Overview
Definition:
Sternal wound dehiscence, also known as sternal non-union or sternal separation, refers to the incomplete or complete separation of the sternal halves following median sternotomy
It is a serious complication often associated with mediastinitis, leading to significant morbidity and mortality
Vacuum-assisted closure (VAC) therapy is a key component in managing such complex wounds, often preceding definitive reconstruction.
Epidemiology:
The incidence of sternal wound dehiscence varies widely, reported between 0.4% to 5% following cardiac surgery
Risk factors include obesity, diabetes mellitus, chronic obstructive pulmonary disease (COPD), prolonged ventilation, re-operations, and poor nutritional status
Advanced age and female gender are also associated with increased risk
In non-cardiac thoracic surgery, rates can be comparable.
Clinical Significance:
Sternal wound dehiscence represents a failure of primary wound healing and poses a significant threat due to the potential for deep sternal infection (osteomyelitis) and mediastinitis
This can lead to sepsis, multiorgan dysfunction, prolonged hospitalization, and increased healthcare costs
Effective management is crucial for patient recovery, functional restoration, and preventing life-threatening complications
This topic is frequently tested in DNB and NEET SS examinations for surgical residents.
Clinical Presentation
Symptoms:
Unstable sternum with palpable clicking or crepitus
Purulent discharge from the sternal wound
Fever, chills, and malaise
Increased chest pain, particularly with deep inspiration or coughing
Shortness of breath or dyspnea
Difficulty in moving the upper extremities
Recurrent sternal wound breakdown or dehiscence after initial closure
Signs of sepsis including tachycardia and hypotension.
Signs:
Visible separation of the sternal wires or closure
Redness, swelling, and tenderness over the sternum
Purulent drainage from the wound edges
Palpable instability of the sternum
Mediastinal widening on chest X-ray
Chest wall crepitus
Signs of systemic infection: fever, tachycardia, hypotension, altered mental status.
Diagnostic Criteria:
Diagnosis is primarily clinical, based on physical examination revealing sternal instability and wound drainage
Radiographic evidence of sternal separation or osteomyelitis (e.g., widening of the mediastinum on CXR, CT scan showing bone destruction or fluid collection)
Microbiological confirmation of infection via wound cultures or blood cultures
Consensus guidelines often define dehiscence by clinical instability and/or radiographic evidence of separation or infection.
Diagnostic Approach
History Taking:
Detailed history of the primary surgery and any immediate postoperative complications
Pre-existing comorbidities (diabetes, COPD, immunosuppression)
Nutritional status assessment
History of wound issues, drainage, or fever
Previous treatments or interventions for the sternal wound
Red flags include sudden onset of chest pain, increased wound drainage, fever, or sternal instability.
Physical Examination:
Careful inspection of the sternal incision for signs of dehiscence, erythema, edema, and drainage
Palpation of the sternum for instability, crepitus, and tenderness
Assess for signs of systemic infection (fever, tachycardia, hypotension)
Evaluate for respiratory compromise and assess chest wall excursion
Examine for associated limb swelling or signs of DVT.
Investigations:
Complete Blood Count (CBC) to assess for leukocytosis and anemia
C-reactive protein (CRP) and Erythrocyte Sedimentation Rate (ESR) for inflammatory markers
Blood cultures to identify causative organisms if sepsis is suspected
Wound culture and sensitivity testing from purulent drainage
Chest X-ray (CXR) to assess mediastinal widening or pleural effusion
CT scan of the chest with contrast is crucial for evaluating the extent of sternal dehiscence, osteomyelitis, and mediastinal abscess
MRI may be useful in specific cases to delineate soft tissue involvement.
Differential Diagnosis:
Superficial wound infection without dehiscence
Post-sternotomy pain syndrome
Rib fractures
Mediastinitis without sternal dehiscence
Thoracic aortic aneurysm
Musculoskeletal chest pain
Other causes of chest wall pain or infection.
Management
Initial Management:
Immediate wound care: gentle debridement of necrotic tissue and purulent material
Copious irrigation with saline
Application of sterile dressings
Hemodynamic stabilization if patient is septic
Broad-spectrum antibiotics guided by local resistance patterns and Gram stain, with subsequent tailoring based on culture results
Pain control and management of respiratory distress.
Medical Management:
Intravenous antibiotics are essential for suspected or confirmed infection
Choice of antibiotics depends on likely pathogens and sensitivities
Common agents include vancomycin, cephalosporins (e.g., cefazolin), and aminoglycosides
Duration of therapy typically extends for 4-6 weeks, often transitioning to oral antibiotics
Nutritional support is critical, aiming for adequate protein intake to promote healing.
Surgical Management:
Surgical intervention is usually required
Initial debridement and thorough irrigation of the wound and mediastinum
The cornerstone of modern management for complex sternal dehiscence with infection is Vacuum-Assisted Closure (VAC) therapy
VAC therapy involves a specialized foam dressing placed over the wound, connected to a suction device, which promotes granulation tissue formation, reduces edema, and manages exudate
Once the infection is controlled and the wound bed is suitable, reconstruction is performed
Options include sternal plating, sternal wires, or muscle flaps (e.g., pectoralis major, rectus abdominis) with or without bone grafts
Chest wall reconstruction may involve prosthetic materials if extensive resection is needed
The timing of reconstruction depends on the control of infection.
Supportive Care:
Intensive monitoring in an ICU setting may be required for patients with sepsis or respiratory compromise
Mechanical ventilation may be necessary
Strict aseptic technique for wound care is paramount
Regular wound dressing changes and VAC system maintenance
Nutritional support (enteral or parenteral feeding)
Physical therapy to maintain respiratory function and mobility
Psychological support for the patient and family.
Complications
Early Complications:
Mediastinitis
Sepsis and septic shock
Hemorrhage
Pneumonia
Acute respiratory distress syndrome (ARDS)
Deep vein thrombosis (DVT) and pulmonary embolism (PE)
Cardiac tamponade.
Late Complications:
Chronic osteomyelitis
Persistent chest wall deformity
Chronic pain
Recurrent dehiscence
Incisional hernia
Adhesions leading to restricted lung function
Psychological sequelae.
Prevention Strategies:
Meticulous surgical technique during sternotomy and closure
Judicious use of sternal wires or plates
Prophylactic antibiotics
Strict glycemic control in diabetic patients
Optimizing nutritional status preoperatively
Minimizing intraoperative contamination
Careful wound care postoperatively
Early recognition and management of wound complications
Smoking cessation counseling.
Prognosis
Factors Affecting Prognosis:
The presence and extent of mediastinal infection
The patient's overall health status and comorbidities
The timeliness and effectiveness of treatment
The development of sepsis
The need for extensive reconstructive surgery
Multidrug-resistant organisms can worsen outcomes.
Outcomes:
With timely and appropriate management, including VAC therapy and definitive reconstruction, the prognosis can be significantly improved
However, sternal dehiscence remains a serious complication with a mortality rate that can range from 10% to 30% in severe cases, particularly if associated with widespread mediastinitis or sepsis
Successful reconstruction leads to restoration of chest wall integrity and improved quality of life.
Follow Up:
Long-term follow-up is crucial to monitor for signs of recurrent infection or osteomyelitis
Serial imaging may be required
Assessment of chest wall function and pain
Rehabilitation and physical therapy may be ongoing
Patients should be advised to report any new chest pain, fever, or wound drainage promptly.
Key Points
Exam Focus:
Sternal dehiscence is a common and serious complication of sternotomy
VAC therapy is a critical adjunct for managing infected and complex sternal wounds
Reconstruction options include sternal plating, wires, and soft tissue/bone flaps
Mediastinitis is a major concern and must be aggressively treated
Risk factors are important for DNB/NEET SS questions.
Clinical Pearls:
Always suspect sternal dehiscence in any patient with sternal wound drainage, fever, or chest pain post-sternotomy
CT scan is indispensable for staging and planning
Aggressive debridement and antibiotic therapy are key
VAC therapy simplifies wound management and prepares the bed for reconstruction
Be familiar with the types of flaps used for chest wall reconstruction.
Common Mistakes:
Delaying surgical intervention due to fear of re-operation
Inadequate debridement of infected tissue
Underestimating the extent of mediastinal contamination
Inappropriate antibiotic selection
Failure to consider nutritional support
Premature removal of VAC therapy before wound bed is ready
Not adequately securing reconstructions.