Patterns of intra-discal vacuum phenomenon in adult degenerative scoliosis

Abstract

Background: Degenerative scoliosis occurs with asymmetric disc and facet degeneration and vertebral wedging. Intra-discal vacuum phenomenon (IDVP) is associated with advanced disc and facet degeneration, but typically poorly visualised on radiograph or magnetic resonance imaging (MRI), and has not been reported in the context of degenerative scoliosis. This radiographic observational case-control study aims to further investigate degenerative scoliosis through evaluation and characterisation of IDVP.

Methods: All scoliosis subjects were isolated from an over-60s population sample of 2020 digitalised computed tomography (CT) abdomen scans, yielding 136 subjects for analysis. One hundred and thirty-six age- and gender-matched non-scoliotic subjects with IDVP were chosen from the same cohort for comparison. The lumbar discs were analysed for severity, distribution and symmetry of IDVP. The lumbar spine was analysed for presence of scoliosis, calculation of pelvic incidence and presence of listhesis. Clinically significant back pain details were recorded and analysed.

Results: Subjects with S-shape curves accounted for 80% (n=109) and C-shape curves in 20% (n=27). Ninety-four (86%) with an S-curve had multilevel contralateral IDVP compared to 15 (55%) of C-curves. IDVP position was distributed towards the upper lumbar spine and with increased asymmetry (concavity-based). Back pain was not significantly increased in scoliotic subjects (39% vs. 32%, P=0.30) and not correlated with location, severity, laterality or distribution of IDVP.

Conclusions: CT analysis of degenerative scoliosis demonstrates predominantly multilevel contralateral asymmetric IDVP, with increased involvement of the upper lumbar spine and formation of S-shape curves, identifying a coronal compensatory correction in the presence of persistent degenerative mobility.

Keywords: Vacuum; adult spinal deformity; computed tomography (CT); disc degeneration; scoliosis.

Figure 1

Study design. CT, computed tomography; IDVP, intra-discal vacuum phenomenon.

Figure 2

Distribution of IDVP in non-scoliotic (A) and scoliotic cases, including C and S curves (B,C) and their respective IDVP incidences of 20% and 80% of all scoliosis cases. Values and corresponding percentages are weighted to represent increasing severity of IDVP. IDVP, intra-discal vacuum phenomenon.

Figure 3

Degenerative C-curve scoliosis with contra-lateral IDVP, partial left side IDVP at L5S1, L4L5, right side L3L4, L2L3 and L1L2, with wedging at L3 and previous fracture L1. Associated end-plate sclerosis and disc osteophytes evident, worst at L45 where IDVP traverses the opposing osteophytes. IDVP, intra-discal vacuum phenomenon.

Figure 4

Degenerative S-curve scoliosis with IDVP at L2L3 and L3L4, associated L2 wedging, endplate sclerosis and disc osteophytes. Deformity and prior autofusion noted at L4L5 and L5S1. Incidental vacuum noted at contra-lateral left sacroiliac joint. IDVP, intra-discal vacuum phenomenon.

Figure 5

Degenerative S-curve scoliosis with multilevel contra-lateral IDVP, total IDVP at T12L1, right side partial IDVP at L1L2 and L3L4, left side partial at L5S1. Incidental (worn out) hip replacement on the left side, which may have previously influenced coronal alignment (Trendelenburg gait). IDVP, intra-discal vacuum phenomenon.

Figure 6

Degenerative S-curve scoliosis and coronal translation to the left side, autofusion with left side asymmetric collapse and concavity at L5S1, right side IDVP, concavity and listhesis at both L45 and L34, accompanying vacuum in the L34 facet joint. IDVP, intra-discal vacuum phenomenon.

Figure 7

Degenerative S-curve scoliosis with acute lumbosacral lordosis, significant lumbar kyphosis, and accompanying concavity multilevel contra-lateral (and anterior) IDVP extending laterally along the lateral disc osteophytes and traversing IDVP beyond the confines of the original disc. IDVP, intra-discal vacuum phenomenon.