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.
Level of Evidence: 3.