Temporal Trends in Vertebral Dimensions - a case study from Finland

Association between vertebral cross-sectional area and lumbar disc displacement - a population-based study

PURPOSE

Vertebral dimensions may constitute a potential risk factor for degenerative changes in the spine. Previous studies have found a positive association between vertebral height and both type 2 Modic changes and intervertebral disc height loss. Also, vertebral endplate size has been associated with disc degeneration. However, only a few studies have investigated the association between vertebral dimensions and lumbar disc displacement (LDD). This study aimed to investigate the association between vertebral cross-sectional area (CSA) and LDD among the general middle-aged Finnish population. We hypothesized that larger vertebral CSA is associated with LDD.

MATERIALS AND METHODS

The study was conducted by using data from the Northern Finland Birth Cohort 1966 (NFBC1966). At the age of 46, a subpopulation of NFBC1966 underwent clinical examinations including magnetic resonance imaging (MRI) (n = 1249). MRI scans were used to measure L4 CSA and evaluate the presence of LDD (bulge, protrusion, and extrusion/sequestration) in the adjacent discs. The association between L4 CSA and LDD was analysed using logistic regression, with adjustment for sex, education, body mass index, leisure-time physical activity, smoking, diet, and L4 height.

RESULTS

Larger L4 CSA was associated with LDD; an increase of 1 cm2 in vertebral CSA elevated the odds of LDD relative to no LDD by 10% (adjusted odds ratio 1.10, 95% CI 1.01-1.19). The association was similar among either sex.

CONCLUSIONS

Larger L4 vertebral CSA was associated with LDD in our study sample. Even though smaller vertebral size exposes our vertebrae to osteoporotic fractures, it simultaneously seems to protect us from LDD.

Prediction of lumbar disc herniation resorption in symptomatic patients: a prospective, multi-imaging and clinical phenotype study

BACKGROUND CONTEXT

Symptomatic lumbar disc herniations (LDH) are very common. LDH resorption may occur by a "self-healing" process, however this phenomenon remains poorly understood. By most guidelines, if LDH remains symptomatic after 3 months and conservative management fails, surgical intervention may be an option.

PURPOSE

The following prospective study aimed to identify determinants that may predict early versus late LDH resorption.

STUDY DESIGN/SETTING

Prospective study with patients recruited at a single center.

PATIENT SAMPLE

Ninety-three consecutive patients diagnosed with acute symptomatic LDH were included in this study (n=23 early resorption and n=67 late resorption groups) with a mean age of 48.7±11.9 years.

OUTCOMES MEASURE

Baseline assessment of patient demographics (eg, smoking status, height, weight, etc.), herniation characteristics (eg, the initial level of herniation, the direction of herniation, prevalence of multiple herniations, etc.) and MRI phenotypes (eg, Modic changes, end plate abnormalities, disc degeneration, vertebral body dimensions, etc.) were collected for further analysis. Lumbar MRIs were performed approximately every 3 months for 1 year from time of enrollment to assess disc integrity.

METHODS

All patients were managed similarly. LDH resorption was classified as early (<3 months) or late (>3 months). A prediction model of pretreatment factors was constructed.

RESULTS

No significant differences were noted between groups at any time-point (p>.05). Patients in the early resorption group experienced greater percent reduction of disc herniation between MRI-0-MRI-1 (p=.043), reduction of herniation size for total study duration (p=.007), and percent resorption per day compared to the late resorption group (p<.001). Based on multivariate modeling, greater L4 posterior vertebral height (coeff:14.58), greater sacral slope (coeff:0.12), and greater herniated volume (coeff:0.013) at baseline were found to be most predictive of early resorption (p<.05).

CONCLUSIONS

This is the first comprehensive imaging and clinical phenotypic prospective study, to our knowledge, that has identified distinct determinants for early LDH resorption. Early resorption can occur in 24.7% of LDH patients. We developed a prediction model for early resorption which demonstrated great overall performance according to pretreatment measures of herniation size, L4 posterior body height, and sacral slope. A risk profile is proposed which may aid clinical decision-making and managing patient expectations.