Customized scaffolds for large bone defects using 3D‑printed modular blocks from 2D‑medical images

Additive manufacturing(AM)has revolutionized the design and manufacturing of patient-specific,three-dimensional(3D),complex porous structures known as scaffolds for tissue engineering applications.The use of advanced image acquisition techniques,image processing,and computer-aided design methods has enabled the precise design and additive manufacturing of anatomically correct and patient-specific implants and scaffolds.However,these sophisticated techniques can be timeconsuming,labor-intensive,and expensive.Moreover,the necessary imaging and manufacturing equipment may not be readily available when urgent treatment is needed for trauma patients.In this study,a novel design and AM methods are proposed for the development of modular and customizable scaffold blocks that can be adapted to fit the bone defect area of a patient.These modular scaffold blocks can be combined to quickly form any patient-specific scaffold directly from two-dimensional(2D)medical images when the surgeon lacks access to a 3D printer or cannot wait for lengthy 3D imaging,modeling,and 3D printing during surgery.The proposed method begins with developing a bone surface-modeling algorithm that reconstructs a model of the patient’s bone from 2D medical image measurements without the need for expensive 3D medical imaging or segmentation.This algorithm can generate both patient-specific and average bone models.Additionally,a biomimetic continuous path planning method is developed for the additive manufacturing of scaffolds,allowing porous scaffold blocks with the desired biomechanical properties to be manufactured directly from 2D data or images.The algorithms are implemented,and the designed scaffold blocks are 3D printed using an extrusion-based AM process.Guidelines and instructions are also provided to assist surgeons in assembling scaffold blocks for the self-repair of patient-specific large bone defects.

Tension-reduced closure of large abdominal wall defect caused by shotgun wound:A case report

BACKGROUND Large abdominal wall defect(LAWD)caused by shotgun wound is rarely reported.CASE SUMMARY Herein,we describe a case of LAWD caused by a gunshot wound in which the abdominal wall was reconstructed in stages,including debridement,tensionreduced closure(TRC),and reconstruction with mesh and a free musculocutaneous flap.During a 3-year follow-up,the patient recovered well without hernia or other problems.CONCLUSION TRC is a practical approach for the temporary closure of LAWD,particularly in cases when one-stage abdominal wall restoration is unfeasible due to significant comorbidities.

Treatment of large defect of abdominal wall after tumors resection by transposition of tissue flaps with pedicle

Objective To report evaluat of division region of abdominal wall large defect after tumors resection and repair methods by tissue flaps with pedicle. Methods Form October 1992 to September 2001, 8 cases large abdominal wall defect after malignant tumors resection(10 × 10 cm-32 cm×32 cm) were reviewed. The defectcontributed:Ⅰ region, 2 cases; twin-Ⅱ region, 2; Ⅲ region, 2; Ⅰ and Ⅱ region of one side, 1 and total abdominal wall,one case, The tissue flaps of transposition included: gracilis myocutaneous flaps, 4; retus abdominal myocutaneous flaps, 2; external abdominal obligue musculo-fascia flaps, 2; latissimus dorsi muscle, tensor fasciae latae muscle and retus femoris muscle flaps each, 1. One patient used MycroMesh also. Results In the course of peroperation, the incisions of 8 cases healed in first time; total tissue flaps survived and all pateints started exercise left the bed in 3 weeks. All 8 patients were followed up average of 2 years and 5 months: the success rate of reconstruction

3D Printing Hip Prostheses Offer Accurate Reconstruction,Stable Fixation,and Functional Recovery for Revision Total Hip Arthroplasty with Complex Acetabular Bone Defect

Complicated and large acetabular bone defects present the main challenges and difficulty in the revision of total hip arthroplasty(THA).This study aimed to explore the advantages of three-dimensional(3D)printing technology in the reconstruction of such acetabular bone defects.We retrospectively analyzed the prognosis of four severe bone defects around the acetabulum in three patients who were treated using 3D printing technology.Reconstruction of bone defect by conventional methods was difficult in these patients.In this endeavor,we used radiographic methods,related computer software such as Materialise's interactive medical image control system and Siemens NX software,and actual surgical experience to estimate defect volume,prosthesis stability,and installation accuracy,respectively.Moreover,a Harris hip score was obtained to evaluate limb function.It was found that bone defects could be adequately reconstructed using a 3D printing prosthesis,and its stability was reliable.The Harris hip score indicated a very good functional recovery in all three patients.In conclusion,3D printing technology had a good therapeutic effect on both complex and large bone defects in the revision of THA.It was able to achieve good curative effects in patients with large bone defects.

Three-dimensional-printed individualized porous implants:A new“implant-bone”interface fusion concept for large bone defect treatment

Bone defect repairs are based on bone graft fusion or replacement.Current large bone defect treatments are inadequate and lack of reliable technology.Therefore,we aimed to investigate a simple technique using three-dimensional(3D)-printed individualized porous implants without any bone grafts,osteoinductive agents,or surface biofunctionalization to treat large bone defects,and systematically study its long-term therapeutic effects and osseointegration characteristics.Twenty-six patients with large bone defects caused by tumor,infection,or trauma received treatment with individualized porous implants;among them,three typical cases underwent a detailed study.Additionally,a large segmental femur defect sheep model was used to study the osseointegration characteristics.Immediate and long-term biomechanical stability was achieved,and the animal study revealed that the bone grew into the pores with gradual remodeling,resulting in a long-term mechanically stable implant-bone complex.Advantages of 3D-printed microporous implants for the repair of bone defects included 1)that the stabilization devices were immediately designed and constructed to achieve early postoperative mobility,and 2)that osseointegration between the host bone and implants was achieved without bone grafting.Our osseointegration method,in which the“implant-bone”interface fusion concept was used instead of“bone-bone”fusion,subverts the traditional idea of osseointegration.

Electroactive barium titanate coated titanium scaffold improves osteogenesis and osseointegration with low-intensity pulsed ultrasound for large segmental bone defects

For large segmental bone defects,porous titanium scaffolds have some advantages,however,they lack electrical activity which hinders their further use.In this study,a barium titanate(BaTiO3)piezoelectric ceramic was used to modify the surface of a porous Ti6Al4V scaffold(pTi),which was characterized by scanning electron microscopy,energy dispersive spectroscopy,X-ray photoelectron spectroscopy,and roughness and water contact angle analyses.Low intensity pulsed ultrasound(LIPUS)was applied in vitro and in vivo study.The activity of bone marrow mesenchymal stem cells,including adhesion,proliferation,and gene expression,was significantly superior in the BaTiO3/pTi,pTi+LIPUS,and BaTiO3/pTi+LIPUS groups than in the pTi group.The activity was also higher in the BaTiO3/pTi+LIPUS group than in the BaTiO3/pTi and pTi+LIPUS groups.Additionally,micro-computed tomography,the mineral apposition rate,histomorphology,and the peak pull-out load showed that these scaffold conditions significantly enhanced osteogenesis and osseointegration 6 and 12 weeks after implantation in large segmental bone defects in the radius of rabbits compared with those resulting from the pTi condition.Consequently,the improved osteogenesis and osseointegration make the BaTiO3/pTi+LIPUS a promising method to promote bone regeneration in large segmental bone defects for clinical application.

Optimal regenerative repair of large segmental bone defect in a goat model with osteoinductive calcium phosphate bioceramic implants

So far,how to achieve the optimal regenerative repair of large load-bearing bone defects using artificial bone grafts is a huge challenge in clinic.In this study,a strategy of combining osteoinductive biphasic calcium phosphate(BCP)bioceramic scaffolds with intramedullary nail fixation for creating stable osteogenic microenvironment was applied to repair large segmental bone defects(3.0 cm in length)in goat femur model.The material characterization results showed that the BCP scaffold had the initial compressive strength of over 2.0 MPa,and total porosity of 84%.The cell culture experiments demonstrated that the scaffold had the excellent ability to promote the proliferation and osteogenic differentiation of rat bone marrow-derived mesenchymal stem cells(BMSCs).The in vivo results showed that the intramedullary nail fixation maintained the initial stability and structural integrity of the implants at early stage,promoting the osteogenic process both guided and induced by the BCP scaffolds.At 9 months postoperatively,good integration between the implants and host bone was observed,and a large amount of newborn bones formed,accompanying with the degradation of the material.At 18 months postoperatively,almost the complete new bone substitution in the defect area was achieved.The maximum bending strength of the repaired bone defects reached to the 100% of normal femur at 18 months post-surgery.Our results demonstrated the good potential of osteoinductive BCP bioceramics in the regenerative repair of large load-bearing bone defects.The current study could provide an effective method to treat the clinical large segmental bone defects.

A novel conceptual design of a biomimetic oral implant and its biomechanical effect on the repairment of a large mandibular defect

This study aimed to propose a novel biomimetic design strategy of an oral implant and to numerically examine its biomechanical effect according to clinical interests.The designed implant conceptually mimicked the morphology and elastic modulus of the mandibular bone.Basing on a CT-image-based patient-specific reconstruction of the tumor-excised mandible,the biomechanical effects of the implants with three materials(PEEK/n-HA/CF,PEEK/HA and Ti6Al4V),two surgical conditions(removed and retained muscles),and two postoperative stages(early and late)were fully investigated by a static finite element analysis.Moreover,according to clinical interests(e.g.failure and stability of the implant and rivets),maximum von Mises stresses and strains of the implant and rivets,maximum implant-bone gap in the early postoperative stage,and maximum von Mises stress of the mandible were mainly analyzed.The results showed that the implant composed of Ti6Al4V material was suitable for the current design strategy with respect to the other two PEEK-based materials.Although the implants in the muscle-retained surgical condition had relative greater indices compared to the muscle-removed surgical condition,the index difference between the two conditions was slight.The biomechanical indices indicating the failure and loosening risks of implant and rivets were much reduced in the late postoperative stage with respect to the early postoperative stage due to the osteointegration at the implant-bone interface.Generally,the proposed novel design strategy could be useful to guide the design of the oral implant addressing different implant materials and surgical conditions,and further made proper suggestion to clinicians and patients.

Mimicking the native bone regenerative microenvironment for in situ repair of large physiological and pathological bone defects

Bone is a complex biological tissue with a complicated hierarchical nanocomposite structure.The native microen-vironment of the bone tissue may be significantly disrupted by large physiological and pathological bone defects.Bone defects are often treated via complex surgical procedures that involve the application of autografts or al-lografts.While these grafting procedures often suffer from insufficient natural bone stock and immunorejection.Moreover,these traditional treatment methods fail to simulate a regenerative microenvironment,which plays a significant role in regeneration of bone tissue and repair of large bone defects.To this end,various biomimetic scaffolds have been devised to mimic the native microenvironment of bone and thereby to simultaneously re-pair bone defects and promote bone regeneration.We propose here a novel concept,in vivo bone regenerative microenvironment(BRM),which enables repair of large bone defects and enhances new bone tissue formation with external regulation.In this review,we mainly focus on materials and methods for fabrication of biomimetic scaffolds,as well as their therapeutic efficacy in modulating the BRM of large physiological and pathological bone defects.

Mechanically strong porous bioceramic tubes facilitate large segmental bone defect repair by providing long-term structurally stability and promoting osteogenesis

Mechanically strong magnesium-doped Ca-silicate bioceramic scaffolds have many advantages in repairing large segmental bone defects.Herein we combine β-TCP with 6 mol%magnesium-doped calcium silicate(Mg6)at three different ratios(TCP,TCP+15%Mg6,TCP+85%Mg6)to find an appropriate ratio which can exert considerable influence on bone regeneration.In this study,the bioceramic scaffolds were assessed for mechanical strength,bioactive ion release,biocompatibility,and osteogenic capacity through in vitro testing.Additionally,the potential for promoting bone regeneration was investigated through in vivo implantation of porous tube-like scaffolds.The results showed that the compressive strength increased with the augmentation of Mg6 component.Especially the compressive strength of the TCP+85%Mg6 group reached 38.1±3.8 MPa,three times that of the other two groups.Furthermore,extensive in vivo investigations revealed that the TCP+85%Mg6 bioceramic scaffolds were particularly beneficial for the osteogenic capacity of critical-sized femoral defects(20 mm in length).Altogether,magnesium doping in bioceramic implants is a promising strategy to provide stronger mechanical support and enhance osteogenesis to accelerate the repair of large defects.