Fatigue testing median sternotomy closures

Area of Science:

• Biomedical Engineering
• Surgical Innovation
• Materials Science in Medicine

Background:

• Sternal dehiscence, a serious complication, often results from sternal wire cutting through bone.
• Evaluating sternotomy closure techniques is crucial for improving patient outcomes and reducing surgical complications.

Purpose of the Study:

• To quantitatively assess and compare the rate of bone cutting for five distinct median sternotomy closure techniques.
• To identify superior closure methods that minimize sternal wire migration through bone.

Main Methods:

• A biological sheep sternum model was utilized to test standard steel wire, peristernal steel wire, figure-of-eight, polyester, and sternal band closure techniques.
• Fatigue testing was conducted using a computerized materials-testing machine, applying loads from 1 to 10 kg to measure displacement and calculate percentage cut-through.
• Paired adjacent bone samples were used to control for biological variability, with each closure method tested against standard closure.

Main Results:

• Peristernal (0.72 mm) and sternal band (0.66 mm) closures showed significantly less displacement than standard closure (0.22 mm).
• Polyester (1.01 mm) and figure-of-eight (0.52 mm) closures also exhibited significant differences in displacement compared to standard closure.
• Statistically significant differences in the percentage of bone cut-through were observed across all tested closure methods versus standard closure (ANOVA, P<0.001).

Conclusions:

• Peristernal and sternal band sternotomy closure techniques demonstrate significantly superior performance in preventing bone cutting compared to standard wire closure.
• The study quantifies the differing rates of bone cutting for various closure methods in a sheep sternum model.
• Caution is advised when using polyester and figure-of-eight closure techniques due to their bone-cutting characteristics.