[Retrograde bone transport nail in a posttraumatic femoral bone defect]

Biomimetic composite hydrogel promotes new bone formation in rat bone defects through regulation of miR-19b-3p/WWP1 axis by loaded extracellular vesicles

OBJECTIVE

This study aims to investigate the mechanism by which biomimetic composite hydrogels loaded with bone marrow mesenchymal stem cells (BMSCs) derived microRNA-19b-3p/WWP1 axis through extracellular vesicles (EVs) affect the new bone formation in rat bone defects.

METHODS

First, synthesize the bionic composite hydrogel Gel-OCS/MBGN. Characterize it through field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and FTIR. Then, conduct performance tests such as rheology, dynamic mechanical analysis, in vitro mineralization, and degradation. Rat BMSCs were selected for in vitro cell experiments, and EVs derived from BMSCs were obtained by differential centrifugation. The EVs were loaded onto Gel-OCS/MBGN to obtain Gel-OCS/MBGN@EVs hydrogel. Cell viability and proliferation were detected by live/dead cell staining and CCK-8 assay, respectively. ALP and ARS staining was used to evaluate the osteogenic differentiation of BMSCs. Differential gene expression analysis of osteogenic differentiation was performed using high-throughput sequencing. TargetScan database predicted the binding site between miR-19b-3p and WWP1, and a dual-luciferase reporter assay was performed to confirm the targeting binding site. A rat bone defect model was established, and new bone formation was evaluated by Micro-CT, H&E staining, and Masson's trichrome staining. Immunofluorescence staining and immunohistochemistry were used to detect the expression levels of osteogenic-related factors in rat BMSCs. RT-qPCR and Western blot were used to detect the expression levels of genes and proteins in tissues and cells.

RESULT

Gel-OCS/MBGN was successfully constructed and loaded with EVs, resulting in Gel-OCS/MBGN@EVs. The in vitro drug release experiment results show that Gel-OCS/MBGN could sustainably release EVs. Further experiments have shown that Gel-OCS/MBGN@EVs could significantly promote the differentiation of BMSCs into osteoblasts. Experiments have shown that WWP1 is a key factor in osteogenic differentiation and is regulated by miR-19b-3p. EVs promote osteogenic differentiation by suppressing WWP1 expression through the transmission of miR-19b-3p. In vivo animal experiments have demonstrated that Gel-OCS/MBGN@EVs significantly promote bone repair in rats with bone defects by regulating the miR-19b-3p/WWP1 signaling axis.

CONCLUSION

Functional Gel-OCS/MBGN@EVs were obtained by constructing Gel-OCS/MBGN and loading EVs onto it. EVs could deliver miR-19b-3p to BMSCs, inhibit the expression of WWP1, and promote the osteogenic differentiation of BMSCs, ultimately promoting bone regeneration in rats with bone defects.

Treatment of a tibial bone defect with a motorized intramedullary bone transport nail: A case review with 32 months follow up

Nowadays, massive segmental bone defects represent a surgical challenge for trauma surgeons. Most of these injuries appear in the context of high-energy trauma, not only significantly affecting the bones, but also involving severe injuries of the adjacent soft tissues. For these reasons, their treatment requires complex reconstruction surgeries.

There are multiple techniques to treat bone defects, bone transport being one of the most widely used. Historically, external fixators (monolateral and circular) have been and still are the gold standard for performing this technique, although they are not exempt from complications. By means of specific intramedullary nails for bone transport, it is possible to minimize the complications of external fixation, allowing large tibial bone defects to be treated through distraction osteogenesis (all-internal system), which is favoured by early weight bearing.

Comparison of Iliac Bone Transplantation with Bone Transport in the Treatment of Femur Fracture and Bone Defect

Objective

To compare the curative effect of iliac bone transplantation with the bone transport in the treatment of femur fracture complicated with a bone defect.

Methods

Patients with femur fractures and defects who were admitted to our hospital from January 1, 2020, to January 31, 2022, and met the inclusion criteria were retrospectively selected and allocated into an iliac bone transplantation group or a bone transport group. The treatment effect and quality of life of the two groups were compared.

Results

A total of 98 patients who met the inclusion standards were enrolled, including 50 cases in the iliac bone transplantation group and 48 cases in the bone transport group. There were no significant differences in IL-6, IL-8, TNF-α, visual analog scale (VAS) score, or Japanese Orthopedic Association (JOA) score between the two groups on postsurgical day 1 (p=0.051, 0.150, 0.102, 0.564, and 0.826 respectively), but there were significant differences in the above index on postsurgical day 7 (all p < 0.01). There were no significant differences in social function, physical function, role function, and cognitive function between the two groups one week after the operation (p=0.245, 0.051, 0.102, and 0.067, respectively), but there were significant differences in the above parameters at one month after operation (p=0.001, 0.005, 0.005, and 0.001, respectively). The total effective rate of the bone transplantation group was significantly better than that of the iliac bone transplantation group (p=0.026). The number of postoperative complications in the bone removal group was significantly fewer than that of the iliac bone graft group (p=0.001).

Conclusion

Bone transport is effective in treating femur fractures complicated with bone defects, with fewer postoperative complications.

Technical considerations for the management of segmental osseous defects with an internal bone transport nail

INTRODUCTION

Traditionally, distraction osteogenesis has been accomplished with an external fixator. All internal transport utilizing magnetic intramedullary nails is a newer technique for bone reconstruction. The Precice Bone Transport Nail is a new implant that allows for noninvasive transport via a magnetically driven motor.

AREAS COVERED

This report describes the function of the Bone Transport Nail along with the technical considerations on how to successfully manage bone defects with this new technology. Appropriate use of the nail, preoperative planning, intraoperative considerations, and postoperative management are discussed in detail.

EXPERT OPINION

The Precice Bone Transport Nail utilizes the technology of the original Precice nail to provide an all-internal option for reconstruction of intercalary defects. This obviates the need for an additional plate with a standard Precice nail when performing bone transport and allows for a less invasive option that decreases operating room time. It provides a more cosmetic result than external fixation and avoids the risks of pin tract infection. Preoperative planning is essential to appropriate execution of the operative procedure and to perform a successful transport. A thorough understanding of the nail design and limitations are a prerequisite as this implant is significantly different from a standard intramedullary nail.

Pain, osteolysis, and periosteal reaction are associated with the STRYDE limb lengthening nail: a nationwide cross-sectional study

Background and purpose - Observing serious adverse events during treatment with the Precice Stryde bone lengthening nail (NuVasive, San Diego, CA, USA), we conducted a nationwide cross-sectional study to report the prevalence of adverse events from all 30 bone segments in 27 patients treated in Denmark.Patients and methods - Radiographs of all bone segments were evaluated regarding radiographic changes in February 2021. We determined the number of bone segments with late onset of pain and/or radiographically confirmed osteolysis, periosteal reaction, or cortical hypertrophy in the junctional area of the nail.Results - In 30 bone segments of 27 patients we observed radiographic changes in 21/30 segments of 20/27 patients, i.e., 19/30 osteolysis, 12/30 periosteal reaction (most often multi-layered), and 12/30 cortical hypertrophy in the area of the junction between the telescoping nail parts. Late onset of pain was a prominent feature in 8 patients. This is likely to be a prodrome to the bony changes. Discoloration (potential corrosion) at the nail interface was observed in multiple removed nails. 15/30 nails were still at risk of developing complications, i.e., were not yet removed.Interpretation - All Stryde nails should be monitored at regular intervals until removal. Onset of pain at late stages of limb lengthening, i.e., consolidation of the regenerate, should warrant immediate radiographic examination regarding osteolysis, periosteal reaction, and cortical hypertrophy, which may be associated with discoloration (potential corrosion) of the nail. We recommend removal of Stryde implants as early as possible after consolidation of the regenerate.