1. Introduction to Chest Wall

The chest wall encompasses all the tissues that surround the chest cavity, including both the bony structures (thorax) and soft tissues (muscles, fascia, fat, skin, nerves, and blood vessels) connecting between bones. The thorax consists of one sternum (breastbone), 12 pairs of ribs, 12 thoracic vertebrae, and costal cartilages, which together form the bony framework (Figure 1). The space enclosed by the thorax is known as the chest cavity, housing vital organs such as the heart and lungs, which are central to the circulatory and respiratory systems. The thoracic cage serves to protect these vital organs and plays a crucial role in maintaining normal respiratory function.

 

2. Chest Wall Disorders

Tumors, infections, trauma, and radiation therapy can all lead to defects in the chest wall, compromising its integrity and stability. (1) Chest wall tumors can be either soft tissue or bone tumors. Soft tissue tumors originate in the soft tissues of the chest wall, including lipomas, neurofibromas, smooth muscle tumors, and liposarcomas. Bone tumors affect the bony structures of the chest wall and may include giant cell tumors, osteosarcomas, and chondrosarcomas, with bone metastases being a common form (Figure 2A). Surgical removal of these tumors may result in significant chest wall defects necessitating chest wall reconstruction. (2) Secondary to infections and radiation damage, soft tissue necrosis can be the second most common reason for chest wall resection, following malignancies. Factors contributing to chest wall infections include immunosuppression (e.g., in diabetic patients), chest wall surgery or trauma, and tissue necrosis caused by chest radiation. While chest wall tuberculosis is relatively rare, surgical excision may be required in the presence of cold abscesses (Figure 2B). (3) Radiation therapy for tumors inevitably damages surrounding normal tissues. Acute changes in normal tissues usually resolve upon treatment completion, but serious late complications occurring several months to years later, known as late radiation tissue injury (LRTI), can affect the chest wall. Breast cancer is a common cause of LRTI in the chest wall (Figure 2C). Radiation-related chest wall injuries impact normal breathing function and may carry the risk of spreading to the costosternal joints, pleural spaces, and the development of infections. In severe cases, thorough debridement and chest wall reconstruction may be necessary.

 

3. Chest Wall Reconstruction

Following chest wall resection due to tumors, infections, or radiation-induced tissue necrosis, substantial chest wall defects can lead to abnormal respiration and respiratory dysfunction. Severe cases may require chest wall reconstruction to restore the integrity of the thoracic cage. The primary goals of chest wall reconstruction are as follows: (1) filling the dead space, (2) restoring skeletal rigidity, (3) preventing lung herniation and scapula impingement, (4) protecting organs within the chest cavity and mediastinum, and (5) maintaining aesthetic appearance.

Not all chest wall resections require reconstruction. If chest wall resection does not compromise chest wall stability and allows normal respiratory function, reconstruction may not be necessary. Chest wall reconstruction includes both bony and soft tissue components. Bony reconstruction employs graft materials to restore chest wall strength and stability, while soft tissue reconstruction uses flaps to ensure airtight closure and aesthetic outcomes. In some cases, soft tissue reconstruction can provide sufficient stability and not hinder normal respiratory function, while in others, soft tissue coverage alone may not offer the required stability, necessitating bony chest wall reconstruction. Therefore, individualized treatment and reconstruction of chest wall defects are crucial, tailored to each patient's specific condition.

The complexity of the chest wall demands innovative and individualized approaches for reconstruction, testing the creativity and personalized treatment awareness of thoracic surgeons. Ideal bony chest reconstruction materials should have the following characteristics: (1) good mechanical strength to ensure chest wall stability and protect the chest cavity and mediastinum, prevent abnormal respiration and lung herniation; (2) inertness, being resistant to breaking or degradation; (3) implantability, non-carcinogenic, facilitating the growth of fibrous tissue covering, and minimizing the risk of infection; (4) malleability, allowing for ease of shaping and adapting to the chest wall's external form; (5) compatibility with chest X-ray imaging for patient follow-up, and (6) affordability. Previous reports on chest wall reconstruction materials include "sandwich" patch materials, titanium alloy plates, and allogeneic bones, each with its own advantages and disadvantages in terms of mechanical strength and infection resistance. By building upon previous experiences and introducing innovations, our Hospital's Chest Wall Surgery Subspecialty team developed a modular chest reconstruction system utilizing titanium alloy materials. This system has been patented by the state and used for chest reconstruction following sternum, costosternal joint, costal cartilage, and rib resection, demonstrating excellent treatment outcomes. Relevant articles have been published in the prestigious international journal "Annals of Thoracic Surgery" (Figure 3).

 

4. Shanghai Pulmonary Modular Chest Wall Reconstruction System and Case Studies

In contrast to traditional reconstruction implants, our reconstruction system employs a modular design. It standardizes and prefabricates modules for the sternum, ribs, and clavicles in various size specifications. These modules can be selected and assembled intraoperatively, depending on the extent and shape of the chest wall defect, thus forming a large-scale implant (Figure 4 and Video 1). These modular composite implants are constructed from titanium alloy materials, offering mechanical strength greater than that of human bone tissue. Additionally, they are interconnected using mortise and tenon joints with screws, as opposed to mimicking the human joint structure, and they do not incorporate muscle attachments. Consequently, the length of the implant is related to the extent of sternum resection, while the thickness and width do not need to correspond to the patient's specific sternum measurements.

Patient 1, a 48-year-old female, was admitted due to intermittent chest pain in the anterior thoracic region for nearly 20 years. A chest CT revealed a lower sternal mass with calcification and lobulations, measuring 77×62mm. After excluding distant metastasis, she underwent a procedure involving the "mid-sternum splitting, partial resection, and reconstruction." Intraoperatively, a massive hemispherical mass measuring 80×70mm was observed in the lower-middle section of the sternum, encapsulated and not invading the ribs, pericardium, visceral pleura of the lungs, or other tissues. The resection involved the complete removal of the lower-middle sternal body and both third ribs and below. This included the rib cartilage and the rib bone ends. Chest wall reconstruction was performed using the modular sternal composite implant system, consisting of 5 sternal body modules and 4 rib modules. The overall implant remained securely fixed without any signs of loosening. Bilateral pedicled pectoralis major muscle flaps were used to cover the sternal implant. The surgery lasted 240 minutes, with an intraoperative blood loss of 100ml. Postoperatively, the patient was hospitalized for 7 days. The pathological examination confirmed a well-differentiated chondrosarcoma. The patient did not receive radiation or chemotherapy and was followed up for 18 months. The sternal reconstruction showed excellent healing, with no signs of infection, fluid collection, or loosening, and there was no evidence of local recurrence or distant metastasis (Figure 5).

Patient 2, a 54-year-old female, was admitted after the discovery of a sternal mass during a routine checkup three months earlier. A PET/CT scan showed sternal manubrial bone destruction with an associated soft tissue mass measuring approximately 88x38mm, exhibiting abnormally elevated glucose metabolism, with an SUVmax of 19.18. No distant metastasis was detected. The decision was made to perform a procedure involving "mid-sternum mass resection and chest wall reconstruction." Intraoperatively, the mass's borders were approximately 10x8x8cm, so a midline vertical incision with a T-shaped incision at the site of the mass's prominence was performed. After thoroughly exposing the soft tissues around the mass, the tumor was removed by cutting the rib cartilage on both sides, followed by resecting the manubrium, first ribs, and the clavicle-sternum junction. The tumor was completely excised. Chest wall reconstruction was executed using the modular sternal reconstruction system, with a sternal reconstruction length of 10 cm, securing the ribs on both sides with two hooks each, and fixing the clavicular ends with clavicular head anchors. Local reinforcement with steel wire was performed at the clavicular head. The pectoralis major muscles on both sides were mobilized and used to cover the modular sternal implant's surface and the posterior aspect. Additionally, the clavicular region was covered using the sternoclavicular muscle and the vessels below the pectoralis major muscles. The surgery lasted 270 minutes with an intraoperative blood loss of 300ml, and the patient was hospitalized for 9 days. The postoperative pathological diagnosis revealed diffuse large B-cell lymphoma. After 30 months of follow-up, the reconstruction site exhibited excellent recovery (Figure 6).

Patient 3, a 45-year-old female, presented with recurrent chest wall metastasis six years after undergoing a right breast lumpectomy. Three years prior, she had undergone abdominal wall reconstruction with inferior epigastric artery perforator flaps. During the past six months, possible chest wall metastasis was discovered upon reevaluating her breast condition. A PET/CT scan upon admission showed elevated glucose metabolism in a soft tissue mass, approximately 31x20mm in size, located beside the right sternal area, with an SUVmax of 11.57. An operation was planned, which involved a "mid-sternum mass resection and chest wall reconstruction." Intraoperatively, a vertical midline incision was made from the sternal angle to the xiphoid process, followed by layer-by-layer dissection of skin, soft tissue, and the musculature adjacent to the sternum. The sternal surface muscles were mobilized and extended to the intrinsic chest wall on both sides. The ribs were adequately exposed, and the tumor was dissected, involving a 2cm sternal cut above the mass, which was followed by the resection of the manubrium, the first to fifth ribs, and the costal cartilage. The chest wall tumor was entirely removed. The modular sternal reconstruction system was employed for sternal reconstruction, which consisted of a sternal reconstruction length of approximately 13cm. Both left and right rib hooks were secured with three fasteners each, and local wire fixation was employed to strengthen the modular xiphoid and the bilateral costal cartilage. The sternal and rib fixation was robust and stable. The mediastinal thymic tissue and the fat at the corners of the pleura on both sides covered the metallic sternum. The surgery took 180 minutes, with an intraoperative blood loss of 150ml, and the patient was hospitalized for 11 days. The postoperative pathological diagnosis indicated malignant tumor with consideration of metastatic breast cancer. After 12 months of follow-up, the reconstructed area displayed excellent recovery (Figure 7).

 

Conclusion

Compared to previous chest wall reconstruction methods, the modular reconstruction system at the Shanghai Pulmonary Hospital offers several advantages: (1) It eliminates the drawbacks of titanium alloy plates that cannot be overlapped and avoids the requirement, as with various custom grafts, to completely resect the tumor within the predetermined range. Using the modular system allows for flexible chest wall reconstruction based on the intraoperative findings and pathology results. (2) The production of combination modules does not rely on the patient's anatomical parameters, enabling factory-based standardized manufacturing, significantly reducing production complexity, and eliminating the need for long preoperative waiting times. (3) It features a non-sealed structure, devoid of dead spaces, reducing the risk of fluid accumulation. (4) It essentially restores the bony anatomical structure of the chest wall. (5) Rib angles are adjustable and can be securely fixed, offering convenient fixation at various points, ensuring strong connections.

Our hospital's modular reconstruction system has been successfully employed in over 30 cases of sternum/chest wall reconstruction. Most patients experience hospitalization periods of fewer than 10 days post-surgery, with no occurrences of abnormal breathing or postoperative complications such as infections or fluid accumulation at the reconstruction site. The dedicated thoracic surgery team at the Shanghai Pulmonary Hospital, Department of Thoracic Surgery, demonstrates a commitment to breaking with conventional methods, continuous innovation, and bringing new hope to patients with chest wall disorders.

Figure 1. Schematic diagram of the thorax

Figure 2. Chest Wall Disorders. A. Hepatocellular carcinoma chest wall metastasis. B. Tuberculous cold abscess. C. Breast cancer Local Recurrence and Thoracic Inlet involvement (LRTI).

Figure 3. Shanghai Pulmonary Chest Reconstruction System Featured in the International Renowned Journal "Annals of Thoracic Surgery" in the Field of Thoracic Surgery.

Figure 4. Multi-Purpose Modular Sternum Reconstruction Composite Implant System. A. Schematic Design of the Modular Sternum Reconstruction Composite Implant System. B. Physical Images of the Multi-Purpose Modular Sternum Reconstruction Composite Implant System (Before and After Assembly).

Figure 5. Case 1. A. Preoperative Chest CT. B. Sternum Mass. C. Intraoperative Reconstruction Result. D. Postoperative Chest X-ray.

Figure 6. Case 2. A. Preoperative Chest CT. B. Intraoperative Reconstruction Result. C. Postoperative Chest X-ray.

Figure 7. Case 3. A. Preoperative Chest CT. B. Intraoperative Reconstruction Result. C. Postoperative Chest X-ray.