You are in: eMedicine Specialties > Plastic Surgery > CHEST Chest Reconstruction, Sternal DehiscenceArticle Last Updated: May 4, 2006AUTHOR AND EDITOR INFORMATIONSection 1 of 12
  Author: Sanjay K Sharma, MD, Consulting Staff, Department of Plastic Surgery, Meridian Plastic Surgery Center, Seton Medical Center Sanjay K Sharma is a member of the following medical societies: American College of Surgeons, American Society for Surgery of the Hand, American Society of Plastic Surgeons, Texas Medical Association, and Texas Society of Plastic Surgeons Editors: Dennis P Orgill, MD, PhD, Associate Professor, Harvard Medical School; Director, Burn Center, Brigham and Women's Hospital; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Jaime R Garza, MD, DDS, FACS, Consulting Staff, Private Practice; Nicolas (Nick) G Slenkovich, MD, Practice Director, Colorado Plastic Surgery Center at Swedish Medical Center; Jorge I de la Torre, MD, FACS, Associate Professor of Surgery and Physical Medicine and Rehabilitation, Residency Program Director, Division of Plastic Surgery, University of Alabama at Birmingham; Director, Center for Advanced Surgical Aesthetics Author and Editor Disclosure Synonyms and related keywords: thoracic reconstruction, trunk reconstruction, plastic surgery, sternotomy, chest reconstruction, sternal dehiscence, midline sternotomy incision, midline sternotomy, sternal wound dehiscence, wide debridement, mediastinitis, sternal instability, post tumor resection, sternum reconstruction, vacuum-assisted closure device, VAC, rigid fixation of the sternum, thoracoacromial system, internal mammary arteries, flap transposition INTRODUCTIONSection 2 of 12
  In thoracic and trunk reconstruction, plastic surgery plays a major role in addressing wound healing problems, complex defects, and cancer reconstruction. The introduction of the midline sternotomy incision allowed access to mediastinal structures and greatly propelled the field of thoracic surgery. The ability to gain access to the mediastinal organs through this approach allows the safe and effective treatment of cardiothoracic disease today. History of the ProcedureEarly use of the midline sternotomy was fraught with high complication rates. Sternal wound infection occurred in as many as 5% of patients, leading to sternal wound dehiscence, with reported incidence of mediastinitis in 0.4-6.9% of patients. These complications often led to significant morbidity, with reported mortality rates of more than of 50%. Sternal dehiscence initially was treated conservatively with open drainage and debridement with packing. Graft exposure, desiccation of wound margins, osteomyelitis, and, ultimately, sudden death, were grave consequences. This led to closed management with catheter-antibiotic irrigation; however, the mortality rate remained approximately 20%. The management of infected sternal wounds changed with the principles of wide debridement and muscle and musculocutaneous flap transposition. In 1976, Lee introduced the greater omentum flap. Jurkiewicz et al then demonstrated the effectiveness of pedicled muscle flaps for management of sternal dehiscence and infection. The use of vascularized regional tissue allowed for greater blood flow, obliteration of dead space, and faster healing time because of quicker resolution of infection. Today, the management of sternal dehiscence and infection involves wide debridement of devitalized infected soft tissue and bone, culture-specific antibiotics, and flap closure (eg, muscle, musculocutaneous, omentum) to achieve wound healing. Thus, the mortality rate from sternal wound dehiscence dropped to less than 10%. EtiologyFactors associated with sternal wound dehiscence Numerous studies were performed to identify causative factors of sternal wound dehiscence and subsequent infection. Factors identified include hypertension, smoking, diabetes, obesity, the use of an intra-aortic balloon pump, and the use of bilateral internal mammary arteries (IMAs). Females are at greater risk than males. Prolonged postoperative ventilatory support is also implicated. ClinicalIn one study, factors associated with mortality included septicemia, perioperative myocardial infarction, and an 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 examination of the patient is warranted. Findings of erythema, fever, increased leukocyte count, and sternal instability are important. If clinical deterioration of the patient or further signs of breakdown are observed (ie, increased erythema, drainage, separation of incision), obtain wound cultures, administer appropriate antibiotics, and perform swift aggressive debridement followed by early flap coverage. This combination can reduce the incidence of mortality, decrease hospital stay, rapidly propel the patient's recovery from thoracic surgery, and avert the complications of mediastinitis. INDICATIONSSection 3 of 12
The main indications for sternal reconstruction are sternal instability with dehiscence, early or subacute infections, and post tumor resection. RELEVANT ANATOMYSection 4 of 12
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 (see Image 1, Image 3). CONTRAINDICATIONSSection 5 of 12
The main contraindications are wounds with active purulence; these wounds require extensive debridement prior to flap coverage to prevent potential flap failure. Additional contraindications for sternal reconstruction are found in patients who are unstable for surgery with poor pulmonary or cardiac reserve or who are terminally ill. Obviously, hemodynamic stability is required for surgical intervention in patients with sternal dehiscence. WORKUPSection 6 of 12
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TREATMENTSection 7 of 12
Medical therapyRecently, a more conservative approach to the management of sternal wound dehiscence has been proposed and utilized. The use of a vacuum-assisted closure (VAC) device, many of which are manufactured by Kinetic Concepts International, in San Antonio, Tex, allows for either sole therapy for sternal wound closure or adjunctive therapy in preparation for muscle flap closure. The principles of adequate wound debridement, treatment of infection, and closure of dead space still predominate as inital 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 therapyRigid fixation of the sternum Sternal nonunion can be treated with removal of sternal wires and debridement of fibrous tissue and devitalized bone, followed by rewiring. 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. 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. Multiple levels of approximation on the rib-sternum are accomplished using the Bailey rib approximator or #5 surgical steel wires. Care is taken to protect the mediastinal structures from the drill, and accurate measurement of screw depth ensures stable fixation with the locking plate. A minimum of 3 screws are placed on either side of the sternum for secure fixation. 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 will address 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. Choice of FlapsPectoralis major Regional muscle flaps include the pectoralis major and rectus abdominus muscle groups. The pectoralis can be used as a turnover flap based on the medial sternal perforators or rotated into the sternal wound based on the thoracoacromial system (see Image 1). This muscle usually is the first choice in flap selection because of its proximity and relative ease of harvest. It can be elevated even when the IMA is sacrificed. 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. 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. Thus, the entire sternum can be covered with this muscle group even when bilateral IMAs are sacrificed. Wide undermining of skin flaps then allows wound closure. Rectus abdominis The rectus abdominus muscle is described as a turnover flap based on the superior epigastric system. Plan accordingly if the IMA is sacrificed on one side of the sternum. If so, mobilize the contralateral rectus. However, if the eighth anterior intercostal perforator to the rectus is preserved, coverage of the sternal wound can be performed even with sacrifice of bilateral IMAs (see Image 2). 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 or bulge is a potential complication, but closure of the rectus sheath without tension is achievable. The great majority of sternal wound coverage 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. Furthermore, the rectus abdominus and pectoralis muscle flaps can be used simultaneously to cover the large complicated sternal wound with minimal morbidity. Omentum 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 by gained by dividing the short gastrics along the greater curvature of the stomach (see Image 3). 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. Potential complications include herniation, wound infection, and bowel injury. Latissimus dorsi and external oblique Other muscle flaps described for sternal wound coverage include the latissimus dorsi and external oblique. 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 (see Image 4). Similarly, the external oblique muscles, based on intercostal perforators, can be turned into small sternal defects for coverage. Each patient presents different problems, such as comorbid conditions or use of IMAs, which must be taken into account in making the final flap selection. Consider as well the surgeon's skill and experience. Intraoperative detailsThe operation usually begins with a thorough debridement of the skin, subcutaneous tissues, and bone of the mediastinal wound. 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. Follow-upDrains 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. COMPLICATIONSSection 8 of 12
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, patients on prolonged ventilatory support, patients with sepsis, and in women with large, pendulous breasts. The use of surgical bras and tapes are necessary in the latter to prevent distraction on the medial chest and separation of the flaps. 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; débride 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 CONTROVERSIESSection 9 of 12
The management and treatment of mediastinitis and sternal wound dehiscence has progressed greatly in the past 25 years. Wound debridement and vascularized flap transposition greatly decrease the morbidity, mortality, and cost of treating this devastating complication of thoracic surgery. With the availability of minimally invasive techniques such as laparoscopic-assisted omentum flap harvest, further reductions in morbidity can be expected. The addition of vacuum-assisted closure devices adds yet another weapon 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. ACKNOWLEDGMENTSSection 10 of 12
The authors and editors of eMedicine gratefully acknowledge the contributions of previous author Saleh M Shenaq, MD†, to the development and writing of this article. MULTIMEDIASection 11 of 12
REFERENCESSection 12 of 12
Chest Reconstruction, Sternal Dehiscence excerpt Article Last Updated: May 4, 2006 | |||||||||||||||||||||||||||||||||
