Filling the gap: a series of 3D-printed titanium truss cages for the management of large, lower limb bone defects in a developing country setting

Custom-Made 3D-Printed Titanium Implants for Managing Segmental Distal Tibial Bone Defects: A Systematic Literature Review

Background: The management of diaphyseal and distal tibial defects and non-unions is a significant challenge. Traditional treatments, such as distraction osteogenesis or Masquelet, are characterized by extended treatment times and elevated complication rates. Innovative approaches, such as customized 3D-printed titanium implants, are often required to restore structural integrity and function. This systematic review aimed to analyze the results achieved to date with this technique. Methods: A systematic review of the literature written in English was performed in PubMed, Scopus, and Cochrane to identify all cases of tibial non-unions or defects treated with customized 3D-printed titanium implants, excluding defects from tumor resection. Studies with a minimum of 12 months of follow-up were included. Results: The causes of treatment were infection in 10 patients, non-union in 6 patients, and severe bone loss after trauma in 3 cases. The size of the defect ranged from 3 to 8.5 cm. Osteointegration was 100% in all studies. The mean time to union was 5.3 months. The complication rate was 16%. Conclusions: Good results were reported in most patients. However, the data are insufficient to define the role of customized 3D-printed implants compared to traditional techniques. Further studies comparing them are needed to draw explicit guidelines.

Application of 3D-printed porous prosthesis for the reconstruction of infectious bone defect with concomitant severe soft tissue lesion: a case series of 13 cases

BACKGROUND

Treating infectious bone defects combined with large soft-tissue lesions poses significant clinical challenges. Herein, we introduced a modified two-stage treatment approach involving the implantation of 3D-printed prostheses and flap repair to treat large segmental infectious tibial bone defects.

METHOD

We conducted a retrospective study of 13 patients treated at our center between April 2018 and March 2022 for tibial infections owing to posttraumatic infection and chronic osteomyelitis combined with soft tissue defects. The average defect length was 14.0 cm (range, 5.7-22.9 cm). The flap area ranged from 14 × 5 to 15 × 8 + 25 × 15 cm. Sural neurocutaneous, lesser saphenous neurocutaneous, and local fasciocutaneous flaps were used to repair the skin defects. In the second stage, 3D-printed prostheses were designed and implanted. Union rate, complications, and functional outcomes were assessed at the final follow-up.

RESULT

The average follow-up period was 31.1 months (range, 17-47 months), with an average interval of 208.1 days (range, 139-359 days) between the two stages. According to our criteria, 7 of the 13 patients achieved radiographic healing without intervention. Two patients developed prosthesis-related complications and underwent revision surgery. Two patients experienced recurrent infections leading to prosthesis removal and debridement surgery, with the infection ultimately eradicated in one and the other undergoing amputation. Three patients experienced noninfectious flap-related complications, however, all eventually healed through surgical intervention.

CONCLUSION

The use of 3D-printed porous titanium prostheses combined with flap soft-tissue repair for the treatment of infectious tibial bone defects did not increase the rate of infection recurrence and provided good functional recovery, offering more options for the treatment of infectious bone defects.

A review of computational optimization of bone scaffold architecture: methods, challenges, and perspectives

The design and optimization of bone scaffolds are critical for the success of bone tissue engineering (BTE) applications. This review paper provides a comprehensive analysis of computational optimization methods for bone scaffold architecture, focusing on the balance between mechanical stability, biological compatibility, and manufacturability. Finite element method (FEM), computational fluid dynamics (CFD), and various optimization algorithms are discussed for their roles in simulating and refining scaffold designs. The integration of multiobjective optimization and topology optimization has been highlighted for developing scaffolds that meet the multifaceted requirements of BTE. Challenges such as the need for consideration of manufacturing constraints and the incorporation of degradation and bone regeneration models into the optimization process have been identified. The review underscores the potential of advanced computational tools and additive manufacturing techniques in evolving the field of BTE, aiming to improve patient outcomes in bone tissue regeneration. The reliability of current optimization methods is examined, with suggestions for incorporating non-deterministic approaches andin vivovalidations to enhance the practical application of optimized scaffolds. The review concludes with a call for further research into artificial intelligence-based methods to advance scaffold design and optimization.

Applying 3D-printed prostheses to reconstruct critical-sized bone defects of tibial diaphysis (> 10 cm) caused by osteomyelitis and aseptic non-union

BACKGROUND

Clinical repair of critical-sized bone defects (CBDs) in the tibial diaphysis presents numerous challenges, including inadequate soft tissue coverage, limited blood supply, high load-bearing demands, and potential deformities. This study aimed to investigate the clinical feasibility and efficacy of employing 3D-printed prostheses for repairing CBDs exceeding 10 cm in the tibial diaphysis.

METHODS

This retrospective study included 14 patients (11 males and 3 females) with an average age of 46.0 years. The etiologies of CBDs comprised chronic osteomyelitis (10 cases) and aseptic non-union (4 cases), with an average defect length of 16.9 cm. All patients underwent a two-stage surgical approach: (1) debridement, osteotomy, and cement spacer implantation; and (2) insertion of 3D-printed prostheses. The interval between the two stages ranged from 8 to 12 weeks, during which the 3D-printed prostheses and induced membranes were meticulously prepared. Subsequent to surgery, patients engaged in weight-bearing and functional exercises under specialized supervision. Follow-up assessments, including gross observation, imaging examinations, and administration of the Lower Extremity Functional Scale (LEFS), were conducted at 3, 6, and 12 months postoperatively, followed by annual evaluations thereafter.

RESULTS

The mean postoperative follow-up duration was 28.4 months, with an average waiting period between prosthesis implantation and weight-bearing of 10.4 days. At the latest follow-up, all patients demonstrated autonomous ambulation without assistance, and their LEFS scores exhibited a significant improvement compared to preoperative values (30.7 vs. 53.1, P < 0.001). Imaging assessments revealed progressive bone regeneration at the defect site, with new bone formation extending along the prosthesis. Complications included interlocking screw breakage in two patients, interlocking screw loosening in one patient, and nail breakage in another.

CONCLUSIONS

Utilization of 3D-printed prostheses facilitates prompt restoration of CBDs in the tibial diaphysis, enabling early initiation of weight-bearing activities and recovery of ambulatory function. This efficacious surgical approach holds promise for practical application.

An innovative intramedullary bone graft harvesting concept as a fundamental component of scaffold-guided bone regeneration: A preclinical in vivo validation

Background

The deployment of bone grafts (BGs) is critical to the success of scaffold-guided bone regeneration (SGBR) of large bone defects. It is thus critical to provide harvesting devices that maximize osteogenic capacity of the autograft while also minimizing graft damage during collection. As an alternative to the Reamer-Irrigator-Aspirator 2 (RIA 2) system - the gold standard for large-volume graft harvesting used in orthopaedic clinics today - a novel intramedullary BG harvesting concept has been preclinically introduced and referred to as the ARA (aspirator + reaming-aspiration) concept. The ARA concept uses aspiration of the intramedullary content, followed by medullary reaming-aspiration of the endosteal bone. This concept allows greater customization of BG harvesting conditions vis-à-vis the RIA 2 system. Following its successful in vitro validation, we hypothesized that an ARA concept-collected BG would have comparable in vivo osteogenic capacity compared to the RIA 2 system-collected BG.

Methods

We used 3D-printed, medical-grade polycaprolactone-hydroxyapatite (mPCL-HA, wt 96 %:4 %) scaffolds with a Voronoi design, loaded with or without different sheep-harvested BGs and tested them in an ectopic bone formation rat model for up to 8 weeks.

Results

Active bone regeneration was observed throughout the scaffold-BG constructs, particularly on the surface of the bone chips with endochondral bone formation, and highly vascularized tissue formed within the fully interconnected pore architecture. There were no differences between the BGs derived from the RIA 2 system and the ARA concept in new bone volume formation and in compression tests (Young's modulus, p = 0.74; yield strength, p = 0.50). These results highlight that the osteogenic capacities of the mPCL-HA Voronoi scaffold loaded with BGs from the ARA concept and the RIA 2 system are equivalent.

Conclusion

In conclusion, the ARA concept offers a promising alternative to the RIA 2 system for harvesting BGs to be clinically integrated into SGBR strategies.

The translational potential of this article

Our results show that biodegradable composite scaffolds loaded with BGs from the novel intramedullary harvesting concept and the RIA 2 system have equivalent osteogenic capacity. Thus, the innovative, highly intuitive intramedullary harvesting concept offers a promising alternative to the RIA 2 system for harvesting bone grafts, which are an important component for the routine translation of SGBR concepts into clinical practice.

3D-printed titanium porous prosthesis combined with the Masquelet technique for the management of large femoral bone defect caused by osteomyelitis

BACKGROUND

The treatment of infected bone defects remains a clinical challenge. With the development of three-dimensional printing technology, three-dimensional printed implants have been used for defect reconstruction. The aim of this study was to investigate the clinical outcomes of three-dimensional printed porous prosthesis in the treatment of femoral defects caused by osteomyelitis.

METHODS

Eleven patients with femoral bone defects following osteomyelitis who were treated with 3D-printed porous prosthesis at our institution between May 2017 and July 2021, were included. Eight patients were diagnosed with critical-sized defects, and the other three patients were diagnosed with shape-structural defects. A two-stage procedure was performed for all patients, and the infection was eradicated and bone defects were occupied by polymethylmethacrylate spacer during the first stage. The 3D-printed prosthesis was designed and used for the reconstruction of femoral defects in the second stage. Position of the reconstructed prostheses and bone growth were measured using radiography. The union rate, complications, and functional outcomes at the final follow-up were assessed.

RESULTS

The mean length of the bone defect was 14.0 cm, union was achieved in 10 (91%) patients. All patients showed good functional performance at the most recent follow-up. In the critical-sized defect group, one patient developed a deep infection that required additional procedures. Two patients had prosthetic dislocations. Radiography demonstrated good osseous integration of the implant-bone interface in 10 patients.

CONCLUSION

The 3D printed prostheses enable rapid anatomical and mechanically stable reconstruction of extreme femur bone defects, effectively shortens treatment time, and achieves satisfactory clinical outcomes.

Reconstruction of an Extensive Segmental Radial Shaft Bone Defect by Vascularized 3D-Printed Graft Cage

We report here a 46-year-old male patient with a 14 cm segmental bone defect of the radial shaft after third degree open infected fracture caused by a shrapnel injury. The patient underwent fixed-angle plate osteosynthesis and bone reconstruction of the radial shaft by a vascularized 3D-printed graft cage, including plastic coverage with a latissimus dorsi flap and an additional central vascular pedicle. Bony reconstruction of segmental defects still represents a major challenge in musculo-skeletal surgery. Thereby, 3D-printed scaffolds or graft cages display a new treatment option for bone restoration. As missing vascularization sets the limits for the treatment of large-volume bone defects by 3D-printed scaffolds, in the present case, we firstly describe the reconstruction of an extensive radial shaft bone defect by using a graft cage with additional vascularization.

The Concept of Scaffold-Guided Bone Regeneration for the Treatment of Long Bone Defects: Current Clinical Application and Future Perspective

The treatment of bone defects remains a challenging clinical problem with high reintervention rates, morbidity, and resulting significant healthcare costs. Surgical techniques are constantly evolving, but outcomes can be influenced by several parameters, including the patient's age, comorbidities, systemic disorders, the anatomical location of the defect, and the surgeon's preference and experience. The most used therapeutic modalities for the regeneration of long bone defects include distraction osteogenesis (bone transport), free vascularized fibular grafts, the Masquelet technique, allograft, and (arthroplasty with) mega-prostheses. Over the past 25 years, three-dimensional (3D) printing, a breakthrough layer-by-layer manufacturing technology that produces final parts directly from 3D model data, has taken off and transformed the treatment of bone defects by enabling personalized therapies with highly porous 3D-printed implants tailored to the patient. Therefore, to reduce the morbidities and complications associated with current treatment regimens, efforts have been made in translational research toward 3D-printed scaffolds to facilitate bone regeneration. Three-dimensional printed scaffolds should not only provide osteoconductive surfaces for cell attachment and subsequent bone formation but also provide physical support and containment of bone graft material during the regeneration process, enhancing bone ingrowth, while simultaneously, orthopaedic implants supply mechanical strength with rigid, stable external and/or internal fixation. In this perspective review, we focus on elaborating on the history of bone defect treatment methods and assessing current treatment approaches as well as recent developments, including existing evidence on the advantages and disadvantages of 3D-printed scaffolds for bone defect regeneration. Furthermore, it is evident that the regulatory framework and organization and financing of evidence-based clinical trials remains very complex, and new challenges for non-biodegradable and biodegradable 3D-printed scaffolds for bone regeneration are emerging that have not yet been sufficiently addressed, such as guideline development for specific surgical indications, clinically feasible design concepts for needed multicentre international preclinical and clinical trials, the current medico-legal status, and reimbursement. These challenges underscore the need for intensive exchange and open and honest debate among leaders in the field. This goal can be addressed in a well-planned and focused stakeholder workshop on the topic of patient-specific 3D-printed scaffolds for long bone defect regeneration, as proposed in this perspective review.

The 3D-Printed Titanium Truss Cage for the Treatment of Concurrent Complex Malunion, Synostosis and Large Bone Defect Following Forearm Injuries: A Case Report

A 28-year-old man sustained a complex forearm injury from high-energy trauma, causing ulnar nerve injury, a bone defect, forearm malunion and synostosis. A 3D-printed titanium truss cage was used to solve these problems. This patient achieved union of the bone defect, was pain-free and had no recurrent synostosis 2 years after reconstructive surgery. The advantages of the 3D-printed titanium truss cage included anatomical fit, immediate mobilisation and low morbidity of the donor side of the bone graft. This study reported a promising result from using 3D-printed titanium truss cages to manage complex forearm bony problems. Level of Evidence: Level V (Therapeutic).

Long Bone Defect Filling with Bioactive Degradable 3D-Implant: Experimental Study

Previously, 3D-printed bone grafts made of titanium alloy with bioactive coating has shown great potential for the restoration of bone defects. Implanted into a medullary canal titanium graft with cellular structure demonstrated stimulation of the reparative osteogenesis and successful osseointegration of the graft into a single bone-implant block. The purpose of this study was to investigate osseointegration of a 3D-printed degradable polymeric implant with cellular structure as preclinical testing of a new technique for bone defect restoration. During an experimental study in sheep, a 20 mm-long segmental tibial defect was filled with an original cylindrical implant with cellular structure made of polycaprolactone coated with hydroxyapatite. X-ray radiographs demonstrated reparative bone regeneration from the periosteum lying on the periphery of cylindrical implant to its center in a week after the surgery. Cellular structure of the implant was fully filled with newly-formed bone tissue on the 4th week after the surgery. The bone tissue regeneration from the proximal and distal bone fragments was evident on 3rd week. This provides insight into the use of bioactive degradable implants for the restoration of segmental bone defects. Degradable implant with bioactive coating implanted into a long bone segmental defect provides stimulation of reparative osteogenesis and osseointegration into the single implant-bone block.