Titanium Scaffolding: An Innovative Modality for Salvage of Failed First Ray Procedures

The First Metatarsophalangeal Joint: Updates on Revision Arthrodesis and Malunions

First metatarsophalangeal joint (MPJ) arthrodesis procedures are a mainstay of forefoot surgery and are associated with high rates of patient satisfaction for addressing a multitude of first ray pathologic conditions. This procedure is often also used as a fallback option for the revision of poor outcomes after other surgical procedures involving the first ray. Despite its successes, there remain instances of complications that can develop after primary first MPJ arthrodesis. This article reviews first MPJ arthrodesis as a procedure for revisional surgery of the first ray, and potential surgical options after failed primary first MPJ arthrodesis.

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.

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.

Surgical Reconstruction of Nonunion after Iatrogenic Scarf Osteotomy

We present the case of a young patient, 32 years old, with nonunion in the diaphysis of the first metatarsal after scarf osteotomy for correction of hallux valgus. After removal of the failed osteosynthesis material and preparation of the bone fragments, a calcaneal bone autograft, previously extracted from the patient, was placed in the nonunion area. The new physiological position of the first metatarsal in the three planes was checked intraoperatively, and autograft and fragment fixation was performed using a combination of a low-profile plate with six screws and two interfragmentary screws. The advantage of using an autogenous graft is that it provides corticocancellous bone and great osteogenic capacity with little antigenic capacity. This makes it an excellent option in many situations in foot and ankle surgery. Regarding the fixation method, we used the two most commonly used techniques for osteosynthesis of bone grafts in cases of bone nonunion, combining plates with locking screws and two interfragmentary screws. This provides greater stability of the bone fragments in the three planes and makes it possible to bring forward when the patient starts postsurgical loading.

Subtalar Joint Distraction Arthrodesis Utilizing a Titanium Truss: A Case Series

Subtalar joint distraction arthrodesis has been recommended for the treatment of conditions such as nonunion or malunion of subtalar joint arthrodesis posttraumatic arthritis. Both conditions are difficult to treat, because the deformities created in the frontal and sagittal planes of these conditions are complex. If these malalignments are not addressed, ankle joint instability and wear occur over time. In general, either autograft or allograft bone has been used to perform distraction arthrodesis of the subtalar joint. Although studies have shown successful use, there have been complications. Autografts have resulted in donor site morbidity and limitations on graft size, and allografts have shown high nonunion rates. Both autografts and allografts have shown graft collapse over time. Recent literature has discussed the use of tantalum technology to span large defects in bone healing. Studies have shown that tantalum provides superior strength and bone incorporation compared with autografts and allografts. This case series presents 2 cases in which tantalum truss technology was used for distraction arthrodesis. Although this series is limited in patient numbers, both cases show effective graft incorporation with no loss in height over time and earlier return to activity compared with previous studies that used autograft and allograft wedges.

3D printed titanium cages combined with the Masquelet technique for the reconstruction of segmental femoral defects: Preliminary clinical results and molecular analysis of the biological activity of human-induced membranes

Introduction:

Traumatic femoral segmental bone loss is a complex clinical problem, one that often requires extreme solutions. This study examines a new treatment strategy for segmental bone loss using patient-specific 3D printed titanium cages in conjunction with the Masquelet technique.

Methods:

The study was composed of a clinical observational case series, and a basic science investigation to evaluate the biological activity of the induced membranes using histology, immunohistochemistry (IHC), and gene expression analysis. Eligible patients were: adult; post-traumatic; with segmental femoral defects; minimum follow-up 1 year; managed under a 2-stage protocol, with an interim antibiotic poly (methyl methacrylate) (PMMA) spacer. Definitive reconstruction was completed with exchange to a 3D printed custom titanium cage filled with bone graft, and stabilized with either an intramedullary (IM) nail or a lateral locked plate.

Results:

Patient-specific 3D printed titanium cages were used in 5 consecutive patients to reconstruct post-traumatic segmental femoral defects. The mean interval between stages was 100.2 days (83–119 days), the mean defect length was 14.0 cm (10.3–18.4 cm), and the mean bone defect volume measured 192.4 cc (114–292 cc). The mean length of follow-up was 21.8 months (12–33 months). There were no deep infections, fractures, nerve injuries, loss of alignment, or nonunions identified during the period of follow-up. All of the patients achieved union clinically and radiographically. Histology and IHC demonstrated a greater number of vessels, cell nuclei, and extensive staining for cluster of differentiation 68 (CD68), platelet and endothelial cell adhesion molecule 1 (PECAM-1), and vascular endothelial growth factor (VEGF) in the induced membranes compared to local fascia controls. Gene expression analysis revealed significant differential regulation of essential genes involved in inflammatory, angiogenic, and osteogenic pathways [interleukin 6 (IL-6), nuclear factor kappa B1 (NF-κB1), receptor activator of nuclear factor kappa-β ligand (RANKL), vascular endothelial growth factor A (VEGFA), angiogenin (ANG), transforming growth factor, beta 1 (TGF-β1), bone morphogenetic protein-2 (BMP-2), growth differentiation factor 5 (GDF-5), growth differentiation factor 10 (GDF-10), and runt-related transcription factor 2 (RUNX-2)] in the induced membranes.

Conclusions:

This study demonstrates that the use of a patient-specific 3D printed custom titanium cage, inserted into an induced membrane in a 2-stage protocol, can achieve very acceptable clinical outcomes in selected cases of post-traumatic femoral segmental defects. Patient-specific 3D printed titanium cages, used in conjunction with the Masquelet technique, are a promising new treatment option for managing complex trauma patients with femoral bone loss.

Level of Evidence:

Level IV (observational case series).