30. Vacuum discs are associated with greater sagittal imbalance and disability in adult spine deformity patients

Abstract

BACKGROUND CONTEXT

Intervertebral vacuum discs (VDs), characterized by intradiscal gas accumulation, signify advanced degenerative changes in the spine and are frequently observed in older patients. Despite VDs’ prevalence, their clinical implications in adult spinal deformity (ASD) remain underexplored.

PURPOSE

This study aims to assess the prevalent characteristics of VDs and their impact on spinal alignment, pain, and surgical outcomes within an ASD cohort.

STUDY DESIGN/SETTING

N/A

PATIENT SAMPLE

N/A

OUTCOME MEASURES

N/A

METHODS

This retrospective analysis included all consecutive patients (2013-2019) undergoing surgery for spinal deformity with lumbar spine CT scans from a single institution. Preoperative CTs were evaluated in all planes at each intervertebral space between T12 and S1 for the presence and size of VDs. Identification of a VD was made from a well-demarcated hypointensity within the intervertebral disc space. Radiographic parameters, including agittal vertebral axis (SVA), coronal balance, pelvic tilt (PT), lumbar lordosis (LL), pelvic incidence (PI), and segmental lordosis (SL), were measured both preoperatively and postoperatively. Patient-reported outcome measures (NPRS leg and back pain, Oswestry Disability Index [ODI]) were systematically collected at the initial preoperative visit and postoperatively at 6 weeks, 6 months, 1 year, and 2 years. Details of the surgical interventions were collected from the EMR. Data analysis was performed using mixed effects models, multivariable models, and linear regression (two-sided a=0.05).

RESULTS

The final cohort included 135 patients (60% female, aged 70 [68, 72] years). VDs were present in 86% of patients. Preoperatively, patients with VDs experienced greater leg pain (+0.9 [0.3, 1.6] vs no VD; p=0.004). Patients with large VD had higher preoperative back pain vs those with small VD (+1.0 [0.5, 1.6]; p< 0.001) or no VD (+0.6 [0.1, 1.1]; p< 0.027). Patients with VDs exhibited significant sagittal imbalance, with lower preoperative lumbar lordosis (-6.3 [95% CI: 8.8, 3.8] vs no VD; p< 0.001), greater LL-PI mismatch (+4.9 [95% CI: 2.4, 7.4] vs no VD; p< 0.001), and lower SL (-2.0 [95% CI: -3.6, -0.5] vs no VD; p< 0.001). Surgical interventions, particularly anterior lumbar interbody fusions (ALIFs), were more frequently utilized at levels with VDs (ALIFs: 17.5% VD vs 6.5% no VD, p< 0.001). ALIFs were associated with a greater change in segmental lordosis than AntLat (+7.0 [2.5, 11.5]; p< 0.001) and no interbody fusion (+8.8 [4.4, 13.1]; p< 0.001) when a VD was present. Additionally, VD at any level was associated with larger pre- to postoperative increases in LL (+3.4 [95% CI: 0.7, 6.0] vs no VD, p=0.015) and larger decreases in PI-LL mismatch (-4.0 [95% CI: -7.1, -1.0] vs no VD; p = 0.008). There was a trend towards a greater pre- to postoperative increase in SL when a VD was present (+1.5 [95% CI: -0.2, 3.2]; p=0.076). Postoperatively, larger decreases in NPRS leg pain were observed when a VD was present (-0.91 [95% CI: -1.63, -0.18] vs no VD; p=0.014). Large VD were also associated with larger decreases in back pain at 6 weeks postop versus small VD (-1.3 [-2.0, -0.6]; p< 0.001) and no VD (-1.2 [-1.8, -0.6]; p< 0.001).

CONCLUSIONS

This study establishes the near ubiquity of VDs in ASD surgical patients. Patients with ASD with VDs suffer more and appear to have more disability but may be able to achieve significant improvement in function and sagittal balance with surgical intervention.

FDA Device/Drug Status

This abstract does not discuss or include any applicable devices or drugs.