Clinical compatibility of magnetic resonance imaging with magnetic intramedullary nails: a feasibility study.

INTRODUCTION: The use of magnetic resonance imaging (MRI) with a magnetic intramedullary lengthening nail in place is contraindicated per the manufacturer due to the concern of implant activation and migration. A prior in vitro study did not confirm these complications only noting that a 3.0 T MRI weakened the internal magnet. Therefore, a retrospective analysis of patients who underwent an MRI with a magnetic nail in place was performed to determine if any adverse effects occurred in the clinical setting. MATERIALS AND METHODS: A retrospective review of all patients who underwent an MRI with a magnetic lengthening nail in place was performed. The time spent being imaged in the MRI, number of times the patient entered the MRI suite, and the images obtained were recorded. Radiographs were performed before and after the MRI to determine if any hardware complications occurred. The patients were monitored for any adverse symptoms while they were in the suite. RESULTS: A total of 12 patients with 13 nails were identified. Two patients underwent imaging with a 3.0 T MRI while the remaining 10 underwent imaging with a 1.5 T MRI. Each patient entered the MRI suite 2.1 times and spent an average of 84.7 min being imaged in the MRI (range 21-494). No patients noted any adverse symptoms related to the nail while in the suite and no hardware complications were identified. CONCLUSION: MRI appears to be safe with a magnetic nail in place and did not result in any complications. Given the manufacturer's recommendations, informed consent should be obtained prior to an MRI being performed and a 3.0 T MRI should be avoided when possible if further activation of the nail is required.

[All internal segmental transport in tibial bone defects: first experiences with the PRECICE bone transport system]. / "All-internal"-Segmenttransport bei Knochendefekt an der Tibia: erste Erfahrungen mit dem PRECICE Bone Transport System.

Bone loss of the distal tibia represents a major challenge for the treating surgeons and the reconstruction technique. This is particularly true for septic bone loss. Several techniques are available, ranging from callus distraction of Ilizarov frames and monorail techniques as well as transport with plates and nails; however, implants for internal segmental transport for bone defects have so far not been available. This case report describes worldwide the first reconstruction of a distal tibial defect by reconstruction of the major arterial flow path with flap coverage and all inside segmental transport using a motorized segmental transport nail without additional osteosynthesis or add-on module.

[Development and principles of intramedullary and extramedullary segmental bone transport: overview and clinical results]. / Entwicklung und Prinzipien des intra- und extramedullären Knochensegmenttransports: Überblick und klinische Resultate.

BACKGROUND: Segmental bone transport using intramedullary or extramedullary techniques is one of the most commonly used procedures for bone defect management in the diaphyseal region of long bones. OBJECTIVE: The purpose of this work is to provide an overview of the historical development and general principles as well as the current status of extramedullary and intramedullary techniques of bone segment transport. In addition, own results on internal segmental bone transport are presented. MATERIAL AND METHODS: A retrospective database analysis included all patients between May 2019 and January 2021 who underwent segmental bone transport via a fully implantable intramedullary segment transport nail system. In addition to the radiological outcome, the clinical outcome was assessed using the lower extremity functional scale (LEFS). RESULTS: A total of 9 patients (8 male, 1 female; age 41.7 ± 3.9 years) could be included. The cause of the segmental bone defect was chronic fracture-related infection in all cases. The segmental defect size was 62 ± 10 mm. Sufficient bridging of the bone defect was achieved in all patients, with a mean distraction rate of 0.9 ± 0.1 mm per day. Bony consolidation of the regeneration was achieved after 292 ± 57 days, and final bony consolidation of the docking zone was achieved after 469 ± 116 days. At 22 ± 3 months after implantation of the segmental transport nail, the LEFS demonstrated a result of 59 ± 4 points. No recurrence of infection or regeneration failure occurred. CONCLUSION: The aim of treating segmental bone defects, in addition to reconstructing a load-bearing bone, is to restore correct joint angles, leg length, and leg axis without torsional deviation and can be achieved via classical external segmental bone transport. In recent years, internal segmental bone transport has been developed as an alternative. It remains to be seen whether the preliminary and reproducibly good clinical and radiological results of segmental transport nails can be confirmed for widespread use in the future.

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.