Sternal resection is primarily required for primary or secondary malignancy, infection, or radiation osteonecrosis (radiation osteitis).^1,2 The resulting chest wall defect involving loss of skeleton and often overlying soft tissue depends on tumor extent and type, and severity of infection or radiation necrosis. Full-thickness sternal resections can compromise chest wall stability or have paradoxical respiratory movements, highlighting the importance of proper reconstruction of the thoracic wall and sternum.

Primary tumors of the thoracic skeleton are rare, accounting for 4.5% to 8% of published series of primary bone tumors with 11% in the sternum and 9% in the clavicles.³ Sternal tumors are classified as primary tumors (i.e., benign or malignant), adjacent tumors with local invasion (i.e., lymphoma or primary neoplasm of lung, breast, pleura, or mediastinum), metastases (i.e., primary neoplasm of breast, lung, or thyroid), and nonneoplastic lesions (i.e., inflammatory masses or bone cysts). The majority of sternal tumors are malignant and frequently represent metastasis or direct invasion by adjacent tumor.^1,4,5 The majority of primary sternal malignancies are bony or cartilaginous in origin.^3–5 The most common primary malignancy of the sternum is chondrosarcoma, and other common primary malignancies include osteosarcoma, solitary plasmacytoma, and Ewing sarcoma.^3–5 Although primary benign tumors of the sternum are rare, the most common benign tumors of the sternum are chondroma and osteochondroma.⁶

Most clavicle tumors are malignant and much more likely to be metastases than primary tumors. Primary neoplasms of the clavicle are rare. The most common primary malignancy of the clavicle is solitary plasmacytoma.⁷ Isolated clavicular resection is rare. Indications for resection include (1) exposure of the base of the neck, superior mediastinum, or brachial plexus, (2) tumor, infection, or injury/trauma of the clavicle itself or in association with sternal/chest wall resection, and (3) dysfunction of the sternoclavicular and acromioclavicular joints.⁸ Distal clavicle pathology generally entails dysfunction of the acromioclavicular joint which is usually managed by orthopedic surgeons specializing in shoulder reconstruction. The distal end of the clavicle is commonly resected for arthritis and dislocation of the acromioclavicular joint. Partial, medial clavicular resection is required during an anterior approach to superior sulcus tumor resection (Chapter 80).⁹ In addition, clavicular resection may be sufficient to provide exposure of the ipsilateral superior mediastinum during head and neck operations obviating the need for a partial or complete median sternotomy.

Careful preoperative evaluation, including assessment of cardiopulmonary reserve, is critical for successful outcome. A detailed history should identify comorbid factors such as advanced age, malnutrition, overall debilitation, and cardiopulmonary disease. Severe respiratory insufficiency is considered a contraindication for extensive sternal resection. There should be a clear understanding of the patient’s prior operations with attention to location of previous incisions and radiation treatment history, including location and dosage of exposure. This information is critical in establishing the reconstructive plan, particularly when assessing availability and usability of muscle and omental flaps.

An extent of disease workup to determine appropriateness of resection should be thoroughly investigated. Given the high propensity for metastases to occur in the sternum and clavicle, there should be investigation for a primary tumor elsewhere. Our preference is a whole body PET/CT scan with intravenous contrast to assess for extrathoracic disease. CT scan of the chest with intravenous contrast is the single best radiographic modality to localize and characterize the sternum, clavicle, and chest wall. Thorough knowledge of the extent of involvement by sternal or clavicular pathology (e.g., mediastinal structures, pulmonary parenchyma, ribs, sternum, clavicles, and overlying soft tissues) is readily obtained through CT scanning. Although MRI of the chest is not mandatory in every case, it can be quite helpful in evaluating invasion of the thoracic inlet, brachial plexus, and subclavian vasculature. MRI is also useful in characterizing cartilage and soft tissue, and is more sensitive in evaluating bone marrow edema and replacement than CT. Image guided (CT or ultrasound) core needle biopsy of chest wall and sternal tumors has been shown to be a safe and highly accurate diagnostic modality to determine malignancy, histological subtype, and high-grade differentiation of musculoskeletal tumors.¹⁰ Preoperative tissue diagnosis should be obtained to determine presence and type of malignancy and also to consider neoadjuvant or definitive chemotherapy depending on the tissue diagnosis.¹⁰ On this basis, imaged guided needle biopsy is routinely performed before resection, and incisional biopsy is rarely needed.¹⁰

Given the rarity of sternal and clavicular mesenchymal tumors, a multidisciplinary team approach to guide management and treatment plans is recommended.¹⁰ Preoperative treatment may be appropriate in some situations (i.e., metastases, high-grade soft tissue sarcoma, osteosarcoma, Ewing sarcoma, and mesenchymal or dedifferentiated chondrosarcoma). Consultation with a plastic surgeon to devise plans for soft tissue reconstruction may be necessary for complex situations, such as those requiring extensive myocutaneous flaps (Chapter 138).

General Principles

The sternum provides structural support for the thoracic skeletal structures and stabilizes the shoulder girdle through the clavicles. In addition, it provides a protective barrier to the mediastinum, particularly the great vessels and the heart. Surgical principles governing resection of the sternum or clavicle emphasize the importance of a complete resection with clear margins. Repair or reconstruction of these bony defects requires the selection of appropriate prosthetic and/or autologous replacement material. It is important to stabilize the chest wall and sternum to maintain the normal dynamics of respiration and to protect mediastinal structures. Current techniques most often entail the use of rigid prostheses and soft tissue (muscle or omentum) coverage to ensure adequate healing. The use of soft tissue reconstructive techniques is imperative in any irradiated field to prevent incisional dehiscence and wound infection. Local wound complications have attendant risks for prosthetic contamination and may delay initiation of adjuvant therapy depending on the tumor type.

Anesthesia

Preoperative placement of a thoracic epidural is used routinely for postoperative pain management unless contraindications exist, such as coagulopathy, systemic infection, anticipated cardiopulmonary bypass (CPB), or immediate need for postoperative therapeutic anticoagulation. Antibiotic prophylaxis is administered prior to incision. Subcutaneous heparin and pneumatic compression stockings are used for deep vein thrombosis prophylaxis, especially since the majority of patients have an underlying malignancy. General anesthesia is induced with initial single-lumen intubation for bronchoscopic examination followed by exchange to a double-lumen endotracheal tube to facilitate resection in the supine position. Single lung isolation is useful especially if there is involvement of adjacent lung parenchyma, concomitant chest wall or rib resection, or to facilitate resection of the sternochondral junction during sternectomy.

Positioning of the Patient

Sternectomy or claviculectomy generally requires the patient to be in the supine position. The chest and abdomen should be prepped widely to provide adequate access to potential muscle or omental flaps. The thighs should be prepped if skin grafting becomes necessary. Prior to tumor resection, there should be consideration for initial harvest of the pedicled latissimus dorsi muscle flap in the full lateral decubitus position through a vertical incision along the anterior edge of the muscle to the axilla or through a standard posterolateral thoracotomy incision. Sterile prepping of the entire ipsilateral upper extremity can facilitate dissection of the latissimus dorsi muscle but is not mandatory. In this case, all intravenous or arterial catheters should be placed in the contralateral arm. The lateral decubitus position is essential for adequate exposure for optimal latissimus dorsi muscle flap harvest. The dissected muscle flap can be tucked into the axilla and later retrieved during sternal or clavicular resection in the supine position. The latissimus dorsi muscle is our preferred flap for soft tissue coverage following sternectomy or claviculectomy. If the latissimus dorsi muscle is not available or suitable, then the pectoralis major muscle (ipsilateral and/or contralateral), transverse rectus abdominus myocutaneous (TRAM) flap, or omentum are alternatives, and can be harvested in the supine position during or after tumor resection. The pectoralis muscle is ideally suited for upper chest wall/sternal defects. The TRAM and omental flaps can reach essentially any part of the anterior and lateral thorax and sternum. However, the use of a superiorly based pedicled TRAM flap is limited given the need for preservation of ipsilateral internal mammary artery, which is generally resected in total sternectomy.

Supine positioning is the ideal position for sternal or clavicular resection. A transverse shoulder roll can be helpful to allow mild neck extension (Fig. 136-1A). In addition, a slight elevation or lateral decubitus position at 30- to 45-degree rotation ipsilateral to the clavicular resection or concomitant chest wall rib resection will provide a wider field for the tumor resection and ease retrieval of the latissimus dorsi muscle flap from the axilla (Fig. 136-1B). The ipsilateral arm should be tucked to the side. This positioning also facilitates the insertion of a thoracoscope when there is involved lung that requires en bloc resection or to evaluate the entry point into the chest wall lateral to the sternum to ensure that adequate margins are achieved in cases of concomitant sternal and chest wall tumor resection or when there is a significant intrathoracic/mediastinal component compared to the extrathoracic sternal part of the tumor.

Incisions

A variety of incisions can be used depending on the location of the tumor. For a sternal or manubrial tumor, a vertical midline incision is made centered over the portion of the involved manubrium or sternum (Fig. 136-2A). For a clavicular/manubrial tumor, or upper sternal tumor, a reverse hockey stick incision can be made (Fig. 136-2B). For a lower sternal tumor involving the sternochondral junctions or chest wall ribs, a partial hemiclamshell incision (Fig. 136-2C) or lower midline vertical incision can be made. In women, the hemiclamshell incision can be extended from the midline sternum to along the ipsilateral breast crease to permit utilization of the ipsilateral pectoralis muscle and breast tissue for soft tissue coverage during reconstruction. Any previous incisional biopsy scars should be excised in an elliptical manner incorporating the entire open biopsy site.

Total Sternectomy (Resection of Costal Cartilages and Sternum)

Strict adherence to aseptic technique is mandatory to avoid incisional wound and prosthetic infection. Perioperative antibiotics are administered within 1 hour before incision. Antimicrobial surgical drapes with an iodophor impregnated adhesive (3M™ Ioban™ 2 Antimicrobial Incise Drape, 3M, St. Paul, MN) is used to maintain adherence of the drape to the patient and prevent contamination of the operative field. This also prevents contact of prosthetic materials to the patient’s skin and flora.

A midline sternotomy incision is made from the sternal notch to the xyphoid. If the tumor extends close or invades the skin, then the overlying skin is resected en bloc with the sternal tumor. Subcutaneous flaps are created circumferentially by dissecting down onto the fascia of the pectoralis major muscles bilaterally. If the tumor invades the pectoralis major muscle, then en bloc resection of the muscle with the tumor is performed with a wide soft tissue margin of at least 4 cm for high-grade, primary sternal malignancies. Otherwise, the pectoralis major muscles are elevated as flaps off the sternum and costal cartilages bilaterally. Dissection is extended to expose the costal cartilages and the sternochondral junctions. Blunt dissection on the inner table of sternum at the sternal notch and at the xyphoid level is performed to release strap muscle attachments and the diaphragm attachments from the inner table of the sternum, respectively. The costal cartilages are divided from a caudal to cranial direction allowing for at least a 4-cm margin (Fig. 136-3A,B). The bilateral pleural cavities are entered. The inferior epigastric arteries are ligated bilaterally. The intercostal neurovascular bundles are ligated and divided. The lower part of the sternum is lifted anteriorly allowing visualization of the sternal undersurface. The anterior mediastinal/pericardial fat, thymus, or pericardium can be resected en bloc if tumor invasion is present. The internal mammary arteries are identified, ligated, and divided bilaterally in the upper sternal area. When the entire sternum is involved by tumor or total sternectomy is required to achieve margin negativity, the sternum is resected in its entirety with the manubrium with or without resecting the clavicular heads. When the manubrium must be resected in its entirety, the sternoclavicular joint can be disarticulated with preservation of the medial clavicular heads bilaterally. In general, the extent of margin clearance is determined primarily by tumor type and grade. For benign and metastatic lesions, negative margins are adequate. For low- and high-grade primary sternal sarcomas, 2- and 4-cm margins are required, respectively. For associated sternal and chest wall tumor resections, one rib above and below the tumor are resected to achieve adequate margins.