Journal of Spine

Introduction: Severe degenerative disc diseases necessitate surgical management with large interbody spacers to regain disc space. Static interbody spacers are the standard of care for minimally invasive lateral lumbar interbody fusion (MIS LLIF). However, using large static interbody spacers requires aggressive endplate preparation prior to implant insertion, which may lead to subsidence and compromised stability. This study describes the clinical and radiographic outcomes of patients treated with expandable interbody spacers following MIS LLIF.

Materials and Methods: This is a single-surgeon, retrospective Institutional Review Board-exempt chart review on 22 consecutive patients who underwent MIS LLIF at 1–2 contiguous level(s) using expandable interbody spacers. Radiographic and clinical functional outcomes were collected and compared at preoperative and postoperative time points up to 24 months. Statistical results were significant if p<0.05.

Results: Twenty-two consecutive patients were evaluated—average age, 57.6 ± 11.0 years; 45.5% were female. Visual Analog Scale (VAS) back and leg pain scores decreased significantly by an average of 7.1 ± 1.2 points at 24 months (p<0.001). Oswestry Disability Index (ODI) scores significantly decreased by a mean of 67.1 ± 10.0 points at 24 months (p<0.001). Lumbar lordosis improved by a mean of 1.8 ± 8.0° at 24 months. Among the 28 spinal levels, 42.9% were at L3–l4 and 39.3% at L4–l5. Anterior, middle, and posterior disc height significantly increased at 24 months by averages of 4.7 ± 3.6, 4.0 ± 3.9, and 1.9 ± 2.4mm, respectively (p<0.001). Neuroforaminal height significantly increased at 24 months by a mean of 2.6 ± 3.7mm (p<0.001). Segmental lordosis significantly improved by 2.5 ± 2.0° at 24 months (p<0.001). There was 100% fusion at all levels, with no cases of radiolucency. One incidence of subsidence (1/28, 3.6%) was reported at 24 months. There were no reported implant-related complications, with 0% pseudoarthrosis and no secondary procedures.

Conclusion: This study showed positive clinical and radiographic outcomes for patients who underwent MIS LLIF with expandable interbody spacers. Sagittal correction and indirect decompression were achieved and maintained up to 24-month follow-up from baseline, based on increased disc height, neuroforaminal height, and segmental lordosis. Functional clinical outcomes significantly improved based on decreased VAS pain and ODI scores at 24 months. The use of lateral expandable spacers was shown to be safe, durable, and effective for the studied patient population.

Background: Achieving and maintaining indirect decompression is critical to the success of open transforaminal lumbar interbody fusion (O-TLIF) because it directly correlates with improved patient outcomes. This has led to significant advancements in interbody design. Expandable interbody devices have been developed to optimize the restoration of disc height, neuroforaminal height, and lordosis while minimizing endplate disruption.

Objective: The objective of this study is to quantify the radiographic outcomes of patients who underwent O-TLIF using an expandable interbody spacer.

Methods: Single-surgeon, retrospective, Institutional Review Board-exempt chart review of 68 consecutive patients who underwent O-TLIF at 1–2 contiguous level(s) using expandable interbody spacers. Radiographic outcomes were collected and compared at preoperative and postoperative timepoints up to 12 months. Statistical results were significant if P<0.05.

Results: Over a three-year period, 68 consecutive patients underwent O-TLIF with a titanium expandable interbody spacer. The patients were 48.5% (33/68) female and 51.5% (35/68) male, with an average age of 52.6 ± 12.7 years. Mean anterior and posterior disc heights significantly improved by 3.8 ± 2.6 mm and 3.0 ± 2.5 mm, respectively, at 12 months (all P<0.001). Mean neuroforaminal height significantly improved by 2.9 ± 3.9 mm at 12 months (P<0.001). Mean intervertebral angle significantly improved by 1.4 ± 4.0° at 12 months (P=0.002). Mean pelvic incidence minus lumbar lordosis mismatch significantly decreased by 2.3 ± 8.4° at 12 months (P=0.035).

Conclusion: Anterior and posterior disc height, neuroforaminal height, and intervertebral angles were restored, providing evidence of indirect decompression. Segmental and lumbar lordosis was sustained. Expandable technology proved to be effective in the studied patients when used in an O-TLIF technique.