Skin deformation during shoulder movements and upper extremity activities.

BACKGROUND

The necessity of sternal precautions for patients following cardiac surgery with median sternotomy has been questioned by clinicians, researchers, and even patients. The primary purpose was to determine if sternal skin deformation during shoulder movements and upper extremity activities is compressive or distractive and if there are any significant differences between the skin deformation at different positions during shoulder movements and upper extremity activities. The secondary purpose was to determine if sternal skin deformation is correlated with scapular stabilizer muscle strength.

METHODS

The research design was a cross-sectional non-experimental descriptive study. A 3D electromagnetic tracking system was used to measure sternal skin deformation quantified by strain.

FINDINGS

The sternal skin strain was -10.8 (SD 6.2) % and -9.8 (SD 6.1) % at 90 and 180° flexion (P=0.45), -2.7 (SD 3.4) % and -10.4 (SD 7.9) % at 90 and 180° abduction (P<0.01), -3.6 (SD 4.1) %, -4.9 (SD 6.4) %, and -6.8 (SD 5.2) % when lifting 0, 5, and 10lb weights (P=0.07), 0.7 (SD 2.5) % for extension, and -1.1 (SD 5.0) % for pushing up from a chair. There is a trend of strain magnitude decrease with the increase of rhomboid strength without significant association (R=0.14).

INTERPRETATION

Our data does not support the restriction for most of the shoulder movements and upper extremity activities following cardiac surgery. The only exception is bilateral shoulder extension. We propose a strategy for preoperative physical therapy to stabilize scapular muscles to decrease mechanical loading translated from shoulder to sternum.