Custom‐made Prosthesis for Reconstruction after Radical Resection for Chondrosarcoma of Manubrium

Abstract

The clinical incidence of tumors in the manubrium is not high. Regardless of whether the tumor is primary or metastatic, the tumor should be completely removed as long as the patient is able to tolerate the surgery. This procedure can lead to sternal defects. Deciding on the method of defect reconstruction is a critical problem that clinicians face. In this , to reduce the limitations of the patient’s upper body movement after surgery due to the inflexibility in the connections of the sternal prosthesis, we created a prosthesis using a computer‐assisted design method and a 3‐D technique, to completely preserve the agility of the sternum and maximize the patient’s post‐operational movement. The method used in the present study takes into consideration the individual’s chest anatomy, sternum stress, and many other biological characteristics. Care is taken to measure the sternum size accurately, to provide personalized treatment, to accomplish precise results, and to reduce potential future damage. The patient’s shoulder function was improved following the procedure.

Introduction

Primary sternal tumors are uncommon and account for only 1% of primary bone neoplasms1. Chondrosarcoma, a type of malignant cartilage‐forming tumor, is the most common primary malignancy of the anterior chest wall2. Sternal chondrosarcomas are resistant to chemotherapy and radiation and, thus, wide resection is the only curative option3. Sternal tumors are a significant challenge in surgery due to the difficulties in full‐thickness resectioning without compromising the stability and reconstruction of the thoracic wall. Reconstruction of the thoracic wall after resection is the key to success3.

Most scholars believe that chest wall defects greater than a size of 6 cm × 6 cm need bony reconstruction to restore the morphological function of the thorax4. Various procedures have been used to reconstruct defects of the thoracic wall; selection of the procedure depends on the surgeons’ experience. Covering the defects and protecting the joint function are the most important tasks in reconstruction5. The main current clinical reparation and reconstruction methods are: use of a titanium plate sandwiched between two polypropylene mesh sheets6 and allograft bone transplantation7. Although the problem of reconstruction is solved, the disadvantages, relating to the useful life, the intensity of prosthesis use, and bone resorption, are obvious. The purpose of the present study is to describe the use of 3‐D image reconstruction and computer‐aided design techniques to achieve the reconstruction of an individualized sternal prosthesis, and the biomechanical reconstruction of the relevant joint using the patient’s own ligaments. The recent clinical results for the patient were positive.

Case Report

Case Presentation

A 56‐year‐old male patient had sustained continued sternal pain after activity 4 months prior to presentation to our clinic. CT examination revealed osteolytic bone destruction of the manubrium; with tumor bones and soft tissue mass formation, the size was approximately 66.6 mm × 67.8 mm × 71.7 mm (Fig. 1A). The tumor of the manubrium was bulging out of the thorax, protruding into the thoracic cavity to compress the left common carotid artery and superior vena cava, with edges irregularly calcified, and, hence, was considered to be chondrosarcoma. Neither the surface of the manubrium articular nor the sternoclavicular joint were involved, and the preoperative joint activity was not significantly limited. Therefore, the tumor was operational, with no clear distant metastasis signs. Before the surgery, the patient was informed of the risks and the circumstances were reviewed by the hospital ethics committee.

Figure 1.

(A) CT scan showing involvement of chest wall structures. (B) Three‐dimensional reconstruction of the bony thorax and tumor. (C) Final prosthesis design.

Preoperative Planning

In the design of the sternal prosthesis, high resolution CT scan data (DICOM format) from the patient’s chest were imported into the Mimics 19.0 (Materialise, Belgium) software to reconstruct a 3‐D model of the bony thorax and tumor (Fig. 1B). The purpose of this analysis is to determine the osteotomy range and to simulate the surgical procedure. The CAD measurement tools were used to accurately measure the size of the tumor, the sternum, and the sternal body marrow cavity, with the distance between the clavicles, sternoclavicular joints and other sternal parameters determined using 3‐D models. According to the shape of the biological manubrium and sternal parameters, a sternal prosthesis was designed and the length of the reconstruction ligament was then determined. Holes are located at the edge of manubrium prosthesis, which are designed for the ligaments to pass through as well as the inert lines that connect the bone to the prosthesis. The upper part of the sternum body and the prosthesis manubrium are connected to the site, adding ladder‐shaped protrusions to prevent the prosthesis inserting into the sternal cavity too deeply. The sternal prosthesis placed in the sternal cavity should be removed before the top of the sternum in the patient, with length of 10–12 mm. The sternal body part of the prosthesis was vertically arranged with 4 holes with a diameter of 5–6 mm for strengthening the fixed and integrated function of bone cement. The middle of the sternum prosthesis was also provided with biofusion holes to increase the biocompatibility of the prosthesis (Fig. 1C). The prosthesis data was then converted to STL format and imported into a laser metal direct‐forming 3‐D printing device to print the titanium alloy‐made sternal prosthesis.

Surgical Technique

During the procedure of sternal prosthesis transplantation, the patient’s own palmaris longus and semitendinosus tendons were prepared for the reconstruction of the interclavicular, costosternal, and sternoclavicular ligaments. The skin was cut adjacent to the tumor surface along the midline and the tumor was removed. The apex of the sternum body was excised (approximately 10–12 mm) before placing the sternal prothesis to expose the sternum body cavity. An independently designed sternum cavity file was used to ream the cavity and the distal sternal prosthesis was fixed with the assistance of bone cement. Holes in the clavicle and ribs were perforated to pass through the ligaments and the inert lines. Reconstruction of the interclavicular ligament was performed using autologous ligaments in the tunnel at the top of the sternum stem. The sternoclavicular ligament was reconstructed using autologous ligaments at the top of the two sides of the sternum prothesis in which the sternoclavicular joints were located. Costosternal ligaments were reconstructed in the same way. Direct implementation of cross‐suturing and tying by ligaments was performed for biological reconstruction of the joint. To improve the stability between the prosthesis and the sternum, fastening by inert wires was performed, preventing loosening in the future (Fig. 2A). The drainage tube is placed after the final flushing is completed. Finally, the soft tissue and skin were sutured layer by layer. The resected specimens were sent for pathological examination.

Figure 2.

(A) Intraoperative view after reconstruction showing the anatomical restitution of the manubrium. (B) Postoperative CT image of the bony thorax and prosthesis. (C) Postoperative 3‐D reconstruction of the bony thorax and prosthesis. (D) Preservation of thoracic morphology and excellent functional results 1 month after surgery.

Results

There is no significant difference between postoperative pathology and preoperative biopsy. The (sternal) chondrosarcoma was grade II, and part of the tumor tissue had necrosis and mucinous degeneration. Excision of the border revealed no tumor tissue. CT shows that the oppression on the blood vessels has been eliminated (Fig. 2B). Three‐dimensional reconstruction by thoracic CT shows a perfect composition of the sternal prosthesis and the sternum; therefore, the sternoclavicular joint is stable (Fig. 2C). Postoperative examination showed a solid chest wall, restored to a good shape. The prosthesis did not appear to be loose, with no deformation, movement or fracture apparent. There was no evidence of infection or foreign body rejection. Follow‐up was performed 1 month after surgery; the patient was experiencing no discomfort, and the Neer function score was 90 (Fig. 2D). Three months after surgery, follow‐up results indicated that there was no limitation of daily activities, and the quality of life had significantly improved.

Discussion

With the burgeoning development of computer‐aided technologies in medical research, computer designed and 3‐D printed partial sternal prostheses are being used in practice8. Issues using prostheses include potential dislocation, inaccurate measurement for and sizing of prostheses, and restrictions of movement following surgery. Incorrectly sized prosthesis can be difficult to place during surgery and there is the risk of internal damage for the patient following the surgery. Other reports indicate the lack of consideration of the flexibility of the prosthesis, with rigid metal connections, which can lead to unrepairable rupture of the prosthesis and the need for more surgery9.

We introduced the use of 3‐D image reconstruction and computer‐aided design techniques to accurately measure the sternal parameters according to the anatomy characteristics of the sternum and referring to the shape of the manubrium, to achieve the reconstruction of an individualized sternum. A postoperative 3‐D reconstruction model shows that the position of the prosthesis is exactly the same as in preoperative planning. In addition, we biomechanically reconstructed the relevant joints using autologous ligaments and strengthened the stability by inserting lines at the same time. It is not only a perfect solution to the postoperatively limited range of upper extremities, but also reduces the fracture of the prosthesis by fully taking into account of the individual’s anatomy, and mechanical and biological characteristics of the sternum. Ultimately, we are able to accomplish a perfect reconstruction of the chest wall shape and also maximize the extent of the sternoclavicular to enable return to the original range of activities. The level of postoperative satisfaction is very high.

Although using computer‐aided design technology and 3‐D printing technology for surgery is time‐consuming and costly, in general, the personalized titanium breast prosthesis still offers many advantages for the repair of sternum defects and the completion of bony thoracic reconstruction, such as achieving precise 3‐D correction, saving time, minimizing surgical incision, and avoiding fluoroscopy. Personalized treatment is at the cutting edge of modern surgery, and, with the help of 3‐D printing technology and precision medicine, could effectively improve surgical procedures.

Conclusion

Compared with traditional surgery, computer assisted surgery allows accurate preoperative planning and simulation of the surgery. The technique described in this study could shorten the duration of surgery and reduce the risk of surgery. The periods of radiation exposure of patients and surgeons are reduced at the same time. It is an advanced technical method which is worthy of further application in the field of precision orthopedics surgery. The method used in the present study takes into consideration the individual’s chest anatomy, sternum mechanics, and many other biological characteristics. Care is taken to measure the sternum size accurately, to provide personalized treatment, to accomplish precise results, and to reduce potential future damage. The patient’s shoulder function was improved following the procedure. However, long‐term follow‐up results are warranted to support the use of this method as a standard procedure.