Rotational hypermobility of disc wedging using kinematic CT: preliminary study to investigate the instability of discs in degenerated scoliosis in the lumbar spine

Natural History of Intradiscal Vacuum Phenomenon and its Role in Advanced Disc Degeneration

STUDY DESIGN

Observational serial computed tomography (CT) analysis of the lumbar spine in a normal-aging population.

OBJECTIVE

To assess the natural history of the intradiscal vacuum phenomenon (IDVP) and its role in disc degeneration.

BACKGROUND

The natural history of disc degeneration is well described but our understanding of the end stage of pathogenesis remains incomplete. Magnetic resonance imaging loses accuracy with advanced degeneration, becoming hyporesonant and indistinct. Cadaveric specimens display adaptive changes in the disc with loss of the hydrostatic capacity of the nucleus, increased intradiscal clefts, and endplate impermeability. IDVP is associated with advanced disc degeneration and CT is the optimal modality to visualize this, yet these insights remain unreported.

PATIENTS AND METHODS

Patients only included historic CT abdomen scans of those over 60 years of age without acute or relevant spinal pathology, with a diagnosis of at least one level with IDVP on the original CT scan, and all of whom had a similar scan >7 years later. A history of clinically significant back pain was also recorded.

RESULTS

CT scans included 360 levels in 29 males and 31 females (mean: 68.9 y), displaying 82 levels of IDVP, with a second scan included after a mean of 10.3 years. Most levels displayed the same level of severity (persisted, 45) compared with where some progressed (26), regressed (8), and fused (3; P < 0.01). There was also an increased incidence, 37/60 (62%) of developing IDVP at another level. Disc heights were reduced with increased severity of IDVP. A record of back pain was evident in 31/60 patients, which was not significantly worse in those with worsening severity or additional level involvement over the study period.

CONCLUSION

As disc degeneration advances, the associated IDVP persists in most cases, displaying a plateauing of severity over long periods, but rarely with progression to autofusion.

The Underexplored Landscape of Hypoxia-Inducible Factor 2 Alpha and Potential Roles in Tumor Macrophages: A Review

Low tissue oxygenation, termed hypoxia, is a characteristic of solid tumors with negative consequences. Tumor-associated macrophages (TAMs) accumulate in hypoxic tumor regions and correlate with worse outcomes in cancer patients across several tumor types. Thus, the molecular mechanism in which macrophages respond to low oxygen tension has been increasingly investigated in the last decade. Hypoxia stabilizes a group of hypoxia-inducible transcription factors (HIFs) reported to drive transcriptional programs involved in cell survival, metabolism, and angiogenesis. Though both tumor macrophage HIF-1α and HIF-2α correlate with unfavorable tumor microenvironments, most research focuses on HIF-1α as the master regulator of hypoxia signaling, because HIF-1α expression was originally identified in several cancer types and correlates with worse outcome in cancer patients. The relative contribution of each HIFα subunit to cell phenotypes is poorly understood especially in TAMs. Once thought to have overlapping roles, recent investigation of macrophage HIF-2α has demonstrated a diverse function from HIF-1α. Little work has been published on the differential role of hypoxia-dependent macrophage HIF-2α when compared to HIF-1α in the context of tumor biology. This review highlights cellular HIF-2α functions and emphasizes the gap in research investigating oxygen-dependent functions of tumor macrophage HIF-2α.

Analysis of lumbar lateral instability on upright left and right bending radiographs in symptomatic patients with degenerative lumbar spondylolisthesis

Background

To evaluate lumbar mobility in various positions using upright left and right bending radiographs in patients with degenerative lumbar spondylolisthesis (DLS), as well as to assess the impact of lateral instability on patient-reported outcomes.

Methods

This study retrospectively reviewed a consecutive series of patients with DLS between January 2019 and October 2020. The enrolled patients were divided into two groups: the lateral instability group (group L) and non-lateral instability group (group NL). Translational and angular motion in both sagittal and coronal planes and patient-reported outcomes were compared between the two groups.

Results

There were 104 (59.8%) patients in group L and 70 (40.2%) patients in group NL, with an average age of 60.6 ± 7.8 years. Patients with a right bending posture in group L had a higher slip percentage (14.2 ± 7.4% vs 9.2 ± 3.2%, p = 0.01) and slip angle (6.3 ± 1.5° vs 2.2 ± 0.8°, p = 0.021). Compared with group NL, group L demonstrated significantly larger angular motion in the coronal plane (2.4 ± 1.3° vs 1.0 ± 0.7°, p = 0.008). Patients with lateral instability had worse preoperative back pain (6.1 ± 1.6 vs 2.7 ± 1.9, p = 0.01) and Oswestry Disability Index (ODI) scores (37.7 ± 5.5 vs 25.6 ± 2.6, p = 0.002). In terms of pain characteristics, group L was characterized by pain when getting out of a car, when rising from a chair, and when climbing stairs (all p values < 0.05).

Conclusion

Lumbar lateral instability, that is, increased mobility in the coronal plane on lateral bending radiographs, translational and/or angular, correlates to more pronounced patient related symptoms in degenerative L4–5 spondylolisthesis. The existence of lumbar lateral instability leads to worse impacts on patient-reported outcomes when patients change their positions including getting out of a car, rising from a chair, and climbing stairs.

Bone Marrow Edema and Low Back Pain in Elderly Degenerative Lumbar Scoliosis: A Cross-Sectional Study

STUDY DESIGN

Cross-sectional study.

OBJECTIVE

To examine whether bone marrow edema is associated with low back pain in elderly patients with degenerative lumbar scoliosis.

SUMMARY OF BACKGROUND DATA

The cause of low back pain in degenerative lumbar scoliosis is unclear.

METHODS

A total of 120 degenerative lumbar scoliosis patients 65 years of age or older were evaluated. Radiography, computed tomography (CT), magnetic resonance imaging (MRI), and tender point examination in the lumbar spine were performed. On MRI, coronal gadolinium-contrasted T1- or T2-weighed fat-saturated images were used to score the size of bone marrow edema. The prevalence of bone marrow edema in patients with and without low back pain was compared; in patients with low back pain, we tested whether the locations of lumbar tender point were consistent with that of bone marrow edema.

RESULTS

Bone marrow edema was found in 62 of 64 (96.9%) patients with low back pain compared with 21 of 56 (37.5%) patients without it (P < 0.001). Bone marrow edema located more frequently on the concave side than on the convex side of scoliosis (P < 0.001). Among patients with low back pain, bone marrow edema score was associated with low back pain severity (r = 0.724; P < 0.001), and the location of lumbar tender point were consistent with that of bone marrow edema (κ value = 0.745; P < 0.001).

CONCLUSION

Bone marrow edema on MRI was closely associated with the presence of low back pain in elderly degenerative lumbar scoliosis.

LEVEL OF EVIDENCE

4.

Micro-computed tomography-based three-dimensional kinematic analysis during lateral bending for spinal fusion assessment in a rat posterolateral lumbar fusion model

Rat posterolateral lumbar fusion (PLF) models have been used to assess the safety and effectiveness of new bone substitutes and osteoinductive growth factors using palpation, radiography, micro-computed tomography (μCT), and histology as standard methods to evaluate spinal fusion. Despite increased numbers of PLF studies involving alternative bone substitutes and growth factors, the quantitative assessment of treatment efficacy during spinal motion has been limited. The purpose of this study was to evaluate the effect of spinal fusion on lumbar spine segment stability during lateral bending using a μCT-based three-dimensional (3D) kinematic analysis in the rat PLF model. Fourteen athymic male rats underwent PLF surgery at L4/5 and received bone grafts harvested from the ilium and femurs of syngeneic rats (Isograft, n=7) or no graft (Sham, n=7). At 8 weeks after the PLF surgery, spinal fusion was assessed by manual palpation, plain radiography, μCT, and histology. To determine lumbar segmental motions at the operated level during lateral bending, 3D kinematic analysis was performed. The Isograft group, but not the Sham group, showed spinal fusion on manual palpation (6/7), solid fusion mass in radiographs (6/7), as well as bone bridging in μCT and histological images (5/7). Compared to the Sham group, the Isograft group revealed limited 3D lateral bending angular range of motion and lateral translation during lateral bending at the fused segment where disc height narrowing was observed. This μCT-based 3D kinematic analysis can provide a quantitative assessment of spinal fusion in a rat PLF model to complement current gold standard methods used for efficacy assessment of new therapeutic approaches.

Current classification systems for adult degenerative scoliosis

At present, a big effort of the scientific community has been directed toward a more proper and standardized approach to the patients affected by degenerative scoliosis, and recent attention has turned toward the development of classification schemes. A literature analysis highlighted several classification schemes developed for degenerative scoliosis patients: the Simmons classification system, the Aebi system, the Faldini working classification system, the Schwab system, and the Scoliosis Research Society system. Aim of the current manuscript is to scrutinize the available literature in order to provide a comprehensive overview of these current classification schemes for adult scoliosis, by describing and commenting clinical development, limits and potential of their application together with their implications for surgical planning.