The incidence and risk factors for adjacent vertebral fractures in community-dwelling people with prevalent vertebral fracture: the 3rd and 4th survey of the ROAD study

Lumbar Disc Degeneration and Vertebral Fracture at the Thoracolumbar Junction Are Risk Factors for Chronic Low Back Pain With Disability: Seven Years' Follow-Up of the Wakayama Spine Study

Introduction Low back pain (LBP) is the leading cause of disability worldwide, with its burden increasing in aging societies such as Japan. Although degenerative spinal changes like lumbar disc degeneration (DD), vertebral fractures, and lumbar spinal stenosis (LSS) are frequently identified on MRI, their combined longitudinal impact on disabling chronic low back pain (DCLBP) remains unclear. The aim of this study was to identify baseline MRI-detected lumbar spinal changes that independently predict disabling chronic low back pain in a general Japanese population. Methods This population-based longitudinal study included 663 community-dwelling Japanese adults from the Wakayama Spine Study, a sub-cohort of the nationwide Research on Osteoarthritis/Osteoporosis Against Disability (ROAD) study. Baseline whole-spine MRI and clinical assessments were conducted between 2008 and 2009, with a seven-year follow-up from 2015 to 2016. MRI findings included Pfirrmann-graded lumbar DD, Genant-graded vertebral fractures at T11-L1, and Suri-graded LSS. The primary outcome was DCLBP, defined as LBP lasting more than three months and an Oswestry Disability Index (ODI) score ≥21%. Multivariate logistic regression was used to identify independent predictors of DCLBP. Results Of 653 participants who completed follow-up with valid ODI responses, 91 (13.9%) had DCLBP. Older age (OR: 1.07 per year, p < 0.0001), female sex (OR: 3.69, p < 0.0001), higher BMI (OR: 1.11 per kg/m², p < 0.0001), greater vertebral fracture burden (OR: 1.32 per grade point, p = 0.0024), and more severe lumbar DD (OR: 1.14 per grade point, p = 0.0305) were independently associated with DCLBP. Conclusion Lumbar DD, vertebral fractures at T11-L1, and LSS are independent risk factors for disabling chronic LBP in the general population. These findings underscore the importance of comprehensive MRI-based spinal assessment in identifying high-risk individuals for early intervention in aging societies.

Association Between Paravertebral Muscle Mass and Improvement in Sagittal Imbalance After Decompression Surgery of Lumbar Spinal Stenosis

STUDY DESIGN

Retrospective observational study.

OBJECTIVE

This study examined associated factors for the improvement in spinal imbalance following decompression surgery without fusion.

SUMMARY OF BACKGROUND DATA

Several reports have suggested that decompression surgery without fusion may have a beneficial effect on sagittal balance in patients with lumbar spinal stenosis (LSS) through their postoperative course. However, few reports have examined the association between an improvement in sagittal imbalance and spinal sarcopenia.

METHODS

We retrospectively reviewed 92 patients with LSS and a preoperative sagittal vertical axis (SVA) more than or equal to 40 mm who underwent decompression surgery without fusion at a single institution between April 2017 and October 2018. Patients' background and radiograph parameters and the status of spinal sarcopenia, defined using the relative cross-sectional area (rCSA) of the paravertebral muscle (PVM) and psoas muscle at the L4 caudal endplate level, were assessed. We divided the patients into two groups: those with a postoperative SVA less than 40 mm (balanced group) and those with a postoperative SVA more than or equal to 40 mm (imbalanced group). We then compared the variables between the two groups.

RESULTS

A total of 29 (31.5%) patients obtained an improved sagittal imbalance after decompression surgery. The rCSA-PVM in the balanced group was significantly higher than that in the imbalanced group (P = 0.042). The preoperative pelvic incidence (PI)-lumbar lordosis (LL) mismatch (P = 0.048) and the proportion with compression vertebral fracture (P = 0.028) in the balanced group were significantly lower than those in the imbalanced group. A multivariate logistic regression analysis identified PI-LL less than or equal to 10° and rCSA-PVM more than or equal to 2.5 as significant associated factor for the improvement in spinal imbalance following decompression surgery.

CONCLUSION

A larger volume of paravertebral muscles and a lower PI-LL were associated with an improvement in sagittal balance in patients with LSS who underwent decompression surgery.Level of Evidence: 3.

Effects of Location and Volume of Intraosseous Cement on Adjacent Level of Osteoporotic Spine Undergoing Kyphoplasty: Finite Element Analysis

OBJECTIVE

Kyphoplasty (KP) is a surgery used to reduce pain and increase stability by injecting medical bone cement into broken vertebrae. The purpose of this study was to determine the ideal amount of cement and injection site by analyzing forces with the finite element method.

METHODS

We modeled the anatomical structure of the vertebra and injected the cement at T12. By increasing the amount of cement from 1 cc to 22 cc, stress applied to T11 and L1 cortical was calculated. In addition, stress applied to the adjacent KP level was calculated with different injection sites (medial, anterosuperior, posterosuperior, anteroinferior, and posteroinferior). After 5 cc cement was inserted, adjacent end plate stress was analyzed.

RESULTS

In this study, break point adjacent bone stress according to the capacity of cement was bimodal. Flexion/extension and lateral bending conditions showed similar break points (11.5-11.7 cc and 18.5-18.6 cc, respectively). When cement injection was changed, front under and back under had the highest stress values among various parts, whereas the center position showed the lowest stress value.

CONCLUSIONS

With increasing amount of bone cement, stress on the upper and lower end plates of the cemented segment increased significantly. Thus, increasing cement amount to be more than 11.5 cc has a potential risk of adjacent fracture. Centrally injected bone cement can lower the risk of adjacent fracture after percutaneous KP.