Sternal Dehiscence Reconstruction 

Updated: Jul 06, 2020
Author: Mark A Grevious, MD, FACS; Chief Editor: Jorge I de la Torre, MD, FACS 

Overview

Background

In 1957, the introduction of the median sternotomy to allow access to intrathoracic organs by Julian et al revolutionized the field of thoracic surgery. Since this landmark introduction, sternal wound infection and dehiscence have been reported to occur in approximately 0.5-8.4% of cases. Sternal dehiscence is the process of separation of the bony sternum, which often is accompanied by mediastinitis (infection of the deep soft tissues). In thoracic and trunk reconstruction, plastic surgeons play a crucial role in addressing wound healing issues and reconstructive techniques of the chest wall. The management of chest wall reconstruction from sternal dehiscence has evolved considerably over the past half century.[1]

History of the Procedure

After introduction of the midline sternotomy into clinical practice, sternal infection rates began to rise; this was directly associated with high complication rates. Initially, sternal dehiscence was treated conservatively with open drainage and debridement with packing. Complications included graft exposure, desiccation of wound margins, osteomyelitis, and, ultimately, death. These complications often led to significant morbidity, with reported mortality rates exceeding 50%. Shumaker and Mandelbaum introduced the concept of closed management with catheter-antibiotic irrigation in 1963.[2] This reduced mortality rates from 50% to 20% overall. Despite this dramatic reduction, catheter-induced erosion of major vessels and resultant fatal hemorrhage was a major risk. Thus, incentive to improve methods of wound care continued.

One of the most common reasons for mediastinal infections, and ultimate sternal dehiscence, is sternal instability. Following a sternotomy, the structural integrity of the sternum is significantly compromised. This explains the importance for the surgeon to take time and use meticulous technique when performing a sternotomy. If a midline sternotomy is not placed properly, sternal instability is almost certain to follow, and the patient is at a much higher risk for mediastinitis.

The management of sternal wounds

Managing infected sternal wounds changed with the introduction of the principles of wide debridement and muscle and myocutaneous flap transposition. This management strategy of sternal wound infections was instituted in 1976, when Lee et al introduced the concept of reducing dead space in the anterior mediastinum by using a greater omental flap.[3, 4] In 1980, Jurkiewicz et al introduced the concept of muscle and myocutaneous flaps, which dramatically improved effectiveness of management of sternal dehiscence and infection.[5] Mathes also contributed with the concept of using muscle flaps in wounds with osteomyelitis.[6]

The use of vascularized regional tissue allowed for greater blood flow, obliteration of dead space, and faster healing time directly from quicker infection resolution. Since the introduction of the omental flap, several other flaps have been introduced to repair chest wall defects. The institution of flaps have led to a decrease in mortality rate of 10%.

Despite these advances, sternal infection and mediastinitis continue to pose clinical management issues. Currently, management of sternal wounds involves a multidisciplinary approach. Time-sensitive, nonsurgical management techniques include early debridement, microbiological analysis, and broad-spectrum antibiotics. Soft tissue flaps do not address repair of the bony sternum, which can lead to chronic pain, paradoxical motion, impaired pulmonary function testing, and cosmetic disapproval from the patient. A relevant development to sternal wound issues has been the development of vacuum-assisted closure devices (VAC) by Argenta and Morykwas, which serve as a bridge between debridement and reconstruction.[7]

A broad range of surgical strategies are currently being used including myo/myocutaneous flaps. In order to address the issue of bony sternal repair, several institutions are now turning toward sternal rewiring and reconstruction with rigid sternal fixation using transverse and longitudinal plates.[8, 9, 10, 11, 12, 13, 14, 15] Additionally, a sternal clamp device, to reduce sternal instability, has now been introduced into the market with promising results, although long-term clinical data are not yet available.

Problem

Problems associated with sternal dehiscence include issues both before and after debridement. Predebridement issues include frank infection and bony destruction of the sternum. Postdebridement issues include possibly sternal instability, paradoxical motion, and pain.

Epidemiology

Frequency

Current literature reflects that anywhere from 0.5-8.4% of median sternotomy incisions are complicated with wound infections, leading to sternal dehiscence.[9, 12, 13] With the introduction of flaps to cover sternal defects, mortality rate from sternal wound dehiscence is approximately 10%.[9, 12, 13] Long-term mortality studies following rigid fixation have yet to be reported.

Etiology

Factors associated with sternal wound dehiscence

Many mechanisms have been proposed to explain the development of sternal wound infection and dehiscence. These theories include inadequate sternal fixation leading to instability and dehiscence of the overlying skin incision and inadequate surgical drainage. Further theories suggest a localized ischemic osteomyelitis. This theory suggests that sternal wires become loose, leading to sternal instability, which ultimately leads to skin dehiscence and osteomyelitic infection.[16] The most commonly cultured organism is Staphylococcus Aureus.

Several retrospective and prospective studies have identified factors relating to increasing risk of sternal dehiscence. Patient risk factors include obesity, diabetes mellitus, chronic obstructive lung disease (COPD), chronic cough from tobacco abuse, steroid therapy, hypertension, immunosuppression, and advanced age. Other risk factors, as reported in a study by Fu et al, include congestive heart failure and respiratory failure.[17]

Operative risk factors include single or bilateral internal mammary artery (IMA) harvesting (significantly decreases blood supply to ipsilateral hemithorax), prolonged operation, excessive hemorrhage, reoperation, break in sterile technique, and the use of an intra-aortic balloon pump. The Fu study also identified the presence of two or more arterial conduits as a risk factor.[17]

Pathophysiology

Wound dehiscence is the partial or complete separation of the layers of the incision. A compromise in factors responsible for wound healing can lead to wound dehiscence. These factors include inadequate nutrition, compromised circulation, and surgical factors. Surgical factors include placing sutures under excessive tension or insufficient tension. Circulatory factors include the presence of diabetes, coagulopathies, or other vascular-related issues. Adequate nutritional intake is also required for proper wound healing.

Presentation

Factors associated with mortality include septicemia, perioperative myocardial infarction, and use of the intra-aortic balloon pump. Strict aseptic technique, attention to hemostasis, and precise motionless sternal approximation are advocated to prevent mediastinitis.

In the clinical evaluation of suspected mediastinitis or sternal dehiscence, careful repeated examination of the patient is warranted. If the patient has multiple risk factors for dehiscence or impairment to wound healing, he or she must be examined at closer intervals. Findings of erythema, fever, tachycardia, increased leukocyte count, purulent discharge, and sternal instability are clinical indicators of sternal dehiscence.

If clinical deterioration of the patient or further signs of breakdown are observed (ie, increased erythema, drainage, separation of incision), immediately obtain wound cultures, administer broad-spectrum antibiotics, and perform swift aggressive debridement. Follow with either the vacuum-assisted closure (VAC) device (to serve as a bridge to reconstruction) or reconstruction with flap coverage or rigid sternal plating. This combination can reduce the incidence of mortality, decrease hospital stay, rapidly propel the patient's recovery from thoracic surgery, and avert the severe complications of mediastinitis.

Pairolero and Arnold have based their classification of sternal wounds on timing of presentation of infection; this classification divides wounds into 3 categories.[18] This classification system does not indicate the type of reconstruction necessary for management of each type of sternal wound. Type II and III wounds are typically referred to plastic surgeons for reconstruction.

  • Type I: Type I wounds occur in the first few days postoperatively, contain early wound separation with or without sternal instability, and are characterized by serosanguineous drainage without cellulitis, osteomyelitis, or costochondritis.

  • Type II: Type II wounds occur within the first few weeks and are characterized by drainage, cellulitis, mediastinal suppuration, and positive cultures. Type II wounds are characterized by fulminant mediastinitis.

  • Type III: Type III wounds occur months to years after surgery and are characterized by the presence of chronic draining sinus tracts, localized cellulites, osteomyelitis, or retained foreign bodies. Mediastinitis is a rare complication of type III wounds.

Indications

The main indications for sternal reconstruction are sternal instability with dehiscence, early or subacute infections, and repair after tumor resection.

Relevant Anatomy

The chest wall skeleton consists of the sternum in the anterior midline, bilateral clavicles, 12 pairs of ribs, with the eleventh and twelfth not associated with costal cartilage. The first seven ribs are "true" ribs, and the last 5 are "false" ribs. The eighth, ninth, and tenth ribs attach to the sternum via costal cartilage. The eleventh and twelfth ribs articulate posteriorly with the vertebrae. Anterior chest wall muscles allow for movement of the extremities. The elasticity of the chest wall supports the mechanics of ventilation.

The paired internal thoracic arteries and the deep epigastric arteries provide the main blood supply to the ventral aspect of the chest. This system connects the major vessels of the neck to those in the groin. Many flaps are based on understanding this vascular supply. Collateral blood supply from the acromiothoracic axis is also important to recognize.

The relevant muscles and structures utilized for sternum reconstruction are the pectoralis major, rectus abdominus, latissimus dorsi, and greater omentum. All except the latissimus dorsi can be harvested in the supine position; the latissimus dorsi should be harvested in the lateral decubitus position. The blood supplies for each flap are well-established and described under each individual section.

Understanding the advantages and disadvantages of all reconstructive options is important. For example, the pedicled latissimus flap is a great flap for lateral chest wall defects but often is inadequate to cover large midline sternal defects.

The blood supplies for each flap are well-established, as shown below.

Pectoralis major muscle flap blood supply and opti Pectoralis major muscle flap blood supply and options for sternal coverage (a, b, c).
Omentum flap showing its blood supply based on the Omentum flap showing its blood supply based on the right or left gastroepiploic arteries.

Contraindications

Wounds with active purulence require extensive debridement prior to flap coverage and/or rigid fixation.

Additional contraindications for sternal reconstruction are found in patients who are unstable for surgery, including those with poor pulmonary function, poor cardiac reserve, or terminal illness. Hemodynamic stability is required for surgical intervention in patients with sternal dehiscence.

 

Workup

Laboratory Studies

See the list below:

  • Obtain aspiration of fluid collections for culture and analysis.

  • Obtain wound cultures if clinical deterioration of the patient or further signs of breakdown are observed (ie, increased erythema, drainage, separation of incision).

  • Wound cultures should include quantitative microbiology count, tissue specimen for analysis, and sternal bone biopsies for culture.

  • Obtain a CBC with differential, blood cultures, C-reactive protein levels.

  • Prealbumin and transferrin levels are often important in preoperative nutrition assessment.

Imaging Studies

See the list below:

  • Plain radiographs (anteroposterior [AP] or posteroanterior [PA]) may detect air in the mediastinum; a sternal stripe reflects air between separated sternal halves.

  • Ultrasonography may be performed.

  • CT scanning can accurately detect sternal disruption, pockets of fluid, abscess, or pleural effusions.

Other Tests

See the list below:

  • MRI can be used to diagnose osteomyelitis or other pathologic processes (eg, recurrent tumor).

  • Bone scans to determine osteomyelitis may have a limited value for the acute wound because of the presence of inflammation and tracer uptake.

  • Bone cultures more accurately assist in making the diagnosis of osteomyelitis in the clinical setting.

 

Treatment

Medical Therapy

If the presence of mediastinitis and sternal disruption are established, the patient should be immediately prepared to go to the operating room for exploration and debridement. The patient should be hydrated and started on broad-spectrum antibiotics. Once cultured, antibiotic therapy can be tailored to the specific organism. This therapy is aimed at preventing septic complications during debridement.

The goal of debridement is to excise all nonviable tissue, foreign bodies, and eradicate the infection. Irrigation may also be used to clean wounds. Several studies examined delayed versus immediate closure. Whether closure is immediate or delayed, the timing of reconstruction should coincide with a clean wound, healthy tissue margins, and time of flap closure or rigid sternal fixation.

Open packing of the sternum is used prior to delayed closure of the sternum. This leads to repeated packing changes, which are painful for the patient and time-consuming. The development of vacuum-assisted closure (VAC) has led to a more conservative approach to the management of sternal wound dehiscence.

The VAC is a negative pressure dressing used for the management of chronic and complex wounds. The advantages of a negative pressure dressing are reduced bacterial load, increased local blood flow to ischemic areas, and accelerated granulation tissue formation. Patients also have a stable sternum and freedom of movement while the wound heals. Song et al showed that using the VAC results in shorter time from debridement to definitive reconstruction.[19] VAC therapy can be used as a stand-alone therapy or as an adjunct to reconstructive surgery. Possible complications from VAC therapy include an increased risk of bleeding, potential damage to the underlying tissue, and, rarely, right ventricular rupture.

The principles of adequate wound debridement, treatment of infection, and closure of dead space still predominate as initial management decisions in treating sternal wounds. The use of VAC helps decrease wound dressing changes, promotes granulation tissue, allows for smaller wounds to heal with secondary intention, and decreases edema in the tissues, which may allow the possibility for sternal salvage with rigid fixation.

Surgical Therapy

Specific methods are discussed below.

Flaps Used in Reconstructing Dehisced Wounds

Once debrided and clean wound margins are established, numerous flaps are available for reconstruction. Pedicled muscular and musculocutaneous flaps are most often used. If no pedicled flap is available, then free flaps are used. Generally, the pectoralis major and rectus abdominis are considered first-line flaps and the omentum is considered second-line.

Pectoralis major flap

The pectoralis flap is the most commonly used pedicle flap. One or both of the pectoralis major muscles may be used to close a defect.[20, 21] See the image below.

Chest wall reconstructed with pectoralis major myo Chest wall reconstructed with pectoralis major myocutaneous flap.

The pectoralis muscle is a type V Mathes-Nahai classification flap, it has 2 dominant vascular contributions. Thus, it is unaffected by the harvesting of the internal mammary arteries (IMA) for coronary bypass. The pectoralis flap can be transposed into the mediastinum based on the more commonly used thoracoacromial pedicle or as a turnover flap based on internal mammary perforators. This muscle usually is the first choice in flap selection because of its proximity and relative ease of harvest. If the IMA is preserved, the muscle, based on perforators lateral to the IMA, can be turned over to cover the inferior sternum. The upper two thirds can be advanced into the defect based on the thoracoacromial vessels. See the image below.

Chest wall reconstructed with right unilateral pec Chest wall reconstructed with right unilateral pectoralis major muscle flap for sternal wound closure.

When both IMAs are sacrificed, rotation-advancement can be performed based on the thoracoacromial vessels. Furthermore, muscle detachment from insertions on the clavicle and medial humerus allows a wider arc of rotation. Wide undermining of skin flaps then allows wound closure. One major limitation of the pectoralis major, when used solely for flap coverage, is the limited extent to which it covers the inferior third of the sternotomy wound.[22] In turn, this is the most common site for dehiscence after flap repair.

In a study of the use of a combination of negative pressure therapy and a pectoralis major muscle flap in the management of post-sternotomy deep sternal wound infections, Lo Torto et al found that fewer complications and less need for revision was associated with monolateral, rather than bilateral, flaps. The complications considered included hematoma, seroma, dehiscence, and re-infection.[23]

A retrospective study by Wyckman et al indicated that in patients who undergo poststernotomy defect reconstruction in association with sternal wound infection, independent factors for unilateral pectoralis major advancement flap loss and complications include older age, male sex, treatment with a greater number of different antibiotics, and a long duration of negative wound pressure therapy. The investigators also found an increase in the number of complications to be linked to the employment of fewer pre-reconstruction wound revisions.[24]

Rectus abdominis muscular and musculocutaneous flap

The rectus abdominis flap was also been advocated for use in coverage. The rectus abdominus muscle is described as a turnover flap based on the superior epigastric system. The rectus muscle is easily dissected and has a wide arc of rotation. It can cover the lower third of the sternum and reach to the sternal notch. In a 2007 study by Davison et al, the rectus muscle alone proved superior in coverage to the inferior sternum.[22] See the image below.

Rectus abdominus muscle flap and eighth intercosta Rectus abdominus muscle flap and eighth intercostal perforator for coverage of sternal defects.

Using the rectus muscle as a flap is considered risky if the ipsilateral IMA has been used for coronary artery bypass. If the IMA is sacrificed on one side of the sternum, the decision is often made to mobilize the contralateral rectus. However, if the eighth anterior intercostal perforator to the rectus is preserved, coverage of the sternal wound can be performed with sacrifice of bilateral IMAs, but this is not always reliable.

In some instances, the muscle can be tunneled under a skin bridge separating the sternum from the donor site; however, carrying the sternal incision to the pubis for exposure and ease of flap inset can avoid undue tension. The risk of abdominal weakness and hernia is a potential complication, but closure of the rectus sheath fascia in place with a double-layered closure likely diminishes this complication.

If both IMAs are sacrificed, a definitive method of closure is the use of free tissue transfer. In one case, a patient who had right breast cancer with postoperative radiation developed an ipsilateral radiation induced sarcoma of the right breast and chest wall. The initial plan was for reconstruction with a pedicled transverse rectus abdominis myocutaneous (TRAM) flap. During the tumor extirpation, both IMAs were transected. The end of the contralateral IMA was dissected and prepared distally, and the rectus muscle was harvested and microvascular reconstruction was employed to cover the defect. See the image below.

Rectus abdominus muscle flap and eighth intercosta Rectus abdominus muscle flap and eighth intercostal perforator for coverage of sternal defects.

The great majority of sternal wound coverage, especially the anterior two thirds, is performed using the pectoralis major, with the occasional use of the rectus abdominus to cover larger lower sternal defects. Nahai et al have developed an algorithm for local flap selection based on whether the saphenous vein is used as a bypass conduit or the IMAs are used in bypass surgery.[25] Furthermore, the rectus abdominus and pectoralis muscle flaps can be used simultaneously to cover the large complicated sternal wound with minimal morbidity.

Omental flap

The omental flap is now widely regarded as a secondary line of flap coverage. Its use has several pointed advantages and disadvantages. Advantages include the ability to cover irregular defects, resistance to infection because of its blood supply and rich lymphatic system, as well as the ability to fill large defects. Potential complications include herniation, wound infection, bowel injury, lack of structural strength, lack of the ability to include a cutaneous island, ventral hernia, and the spread of infection from the mediastinum to the abdominal cavity.

In patients with previous irradiation to the chest wall, careful flap selection is paramount. Radiation effects include interference with DNA repair mechanisms, damage to the microcirculation of flaps with endothelial cell injury, and progressive fibrosis of skin. This can lead to wound healing, wound dehiscence, or total flap failure. Thus, awareness of the radiation field and muscle groups involved can guide the surgeon to alternate flaps for sternal coverage. The omentum has been used effectively for many years in the management of sternal wound dehiscence. Its broad, pliable, fatty nature allows it to conform and seal off the deep recesses in large wounds. Its rich abundant source of lymphatics also aids in clearing infection. Determine considerations for use preoperatively. A careful patient history is necessary to uncover previous gastric or colon procedures.

The approach usually is via midline laparotomy, although an approach through a previous cholecystectomy scar (right subcostal) can be effective in smaller patients. The omentum can be cleared of adhesions that may be present from previous abdominal surgery. Its blood supply is based on the right or left gastroepiploic artery, and significant mobilization can be gained by dividing the short gastrics along the greater curvature of the stomach. See the image below.

Omentum flap showing its blood supply based on the Omentum flap showing its blood supply based on the right or left gastroepiploic arteries.

The risk of seeding infection into the peritoneal cavity is not substantiated in the literature, although gastric outlet obstruction is associated with excessive cranial traction on the antrum of the stomach during mobilization and inset of the omentum flap. Numerous reports in the literature state the effectiveness of the omentum flap in sternal coverage.

Latissimus dorsi and external oblique flaps

These muscle flaps are more suitable for smaller defects and should be reserved as back-up flaps in the event of flap failure. If detached from its insertion, the latissimus dorsi, based on the thoracodorsal artery, can fan across the anterior chest and cover the mediastinum. Patients must be turned into a lateral decubitus position for the maturation of the flap. Similarly, the external oblique muscles, based on intercostal perforators, can be turned into small sternal defects for coverage. See the image below.

Latissimus dorsi can be used as an island flap to Latissimus dorsi can be used as an island flap to cover the anterior chest and sternal defects.

Each patient presents with individualized issues that must be taken into account in making the final flap selection. The surgeon's skill and experience in concordance with the literature guide proper methods of reconstruction.

Rigid Fixation of the Sternum

Using soft tissue flaps as the primary method for addressing sternotomy wounds does not address the issue of the bony sternum. Complications of solely using flaps include loss of chest wall stability, chronic pain, paradoxical chest wall motion, and pulmonary function decreases. Limiting motion between relative segments of bone expedites sternal union and primary osseous healing. Throughout the literature, sternal plating has been shown to alleviate musculoskeletal pain in those with chronic sternal nonunion. Several surgeons now use rigid fixation techniques to stabilize the sternum prior to flap advancement. Restoration of sternal integrity approximates 96-98%.[9, 10, 11, 12, 13, 26]

Sternal nonunion can be treated with removal of sternal wires and debridement of fibrous tissue and devitalized bone, followed by rewiring or sternal plate fixation. However, in-vitro studies have shown the superiority of rigid plate fixation vs wire fixation.[27]  Sternal plating concerns include the possibility of foreign body infection and necessary plate removal because of loosened or incorrectly placed hardware.

Newer plate fixation technology, with locking screws, enables primary bone healing and accelerates recovery of sternal wounds by allowing a tension-free repair followed by elevation of pectoralis muscle flaps for closure if needed. Rigid fixation of the sternum also allows for a more rapid physiologic recovery of chest mechanics and decreases the possible paradoxical chest motion that accompanies sternal dehiscence. Ciclioni et al report that only 1 out of 50 patients presented with pectoralis dehiscence following sternal plating.[26]

Newer rigid sternal fixation systems consist of titanium unilock screws and thick reconstruction plates available in different lengths. The plates are made of 2 parts that are connected to each other by an emergency release pin. These plates can be placed transversely or longitudinally. Care is taken to protect the mediastinal structures from the drill, and accurate measurement of screw depth ensures stable fixation with the locking plate.

Recent studies have determined that titanium plate fixation is effective to stabilize complicated sternal dehiscence.[13] Studies indicate that transverse plate fixation achieves total sternal stabilization.[13] B Voss et al examined differences in transverse vs longitudinal placement of the plates.[13] They determined that transverse plate placement has a requirement for more invasive access and is associated with more complications, including pain and limited mobility of the ribs. Therefore, longitudinal plate placement is easier to apply and associated with fewer complications.

Similarly, a study by S Voss et al indicated that while titanium plates can restore thoracic stabilization in median sternotomy patients who have complicated dehiscence, they are associated with a not negligible rate of postoperative infection and pain. The study, which looked at midterm data on 34 patients with thoracic instability following open heart surgery, found that at a median period of 1.4 years after plate surgery, the thorax was once again stable in all patients. The investigators reported that bone consolidation was complete in 25.8% of the patients, nearly complete in 38.7%, partial in 9.7%, and absent in 25.8%. However, 12 patients (35.3%) experienced pain on movement, and five patients (14.7%) suffered chronic pain. Plates were removed from eight patients (23.5%) due to pain, at a median of 10.9 months, and from five patients (14.7%) due to infection, at a median of 2 months.[28]

Introduced as an alternative rigid fixation system, a sternal clamp device, the Rapid Sternal Closure (RSC) Talon system (KLS-Martin, Germany), received US Food and Drug Administration (FDA) approval several years ago; it acts transversely.

Radical Sternectomy

When significant osteomyelitis of the sternum has occurred, fixing the sternum is impossible. The persistent infection results in a recurring sinus tracts and infectious drainage unless the infected bone and hardware are removed. Limited resection often results in postoperative pain when the residual sternum rubs or clicks together. Radical resection of the sternum addresses this problem; patients rarely experience significant functional limitations after total sternectomy. If the manubrium is unaffected, it should be preserved and stabilized. Resected bone that appears grossly to have evidence of infection should be sent for cultures to ensure appropriate postoperative antibiotic coverage.

Intraoperative Details

The operation usually begins with a thorough debridement of the skin, subcutaneous tissues, and bone of the mediastinal wound. See the images below.

Infected sternal wound. Infected sternal wound.
Chest wall infection after debridement of all nonv Chest wall infection after debridement of all nonviable and infected tissue.

Tissue should be sent for culture, as should routine swab cultures of purulent wounds. Bone should be sent to pathology to rule out osteomyelitis. Depending on the hemodynamic status of the patient, a radical debridement can be followed by immediate flap reconstruction or staged with daily wound care, treatment of infection, and stabilizing the patient prior to definitive wound closure.

Important considerations for successful closure of these wounds include tension-free muscle flap advancement and skin closure and the use of closed suction drains placed beneath both the muscle flaps and skin flaps. See the images below.

Chest wall reconstructed with right unilateral pec Chest wall reconstructed with right unilateral pectoralis major muscle flap for sternal wound closure.
Chest wall reconstruction following sternal infect Chest wall reconstruction following sternal infection using a free transverse rectus abdominis myocutaneous (TRAM) flap.

Follow-up

Drains are usually removed when output is less than 20 mL/d. Patients are cautioned against resistive exercises or activities that put stress on the suture line or central chest for at least 6 weeks.

Complications

Drains

Closure of flaps over drains is necessary to prevent seroma formation and subsequent wound healing problems. Complications of flap closure of sternal wounds include hematoma, dehiscence, and sternal necrosis with osteomyelitis. Hematoma formation can be prevented with careful attention to hemostasis, careful dissection of pedicles, and closure over suction drains. Place drains under the muscle/omentum flap, under skin flaps, and at large undermining or dissection sites. Dehiscence is observed in obese patients, older patients with chronic obstructive pulmonary disease (COPD), patients on prolonged ventilatory support, patients with sepsis, and in women with large pendulous breasts. In the latter, surgical bras and tapes are necessary to prevent distraction on the medial chest and separation of the flaps.[29]

Debridement

Sternal necrosis and osteomyelitis occur in patients with profound sepsis, with gram-positive infections, and on whom inadequate debridement is performed. Debridement is the cornerstone in healing these wounds; debride viable, bleeding bone. Some advocate resection of the entire sternum and costal cartilages to reduce the chance of recurrent infection. Regardless, perform bone biopsies at the farthest margin of debridement.

If dehiscence is observed early, 1-stage debridement followed by immediate flap transposition can be performed. However, if the wound is grossly purulent at initial debridement, performing wound care with dressing changes is a reasonable course of action. Further debridement may be necessary with quantitative cultures, assuring a noninfected wound prior to closure. Depending on the extent of infection, a course of intravenous antibiotics for 6 weeks may be necessary to eradicate the infection.

Future and Controversies

The management and treatment of mediastinitis and sternal wound dehiscence has progressed greatly in the past 50 years. Wound debridement, vascularized flap transposition, and rigid sternal stabilization greatly decrease the morbidity, mortality, and cost of treating this devastating complication of thoracic surgery. The addition of vacuum-assisted closure (VAC) devices and development of newer rigid plate technology add weapons in the armamentarium for the management of these complex wounds. Future developments for managing difficult wound problems undoubtedly will arise, allowing the specialty of plastic surgery to contribute to the well-being of patients.

A retrospective study by Tarzia et al found a lower rate of complications and mortality associated with VAC for sternal wound dehiscence than with conventional treatment for the condition. In the study, involving patients who suffered sternal wound dehiscence after cardiac surgery, there was no dehiscence-related mortality in patients treated with VAC, compared with 11% mortality in those who received conventional treatment. The VAC group also experienced a significantly lower incidence of mediastinitis, sepsis, delayed sternal wound dehiscence infection, and other complications. The rate of surgical sternal and superficial revisions was also significantly lower in these patients.[30]