The current concept of large-segment bone defect treatment is still to complete the replacement and fusion of bone tissue by means of autologous, allogeneic or artificial bone graft filling, that is, "bone-bone" interface fusion. The theory is deeply rooted, but the clinical effect is poor. A research team from research institutions such as Peking University Third Hospital used a custom-made 3D-printed titanium alloy porous implant to repair large-segment bone defects in a research work, realizing the patient's early limb function recovery and long-term "implant- Reliable fusion of the "bone" interface, with significantly improved efficacy.
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Makalah penelitian terkait diterbitkan dalam jurnal Bioactive Materials
https://doi.org/10.1016/j.bioactmat.2021.03.030
This research work was supported by the National Key RD Program of the Ministry of Science and Technology of the People's Republic of China (2016YFB1101501).
block Traditional "bone-bone" fusion treatment concept
Defek tulang segmental yang besar akibat trauma, infeksi, atau reseksi tumor selalu menjadi masalah klinis yang menantang. Sekitar 5 persen -10 persen patah tulang mengalami penyatuan atau non penyatuan yang tertunda, dan hampir semua kehilangan tulang segmental mengakibatkan non penyatuan. Di seluruh dunia, lebih dari 2,2 juta cangkok tulang dilakukan setiap tahun untuk mengobati cacat tulang di bidang ortopedi, bedah saraf, dan kedokteran gigi.
Classical techniques for the treatment of large bone defects include the Ilizarov technique, the induction of bone regeneration through biofilms (Masquelet technique), autologous vascularized cortical bone grafting, and titanium mesh (filled with autologous or allogeneic bone) implantation techniques. The above treatments have their own characteristics depending on the technology, but they are essentially based on the concept of "bone-bone" fusion, that is, autologous bone, allogeneic bone or artificial bone is transplanted and filled in the defect area, and replaced by bone tissue repair. Complete the connection and fusion of the bones at both ends of the defect area.
Namun, praktik klinis menunjukkan bahwa perawatan ini tidak ideal dan terkadang bahkan tidak dapat diandalkan. Transportasi tulang melalui prosedur Ilizarov biasanya membutuhkan waktu beberapa bulan untuk sembuh, selama waktu tersebut pasien tidak dapat bergerak secara normal. Metode ini bahkan lebih kecil kemungkinannya untuk digunakan untuk pengobatan cacat tulang multi-segmental tulang belakang. Teknik Masquelet dan metode pencangkokan tulang kortikal vaskularisasi autologous membantu meningkatkan fusi tulang, tetapi sulit untuk mencapai stabilisasi pascaoperasi segera. Karena kebutuhan akan tulang alogenik/autologus dalam jumlah besar sebagai bahan cangkok tulang, operasi pengangkatan tulang tambahan (seperti pengangkatan tulang iliaka) sering diperlukan. Metode penanaman jaring titanium ke daerah cacat tulang memberikan kemudahan untuk aplikasi berbagai bahan cangkok sampai batas tertentu, tetapi efek fiksasinya terbatas, dan juga memiliki kekurangan yaitu mudah melonggarkan, ambles atau berpindah. Faktanya, teknik seperti Ilizarov dan Masquelet juga sulit diterapkan di situs disosiasi tertentu, seperti metafisis.
To sum up, various traditional techniques based on the concept and theory of "bone-bone" fusion have many shortcomings or defects in the treatment of large segmental bone defects: the treatment process is long, and the limbs of patients after surgery are not immediately, early, or surgically removed. After a long period of time can not bear weight.
blok cetakan 3D implan titanium berpori
"Implant-bone" interface fusion
Dibandingkan dengan-metode yang disebutkan di atas yang memerlukan pengisian tulang alogenik/autologus dalam jumlah besar, penerapan implan paduan titanium berpori 3D-untuk memperbaiki dan merekonstruksi cacat tulang tampaknya memiliki keuntungan yang jelas. Pertama, implan dapat disesuaikan secara tepat sesuai dengan bentuk cacat tulang, tanpa memerlukan cangkok tulang; selain itu, sesuai dengan keunggulan prostesis logam, perangkat fiksasi dapat dirancang untuk mencapai stabilisasi langsung antara implan dan tulang yang berdekatan, sehingga pasien dapat bangun dari tempat tidur lebih awal setelah operasi; Fitur struktural berpori, menarik jaringan tulang yang berdekatan untuk tumbuh ke dalamnya, dan akhirnya mencapai fusi permanen dari antarmuka tulang-implan.
Gambar 1. Analisis radiologis dan biomekanik dari implan Ti6A14V berpori cetak 3D untuk merekonstruksi defek femur 4 cm. (A) Gambar sinar-X-pada 1, 3 dan 6 bulan setelah implantasi (i-iii) Gambar tomografi terkomputasi pada 1, 3 dan 6 bulan setelah implantasi (iv-vi) . Panah biru menunjukkan tulang yang baru terbentuk di lokasi cacat atau di permukaan luar implan. (vii) Skor radiologi setiap kelompok. (n=4) (B) Gambar rekonstruksi 3D MicroCT (i-iii) dari kelompok 1, 3, dan 6 bulan setelah pengorbanan (abu-abu menunjukkan paduan titanium, hijau menunjukkan tulang baru). (iv) Hasil kuantitatif fraksi volume tulang di peri-implan dan di-regio foram dari setiap kelompok (n=4).
Namun, efek terapeutik klinis dari penggunaan implan berpori cetak 3D untuk memperbaiki cacat tulang (terutama cacat tulang segmen-besar) tidak hanya memerlukan konfirmasi hasil pengamatan kasus-lanjutan, tetapi juga hasil studi eksperimental hewan yang relevan sebagai bukti. Untuk itu, tim peneliti melakukan-eksplorasi dan penelitian yang mendalam dan sistematis.
Figure 2. Biomechanical analysis of 3D printed porous Ti6A14V implants for reconstruction of 4 cm femoral defects. (A) Three-point flexural strength of each group of samples (n = 4) (B) Stress distribution of the "implant-bone" complex at (ii) 1000 N, (iv) 2000 N and (vi) 3000 N. Displacement distribution of the "implant-bone" complex at (i) 1000N, (iii) 2000N and (v) 3000N. (p<0.01,><>
In view of the shortcomings of the traditional "bone-bone" fusion method in the treatment of large-segment bone defects, and based on the experience of exploratory treatment of large-segment bone defects and the results of relevant animal experiments, the research team proposed a new large-segment bone defect. The technology and concept of bone defect repair and reconstruction: "implant-bone" interface fusion.
Figure 3. Histological analysis of 3D-printed porous Ti6A14V implants for reconstruction and repair of 4 cm long femoral defects. (A) Goldner's trichrome staining (i-iii) of 1, 3 and 6 month groups. (iv) Quantitative results of implant-bone growth and implant-bone contact rates in the three groups. (v) The ratio of mineralized bone to osteoid in each group (n = 10). (B) Fluorescent labeling of new bone around the implant and in the pores. (White arrows indicate titanium columns, green and yellow bands indicate calcein- and tetracycline-labeled new bone, respectively). (i) Osseointegration around the implant in the 1-, (iii) 3- and (v) 6-month groups. (ii) 1-, (iv) 3-, (vi) osseointegration in plant pores in 6-month groups.
The basic idea is: a. The 3D printed porous titanium alloy prosthesis is implanted into the bone defect area, and the two ends of the implanted prosthesis are connected and fixed with the adjacent host bone, so as to realize the immediate (or early) functional recovery of the patient's limb; b . The implanted prosthesis is designed as a porous structure to attract adjacent bone tissue to grow into it and surround it to achieve "implant-bone" interface fusion.
Figure 4. 3D printing of porous Ti6Al4V implants to reconstruct spinal bone defects (case 1). (A) (i-vi) 1 month (i), 3 months (ii), 7 (months iii), 12 months (iv), 24 months (v) and 32 (vi) postoperatively "Implant-bone" X-ray image of Moon. Blue arrows indicate the implant-bone interface or new bone on the outer surface of the implant. (B) CT images at 3 months (i), 7 months (ii), 12 months (iii), 28 months (iv), 32 months (v) and 36 months (vi) after surgery. Blue arrows indicate the implant-bone interface or newly formed bone on the outside of the implant.
Of course, if the porous structure of the implant grows through the bone tissue, it is ideal to form a "bone-bone" fusion, but it is difficult to become a reality. However, when the two ends of the implant prosthesis are effectively fused with the host bone at a distance of several millimeters, it can already meet the needs of the patient to restore the motor function of the limb. The research team applied the 3D-printed porous titanium alloy implants made by electron beam melting (EBM) technology to the clinical treatment of a group of large-segment bone defects, and achieved better than expected results. At the same time, the research team used the small-tailed Han sheep to create a long-segment femoral defect model to study the osseointegration characteristics of this method, and to provide a supporting basis for the treatment effect of clinical cases.
Gambar 5. Implan Ti6Al4V berpori 3D-untuk merekonstruksi defek femoralis (kasus 2). X dari defek femur 11 cm yang direkonstruksi segera setelah operasi terakhir (A) dan 2 (B), 5 bulan (C), 8 bulan (D), 14 bulan (E) dan 20 bulan (F) setelah gambar garis implantasi. Panah biru menunjukkan osseointegrasi antara implan dan tulang inang.
Figure 6. 3D-printed porous Ti6Al4V implant to reconstruct pelvic bone defect (case 3). Photographs of the actual "implant-bone" complex specimen taken from (A) lateral and (B) anteroposterior views. The location of the "implant-bone" interface area indicated by the blue arrow (C) Histological image of the "implant-bone" interface, showing new bone growing into the porous implant pores. Micro-CT images of the "implant-bone" contact area in (D) midsagittal plane, (E) coronal plane and (F) transverse plane.
In this study, the research team successfully treated large segmental bone defects caused by various etiologies by 3D printing porous titanium alloy implants without using autologous/allogeneic bone grafts or any osteoinductive agents. immediate and long-term biomechanical stability. Animal experiments have shown that bone can grow into the pores to a certain extent and gradually remodel, so that the "implant-bone" complex can achieve long-term mechanical stability. In addition, this study also proposes a new "implant-bone" interface fusion concept for the treatment of large segmental bone defects, which is different from the traditional "bone-bone" fusion concept.
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