Convergence of Scaffold Guided Bone Regeneration and RIA Bone Grafting for the Treatment of a Critical-Sized Bone Defect of the Femoral Shaft

Abstract

BackgroundCritical-sized bone defects, mainly from trauma, infection or tumor resection are a challenging condition, often resulting in prolonged, complicated course of treatment. Autografts are considered as the gold standard to replace lost bone. However, limited amount of bone graft volume and donor site morbidity have established the need for the development of alternative methods such as scaffold-based Tissue Engineering (TE). The emerging market of additive manufacturing (3D-printing) has markedly influenced the manufacturing of scaffolds out of a variety of biodegradable materials. Particularly medical-grade polycaprolactone and tricalcium phosphate (mPCL-TCP) scaffolds show appropriate biocompatibility and osteoconduction with good biomechanical strength in large preclinical animal models. This case report aims to show first evidence of the feasibility, safety, and efficacy of mPCL-TCP scaffolds applied in a patient with a long bone segmental defect.Case presentationThe presented case comprises a 29-year-old patient who has suffered a left-sided II° open femoral shaft fracture. After initial external fixation and subsequent conversion to reamed antegrade femoral nailing the patient presented with an infection in the area of the formerly open fracture. Multiple revision surgeries followed to eradicate microbial colonization and attempt to achieve bone healing. However, 18 months after the index event, still insufficient diaphyseal bone formation was observed with circumferential bony defect measuring 6 cm at the medial and 11 cm at the lateral aspect of the femur. Therefore, the patient received a patient-specific mPCL-TCP scaffold, fitting the exact anatomical defect and the inserted nail, combined with autologous bone graft (ABG) harvested with the Reamer Irrigator Aspirator system (RIA – Synthes®) as well as bone morphogenetic protein-2. Radiographic follow-up 12 months after implantation of the TE scaffold shows advanced bony fusion and bone formation inside and outside the fully interconnected scaffold architecture.ConclusionThis case report shows a promising translation of scaffold-based TE from bench to bedside. Preliminary evidence indicates that the use of medical-grade scaffolds is safe and has the potential to improve bone healing. Further, its synergistic effects when combined with ABG show the potential of mPCL-TCP scaffolds to support new bone formation in segmental long bone defects.

Growth Factors in Oral Tissue Engineering: New Perspectives and Current Therapeutic Options

“…Newly discoveries in the field of tissue engineering try to reestablish tissues injured by to pathologies, trauma, or congenital defects. Large mandibular or maxillary bone defects due to trauma or residual of large tumour removal have been commonly treated by using autologous graft [ 12 ]. Three-dimensional maxillary bone volume recoveries choosing autogenous bone graft is today a stable and predictable treatment option.…”

Bone transport combined with bone graft and internal fixation versus simple bone transport in the treatment of large bone defects of lower limbs after trauma

“…However, since we removed the transport frame in time when the bone defects were shortened to within the critical-sized bone defects (5 cm), the time of wearing an external fixator would be further shortened compared with the above studies. The reason why we choose 5-cm-length as a critical criterion is that many studies have shown for bone defects within this length, the scheme of non vascularized autologous bone transplantation has definite curative effects and the amount of autologous bones to be taken is appropriate [12][13][14]. For bone defects beyond this length, autologous bone transplantation is limited, including insufficient materials, bone resorption or necrosis etc.…”

“…For large segmental bone defects that are greater than the critical-sized bone defects (5 cm), there will be uncontrollable bone necrosis and resorption. Therefor, the curative effects of non vascularized autologous bone graft are not accurate [12][13][14][15].…”

Masquelet technique in military practice: specificities and future directions for combat-related bone defect reconstruction

“…In load bearing tissues, they also serve as temporary mechanical support structures [65]. The ability of 3D-printing allows the design and manufacture of osteoconductive scaffolds which are optimized for clinical translation in terms of pore size, layering, and degradation [66,67]. Mainly to overcome graft limitation quantity, a huge diversity of synthetic scaffolds has been developed in preclinic models to be mixed with the ABG during stage 2 [62].…”