engleski

Problem of structure and strength of the sternum in cardiac surgery median sternotomy

Median sternotomy is the most used operative approach in cardiac surgery. Sternum dehiscence is a rare, but very hard complication accompanied by high mortality rate. The properties of sternum are a very important factor in developing sternal dehiscence. We investigated the structure and strength of the sternum. We also constructed a machine for dynamic testing of suture and serklage after cardio-surgical median sternotomy. Research was done on 96 cadaveric sternums. The samples were from persons of both sex, mainly from elderly people. Morphometric analysis was performed. Sternum mineral density was determined by using radiographic absorptiometry with aluminium step-wedge and using dual energy X-ray absorptiometry. Median sternotomy and serklage with steel wires were made on five sternums using different techniques. Special machine was constructed for the dynamic testing of median sternotomy serklage. Toughness of the sternum, divided into six pieces, was determined by Charpy pendulum. Real mineral density was detected by measuring volume of the samples and then by ashing. There are great variations in mineral density (range 105-280 g/cm3) and toughness (range 12-45 J/cm2) of sternums, specially dependent on sex and age. Results suggest that osteoporotic process occurs on the sternum. Maps of regional mineral density and toughness have been achieved. Morphometric analysis resulted in classification of the sternum shapes. Sternum properties are important in estimating the risk of sternal dehiscence after cardio-surgical median sternotomy. Testing median sternotomy serklage and suture using dynamic model simulates similar physiological conditions. This method is useful in testing different closure tehniques.

sternum ; sternotomy ; biomechanics

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