Keywords Ewing's sarcoma - sternum - prosthesis - bioceramics - tissue engineering
Introduction
Ewing's sarcoma is the second most frequent primary malignant bone tumor in adolescents
and young adults.[1 ]
[2 ] Between 80 and 100, new patients are reported each year in France.[3 ] It has a remotely strong invasive power, at the time of diagnosis ∼20 to 25% patients
present with metastatic disease. Metastasis usually occurs to the lungs (70–80%) and
to the bone (40–45%).[4 ] Locations on the thoracic wall represent up to 20% of primary and secondary locations.[5 ] The treatment is based on a general chemotherapy combined with a wide resection
of the tumor which can lead to a massive loss of bone substance, thus a reconstruction.
The development of biomaterial and the evolution of tissue engineering offer a promising
solution to the replacement and transplantation of defective tissues within the human
body. The objective is to produce devices with the potential to integrate and regenerate
a specific functional tissue during their in vivo implantation.
Among these materials, bioceramics were established as an alternative to other polymers
or metals for the replacement of bone structures. In 2005, Baino et al[6 ] stated that the main qualities of a biomaterial used in vivo are biocompatibility,
optimal geometry allowing the guidance of tissue reconstruction, bioactivity stimulating
the integration/incorporation of an implant, biomechanical qualities about the tissue
it aims at replacing and biological properties allowing the development of angiogenesis
and the stimulation of cell differentiation.
Here, we deal with the use of a radiolucency porous bioceramic prosthesis as a sternal
replacement of a wide tumor resection in an oncologic context.
Case Report
In January 2019, our department of pediatric surgery provided care for a 13-year-old
patient with metastatic Ewing's sarcoma and a primary lesion on the manubrium of sternum
spread all over the mesosternum diagnosed 6 months earlier ([Fig. 1 ]).
Fig. 1 Preoperative computed tomography scan view of the sternum tumor.
The patient presented with pulmonary metastasis and a lumbar intramuscular. She was
treated with a neoadjuvant chemotherapy according to the COMBINAIRE R3 protocol in
which she was included allowing the regression of most metastases except for a secondary
ischial lesion ([Fig. 2 ]).
Fig. 2 (A ) Positron emission tomography (PET) scan prechemotherapy. (B ) PET scan postchemotherapy.
Focal radiation therapy was not possible due to the high risk of severe myocardial
injuries caused by the sternal location of the tumor. A wide sternum resection was
done with a replacement by a porous ceramic prosthesis (sternum CERAMIL; I.CERAM,
Limoges, France) ([Fig. 3 ]).
Fig. 3 Ex vivo image of the implant.
The implant is available in five sizes and three half sizes for replacement of the
manubrium. It is delivered with trial implants allowing the choice of the size and
the optimization of preparation of the implantation area ([Fig. 4 ]).
Fig. 4 (A ) Available implant sizes. (B ) Ancillary of trial implants.
It is also possible to order custom implants for the patient if the clinical situation
requires it.
Following the midline incision from the suprasternal notch to the xiphoid process,
the pectoralis major muscle was sticking out on its whole sternal insertion revealing
the costal cartilages from C1 to C8. A subperichondrial resection of the middle portion
of all the costal cartilages as well as the two collarbones with clavicular osteotomy
were performed. The sternum was raised like a hood.
The preperforated sternal prosthesis CERAMIL was positioned in place of the removed
sternum and was successively attached to each costal cartilage stump with a nonabsorbable
suture in no. 3 Mersuture type polyester. The sutures were loose in order, on the
one hand, to preserve the mobility of the thorax and, on the other hand, to avoid
the section of the wire on the ceramic matrix ([Fig. 5 ]).
Fig. 5 (A ) Intraoperative view after sternum resection. (B ) Intraoperative view of I.Ceram porous alumina sternal prosthesis insertion with
sutures.
After its positioning, the prosthesis was relatively mobile compared with deep layers,
but the overall showed a satisfactory rigidity. A chest Blake drain placed under the
prosthesis at the end of the surgical procedure was removed on day 6. There were no
complications in the early management of the patient.
At week 3, the evolution was satisfactory: a nocturnal noninvasive ventilation (NNIV)
was still necessary, but the patient had no respiratory trouble. NNIV was maintained
for 6 weeks. The local morphological appearance was satisfactory with admitted cutaneous
healing. On palpation, the sternum was closely linked to the rib cage with no abnormal
mobility. The patient did not complain of any pain. A computed tomography (CT) scan
was performed 3 weeks postoperatively when mediastinitis was suspected. An implant
in place was found without scannographic artifact allowing a precise study of the
position of the implant and the surrounding structures ([Fig. 6 ]).
The microscopic analysis of the sternal resection revealed a scar tissue and a necrotic
appearance of the lesion without any residual viable tumor cell. The lesion was completely
removed, with clear margins.
Fig. 6 Three-week postoperative computed tomography scan.
At the 28-month follow-up, the patient did not present any functional thoracic complaint
and nor any functional respiratory symptoms. There was no secondary displacement of
the prosthesis, no chronic pericardial irritation or pleural effusion. The patient
was satisfied with the clinical result and the morphological aspect of her thorax
and could take part in leisure physical activities. Her clinical condition was compatible
with good tolerance of this type of implant in children ([Fig. 7 ]).
Fig. 7 Appearance of the thorax at 28 months postoperatively.
Discussion
To this day, there is no referential approach for sternal reconstruction. Several
techniques have been used such as bone graft, the use of metallic-structured implants
or muscular flaps.[7 ]
[8 ]
[9 ] None is yet fully satisfactory to this indication. Indeed, the ideal characteristics
for a sternal reconstruction prosthesis are a rigidity allowing the protection of
mediastinal organs, a malleable inclination to maintain a satisfactory mechanical
ventilation, radiolucency to create an anatomic reference to do a better follow-up
and identify a possible local neoplastic relapse and a bioinertia to allow the in-growth
of fibrous tissue and decrease the likelihood of infection.[10 ]
[11 ] The CERAMIL® sternum in porous alumina (Al2 O3 ) has already been implanted into adults in sternal replacement during its invasion
by a tumor or its postoperative cardiac infectious destruction with a median follow-up
of 18 months showing a satisfactory evolution.[12 ] No complication, especially infectious, was observed during this study.
Fouilloux et al[13 ] mentioned in 2019 the first implantation case in a 9-year-old child showing a congenital
sternum agenesis with no postoperative complication of the implant after 12 months.
Denes et al,[14 ] as a commentary to the article of Baino et al, pointed out that this device meets
the main qualities of a bioceramic. Its porous structure (a diameter ranging from
100 to 900 μm) allows a quick invasion of the ceramic by the osteoblasts allowing
the biointegration on a long-term basis and as a result the stability of the ceramic
within the bone while maintaining its biomechanical properties similar to the bone
tissue (the mechanical resistance to compression being of 20 MPa). This balance between
the porosity of the material and its mechanical properties is a crucial aspect for
its bone application. Biocompatibility and bioinertia were established in the long
term by the implantation of more than 5,000 bioceramic devices.
These metastatic pulmonary lesions represent 50% of secondary lesions in Ewing's sarcoma.[1 ]
[15 ] Such a prosthesis has the advantage of being radiolucent and not creating artifacts
in case of a CT scan. In the context of postoperative oncology monitoring of pulmonary
metastases from Ewing's sarcoma, this has a clear advantage over titanium prostheses.
It has been recently shown that bacterial adhesion is less important on porous alumina
than on other materials such as titanium or stainless steel,[16 ]
[17 ] which is another asset in surgeries with risks of infection such as wide oncologic
excision of the sternum.
Conclusion
The alumina sternal prosthesis appears to be a reliable option in sternal replacement
indications for children. This first case of implantation of a porous alumina prosthesis
in an oncologic context confirms it. However, a long-term follow-up for this implant
seems must be required.
