The correlation between volumetric bone mineral density and morphological parameters of the proximal femur and clinical outcomes in ankylosing spondylitis patients with hip involvement

Use of double-echo ultrashort echo time magnetic resonance imaging to assess proximal femoral cortical bone changes in axial spondyloarthritis

OBJECTIVE

We quantitatively evaluated proximal femoral cortical bone changes associated with generalized bone loss in axial spondyloarthritis (axSpA) patients using double-echo ultrashort echo time (UTE) MRI. To achieve non-radiation, clinically available visualization of cortical microstructural deterioration in the proximal femur of axSpA and to determine the factors influencing it.

MATERIALS AND METHODS

Patients with axSpA (n = 83) and age- and sex-matched healthy controls (n = 61) were recruited and underwent double-echo UTE MR scan of the nondominant proximal femur. Porosity index (PI) and cortical bone thickness (CbTh) were measured by two radiologists and their average measurements were used for subsequent analyses. Additionally, demographic characteristics of all subjects and disease-specific characteristics of axSpA patients were recorded. Proximal femoral cortical bone PI and CbTh values were compared between axSpA patients and healthy controls using independent samples t-test. Correlation analyses (Pearson or Spearman or Point-biserial correlation coefficients) were conducted to investigate factors potentially associated with UTE measurements in axSpA patients, and Bonferroni correction was applied at the α = 0.002 level for more stringent correction. Multiple linear regression analyses were performed to further identify influencing factors of UTE measurements with multiple correlated variables.

RESULTS

A total of 72 axSpA patients and 52 healthy control subjects were finally included. Patients and control subjects were comparable in sex, age, and body mass index (BMI). Proximal femoral cortical PI was higher (p < 0.001) and CbTh was lower (p < 0.001) in axSpA patients than in healthy controls. Sex (p < 0.001), BMI (p = 0.003), disease duration (p = 0.044), onset age (p = 0.01), alkaline phosphatase (ALP) (p < 0.001), radiographic axSpA (r-axSpA) (p = 0.02), Sacroiliac Joint Structural Score (SSS)-backfill (p = 0.03), SSS-ankylosis (p = 0.01), and nonsteroidal anti-inflammatory drugs (NSAIDs) use (p = 0.03) were potentially correlated to proximal femoral cortical PI, and among them, sex (p < 0.001) and BMI (p = 0.01) were independently associated demographic characteristics, and ALP (p = 0.02), SSS-backfill (p = 0.044) and SSS-ankylosis (p = 0.01) were independently associated disease-specific characteristics, and when all types of variables were considered, sex (p < 0.001), BMI (p = 0.016), and SSS-ankylosis (p = 0.042) were independently associated with PI. BMI (p = 0.043) and NSAIDs use (p = 0.041) were potentially negatively associated with CbTh.

CONCLUSION

Double-echo UTE measurements revealed deteriorated proximal femoral cortical bone microstructure in axSpA patients than controls, potentially associated with sex, BMI, disease duration, onset age, ALP, r-SpA, SSS-backfill, SSS-ankylosis, and NSAIDs use, where sex, BMI, ALP, SSS-backfill and SSS-ankylosis were the independently relevant factors. It offers a novel tool for axSpA's cortical bone assessment.

The state of bone mineral density in men with ankylosing spondylitis and its relationship with the course of the disease

Introduction

The aim of the study was to study the structural and functional state of bone tissue in men with ankylosing spondylitis (AS) and to assess its relationship with the course of the disease.

Material and methods

A study was conducted with the participation of 105 men with AS aged from 22 to 59 years (average age was 40.7 ±0.8 years) with a duration of the disease of 8.7 ±0.5 years and 29 persons of the control group. Disease activity and the degree of functional limitations were determined by the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Ankylosing Spondylitis Activity Score correlated with C-reactive protein (ASDAS-CRP) and the Bath Ankylosing Spondylitis Functional Index (BASFI). Laboratory examination included determination of C-reactive protein (CRP). Bone mineral density (BMD) of the lumbar spine and femoral neck was determined by the method of dual-energy X-ray absorptiometry on the Hologic Discovery Wi device (S/N 87227).

Results

In men with AS, a decrease in BMD (according to the Z-score and T-score) was found in 41.9%, while the percentage of patients with osteoporosis at the level of the femoral neck and lower back was 16.7%. Development of osteoproliferative changes was observed in 42 (40%) patients. Bone mass loss was associated with high activity of the inflammatory process according to ASDAS, BASDAI (r = -0.39, -0.65), and CRP (r = -0.28, -0.38) and low functional capacity according to BASFI (r = -0.27, -0.59), while syndesmophytosis had a reliable association with the age of the patients, the duration of the disease and low functional capacity. Low-energy fractures occurred in 11.4% of men with AS. The presence of fractures was associated with high disease activity (ASDAS, BASDAI, CRP) and was not related to the age of the patients or duration of the disease.

Conclusions

A decrease in BMD and the development of fractures were closely associated with high activity of the inflammatory process and low functional capacity, while syndesmophytosis was related to the age of patients and the duration of the disease.