Sternal instability following coronary artery bypass grafting

Several cases of sternal instability have been noted in patients following coronary artery bypass graft surgery attending our cardiac rehabilitation programme. The purpose of this prospective study was to identify factors associated with sternal instability following sternotomy involving saphenous vein grafts (SVG) and unilateral or bilateral internal mammary artery (IMA) grafts. A rating scale for quantifying sternal instability was developed and used by the physiotherapists to assess all patients. Inter-therapist and intra-therapist reliabilities for the scale were calculated and these were 0.97 and 0.98 (ICC) respectively. Twenty-four patients who underwent coronary artery bypass grafting with a sternotomy incision presented with the complication of sternal instability 6-8 weeks following surgery. They represented 16.3% of the 147 patients presenting for cardiac rehabilitation who had undergone surgery interstate over an 18-month period. Sternal symptoms reported were pain, crepitus, and/or clicking at rest or on trunk and upper limb motion. Risk factors to wound healing such as obesity, diabetes, bilateral IMA grafting, osteoporosis, repeat operations, and prolonged post-operative mechanical ventilation were noted. A significantly higher proportion of patients with bilateral IMA grafting (31.5%) as opposed to unilateral IMA grafting (14.3%) had sternal instability (P <. 05). Quantifying the degree of sternal instability may play a role in identifying management options, patient progression and the point of intervention.