Francesco Puma and Jacopo Vannucci
INDICATIONS
Chest wall reconstruction is indicated in widely different clinical situations, such as resection of tumors, infected or irradiated wounds, congenital deformities, and posttraumatic injuries. In this section we will analyze the various technical options for reconstruction in the oncologic setting.
Chest wall resection and reconstruction for neoplastic disease can be carried out in three different clinical circumstances:
1. primary chest wall tumors;
2. chest wall metastasis or direct infiltration from other malignancies;
3. direct invasion from non-small cell lung cancer (NSCLC).
Such classification is necessary because extent of resection is actually different according to indications: It usually involves some ribs, in the treatment of NSCLC; it often entails a large excision of soft tissues and bony thorax for primary chest wall tumors; it is widely variable in the other possible conditions. Reconstruction may be delegated only to the thoracic surgeon, but in the case of extensive skin and soft tissue resection, repair should include teamwork with plastic surgeons. A multidisciplinary approach is often required.
Primary Chest Wall Tumors
The majority of benign chest wall tumors requiring a thoracectomy arises from the bony thorax (osteochondroma, chondroma), followed by soft tissue tumors (fibrous dysplasia, desmoid tumors, etc.) and by tumors of neural origin (neurofibroma, neurilemmoma). These lesions are often, but not always, slow-growing tumors and are usually asymptomatic, rarely being painful, as in case of osteochondroma or fibrous dysplasia when complicated by pathologic fractures. Chondroma is another common benign tumor, which can easily create problems of differential diagnosis with the corresponding well-differentiated malignant tumor.
Primary malignant chest wall tumors are mainly represented by sarcomas. The most common is chondrosarcoma, a chemo- and radioresistant tumor, its prognosis is related to its grade, dimension, and width of resection. Other malignancies are Ewing’s sarcoma, osteosarcoma, synovial sarcoma, fibrous histiocytoma, plasmacytoma, and a variety of soft tissue sarcomas. Ewing’s sarcoma and plasmacytoma are responsive to chemotherapy. Different biology can grade these tumors from indolent to rapidly aggressive and occasionally related to latent or manifest systemic disease. Multifocal tumor is a possible entity that heavily limits the surgical indication.
Metastatic Chest Wall Tumors
Bloodstream metastases to the chest wall infrequently occur from epithelial tumors such as carcinomas of the thyroid, breast, and kidney, but also from other primaries. Palliation is generally obtained by radiation therapy and resection is rarely indicated.
Surgery might be considered in selected cases: (a) As part of a multidisciplinary treatment program (e.g., differentiated thyroid tumors); (b) as a treatment of a local complication such as radiation or infected wound (occasional in breast cancers); (c) for a bleeding lesion (typical of renal cell carcinoma); (d) for the sole palliation, generally for pain relief (occasional in every histology).
Chest Wall Involvement by Lung Cancer
Peripheral NSCLC sometimes infiltrates the parietal pleura or the chest wall and this condition is defined as T3 tumor; invasion of the vertebral body is defined as T4. In patients with vertebral body involvement surgery is rarely indicated and the related techniques will not be analyzed in this chapter. Surgical indication is disputed in T3N2 disease, but cT3N0–1 can undergo en-bloc chest wall and lung resection with satisfactory oncologic outcome. Many experiences encourage the role of surgery but there are some peculiar aspects that define the indication to surgery as part of a possible multimodality treatment. Prognostic factors are multiple and mainly dependent on complete resection, N status and depth of infiltration; the latter is also a key factor to assess the correct technique. Currently there are some uncertainties on the extent of resection. When the tumor clearly infiltrates ribs and/or soft tissues, the only radical operation is the concomitant chest wall and lung en-bloc resection. If the parietal pleura is marginally infiltrated, extrapleural lobectomy without chest wall resection could be performed, provided that the extrapleural plane is easily achieved and the outer surface of the detached parietal pleura is left absolutely intact (however, only the final pathologic examination can definitely rule out the possible full-thickness parietal pleural involvement). It is important to interrupt the extrapleural dissection in case of resistance to the maneuver. If the procedure goes smoothly, a full-thickness chest wall resection could be an overtreatment because the tumor can be fixed to the parietal pleura only by inflammatory adhesions, or be confined just to the pleural plane. The decision must be made intraoperatively and requires an experienced surgeon.
If the parietal pleura is invaded, many authors deem extrapleural lobectomy a not surely radical operation because of the higher probability of local recurrence. In fact, although data are not definitive, in T3 tumors, chest wall and lung en-bloc resection should lead to better long-term outcome than extrapleural lobectomy. Anyhow, concomitant chest wall and lung resection is unquestionably required if the patient complains chest pain or if parietal pleura infiltration is not minimal.
PREOPERATIVE PLANNING
Evaluation of the Patient
Functional Assessment
Analysis of preoperative functional studies is beyond the scope of this chapter. Synthetically, we should consider adequate for a major chest wall resection the same functional respiratory, metabolic, and cardiovascular parameters used to judge a patient eligible for a pulmonary lobectomy. If a large thoracectomy en-bloc with a major pulmonary resection has been scheduled, the patient should be functionally fit for pneumonectomy.
Clinical Data of the Patient
Chest wall resection should be undertaken after a meticulous treatment plan resulting from deep knowledge of the disease and adequate assessment of the patient. Clinical history and physical examination are fundamental both for correct diagnosis and therapeutic plan.
Multiple factors influence the technique of resection and reconstruction of the chest wall: Some of them are related to the patient and to his clinical history, others are linked to the disease.
The most important patient-related factors to be considered are: Comorbidities, performance status, symptoms, lifestyle, occupation, age, previous radiation therapy, previous surgery or chemotherapy, body habitus, infection, skeletal muscle function, body mass, and nourishment. Chest pain should be carefully investigated because it is the most important sign of local invasion. The growth rate of the tumor, when detectable, is a critical prognostic factor. Thorough physical examination is essential for surgical planning: The characteristics of the mass, its relationship with both the superficial and deep layers, and any local sign of infection must be carefully examined.
Tumor biology, prognosis, and possible multimodal treatment planning represent the most important disease-related factors, influencing the presumed extent of resection and the kind of reconstruction.
Instrumental Evaluation of the Disease
Imaging
Contrast-enhanced computed tomography (CT) is the imaging test of choice to define size, localization, radiodensity, shape, contour, margins, boundaries, homogeneity/heterogeneity, calcifications, necrosis, vascularity, patterns of contrast enhancement, and distant metastasis; cleavage planes and possible infiltration into adjacent structures may be not definitively determined in all patients.
Magnetic resonance imaging (MRI) is to be considered complementary and not alternative to CT scan. It is recommended in selected cases to evaluate soft tissue planes and to better assess neural, spinal, and vascular involvement.
Biopsy
Even though advances in imaging techniques can make biopsy unnecessary in very selected cases, tissue diagnosis is essential for a correct treatment strategy. In fact, only when the benign or malignant nature of the chest wall tumor has been established, surgical planning can be correctly drawn up. Furthermore, some diseases such as chest wall metastases, Ewing’s sarcoma, and plasmacytomas require chemotherapy and surgery should be only considered as part of a multimodal approach.
Biopsy options include fine-needle aspiration, core-needle biopsy, incisional biopsy, and excisional biopsy. Fine-needle aspiration has a poor diagnostic yield in primary chest wall tumors and should be performed only if chest wall invasion from lung cancer or from other malignancies is suspected. Conversely, the very high diagnostic accuracy of core-needle biopsy makes incisional biopsy rarely needed in the diagnosis of primary tumors. Excisional biopsy is mandatory in case of a chondromatous lesion but can be a reasonable alternative to minimal biopsies also for other tumors, providing that the resulting chest wall defect is small. In conclusion, the choice between the different options for biopsy must be essentially individualized on the basis of the features of the lesion.
Nuclear Imaging Tests
Both 18FDG-positron emission tomography and bone scan may be useful in selected cases to assess the extent of the disease.
SURGERY
The correct approach comes from the analysis of three different points:
a. Resection
b. Restoration of skeletal stability
c. Soft tissue coverage
Resection
The extent of resection varies depending upon the indications.
Benign chest wall tumors: The correct treatment is tumor removal with clear margin. As a rule, resection should not be extended to the skin and the adjacent musculature if not clearly required, but care must be taken to avoid an incomplete resection. In selected cases a wider excision is recommended for the risk of an undiagnosed malignant tumor (chondrosarcoma), or for the possible high local recurrence rate (Desmoid tumors).
Primary malignant chest wall tumors: Wide en-bloc resection is the key for a successful management. It is generally defined as wide en-bloc resection of a tumor excision with 4-cm free resection margins, including the involved skin and soft tissues, ribs and/or sternum, and any other structure invaded by the disease. If a previous surgical biopsy has been done, en-bloc resection of the entire biopsy site must be performed, to avoid the high risk of tumor seeding during the procedure. Radical surgery is often the only real therapeutic chance and the extent of resection should not be limited by anticipated difficulties in reconstruction.
Chest wall direct invasion by lung cancer: Chest wall and lung en-bloc resection is the standard of care. There is no unanimous agreement about the security margin: Theoretically one rib above and below the macroscopic tumor should be recommended with a lateral margin of 3 to 4 cm. Some authors deem 1 cm of free margin in all directions sufficient to balance the surgery-related morbidity, being complete resection the goal to be achieved.1 We think that the security margin must be possibly wide: A minimum resection margin, even if microscopically negative, should be categorized as a compromise solution, to be reserved for those patients in whom the other technical solutions would result in an excessive surgical trauma. In this context, the most common situation is chest wall invasion near the paravertebral sulcus without direct spine involvement, where a minimum histologically negative resection margin could be considered acceptable, making a balanced assessment between risk of local recurrence and trauma related to the vertebral bodies resection.
Chest wall metastasis or direct invasion from other malignancies: A minimum resection margin is generally considered satisfactory. Surgery is rarely indicated, if any, always in the context of a multimodal treatment. If resection is required for a radiation wound or for an ulcerated, infected tumor, wide resection should be performed: Despite extensive resection and apparent removal of any residual infected tissue, the use of synthetic prosthetic material is contraindicated and the resulting dead space must be obliterated by well-vascularized flaps, preferably by a pedicled omental flap.
Technique
Resection of primary or secondary chest wall tumors must be performed en-bloc with the adjacent involved tissues, to avoid tumor seeding. Only few tips and tricks may be provided: The procedure is not technically demanding but a precise method is required. When dealing with lung cancer infiltrating the chest wall, thoracectomy should be performed first, going ahead with en-bloc lobectomy only when the involved chest wall has been freed into the pleural cavity. The chest should be approached well distant from the involved area, to properly assess the local extent of disease, without risks of tumor seeding. Chest wall resection should start with the easier side to expose (i.e., from back to front, for anterior thoracectomies; from front to back, for posterior resection; from below to above, for resection of the first five ribs and vice versa for lower rib resections). In selected lung cancer patients requiring extended thoracectomy, a preliminary atypical lung resection with linear staplers may be useful, provided that a macroscopically free resection margin has been achieved. Subsequently, thoracectomy en-bloc with sublobar resection is carried out. Completion lobectomy and mediastinal lymph node dissection can be performed at the end of the demolitive phase, without any technical obstacles. This surgical strategy facilitates both chest wall and lung resection; in fact, lung adhesion to the chest wall may preclude adequate exposure of the opposite side of the ribs to be removed and a large segment of resected chest wall, dropped into the pleural cavity, can hinder hilar dissection and prevent the lung to be moved inside the chest. However, in most cases requiring an extended thoracectomy, a wide wedge resection is not feasible with a safe margin and the above described technique may be contraindicated.
In posterior thoracectomies, resection of the vertebral transverse process must be carried out with caution. In fact, control of bleeding near the intervertebral foramen is extremely delicate due to the adjacent spinal cord; moreover, the dura mater can be torn during paravertebral sulcus dissection, with possible cerebrospinal fluid leak. For such reasons, the vertebral transverse process should be resected only if the head of the rib is dorsally infiltrated by the tumor; in the other conditions, if necessary, the ribs can be completely disarticulated with a precise technique. Ribs are strongly connected to the spine by a peculiar kind of articulation. Rib head articulates with the body of the thoracic vertebrae and the rib tubercle with the transverse process, with a relatively long overlapping of the bone segments. This type of articulation is categorized as arthrodial joint and is characterized by tight joint capsules, strengthened by multiple and tough ligaments. To achieve complete rib disarticulation, anterior costal interruption is performed first, to allow a higher mobility of the posterior segment of the chest wall to be resected. The erector spinae muscles are then incised to expose the costotransverse joint. The tubercular ligament is cauterized and a curved heavy periosteal elevator is inserted between the transverse process and the rib (Fig. 16.1). To release the neck of the rib it is necessary to divide the costotransverse ligament, which is generally very strong, so much so that rib neck fracture may be easily produced. The cautious use of a light hammer can be helpful to facilitate insertion of the periosteal elevator. The rib neck is dislocated anteriorly by the periosteal elevator, wedged forward with a progressive lever action, until the costal head has been detached from the vertebral body; at the end of the procedure the residual costovertebral ligaments are divided by scissors.
Figure 16.1 The periosteal elevator is wedged forward between rib tubercular facet and vertebral transverse process. Vigorous, active pendulum movement (arrow) achieves disarticulation without fracture.
Figure 16.2 PET-CT scan of a cT3 left upper lobe lung cancer, suitable for double-step anterior resection and reconstruction.
For lung cancer invading very anteriorly the chest wall and requiring en-bloc thoracectomy with division of costal cartilages, an anterolateral thoracotomy is the most intuitive choice because surgical dissection of the costochondral joints is hampered by lung infiltration, if approached posteriorly (Fig. 16.2). On the other hand an anterior approach may have two drawbacks: (1) It does not allow the ideal surgical exposure of the chest wall, posteriorly to the midaxillary line; (2) the resected thoracic wall segment, released within the pleural cavity, is cumbersome and can hamper hilar dissection. In such circumstance, we found advantageous a preliminary short longitudinal parasternal incision to cut the invaded costal cartilages close to the sternum, easily achieving the appropriate resection margin. Before wound closure, a variable number of heavy nonabsorbable stitches are placed on the remaining healthy tissues and/or through the sternum, to medially anchor the future prosthesis: The needles are removed and the stitches knotted distally and temporarily abandoned inside the chest. Then a posterolateral thoracotomy is performed to conclude the en-bloc pulmonary resection facing the easier lateral side of the thoracectomy. The reconstructive phase is facilitated by fixing the prosthesis to the far anterior border of the defect, collecting the anterior stitches previously placed, which are secured to the prosthetic mesh by free needle (Fig. 16.3).
Restoration of Skeletal Stability
The reconstructive technique should ensure early return to normal breathing, protection of intrathoracic organs, restoration of physiologic volume of the rib cage, and satisfactory cosmetic result.
Return to efficient ventilation and protection of intrathoracic viscera are the fundamental targets. A multidisciplinary team, including plastic surgeons, is recommended if an extensive soft tissue and skin resection has been scheduled: It is worth underlining that correct surgical planning constantly requires soft tissue coverage and skin closure, while rigid stabilization of the bony thorax is not always necessary and represents a controversial issue. Reconstruction of the bony thorax is unnecessary for small defects not overlying cardiac structures, which do not significantly impair breathing. In fact, soft tissues reconstruction may provide normal respiratory mechanics in patients with a small chest wall defect and good baseline lung function. Large full-thickness defects not adequately stabilized may act as a sort of traumatic flail chest. However, the two conditions are not exactly comparable: Paradoxical movement of the chest wall after multiple ribs resection is usually not a life-threatening condition as severe traumatic flail chest could be. Probably for these reasons, some surgeons do not usually repair the bony defect, thus underestimating the problem of paradoxical breathing.2 We do not agree with this behavior, although there is no conclusive evidence to support the necessity for bony reconstruction of a large chest wall defect. First of all, an inadequate bony reconstruction after wide thoracectomy may have serious pathophysiologic consequences, affecting both postoperative course and pulmonary status of the patient. Secondly, progress currently achieved in the field of chest wall prostheses allows an easy and safe stabilization of the bony thorax, with minimal morbidity related to the reconstructive procedure. A significant paradox impairs ventilatory mechanics, weakens cough effectiveness, causes mucus retention, increases the risk of pneumonia, and often leads to prolonged postoperative mechanical ventilation, which in itself increases the risk of infection. Respiratory failure is the possible final outcome of these pathophysiologic events. The high incidence of respiratory complications reported after chest wall resection has been correlated to the residual paradoxical movement, resulting from an inadequate reconstruction. In fact, a lower incidence of respiratory complications has been reported by those authors who systematically use skeletal stabilization for large defects.3 For such reasons we believe that any chest wall defect that has the potential for paradox, requires restoration of the skeletal stability. Regardless of the adequacy of soft tissue coverage, prevention of the paradoxical chest wall movements should represent a fundamental goal in surgical planning.
Figure 16.3 A: Preliminary limited longitudinal left parasternal incision: The sternocostal joints of the second, third, and fourth ribs are interrupted and nonabsorbable stitches are placed on the peristernal tissues and temporarily abandoned inside the chest cavity. B: Posterolateral thoracotomy allows to easily complete the posterior section of the involved ribs and the pulmonary resection. Chest wall reconstruction is facilitated by fixing the prosthesis to the far parasternal border of the defect, collecting the anterior stitches previously placed.
Size and location of the defect are the two interdependent factors mainly influencing the likelihood of occurrence and the entity of a postoperative paradox.
Size of the defect. Number, length of rib resection and width of skin soft tissues excision are to be taken into account. There is not a definite threshold that, per se, makes rigid stabilization of a chest wall defect mandatory, even though, roughly, it would be preferable to reconstruct every large bone defect. It has been reported that the >5-cm resection of two consecutive ribs should require rigid stabilization but actually, even a larger defect may be left unreconstructed, thus proving that location more than size of the defect is the basic factor in the decision-making process.
Location of the defect. To guide the decision whether bony chest wall reconstruction is necessary or not, the hemithorax can be topographically divided into “noncritical” and “critical” areas. The latter usually require skeleton reconstruction after full-thickness resection.
Noncritical areas are the apical and the posterior regions; critical areas are the basal, the lateral, and the anterior regions.
The apical region (including first, second, and third ribs) is frequently involved by chest wall resection for the treatment of Pancoast tumors. Resection of the posterior half of the first three ribs does not require bony reconstruction, because the defect lies beneath the scapula. Even if complete resection of the first three ribs is performed, stabilization is not required since the resulting defect works as a thoracoplasty, causing reduction in size of the chest cavity with obliteration of the apical pleural space.
The posterior region is located between the posterior spinal line and the posterior axillary line. Chest wall instability is rarely significant in this area for the following reasons: It is well protected by a thick layer of muscles (latissimus dorsi, trapezius muscle); the supine decubitus of the patient reduces the paradoxical movement of the chest wall. Bony reconstruction is required if the tip of the scapula can fall within the defect and get trapped during movements of the arm (such event must be anticipated if the defect includes the fifth rib). In case of extended soft tissue resection, reconstruction of the posterior thorax is usually achievable by a variety of pedicled flaps.
The lateral region (including fourth, fifth, and sixth ribs between the anterior and posterior axillary lines). Bony reconstruction is recommended after large thoracectomy involving this area, because it is relatively protected only by the serratus anterior and the cranial digitations of the external oblique muscle. Serratus anterior, pectoralis major, and latissimus dorsi muscle flaps can be used for closure of an axillary defect.
The basal region includes the ribs from seventh to tenth, whose resection is followed by an important paradox. In fact, during the breathing cycle, these ribs undergo a significant excursion, since they move laterally when are elevated (the so-called “bucket-handle” movement). Latissimus dorsi muscle flap may reliably cover large defect of this area. Also the diaphragm can be used, suturing it to the lower untouched rib. If the peritoneum has been opened, omental flap can be considered the first choice to cover prosthetic material.
The anterior region has the following boundaries: (a) laterally: anterior axillary lines; (b) cranially: jugular notch and subclavicular fossa; (c) caudally: costal margin. Sternum and costal cartilages are the skeletal structures of the anterior region, forming a rigid protection to the heart and mediastinum, providing the fulcrum for rib cage movements. The sternal manubrium articulates with the clavicles and participates to the shoulder girdle function. Pectoralis major muscles are the principal muscular layers covering the anterior region. The reconstruction technique of this area should restore the skeletal wall stability and also protect the heart with a solid and rigid support. A regional flap for wound coverage is always needed if the pectoralis major muscles are involved in the resection.
Restoration of normal volume of the rib cage and limitation of thoracic deformity could be considered relatively minor goals to achieve, but are anyway significant. The loss of about 50% in volume of a hemithorax results in a restrictive ventilatory deficit, which usually does not produce dramatic effects in patients without preoperative pulmonary impairment. However, in patients with poor baseline lung function, the physiologic rib cage configuration must be restored to avoid postoperative respiratory failure.
Limitation of chest wall deformity must be considered both from a cosmetic and functional point of view. Resection of long segments of at least three consecutive ribs in critical areas may result in significant deformity and volume reduction of the hemithorax. The use of a large nonrigid prosthesis can alter the anatomical shape of the chest because the mesh must be placed under tension, stretched between the ribs bordering the defect; the result is equivalent to a straight line drawn between the rib stumps. The possible technical solutions will be discussed later.
Prosthetic Material for Chest Wall Stabilization
The ideal prosthetic material should be:
strong enough to withstand physiologic stresses;
elastic and flexible, to avoid progressive limitation of the pulmonary function;
light and smooth, unable to induce decubitus ulcers and pain;
easy to mold;
incorporable into the host tissue;
solid, to ensure protection to the visceral structures;
securely fixable;
biocompatible, unable to induce allergic or adverse foreign body reactions;
durable and not subject to deterioration over time;
resistant to infection and to radiation;
not dangerous in case of blunt trauma;
radiolucent and nonmagnetic;
inexpensive;
readily available.
No single material fulfills all these features, even though significant improvements have been achieved in the field of prosthetic substitutes for the chest wall. The different techniques currently available for restoration of the chest wall stability will be briefly discussed.
Grid of Nonabsorbable Sutures
It is a simple way to reduce chest wall paradoxical movement. Multiple heavy nonabsorbable sutures can be utilized, placed between the superior and inferior untouched ribs, delimiting the defect. When the sutures are tightened in tension, the final result is a semirigid grid, which will act as a support to the overlying myoplasty.
Indications. This method can be considered as a compromise solution to be used when the reconstruction of the bony thorax is not certainly required. Small defects can be effectively bridged by this method, which is also very useful for skeletal stabilization in contaminated or irradiated fields, where any prosthetic material should be avoided. The procedure can also be effectively used in combination with mesh prosthesis, to increase the strength of the reconstruction.
Pros. Suture grid is an undemanding and cheap procedure, useful to create a semirigid support for the overlying muscular layers. The primary advantage is avoidance of any prosthetic material. A possible mild wound infection could be well tolerated with no risk of rejection of the used material and no loss of solidity of the reconstructed chest wall. The chest tubes through the large meshes of the grid easily drain the wound.
Cons. It is a rough technique. The problem of postoperative paradox is attenuated, but not abolished. The method does not provide a rigid plate for protection of visceral structures. Prolonged postoperative pain may occur, if a subcostal nerve is trapped by the suture.
Techniques
We generally use no. 2 braided polyester suture, placed approximately 3 cm from each other, to encircle the costal edges. A Langenbeck periosteal elevator is used to carefully free the subcostal neurovascular bundle from the costal groove, in order not to entrap the nerve in the suture, thus decreasing postoperative pain. The use of a drill to perform transcostal sutures is not recommended, since after multiple holes the bone becomes too fragile, as the stitches must be tightened in tension.
Mesh and Soft Patch Reconstruction—Bioabsorbable Material
The long-term stability of any chest wall reconstruction with prosthetic meshes is due to repair by tissues incorporating the employed material. The mesh acts as a scaffold for scar tissue growth. Basically this is the rationale in the use of reabsorbable materials. Bioabsorbable material has been experimented alone or in combination with a nonabsorbable suture grid, but it did not find widespread clinical application, because no significant advantages were demonstrated over the use of nonreabsorbable mesh. Recent technologic advances in biomaterials, mainly developed for tissue reinforcement in ventral hernias’ repair, renewed interest in the use of absorbable materials for chest wall reconstruction. Synthetic and biologic absorbable materials are available. In our preliminary experience we achieved good results with the use of GORE BIO-A Tissue Reinforcement, (W. L. Gore & Associates, Flagstaff, AZ). This is a synthetic bioabsorbable prosthesis, characterized by a web-like structure, similar to collagen fiber network, that is substituted within a 6-month period by scar tissues of the same thickness. Among biologic material, the acellular bovine pericardium (Veritas Collagen Matrix, Synovis Surgical Innovations, St Paul, MN, USA) and the acellular porcine collagen (Permacol, Covidien, Mansfield, MA) proved to be highly resistant to infection in complicated abdominal hernias repair and have occasionally been experimented for chest wall reconstruction, in combination with other prosthetic materials.
Indications. The sole use of absorbable material has probably little significance, since the indication should be limited to stabilization of small defects. Indeed reabsorbable implants are useful in combination with other techniques, especially in potentially contaminated fields, or if postoperative irradiation is contemplated.
Pros. Complete integration of the prosthesis into the host tissues. Efficient scaffold for tissue regeneration. Slow reabsorption time. Better resistance to infection than nonabsorbable mesh. Excellent biocompatibility.
Cons. Unsuitable method to repair large defects if the material is utilized alone. Visceral protection unsatisfactory.
Mesh and Soft Patch Reconstruction—Nonabsorbable Synthetic Material
Nonabsorbable synthetic tissues are the most commonly used products for chest wall reconstruction. A variety of meshes are available, basically categorized by weight (heavyweight; lightweight) and pore size (macropore, micropore). “Heavyweight” meshes are specially designed to ensure long-term mechanical stability and are therefore, suited for chest wall reconstruction. Conversely, “lightweight” meshes are appropriate for ventral hernia repair because they are woven with thin fibers and are mainly designed to improve flexibility rather than stability of the reparative process. The mesh can be woven with monofilament or multifilament fibers with a different design that specifically affects the pores’ size between the fibers. Pores’ size is very important as it is directly related to ability of the prosthesis to be incorporated or not into the surrounding tissues.
Macropore tissues, such as polypropylene mesh, (Prolene, Ethicon, Cincinnati, OH, USA; Marlex, Bard, Billerica, MA, USA) facilitate the tissues’ growth inside, eliciting dense scar formation and ensure good mechanical strength until the conclusion of the biologic processes of incorporation. During the incorporation process, the macropore meshes may cause foreign body reaction, variable inflammatory response, and always induce adhesions to the neighboring tissues. Before incorporation, the mesh is permeable to air and liquids and, for such reason, is unsuitable in case of pneumonectomy. After long-term implantation the macropore mesh undergoes shrinkage and thickening. Micropore meshes, such as expanded polytetrafluoroethylene (PTFE soft patch) (Gore-Tex, W. L. Gore & Associates, Flagstaff, AZ, USA) are poorly integrated into the host tissue, because the very small size of the pores (less than 10 μm) prevents cell growth within the fabric. On the other hand, such mesh is impermeable, does not undergo significant shrinkage and causes less intense foreign body reaction and inflammatory response than macropore meshes.
Indications. Nonabsorbable synthetic meshes are suitable for reconstruction of small-moderate defects in critical areas. For reconstruction of wider defects, such material can be favorably used in combination with others techniques: Grid of sutures, titanium plates, methyl methacrylate (MMA).
Pros. Both macropore and micropore meshes display excellent mechanical strength, if correctly positioned. The better incorporation into the host tissue achieved by the macropore meshes is a value in chest wall surgery, since thickening and possible adhesion formation are not a problem, as opposed to abdominal wall surgery. However, complete mesh incorporation does not seem essential because no significant differences in outcomes and complications were found between the use of micropore and macropore meshes in chest wall surgery.4 Micropore mesh is preferable if impermeability is required (i.e., chest wall reconstruction after pneumonectomy, prosthetic reconstruction of the diaphragm) and/or when visceral adhesions should be minimized.
Cons. Nonabsorbable synthetic mesh is inadequate to reconstruct very large chest wall defects because it does not warrant satisfactory mechanical stability, reliable visceral protection, and chest wall shape restoration. The mesh must be placed under tension with interrupted suture around the defect’s margins and consequently, chest wall contour is altered if long rib segments have been resected. Pericostal suture may cause neuropathic pain. Infection, although infrequent, is a serious complication, and this material should not be used in contaminated or irradiated fields.
Techniques
A paper template of the defect is useful to customize the prosthetic material. The trimmed mesh should be sutured in a radial fashion to the chest wall under tension. Multiple heavy permanent sutures are placed through the superior and inferior untouched ribs and possibly to bone stumps delimiting the defect. The mesh should be also fixed to the soft tissues all around the defect to obtain a tight fixation. It is advisable to pass only few stitches around the inferior rib, taking care not to injure the intercostal nerve; interrupted transverse sutures to the intercostal muscles can complete anchoring to the lower edge of the defect. When the nonabsorbable mesh is used in combination with other material, its position in the context of the prosthesis is variable: We experienced the association of grid of sutures with nonabsorbable meshes placing the mesh above, underneath, or within the grid. The last method seems to be the most reliable and we use to tie the grid of sutures at the end of the procedure, so as to control the tension of the implanted prosthesis (Figs. 16.4 and 16.5). Titanium plates and omentum must always be positioned over the mesh (Figs. 16.6, 16.7 and 16.13).
Figure 16.4 Wide thoracectomy of sixth, seventh, and eighth ribs (A); reconstruction by grid of sutures and mesh (B).
Figure 16.5 Preoperative image of a primary chest wall tumor (A); surgical specimen of full-thickness chest wall resection (B); resulting thoracic defect (C); prosthetic reconstruction by polypropylene–PTFE and nonabsorbable sutures grid (D).
Figure 16.6 A: Titanium repair by Stratos system for left anterolateral defect. B: Chest x-ray shows the contralateral rib anchorage of the medical agrafes.
Figure 16.7 Right anterior chest wall schwannoma. A: Specimen. B: Intraoperative image after PTFE mesh and triple titanium bars placement (Synthes system). C: Postoperative chest x-ray shows a valuable recontruction. D: Rib fracture and lower bar rotation after mild trauma, occurred 2 years after surgery. The patient remained asymptomatic.
Biologic Bone Graft
Bone grafts have been almost exclusively used for reconstruction after sternal resection; the isolated use of biologic soft tissue graft has little role in chest wall reconstruction, as discussed above.
Biologic bone substitutes are: Autograft (obtained from the patient’s own tissues); allograft (cadaveric human graft, received from a bone bank); xenograft (obtained from a species other than human). The latter two materials need to be processed to achieve complete sterility and to lose any antigenic power and infectivity. If adequately vascularized, only autografts may have osteogenic properties, contributing to new bone formation. For allografts and xenografts the concept is roughly the same described for synthetic tissues: The graft provides a scaffold that is slowly reabsorbed and replaced by new native tissue. However, unlike the absorbable material, the biologic bone graft is capable to maintain an absolute mechanical strength during the whole process of host tissues’ restoration. Autografts are unsuitable for reconstruction of large chest wall defects because of the additional trauma, related to bone harvesting. Bovine bone xenograft has been completely abandoned. Conversely, the current possibility of sternal reconstruction with sternochondral allograft obtained by bone banks and fixed to the skeleton of the recipient by titanium plates and screws has raised great interest.5
Indications. Biologic bone grafts are indicated only for reconstruction of wide sternal defect. The technique is still experimental.
Pros. The hypothetical advantage of bone autograft, represented by osteogenic potential capacity, does not seem to be sufficient to justify its use. Bone allografts show theoretical, mechanical, and biologic advantages, are available from bone banks and are interesting mainly because they do not entail a heavier surgical trauma. So far biologic and technical problems have not been reported. The allogenic sternum can be easily tailored to obtain the geometric coverage of the entire chest wall defect; in particular the sternoclavicular joints’ reconstruction is feasible, thus limiting the functional impairment of the shoulder girdle after resection of the sternal manubrium.
Cons. Bone autografts should not be used because they entail an additional surgical trauma that is not counterbalanced by the potential benefits. The use of bone allografts is still investigational; only few studies have been reported and further experience is needed to evaluate the long-term outcomes.
Techniques
The allogenic sternum is trimmed to exactly match the geometric shape of the defect, like the piece of a jigsaw puzzle. Graft measurement can be conducted directly on the surgical specimen, or alternatively, on the defect, by using a template. Once proportions have been optimized and chest anatomy is restored, the graft is fixed to the adjacent skeleton with a variable number of titanium screws and bars (Synthes). Transposition of pectoralis major flap to the midsternum is then performed bilaterally.
Methyl Methacrylate “Sandwich Technique”
MMA is an acrylic resin extensively used as cement in various medical fields, primarily in orthopedic and dental surgery. The use of this material wrapped between two layers of polypropylene mesh was described in 1981 for the reconstruction of large chest wall defects. Since then, the “sandwich technique” has been widely applied in chest wall surgery with only minor technical modifications. The meshes, enveloping the resin, are used to secure correct positioning of the MMA plate and to anchor it to the neighboring tissues.
Indications. The sandwich prosthesis is particularly suitable for repair of wide sternal defects and after extensive thoracectomies requiring restoration of the rounded thoracic contour.
Pros. The prosthesis is: Malleable (suitable for restoration of the thoracic shape); rigid (excellent for skeletal stabilization and intrathoracic organs’ protection); customizable (fit for any size and shape of defect).
Cons. The main concern is risk of infection, since such prosthesis is not incorporable into the host tissues. Other significant disadvantages can be attributed to the MMA plate, because (a) it can undergo fragmentation and migration; (b) it is rigid and may cause long-term pain and restrictive ventilatory deficit; (c) it has a finite lifespan and should not be implanted in young patients with very long life expectancy; (d) it is irritating for the human airway and inhalation exposure is dangerous during processing; (e) if implanted during the polymerization phase it may cause thermal necrosis to the host tissues because it produces an intense exothermic reaction.
Techniques
1. A paper template of the defect is carefully modeled.
2. Two layers of the mesh are cropped 1 cm larger than the defect.
3. MMA is provided as a powder, which mixed with liquid, becomes a pliable, dense paste that gradually hardens, resulting in thermal reaction.
4. At the beginning of processing, the paste is malleable and must be carefully spread on the mesh to let it permeate the fabric porosity. A free rim of mesh, measuring at least a couple of centimeters all around, should be preserved.
5. The second layer of the mesh is applied on top of the paste and pressed on it.
6. The resulting “sandwich” prosthesis should be shaped and rounded according to the chest wall contour, before the cement becomes hard.
7. To prevent migration of the plate, the MMC has to be secured between the two layers of mesh by strong nonabsorbable sutures, tied all around its edges.
8. When the prosthesis is cooled and hardened, it is fixed to the margins of the defect, anchoring the free rim of the mesh to the bone stumps and to the intercostal muscles.
Tips. The MMA plate should be fashioned definitely smaller than the defect and must be smoothed immediately after it has been spread between the two layers of the mesh. In such a way the possible occurrence of long-term postoperative pain and decubitus ulcers is reduced. Plate migration can be prevented by securing it within the meshes, by multiple sutures around the edges. MMA fragmentation is avoided by using only strips of the material, rather than creating a unique plate. A steel mesh added to the MMA, as described in the original technique, is not recommended because it enhances prosthetic rigidity.
Titanium Plate and Screws
Stainless steel was rarely used in the reconstruction of chest wall defects, as no advantages of such material were demonstrated over synthetic nonabsorbable meshes. The recent introduction into clinical practice of titanium devices, specifically designed for chest wall repair, provides the thoracic surgeon with new and interesting technical options. In fact, titanium has the highest strength-to-weight ratio than any other metal alloy; it is biocompatible, chemically inert, corrosion resistant, and stiff and tough but pliable and moldable. Furthermore, it is compatible with CT and MRI imaging. For all these properties it is very suitable for medical applications.
Two different titanium devices are currently available for chest wall reconstruction: The Stratos system (Stratos, MedXpert GmbH, Germany), consisting of titanium bars, anchored by rib clips (Fig. 16.6), and the Synthes system using titanium screws for fixation of different plates and bars (Fig. 16.7) (Synthes, Canada Ltd.).
Indications. Titanium devices have been developed both for rib fractures’ fixation and for chest wall reconstruction after wide resection; for the latter indication the material is generally used in combination with soft patches.
Pros. The titanium devices currently available allow a light, biocompatible, well-tolerated and reliable chest wall repair. They are suited for reconstruction of very large rib and sternal defects. Restoration of the thoracic shape, avoidance of paradoxical chest wall movements, and re-establishment of a rigid support for visceral protection are achievable by a relatively simple procedure. The method allows restoration of the anatomic rib continuity, which probably preserves more physiologic breathing mechanics after wide thoracectomies than single-plate or mesh prosthesis.
Cons. Titanium alloy prostheses are expensive and their use should be justified only in selected clinical situations. The fracture of titanium devices is rather unlikely, but in case of postoperative blunt trauma, the adjacent bones could be particularly liable to fractures, especially at the level of prosthetic anchoring (Fig. 16.7); even a violent sneezing could be dangerous if the plates have been implanted on osteoporotic ribs. This appears to be the main problem in using titanium devices. Chronic chest pain is possible with the Stratos system, if the subcostal nerve has been entrapped by the rib clip clamp.
Techniques
The Stratos system includes different connecting bars and rib clips with three possible angulations, customizable to the variable anatomical situations. Special bending instruments have been developed to individualize the prosthesis. First, the clips must be firmly secured to the rib stumps by apposite pliers, avoiding to entrap the subcostal nerve and to fix the clip to the costal cartilages. To achieve a tight fixation of the rib clips, the superior and inferior edges of both costal stumps must be adequately exposed, for at least the length of the rib clip. The connecting bars are then cut and bent to obtain the appropriate size and shape, suited to the chest contour. The bars are tightened to facilitate their final fixation to the rib clips, by means of appropriate crimping pliers (Fig. 16.6).
The Synthes system consists of precontoured plates and screws, mainly designed for rib fractures’ fixation, but also suited for chest reconstruction after thoracectomy. The Synthes plates are to be modeled on the anatomic thoracic defect using the provided malleable template: The titanium plate is cut to the appropriate length, longer than the defect to allow the placement of at least three screws on each bone stump for an adequate fixation. Dedicated pliers are used to achieve the required longitudinal and axial twist of the plate. The screw length is carefully calculated to secure the prosthesis to the posterior cortex, without protruding excessively toward the chest cavity: Drill bits with stops at the desired length are provided to prevent overdrilling. Without removing the periosteum, the plate is secured to the bone by three consecutive screws on each bone stump. Stable fixation is guaranteed by perfect screw length and by screw heads firmly locked into the threaded holes of the titanium plate (Fig. 16.7).
Tips. We have experienced both devices with satisfactory results. The Stratos system offers an easy to learn and quick procedure because fixation to the adjacent bones is simply achieved by the rib clips. However, direct anchoring of the bar to the sternum is impossible and surgical exposure of the contralateral rib cage may be required in case of an anterior defect (Fig. 16.6). Stratos clips are not indicated even for repair of posterior defects, when at least a 6-cm dorsal rib stump is not available. The Synthes system requires a learning curve. Perfect alignment of the drill hole with the plate hole is necessary; any dead space between struts and bone should be carefully avoided; the rib stump must be drilled in the center and at the defined depth; customizing the bars is complicated, since the bar’s holes must be strictly aligned to the axis of the rib stump. For all these reasons the Synthes technique might be considered a tedious and time-consuming method, but in our experience, it seems to be more versatile than the Stratos technique.
Soft Tissue Coverage
Adequate soft tissue coverage is the main purpose and can be accomplished by various technical solutions, chosen on the basis of multiple factors.
Correct surgical planning is the key to successful outcome. Width and depth of the presumed defect must be predicted to evaluate if a multidisciplinary approach, generally involving plastic surgeons, is required. In such a case surgical strategy should be accurately planned together. Even though the best soft tissue reconstruction is always the simplest possible, coverage of large full-thickness chest wall defects is not a simple procedure, and should not be underestimated from a technical point of view, especially if a very large skin resection is expected.
Regardless of the method of rigid stabilization performed, consistent, viable, and possibly bulky soft tissues should be rebuilt over the skeletal reconstruction, avoiding the closure of skin and subcutaneous tissues directly above bare prosthetic material. In major defects this goal is achieved by flaps: Adequate vascularization is the prerequisite of any flap and understanding of the blood supply of the tissues to transpose is the key factor.
Flap Classifications
A variety of criteria can be adopted for flaps’ classification. The simplest categorization divides flaps into local and distant. Local flaps include tissues transferred from a neighboring area. Distant flaps are tissues transposed from a remote location. A distant flap is called pedicled flap if it is transposed preserving (entirely or partially) its original blood supply; a free flap is a distant flap, transposed detaching its vascular pedicle, which should be subsequently connected to the local vessels by vascular anastomosis.
Figure 16.8 Type III muscle flap according to Mathes and Nahai classification. A: Serratus anterior. B: Rectus abdominis.
According to the tissues transposed, the flap can be divided into simple, if it is composed by one type of tissue and composite, when it is constituted by multiple tissues (in chest wall reconstruction the latter are mostly myocutaneous flaps).
According to the vascularization, the flaps can be divided into: Random flap (when a precise anatomical vascularization is not identifiable) and Axial flaps (when the vascular supply derives from anatomically recognizable vessel/s). The patterns of axial blood supply of the muscle flaps have been accurately classified by Mathes and Nahai into five types: Type I – one vascular pedicle. Type II – dominant pedicle/s and minor pedicle/s. Type III – two dominant pedicles. Type IV – segmental vascular pedicles. Type V – one dominant pedicle and secondary segmental pedicles (Figs. 16.8 and 16.9).6
Pectoralis major muscle flap is the first choice for upper sternal defects.
Insertion. Intertubercular groove of the humerus.
Origin. Outer surface of the sternum. Ribs and costal cartilages (second to sixth).
Clavicle. Aponeurosis of external abdominal oblique muscle on the midline.
Blood supply. Thoracoacromial vessels (dominant pedicle). Perforators’ vessels from the internal thoracic artery and from intercostal arteries (secondary pedicles).
Innervation. Medial pectoral nerve and lateral anterior thoracic nerve.
Mathes and Nahai flap classification. Type V (One dominant pedicle and secondary segmental pedicles) (Fig. 16.9).
Type of flap. Muscle flap. Myocutaneous flap.
Sites of use. Upper sternum. Upper ventral chest wall defect. Upper dorsal chest wall defects. Axillary defects. Neck.
Figure 16.9 Type V muscle flap according to Mathes and Nahai classification. A: Pectoralis major. B: Latissimus dorsi.
Techniques.
Advancement flap. The muscle is elevated off the chest wall starting from the midline to the lateral side. The flap should be based on the dominant vascular pedicle and the secondary perforator branches from the internal mammary artery must be carefully ligated. Dissection is carried out to obtain the sliding of the muscle to the desired site without any tension. Additional length can be obtained by dissection of the clavicular insertions of the muscle. Advancement pectoralis major flap is an easy procedure, widely used, mainly in the treatment of deep sternal wound infection.
Rotation flap. This muscle flap or myocutaneous flap is also based on the thoracoacromial vessels. It is mainly used to provide coverage of head and neck areas but, since a wide arc of rotation is possible, the flap has been also used to cover axillary, shoulder and upper dorsal chest wall defects. Rotation pectoralis major flap requires cooperation with plastic surgeons to minimize the morbidity rate, primarily represented by possible flap necrosis.
Turnover flap. It is obtained by basing the flap on the internal mammary perforator arteries. Division of the dominant vascular supply and humeral and clavicular insertion are needed.
Advantages. Large muscle readily available for one-stage reconstruction of anterior defects. No change of surgical position is generally required.
Disadvantages. The pectoralis major flap can be inadequate to fill the inferior third of the anterior chest wall; it does not always provide sufficient bulk to fill wide defects, especially in female and in debilitated patients. Detachment of the muscle from its insertion on the humeral bone may cause functional sequelae.
Latissimus dorsi muscle flap is one of the most commonly used flaps in reconstructive surgery because of the muscle broadness and its long and reliable vascular pedicle.
Insertion. Intertubercular groove of humerus.
Origin. Iliac crest, spines of lower six thoracic vertebrae, lumbar vertebrae, sacral vertebrae, lower four ribs.
Blood supply. The thoracodorsal artery (dominant pedicle): It is the terminal branch of the subscapular artery, which originates from the axillary artery. The secondary segmental pedicles are the perforating branches of the intercostal and lumbar arteries, which constitute the blood supply for the medial and inferior edge of the muscle.
Innervation. Thoracodorsal nerve.
Mathes and Nahai flap classification. Type V (One dominant pedicle and secondary segmental pedicles) (Fig. 16.9).
Type of flap. Muscle flap. Myocutaneous flap.
Sites of use. Lateral, midposterior, midlateral, anterior regions.
Techniques. A muscle-sparing thoracotomy must be obviously planned. Considering the blood supply coming from above, the flap has to be fashioned by cutting the inferoposterior part of the muscle. This muscle provides a great spectrum of flap size that is of maximal dimension when the dissection is carried out along the rachis. If a myocutaneous flap is required, the skin surface can overlap the muscle perimeter. If any cut had been previously performed on the muscle, the distal portion cannot be used. Latissimus dorsi can be posteriorly or anteriorly rotated after dissection of the three sides rising to the neck (posteriorly) and sternum (anteriorly); if the flap is well prepared, tension and rotation impairment should not be encountered due to the possible flap size.
Advantages. Latissimus dorsi has a valuable rotation degree that provides a great space for rotation flap although translational advancement for anterior defect can be performed. The use of this flap can provide coverage to the largest thoracectomies suitable for soft tissue reconstruction. The regional blood supply allows consistent myocutaneous flap.
Disadvantages. In case of large myocutaneous flap, the primitive posterior muscle site can require skin grafting. The dorsal primary pedicle can be damaged by previous upper chest radiation. In case of posterolateral thoracotomy the muscle part to be rotated can be consistently reduced.
Serratus anterior muscle flap is generally adopted for intrathoracic use.
Insertion. Scapula (medial margin and inferior angle)
Origin. Rib surface (first to eighth)
Blood supply. Serratus branch of thoracodorsal vessels and long thoracic artery and vein
Innervation. Bell’s nerve
Mathes and Nahai flap classification. Type III (two dominant pedicles) (Fig. 16.8).
Type of flap. Muscle flap, myocutaneos flap if used with pectoralis major or latissimus dorsi.
Sites of use. Lateral region if used alone. Lateral posterior if used with latissimus dorsi, lateral anterior if used with pectoralis major. Intrathoracic use is the main indication.
Techniques. If thoracotomy encompasses muscles incision, the serratus anterior can be the best solution because usually preserved by common thoracotomies. The pedicle is cranial and posterior coming from the subscapular artery. The need of preservation of the dominant blood supply is basic and allows complete detachment from the ribs. Introduction into the pleural space is usually carried out through the second intercostal space and fashioned for mediastinal or parietal purposes.
Advantages. The main anatomical feature is that it can be used as an adjunctive flap to pectoralis major and latissumus dorsi. Suitable for lateral plasty. Very easy to use as an intrathoracic flap.
Disadvantages. Limited surface, limited translational potentials if used alone.
Rectus abdominis muscle flap is very useful for the repair of anteroinferior chest wall defects.
Insertion. Costal cartilages (fifth to eighth)
Origin. Pubis cresta
Blood supply. Internal mammary and inferior epigastric vessels
Innervation. Intercostal nerves (seventh to twelfth)
Mathes and Nahai flap classification. Type III (two dominant pedicles) (Fig. 16.8).
Type of flap. Muscle flap, myocutaneos flap
Sites of use. Lower sternum, anterior lower chest wall.
Techniques. The technique is based on flap preparation on the mammary artery pedicle because the inferior epigastric is divided for the thoracic surgery procedure. The possible rotation is both vertical and horizontal. After a longitudinal skin incision, the ipsilateral rectus abdominis is dissected and rotated to the defect. Accurate measurement from the vascular pedicle and the defect must be obtained to create a fitting flap. The flap can sometimes be prepared by saving the skin between the donor site and the defect. It can be achieved with a subcutaneous bridge where the flap can be slided to the defect.
Advantages. This flap is really useful in reconstruction of the anterior chest wall especially the lower sternum. It potentially provides very long graft to be placed with a considerable rotation degree. It can be the flap of choice if other possible tissues have been irradiated.
Disadvantages. Vascular patency of the internal mammary artery must be quantified and maintained after the axial rotation.
Omentum. Muscle flaps are undoubtedly the first choice for soft tissue coverage after extensive full-thickness chest wall resection. Omentum is to be considered a precious alternative in very selected cases, especially in infected or irradiated wound, when retrieval of a well-vascularized replacement tissue is the primary issue. In fact it has been proved as a very valuable option in the treatment of deep sternal wound infection (Fig. 16.10).
Figure 16.10 Large sternal defect after infectious disease (A), laparoscopically prepared omental flap (B) is brought to the defect (C). View of the laparoscopic operating field; the omentum is transposed to the chest through a small diaphragmatic incision (D).
Blood supply. Most of the blood supply of the omentum is derived by the gastroepiploic arcade, which is formed on the side of the greater curvature of the stomach by anastomosis between the right and left gastroepiploic vessels. At least three omental arteries branch off from the gastroepiploic arcade, forming a constant peripheral vascular connection called Barkow’s arcade, characterized by an extensive anastomotic network.
Type of flap. Simple, pedicled flap.
Sites of use. Sternal defects are suited for omental flap, because deep sternal wound infection is the most frequent indication for such type of repair. However the omental flap can reach every site of the thorax, if necessary. Also wide basal defects appear to be suitable for omental reconstruction, especially if the diaphragm has been involved by the resection and the abdominal cavity has been opened (Fig. 16.11).
Techniques. Thoracic transposition of pedicled omentum can be achieved with an open procedure or by laparoscopy (Figs. 16.10 and 16.11). The latter technique is now to be considered the first choice. The patient is placed in the supine position with both arms adducted with an inflating bag positioned under the shoulders. A 10-mm Hasson trocar is placed through a 2-cm midline vertical incision, just above the umbilicus; a 30-degree telescope is then inserted and the pneumoperitoneum is established. Three operative ports with 5-mm trocars are sufficient to obtain a good surgical maneuverability. In our experience, the use of ultrasound scissors has been helpful (Harmonic Scalpel; UltraCision: Ethicon Endo-Surgery, Inc, Cincinnati, Ohio) to divide possible adhesions and separate omentum from the transverse colon, if necessary. Through a right or left subcostal port the gastric wall is grasped to facilitate dissection. If a long and bulky flap is needed, complete mobilization of the omentum based on the right gastroepiploic artery is performed. Alternatively, for lower sternal defect in a suitable anatomy, the gastroepiploic arcade may be left untouched and the omental flap may be simply developed at the expense of Barkow’s arcade, dividing some of the anastomosing arteries. The decision is made on the basis of required flap bulk and length and the individual anatomical variability, which is remarkable in this area. Thoracic transposition of the mobilized omentum is achieved through a 5-cm substernal diaphragmatic incision, if the flap has been developed to obliterate the space of an anterior defect; if the omental flap has been designed to cover defects located elsewhere, the site of transdiaphragmatic thoracic transposition is chosen on the basis of the target location of the pedicled tissue flap. Great care must be used to control the correct position of the stomach’s greater curvature, which could have been stretched cranially during the omental transposition.7
Figure 16.11 Operative field of infected sternal metastasis of mammary cancer (A), intraoperative view of the large defect after resection of skin, pectoralis muscles, sternum, and thymus gland (B), omental flap completely fills the anterior gap after resection (C), soft tissue coverage has been achieved by the ipsilateral mammary gland (D).
Advantages. This flap is seldom required for chest wall reconstruction but the technique must belong to the thoracic surgeons’ armamentarium, because the possible fields of application of the omentum are multiple and potentially extremely useful. Omentum has a very rich blood supply, induces neovascularity and can survive in highly contaminated fields, where it aids to eradicate infection; it conforms to every recess and its possible large size makes it suitable to cover wide prosthetic reconstruction in different thoracic sites.
Disadvantages. Omentum has no structural support and should be placed on a rigid base. When harvested by laparotomy the thoracic omental transposition entails multiple drawbacks: Heavier surgical trauma, increased postoperative pain, oral nutrition delay, and possible abdominal hernia. All these disadvantages are avoided by laparoscopic omentoplasty.
Diaphragm. Phrenoplasty is a possible method of chest wall reconstruction, even if it should not be classified within the soft tissues coverage procedures. Phrenoplasty is an old technique developed in the tuberculosis era, for the management of dead space after lobectomy. The application of this procedure for chest wall reconstruction has not been adequately reported in the literature.
Sites of use. Defects in the basal area are very well reconstructed by the diaphragm, regardless of whether the muscle was partially involved in the resection: In particular the technique of phrenoplasty is suited for repair of defects resulting from resection of the seventh, eighth, ninth, and tenth ribs.
Techniques. The concept is simply reattaching the diaphragm at a higher level (Fig. 16.12). The phrenic nerve innervates the diaphragm from the center outward and it is possible to preserve the main branches of the nerve, by peripheral incision of the muscle. Muscle incision at the level of the costodiaphragmatic recess gets a large flap that is secured by heavy nonabsorbable pericostal sutures to the lower uninvolved rib. Even if the diaphragm has been partially resected, the flap can be elevated at the desired level, at the expense of the phrenic dome. The technique allows transformation of a thoracic defect into an abdominal defect, with fewer pathophysiologic consequences; reconstruction of the gap is as well required to prevent an abdominal hernia development. A variety of methods can be used for such purpose. Titanium bars and omentum covering a synthetic mesh are reasonable choices (Fig. 16.13).
Figure 16.12 Lower chest wall defect, suitable for reconstruction with the diaphragm. The diaphragm has been radially incised and fixed to the lowest uninvolved rib. A: Anterior view. B: Lateral view.
Figure 16.13 A: Intraoperative image of diaphragmatic reconstruction after left eighth, ninth, and tenth ribs resection. B,C: Abdominal defect reconstruction by PTFE prosthesis, covered by omental flap and single titanium bar placement. D: Postoperative chest x-ray shows a linear diaphragmatic profile.
Advantages. The pathophysiologic consequences of the defect are strongly limited, in particular those of respiratory type because no paradoxical movements of the wall can occur.
Disadvantages. A mild reduction of the pleural cavity volume is the only drawback of this technique.
CONCLUSIONS
Chest wall surgery is a fascinating topic due to its multiple pathophysiologic implications, the continuous improvement of techniques and materials, and the variety of the possible surgical solutions.
Acknowledgments
Special thanks to Elisa Scarnecchia for pictures and artworks. The authors also acknowledge Beatrice Sensi and Mark Ragusa for the editing support.
Recommended References and Readings
1. Riquet M, Arame A, Le Pimpec Barthes F. Non-small cell lung cancer invading the chest wall. Thorac Surg Clin. 2010;20(4):519–527
2. Facciolo F, Cardillo G, Lopergolo M, et al. Chest wall invasion in non-small cell lung carcinoma: A rationale for en bloc resection. J Thorac Cardiovasc Surg. 2001;121(4):649–656.
3. Weyant MJ, Bains MS, Venkatraman E, et al. Results of chest wall resection and reconstruction with and without rigid prosthesis. Ann Thorac Surg. 2006;81(1):279–285.
4. Deschamps C, Tirnaksiz BM, Darbandi R, et al. Early and long-term results of prosthetic chest wall reconstruction. J Thorac Cardiovasc Surg. 1999;117(3):588–591
5. Marulli G, Hamad AM, Cogliati E, et al. Allograft sternochondral replacement after resection of large sternal chondrosarcoma. J Thorac Cardiovasc Surg. 2010;139(4):e69–e70.
6. Mathes SJ, Nahai F. Classification of the vascular anatomy of muscles: Experimental and clinical correlation. Plast Reconstr Surg. 1981;67(2):177–187
7. Puma F, Fedeli C, Ottavi P, et al. Laparoscopic omental flap for the treatment of major sternal wound infection after cardiac surgery. J Thorac Cardiovasc Surg. 2003;126(6):1998–2002.