Rib cage motion in ankylosing spondylitis patients: a pilot study

Abstract

Background Assessment of chest expansion is one of the measures of rib cage mobility recommended as “core set for assessing Ankylosing Spondylitis” (AS). A recently developed instrument for measuring respiratory movements is introduced. Purpose To compare chest and abdominal wall movements in AS patients with those of controls using a newly developed instrument. Study design A comparative study. Patient sample Fourteen male AS patients were invited to the study. All subjects answered a standardized questionnaire concerning general health. Outcome measures Body height and weight and respiratory movements. Methods Upper and lower chest wall and abdominal motion was measured bilaterally for a period of 1 minute during deep breathing by using a new instrument based on a laser technique, The Respiratory Movement Measuring Instrument (ReMo, Reykjavík, Iceland). Results were compared to healthy controls matched for age, gender, and body mass index. Results The patients' mean age was 47±9.5 years, and they had a history of AS for 13±6 years. Their mean BMI was 27±3.6. The respiratory movements of the upper thoracic level were significantly lower than in the reference group (right p=.01, left p=.05). They had, however, a normal range of lower thoracic and abdominal movement and their respiratory movement patterns were symmetrical. Conclusion The AS patients had reduced upper thoracic movements but normal lower thoracic and abdominal wall movements.