Vacuum Facet Phenomenon in Computed Tomography Imaging: A Sign of Instability in Degenerative Spondylolisthesis?

Evolution of lumbar degenerative spondylolisthesis with key radiographic features

Spondylolisthesis is a common finding in middle-aged and older adults with back pain. The pathophysiology of degenerative spondylolisthesis is a subject of controversy regarding not only its etiology but also the mechanisms of its progression. It is theorized that degeneration of the facets and discs can lead to segmental instability, leading to displacement over time. Kirkaldy-Willis divided degenerative spondylolisthesis into three phases: dysfunction, instability, and finally, restabilization. There is a paucity of literature on the unification of the radiological hallmarks seen in spondylolisthesis within these phases. The radiographic features include (1) facet morphology/arthropathy, (2) facet effusion, (3) facet vacuum, (4) synovial cyst, (5) interspinous ligament bursitis, and (6) vacuum disc as markers of dysfunction, instability, and/or restabilization. We discuss these features, which can be seen on X-ray, CT, and MRI, with the intention of establishing a timeline upon which they present clinically. Spondylolisthesis is initiated as either degeneration of the intervertebral disc or facet joints. Early degeneration can be seen as facet vacuum without considerable arthropathy. As the vertebral segment becomes increasingly dynamic, fluid accumulates within the facet joint space. Further degeneration will lead to the advancement of facet arthropathy, degenerative disc disease, and posterior ligamentous complex pathology. Facet effusion can eventually be replaced with a vacuum in severe facet osteoarthritis. Intervertebral disc vacuum continues to accumulate with further cleft formation and degeneration. Ultimately, autofusion of the vertebra at the facets and endplates can be observed. With this review, we hope to increase awareness of these radiographical markers and their timeline, thus placing them within the framework of the currently accepted model of degenerative spondylolisthesis, to help guide future research and to help refine management guidelines.

Severe Intervertebral Vacuum Phenomenon is Associated With Higher Preoperative Low Back Pain, ODI, and Indication for Fusion in Patients With Degenerative Lumbar Spondylolisthesis

STUDY DESIGN

Retrospective study of prospective collected data.

OBJECTIVE

To analyze the association between intervertebral vacuum phenomenon (IVP) and clinical parameters in patients with degenerative spondylolisthesis.

SUMMARY OF BACKGROUND DATA

IVP is a sign of advanced disc degeneration. The correlation between IVP severity and low back pain in patients with degenerative spondylolisthesis has not been previously analyzed.

METHODS

We retrospectively analyzed patients with degenerative spondylolisthesis who underwent surgery. Vacuum phenomenon was measured on computed tomography scan and classified into mild, moderate, and severe. A lumbar vacuum severity (LVS) scale was developed based on vacuum severity. The associations between IVP at L4/5 and the LVS scale, preoperative and postoperative low back pain, as well as the Oswestry Disability Index was assessed. The association of IVP at L4/5 and the LVS scale and surgical decision-making, defined as decompression alone or decompression and fusion, was assessed through univariable logistic regression analysis.

RESULTS

A total of 167 patients (52.7% female) were included in the study. The median age was 69 years (interquartile range 62-72). Overall, 100 (59.9%) patients underwent decompression and fusion and 67 (40.1%) underwent decompression alone. The univariable regression demonstrated a significantly increased odds ratio (OR) for back pain in patients with more severe IVP at L4/5 [OR=1.69 (95% CI 1.12-2.60), P =0.01]. The univariable regressions demonstrated a significantly increased OR for increased disability with more severe L4/L5 IVP [OR=1.90 (95% CI 1.04-3.76), P =0.04] and with an increased LVS scale [OR=1.17 (95% CI 1.02-1.35), P =0.02]. IVP severity of the L4/L5 were associated with higher indication for fusion surgery.

CONCLUSION

Our study showed that in patients with degenerative spondylolisthesis undergoing surgery, the severity of vacuum phenomenon at L4/L5 was associated with greater preoperative back pain and worse Oswestry Disability Index. Patients with severe IVP were more likely to undergo fusion.

Research progress of diagnosing methodology for lumbar segmental instability: A narrative review

OBJECTIVE

Lumbar segmental instability (LSI) is due to a pathologic movement of the vertebral body on the vertebra below and often causes clinical symptoms. The study was to achieve the research progress of diagnosing methodology for lumbar segmental instability and help clinicians make treatment choices.

METHODS

The data for this study were collected from the MEDLINE, Springer, Web of Science, PubMed, EMBASE, the Cochrane Central Register of Controlled Trials, Evidence Based Medicine Reviews, VIP, and CNKI. The search terms were integrated as follows: "(∗lumbar instability∗ OR ∗lumbar spondylolisthesis∗) and (∗image∗ or ∗diagnosis∗)". Studies without clear radiographic instable criteria, case reports, letter, and basic research were excluded.

RESULT

In total, 39 articles published met our inclusion criteria. The various modalities were used to diagnosis LSI in these studies included radiographs, facet joint degeneration and physical examination tests.

CONCLUSION

Overall, there have been a variety of researches to develop the diagnosing methodology for LSI, and many have been successful, although no consensus has been reached yet. However, it is believed that the diagnosis of LSI will become easier and more accurate in the near future.

An Omitted Radiological finding in the Pediatric Age Group: Physiological Sacroiliac Joint Vacuum Normal Variant

INTRODUCTION

Gas accumulation in human joint spaces has been generally described as the vacuum phenomenon (VP). To date, the sacroiliac joint VP has been associated mostly with pathological, particularly degenerative conditions (e.g., arthritis, obesity, discal degenerations, fractures, dislocations, avascular necrosis).

OBJECTIVE

The study aimed to examine the characteristics of the physiological form of VP and its radiological patterns in a sample of pediatric patients.

METHODS

A sample of seventy patients between 0 and 17 years old (mean age, 11.4 ± 5.54) were included in the study. Sample VP cases was evaluated according to types, age group, anatomic localization, gender, and sides. RESULTS: Two (2.9%) of sample children had degenerative VP, with 24 (34.2%) of patients demonstrating physiological VP in the sacroiliac joints. VP rates significantly increased after nine years of age (p < 0.01) and 83% of physiological VP cases were determined to be bilateral.

CONCLUSIONS

Although degenerative VP is a rare entity in children, non-pathological VP can be a more common aspect of sacroiliac anatomy. Although sacroiliac VP is frequently an underreported or omitted finding in imaging studies, this condition may be clinically important as a clue for other degenerative diagnoses. Normal variants of VP may be clinically important in children since they may mimic inflammatory and infectious pathologies during magnetic resonance imaging and computed tomography images.

A less invasive treatment by a full-endoscopic spine surgery for adjacent segment disease after lumbar interbody fusion

Background

Full-endoscopic spine surgery (FESS) is a suitable treatment for lumbar disc herniation (LDH) and foraminal stenosis. This study investigated the usefulness of FESS in treating adjacent segment disease (ASD) after lumbar interbody fusion (LIF).

Methods

Between September 2015 and March 2019, a total of 13 patients with symptomatic ASD after LIF underwent FESS. Discectomy and foraminoplasty using a 3.5-mm diameter high-speed drill were performed for treating LDH and foraminal stenosis. Preoperative and postoperative statuses were evaluated using Numerical Rating Scale (NRS) and the modified Japanese Orthopedic Association (mJOA) scores.

Results

The patients' mean age was 64.8 years; there were 10 male and 3 female patients. The mean operative time was 52.7 min. The mean pre- and postoperative NRS scores were 7.6 and 3.1, respectively. The mean pre- and postoperative mJOA scores were 10.5 and 16.1, respectively, and the mean recovery rate was 32.8%. Subsequent operative treatments were required in 3 patients for postoperative complication, insufficient decompression, and recurrence LDH.

Conclusions

FESS is a safe and effective minimally invasive treatment for ASD after LIF and a potential alternative to extend the LIF to the adjacent vertebra or sacrum.