Rib cage motion in ankylosing spondylitis patients: a pilot study

Spine J. 2008 May-Jun;8(3):505-9. doi: 10.1016/j.spinee.2006.12.009. Epub 2007 Feb 20.


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.

MeSH terms

  • Abdominal Wall / physiopathology
  • Diagnostic Techniques, Respiratory System / instrumentation*
  • Humans
  • Lasers
  • Male
  • Middle Aged
  • Monitoring, Physiologic / instrumentation*
  • Monitoring, Physiologic / methods
  • Motion
  • Pilot Projects
  • Respiratory Mechanics / physiology*
  • Spondylitis, Ankylosing / physiopathology*
  • Thoracic Wall / physiopathology*