How Is the Sternum Closed After Open Heart Surgery?

After open heart surgery, the sternum is most commonly closed with stainless steel wires that loop around or through the bone and are twisted tight to hold the two halves together while they heal. This wire closure technique has been the standard since the early decades of modern cardiac surgery, and it remains the most widely used method worldwide. But wire closure is not the only option, and the choice of technique matters more than many patients realize, particularly for people at higher risk of complications.

Why the Sternum Needs to Be Split in the First Place

A median sternotomy, the vertical cut down the center of the breastbone, gives the surgeon the widest and most direct access to the heart. It remains the most common approach for coronary artery bypass grafting, valve replacements, and many other cardiac procedures. The sternum is divided using a specialized oscillating saw, then a retractor holds the two halves apart for the duration of the operation. Once the heart work is done and all bleeding is controlled, the surgeon needs to bring those halves back together precisely enough for the bone to fuse over the following weeks and months.

In some cases, minimally invasive alternatives avoid a full sternotomy altogether. A J-shaped upper mini-sternotomy, for example, uses a much smaller incision and splits only part of the breastbone. This approach is well established for aortic valve replacement and produces outcomes comparable to full sternotomy.¹ But for the majority of open heart operations, a full median sternotomy is still the go-to, and closing it properly is a critical final step.

Stainless Steel Wires and How They Are Applied

The original sternal closures used thick braided sutures, but surgeons moved to stainless steel wire because braided material was thought to carry a higher infection risk.² Wire closure has been the backbone of sternotomy technique ever since. The surgeon typically drills or passes six to eight individual wires through or around the sternum at intervals along its length, then twists them snugly to compress the two bone halves together. The twisted ends are tucked down flat against the bone so they do not poke into overlying tissue.

Two main wire patterns are used. Simple interrupted wires pass in a single loop around the sternum at each point. Figure-of-eight wires cross over each other in an X pattern, theoretically distributing force over a wider area. Surgeons have debated for years which is better, but the evidence consistently shows no meaningful difference. A prospective randomized trial comparing the two in nearly 200 patients undergoing bypass surgery found an overall dehiscence rate of about 8%, with no significant difference between groups.³ A separate review reached the same conclusion: the figure-of-eight technique is not superior to simple wires.⁴ In practice, many surgeons use whichever pattern they trained on, or combine both in a single closure.

Rigid Plate Fixation

If you have ever seen plates and screws used to fix a broken arm, rigid sternal fixation works on the same principle. Small titanium plates are screwed directly into the bone on either side of the cut, locking the halves together far more rigidly than wire can. This approach has gained ground over the past two decades, especially for patients considered high risk for wire failure.

The clinical evidence favoring plates is striking. One retrospective study found that plate fixation cut the sternal dehiscence rate to about 3% compared with roughly 12% for wire closure, and patients went home about a day and a half sooner.⁵ In another study, rigid fixation was the strongest predictor of shorter time on the ventilator and shorter ICU stays, even after controlling for other factors.⁶ A cost-benefit analysis found that all 37 readmissions for sternal wound complications during the study period occurred in the wire group, none in the plate group, despite the plate patients actually being heavier and having more diabetes.⁷

When rigid fixation was combined with an enhanced recovery protocol at one institution, over 93% of patients went home directly rather than to a rehabilitation facility, compared with about 66% for standard wire closure without the protocol.⁸ The plates cost more upfront, which is the main reason they are not yet universal. But the savings from fewer complications and shorter hospital stays appear to offset that cost, and adoption has been growing steadily.

Nitinol Clips and Other Newer Approaches

Between traditional wires and rigid plates, a middle tier of closure devices has emerged. One of the more interesting is the nitinol clip, made from a nickel-titanium alloy that has a “shape memory.” The clips are cooled below 10°C, which makes them flexible and easy to position around the sternum. Once they warm to body temperature, they spring back to their original shape, gripping the bone tightly like a clamp.⁹

A study comparing nitinol clips to standard wires in over 1,100 patients found a slightly lower rate of deep sternal wound complications with the clips, though the difference was not statistically significant. What was notable: the two deaths from sternal wound complications both occurred in the wire group, with zero mortality in the clip group.¹⁰ These clips are more commonly used in Europe than in the United States.

Researchers have also experimented with absorbable mesh plates, which sit on the surface of the sternum and add stability while being gradually absorbed by the body. In testing, the mesh significantly reduced bone movement in multiple directions compared to wires alone.¹¹ These remain relatively niche, but they represent the ongoing push to find closure methods that are stronger, less prone to complications, and friendlier to the healing process.

The Bone Wax Problem

Before the sternum is closed, surgeons often need to control bleeding from the cut bone edges. For decades, the standard tool for this was bone wax, a waxy substance pressed into the marrow spaces to plug bleeding. The trouble is that bone wax does not dissolve. It sits in the bone permanently, blocking the cells responsible for bone regrowth and preventing the two halves from fusing properly at the wax-covered spots.

Research has confirmed that this is more than a theoretical concern. One study identified bone wax as an independent risk factor for sternal dehiscence, with the complication appearing more than twice as often in patients where it was used.¹² Residual bone wax has been found causing chronic inflammation up to ten years after surgery. Newer absorbable formulations are being developed that stop the bleeding just as effectively but are gradually absorbed by the body, allowing bone healing to proceed and potentially eliminating the infection risk associated with traditional wax.²

What Can Go Wrong

Sternal dehiscence, where the bone halves partially or fully separate, is the most feared mechanical complication. Deep sternal wound infection is the most feared infectious one, though the two often go hand in hand. A large prospective multicenter study found that about 2.3% of sternotomy patients developed a deep sternal wound infection. The strongest risk factors were obesity, reoperation, and the need for medications to support heart function after surgery.¹³

Using both internal mammary arteries for bypass grafts (rather than just one) also raises the risk of sternal wound problems, because harvesting those arteries reduces blood supply to the breastbone. A meta-analysis found that bilateral grafting roughly 1.5 times the odds of sternal wound infection compared with single-artery grafting, a risk that was even more pronounced in people with diabetes and in older patients.¹⁴ However, the technique used to harvest those arteries matters. “Skeletonizing” the artery, where the surgeon strips it cleanly from surrounding tissue rather than taking a wide pedicle, appears to cut the infection risk significantly.¹⁵ And long-term studies suggest that the survival advantage of using both arteries can outweigh the modestly higher wound risk, particularly in diabetic patients.¹⁶

When dehiscence does happen, it frequently shows up on chest X-rays before the patient develops obvious symptoms. In one study, wire abnormalities like displacement or rotation were visible on imaging in nearly 90% of dehiscence cases, and those radiographic signs preceded the clinical diagnosis about two-thirds of the time.¹⁷ This is one reason surgeons pay close attention to follow-up chest films, even when a patient feels fine.

Managing Sternal Wound Complications

If a deep sternal wound infection or mediastinitis develops, treatment has improved significantly. Vacuum-assisted closure therapy, which involves placing a sealed sponge dressing over the wound and applying negative pressure to draw out fluid and promote healing, has become a frontline treatment. One comparative study found that patients treated with vacuum-assisted closure had significantly shorter treatment times, shorter hospital stays, and lower in-hospital mortality compared with conventional wound management.¹⁸ In another series of complex post-cardiac-surgery wounds, vacuum therapy achieved complete healing in about 58% of cases within an average of roughly 25 days, though patients with advanced local infections required additional surgery and prolonged treatment.¹⁹

How Long the Sternum Takes to Heal

Bone healing after sternotomy is slower than many patients expect. A CT-based study tracking sternal fusion after bypass surgery found that at three months, not a single patient had achieved complete healing. By four to five months, only two patients out of the entire cohort had fully healed. At six months, roughly 35% of patients still showed poor healing, while just under 7% had complete fusion. The good news: on later scans, about 98% eventually achieved complete healing.²⁰

The healing also varied by location along the breastbone. The manubrium, the thicker upper portion, healed the most slowly, with nearly 73% of patients showing no healing there on early scans. The middle and lower sternum fused more reliably. This uneven healing pattern is one reason sternal precautions, which restrict activities that stress the chest, typically extend for six to eight weeks after surgery, even though patients often feel much better before then.

Sternal Precautions and Whether They Need Updating

If you have had open heart surgery, you were almost certainly told not to lift anything heavier than about 10 pounds for weeks afterward, and to avoid pushing, pulling, or reaching overhead with your arms. These “sternal precautions” have been standard advice for decades. But some of the research behind them suggests the picture is more nuanced than a blanket weight limit.

Studies measuring actual sternal movement during daily activities found that the activities producing the most bone separation were not overhead reaching but rather pushing up from a chair and transitioning from lying down to sitting up. Meanwhile, lifting a container weighing up to roughly a gallon of water produced very little sternal movement. Patients with chronic sternal instability reported pain far more often during one-armed, loaded activities (about 78% of the time) than during two-armed movements without weight (about 13%).²¹ Another study that directly measured skin deformation over the sternum during shoulder movements and upper extremity activities concluded that the data do not support restricting most shoulder movements and arm activities after cardiac surgery.²²

The practical takeaway for patients is that blanket rules like “nothing over 10 pounds” may be overly conservative for many activities while missing the movements that actually stress the sternum. Pushing yourself up from a bed or chair with your arms, for instance, is probably riskier than gently lifting a light bag of groceries with both hands. Some cardiac rehabilitation programs have begun shifting from rigid weight limits toward movement-based guidance, teaching patients which patterns of motion to avoid rather than just how many pounds they can lift.

Postoperative Support Vests

A thorax support vest, essentially a firm corset-like garment worn around the chest, is another tool that can improve outcomes after sternotomy. A randomized trial found that patients wearing a support vest had fewer mechanical sternal complications, better anatomical healing, shorter hospital stays, and no re-operations for dehiscence before discharge. They also reported less pain, with the benefit being most pronounced in patients under 70, in heavier patients, and in those who had both internal mammary arteries harvested.²³ Despite the evidence, support vests are not universally prescribed. Some institutions use them routinely; others only for high-risk patients. If you are preparing for open heart surgery and have risk factors like obesity or diabetes, asking your surgical team about a support vest is reasonable.

When the Sternum Is Left Open on Purpose

In some situations, particularly in children after repair of complex congenital heart defects, the surgeon deliberately does not close the sternum at the end of the operation. This is called delayed sternal closure, and it is done because closing the chest immediately can compress an already-struggling heart. Studies in pediatric patients have shown that closing the sternum reduces cardiac output by about 14% and drops blood pressure by about 7%, effects that a healthy adult heart can absorb but that a freshly repaired infant heart sometimes cannot.²⁴

When delayed closure is needed, the wound is covered with a synthetic membrane that is sutured to the skin edges, and the child is kept in the ICU with the chest open but sealed. Criteria for proceeding to definitive closure include stable heart function for at least 24 hours, normal clotting, balanced fluid status, and no acidosis. The actual closure then uses the same metal wires described earlier, placed through or around the sternum in the standard fashion.²⁵ While it sounds alarming, delayed sternal closure is a well-established strategy that has saved many lives in pediatric cardiac surgery.