Study design: Test-retest repeated measures and correlational design.
Objectives: To examine the reliability and validity of a "modified" digital inclinometer to assess scapular upward rotation during humeral elevation in the scapular plane
Background: Evidence exists that scapular motion is related to shoulder pathology; however, evaluation and treatment planning for shoulder rehabilitation often fails to include an objective assessment of scapular motion.
Methods and measures: Two-dimensional measurements by the inclinometer were taken with the arm in a static position. These data were compared to 3-dimensional measurements obtained using a magnetic tracking device with the arm fixed and during arm movement. Both methods were used to assess scapular upward rotation positions with the arm at rest and at 60 degrees , 90 degrees , and 120 degrees of humeral elevation in the scapular plane. Both scapulae were tested on a total of 39 subjects, 16 with shoulder pathology and 23 without. Reliability was assessed using repeated measurements from the inclinometer. Validity was assessed using 2 separate comparisons: inclinometer and magnetic tracking device under static arm conditions and inclinometer and magnetic tracking device during active arm elevation. Reliability and validity were assessed at all 4 arm positions.
Results: Intraclass correlation coefficients (ICC [3,1]) varied from 0.89 to 0.96. Pearson Product Moment correlation coefficients, used to assess validity of the static inclinometer, varied from r = 0.74 to 0.92 compared with the static magnetic tracking measures, and from r = 0.59 to 0.73 compared with the active magnetic tracking measures taken during arm elevation.
Conclusions: The "modified" digital inclinometer demonstrated good to excellent intrarater reliability and good to excellent validity when measuring scapular upward rotation during static positions of humeral elevation in the scapular plane.