one-level TDR. Methods. Seventy-eight patients were included: 14 TDR at L4-L5 and 64 TDR at L5-S1 level. Clinical assessment was performed on leg pain and axial back pain Visual Analog Scale (VAS), Oswestry Disability Index, and Short Form-36 Health Survey. Radiographic assessment included full spine standing anteroposterior and lateral films. Data were compared according to the initial lumbar sagittal alignment described by Roussouly. Results. Forty-five female patients and 33 male patients with a mean age of 41.7 years (95% confidence interval [40.3-43.1]) were included. The mean follow-up was 46.4 months (95% [40.6-51.6]). Two patients were considered as Roussouly type 1 (2.6%), 36 patients as type 2 (46.2%), 33 patients as type 3 (42.3%), and 7 patients as type 4 (9%). Preoperatively, there were no clinical differences depending on Roussouly's type of back. Pelvic incidence (P<0.001), sacral slope (P<0.001), lumbar lordosis (P<0.001), and spinosacral angle (P<0.001) were different between the Roussouly's types of back. Postoperative clinical outcome improved (P<0.001) but did not vary according to the Roussouly types except for leg pain VAS (P = 0.03). Post hoc tests did not reveal difference between the Roussouly's types and leg pain VAS. Postoperative radiographic outcomes did not change excepted for the lumbar lordosis (P<0.001), thoracic kyphosis (P = 0.007), and spinosacral angle (P = 0.02). The Roussouly type had no effect on the postoperative course of radiographic parameters. Conclusion. Equivalent clinical and radiographic outcomes have been highlighted independently of the increasing of the sacral slope for patients with one-level lumbar TDR.