Understanding the biomechanics of midline sternotomy repair is important to successful surgical outcome. High-risk patients, particularly those with immunosuppression, diabetes, and osteoporosis, should be identified. Details of technique should be monitored, and closure should incorporate lateral support of the sternum in patients at risk. Sternal dehiscence can occur under physiologic loads. Closure techniques and materials should insure stable repair, with avoidance of material migration through the bone.