So sorry to hear of these problems. I have heard of them before. I do know that people with diabetes, or who are obese, are more susceptible to separation of the sternum.
There is lots of information on the web about this subject. If they have to, I think they can put in a metal plate!
Here is an excerpt I found with a doctor answering questions about sternal healing and separation:
Response to questions by Dr.J.F.Morin
Chest Pain Post open Heart Surgery
Most patients undergoing open heart surgery for a congenital defect, valve repair or replacement or coronary artery bypass will have incisional pain that subsides gradually over the first month post-surgery. This pain is aggravated by coughing, sneezing, rotation of the chest or elevation of the arms. Due to the fact that they lie on their back for quite a while (4-5 hours in the operating room and 12-24 hours in the intensive care unit) the patients complain of thoracic and lumbar back pain that resolves within two to three weeks. Shoulder pain irradiating to the arms and fingers is not unusual. This is related to over stretching of brachial nerves while opening the sternum to perform the surgery. The incisional sternal pain is described as an ache. Many patients report a sensation of numbness on the left side of their chest which results from the dissection of the internal mammary artery. Some patients can barely wear a shirt for a few weeks following their surgery due to a hyperesthesia over their sternal skin. Fortunately, all these malaises subside within 1 or 2 months post surgery.
In a small number of cases, the sternal pain is out of proportion or persists beyond the expected recovery period. In these patients, a wound complication such as sternal dehiscence or infection has to be ruled out. Sternal dehiscence and/or infection is rare (2-5%) but dreadful for the surgeon and patient. Dehiscence of the sternum is usually, but not necessarily, secondary to infection. The infection prevents the bone healing process and leads to mediastinitis and sternal instability. These patients are usually septic and require urgent debridement of the infected and necrotic bone and reclosure of the sternum and/or a muscle flap to cover the bone defect. Some predisposing factors leading to this complication have been identified such as obesity, diabetes, patients with chronic obstructive pulmonary disease requiring prolonged ventilation post-operatively and patients where both mammary arteries were used. In older patients with osteoporotic bone, the sternal wires may cut through the bone and lead to dehiscence without fever. These patients complain of "clicking" sternum or sternal pain while turning, coughing or elevating their upper extremities. This pain is bearable but annoying for most patients. One option for the patient is to live with this unstable sternum. The pain subsides with time but may come back while the patient is participating in strenuous exercise. However, this condition never compromises the cardiac or pulmonary function of the patient. the other option is to rewire their sternum. Occasionally, the persistent pain arise from non-union of a broken rib, dislocation of a costo-chondral junction, or a subcutaneous stitch or wire. Other causes have to be ruled out in cases of persistent chest pain post open heart surgery. A small proportion of patients (10%) have closure of a coronary artery graft with recurrent angina. This condition is usually quite well identified by the patient who experiences the same kind of pain as before surgery.
On rare occasions, especially in-patients with atypical angina symptoms, the patient may have an unrecognized lung, gastroesophageal or psychosomatic disorder. A few weeks post surgery, some patients present post-cardiotomy syndrome (Dressler's Syndrome) manifested by pleuretic chest pain (pain with deep breathing), fever, fatigue and pleural and/or pericardial rub on auscultation. This inflammatory process resolves spontaneously within a few weeks in most patients. On occasions, they may require antiflammatory drugs to relieve their symptoms.
The most difficult situation is when a patient has chronic sternal pain and all other conditions have been ruled out. In my practice, I have a patient that I have been following for the past 2 years for continuous sternaI pain post coronary artery bypass surgery. He has been taking pain killers (codeine) regularly without great relief. Local anesthesia (tested of the sternal skin did not help much. The pain clinic was unsuccessful (biofeedback) in controlling the pain, and suggested long term pain killer intake. A CAT scan of the chest and gallium scans when repeated were negative. Removal of the sternal wires did not help. the only option left, if the patient cannot tolerate the pain, might be removal of the sternum! I am not too keen in doing so......