Relationship between Functional Disability and Bone Loss in Spondyloartropathy Patients

Objective: To determine the relationship between bone mineral density (BMD) and functional status of spondyloarthropathy (SpA) patients. Methods: BMD (g/cm ) of 139 SpA patients was determined at the lumbar spine and the upper part of the left and right femur by dual energy X-ray absorptiometry (DXA). The functional disability in patients with SpA was assessed using the Bath Ankylosing Spondylitis Functional Index (BASFI), the Bath Ankylosing Spondylitis Patient Global Assessment (BAS-G), the Health Assessment Questionnaire Modified for the SpA (HAQ-S); spinal mobility by measuring metrology indices (tragus-to wall distance, lateral flexion, modified Schober’s distance, and intermalleolar distance). Physical activity was measured by amount of time spent exercising per week. In order to find out whether there was a relationship between functional indices and BMD linear regression stepwise selection was employed. Results: No significant association between frequency of exercise and BMD was detected in SpA patients. Femur BMD was associated with BASFI, HAQ-S and all components of metrology indices, except for tragus to wall distance for left femur. Significant decreases of right and left femur BMD, except for the spine BMD, were associated with cases of severe impairment of lumbar side flexion, and impairment of modified Schober’s test and intermalleolar distance. Spinal BMD was associated only with HAQ-S. Conclusions: Femur BMD of SpA patients was found to be associated with both subjective (BASFI, HAQ-S) and objective (tragus to wall distance, lumbar side flexion, modified Schober’s test and intermalleolar distance) functional indices. Prevention of bone loss of SpA patients relies upon preservation and control of functional status of the patient.