1 Introduction

Latest advance in limb lengthening surgery – Intramedullary magnetic Nail - is totally implanted, telescopic, interlocking intramedullary (IM) nail. Its distraction mechanism consists of a spindle that is coupled to an incorporated cylindrical magnet through a gearbox. Two revolving solid-state magnets placed externally on the surface of the limb provide an external magnetic field that causes this internal magnet to rotate in response to it. The exact regulation of the magnetic contact is regulated by the external remote controller (ERC), which functions at a predefined distance from the implant.^1–3 This method of limb lengthening is becoming widely used due to its potential to facilitate precise and controlled bone healing while minimizing soft tissue disruption and postoperative complications. However, due to its’ increasing utilization, periprosthetic fractures become common complication. The question on how to treat this type of fractures is still open. The fact that there is no bibliography about periprosthetic fractures of Intramedullary magnetic femoral Nail makes it challenging for orthopedic surgeons to develop standardized treatment protocols. The absence of specific guidelines necessitates a reliance on general principles of fracture management and the adaptation of techniques used for other types of intramedullary devices. This case report presents a successful fixation of a periprosthetic fracture that was achieved without halting the limb lengthening process, illustrating an innovative approach to managing this complication.

2 Case report

A 21-year-old male patient presented to the outpatient office with a significant limb length discrepancy. The patient was able to walk only with crutches due to the fact that the lower limb discrepancy prevented him from placing his left foot on the floor, impacting his gait and mobility. The patient did not have any remarkable medical or surgical history, with no visible scars, neither any previous therapies mentioned. The clinical assessment suggested that the limb length discrepancy resulted from an episode of osteomyelitis during childhood. The access to a complete medical history was limited due to the origins of the patient, so this clinical detail had to be derived from his presentation and initial whole-leg x-rays. There was no relevant family or psychosocial history, including genetic information, to contribute to his diagnosis.

3 Clinical findings

Upon physical examination, the patient's left lower limb extremity demonstrated a substantial limb length discrepancy. Galleazzi test and Prone test were performed in order to determine the affected bone. After the positive Galleazzi sign, both femurs were measured, showing the left femur being 120 mm shorter than the right. However, the Range Of Motions (ROM) in his knee and hip joints appeared normal. He had no tenderness or any other abnormality over his left limb. There were no features of active infection or any system involvement; the patient's physical examination was otherwise unremarkable.

4 Diagnostic assessment

Whole Leg Radiographs (Fig. 1) confirmed that the limb length discrepancy was isolated to the femur. Using imaging software, the exact limb length difference was measured to be 120 mm. No abnormalities were seen in the left tibia. The main diagnostic issue was that this patient's geography and cultural background made it impossible to obtain a complete history of his previous healthcare. Diagnostic reasoning was, therefore, based on the clinical presentation and radiographic findings, which appeared to support a diagnosis of post-infectious growth disturbance due to childhood osteomyelitis being responsible for the limb length discrepancy. Other possibilities, such as congenital limb deformity or trauma, were considered less likely by the history given from the patient and his clinical presentation.

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Fig. 1 Preoperatie AP Whole Leg Radiographs showing 120mm limb length discrepancy.

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5 Differential diagnosis (if any)

The episode of childhood osteomyelitis that patient mentioned may have been poliomyelitis.

6 Therapeutic intervention

Main therapeutic goal was to address the limb length discrepancy by achieving a 70 mm lengthening of the left femur using an intramedullary magnetic femoral nail from NuVasive. The initial surgical procedure involved the insertion of the nail without complications (Fig. 2), and the patient was discharged three days postoperatively with instructions for routine follow-up and for the utilization of the external magnet. One week postoperatively the distraction process was being performed without complications, no signs of infection were noted and the patient had normal ROM in all of his left lower limb's joints (Fig. 3).

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Fig. 2 1st postoperative day AP (a) and Lateral (b) Radiographs of proximal and distal femur.

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Fig. 3 12 days postoperative AP (a) and Lareral (b) Radiographs of proximal and distal femu. Distraction at the osteotomy site (distal femur) can be seen.

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Fourteen days postoperatively, the patient presented to the emergency department with acute pain in his proximal left femur that was radiating to his left glute. Patient indicated that the pain occurred after his fall during physiotherapy. Radiographs revealed a periprosthetic fracture around the proximal screws of the intramedullary nail (Fig. 4). Two management strategies were considered: (1) discontinuing the distraction therapy, reducing and fixating the fracture with a plate and screws, allowing for fracture healing, and then restarting the disctraction process (limb lengthening) after performing new osteotomy; or (2) applying a plate and screws while using one proximal screw of the nail to secure the plate to the femur, thereby allowing the continuation of the lengthening therapy.

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Fig. 4 AP (a) and Lateral (b) radiographs of proximal femur confirming a diagnosis of periprosthetic fracture around a proximal screw of intramedullary magnetic nail.

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We opted for the second approach to minimize additional surgical interventions and continue the distraction therapy uninterrupted. Surgery was performed under general anesthesia with the being patient placed supine on a radiolucent flat table, with a small bump under the ipsilateral buttock and brought to the edge of the table. The chosen approach for this case was a direct lateral approach, providing better exposure of the fracture. An anatomical proximal femoral 4.5mm LCP plate was chosen for fixation of the fracture. Proximally to the fracture, the plate was fixated with 4 cortical screws and one screw of the Magnetic Nail. Distally to the fracture, the plate was fixated to the femur with three cerclage wires (Fig. 5). The screw of the Magnetic that was used for the fixation of the plate has virtual meaning in the indtramedualar stability of the Nail. This method ensured anatomical reduction and stable fixation of the fracture without compromising the ongoing lengthening process. This approach is similar to the management of periprosthetic fractures around total hip replacements, where stability and the preservation of implant function are key considerations.

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Fig. 5 a) AP radiograph of femur 2 days postoperatively ORIF b) Lateral radiograph of femur 2 days postoperatively ORIF c) AP whole leg radiograph and the end of the lengthening therapy. 40mm limb length discrepancy can be seen.

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7 Follow-up and outcomes

Postoperative x-rays confirmed satisfactory anatomical reduction and stable internal fixation of the fracture. The patient resumed the lengthening therapy using the external magnet two days postoperatively. Following the second surgery, the patient was discharged five days later with instructions of non-weight bearing and closely monitored through outpatient visits. Initially, follow-ups occurred weekly in order to ensure the stability of the Intramedullary nail, transitioning to bi-weekly as bone healing progressed. The lengthening therapy concluded on January 20th, achieving a total limb lengthening of 80 mm (instead of planned 70 mm due to 10 mm distraction at the fracture site), reducing the limb length discrepancy to 40 mm (Fig. 5). The patient exhibited good ROM, reported no pain, and demonstrated a normal gait with the use of a corrective shoe. There were no adverse or unanticipated events during the follow-up period.

8 Discussion

This case illustrates a novel approach to managing periprosthetic fractures in limb lengthening procedures using an intramedullary magnetic femoral nail, allowing the continuation of lengthening therapy and minimizing additional surgical interventions. The integration of the intramedullary nail's proximal screw with a proximal femoral plate proved effective, facilitating uninterrupted lengthening and reducing the patient's overall surgical burden. The latest advance in limb lengthening surgery, the intramedullary magnetic nail, offers precise and controlled bone healing while minimizing soft tissue disruption and postoperative complications. However, the increasing utilization of this technique has led to a rise in periprosthetic fractures, for which there are no standardized treatment protocols. The absence of specific guidelines necessitates a reliance on general principles of fracture management and the adaptation of techniques used for other types of intramedullary devices.

In cases of periprosthetic fractures, appropriate resuscitation and optimization are crucial, as morbidity and mortality rates are similar to those of hip fracture populations.⁴ Whole length femur films and dedicated knee radiographs are necessary, and previous radiographs may help assess implant stability.^5,6 Computed tomography can provide additional detail regarding fracture propagation, especially with a femoral implant present. In this case, thorough radiographic assessment confirmed the periprosthetic fracture around the proximal screws of the intramedullary nail.

This case highlights the importance of innovative surgical solutions in managing complex complications in limb lengthening procedures. The successful outcome supports the feasibility and effectiveness of using a proximal femoral plate integrated with the intramedullary nail's screw for fracture management. However, the lack of existing literature on periprosthetic fractures in limb lengthening with intramedullary magnetic nails underscores the need for further research. Future studies should focus on establishing standardized treatment protocols and exploring the limits of “too flexible or rigid' fixation.

In conclusion, this case demonstrates a successful management strategy for periprosthetic fractures during limb lengthening with intramedullary magnetic nails. By allowing the continuation of lengthening therapy, we minimized additional surgical interventions and achieved a favorable patient outcome. Further research is essential to develop evidence-based guidelines for managing such complications in limb lengthening procedures. The successful outcome of the reported case underlines the importance of innovative surgical solutions in managing complex complications in limb lengthening procedures. By integrating advances in implant technology with established principles of fracture management and femur plating, orthopedic surgeons can optimize patient outcomes and minimize the surgical burden associated with periprosthetic fractures.

Ethical statement

This case report has been prepared in compliance with ethical principles outlined in the Declaration of Helsinki and its subsequent amendments. No experiments were conducted in the preparation of this case report; instead, it is based solely on the clinical observation and treatment of the patient described herein. Patient consent for publication was obtained and all identifying information has been anonymized to protect patient privacy. We affirm that all patient care and documentation presented in this report adhered to the highest standards of medical ethics and professionalism. We are committed to maintaining patient confidentiality and upholding the integrity of medical reporting in accordance with established guidelines.

Financial support and sponsorship

The authors declare that they have no known financial support or sponsorship that could have appeared to influence the work reported in this paper.

Informed consent

We hereby confirm that written informed consent has been obtained from the patient for the publication of this case report. All identifying information has been omitted or altered to protect the patient's privacy.

CRediT authorship contribution statement

Egor Kostin: all played integral roles encompassing the conceptualization and design of the research, the meticulous acquisition, comprehensive analysis, and insightful interpretation of the acquired data. addition to reviewing the manuscript critically for substantial intellectual input, actively participated in its drafting, further enhancing its intellectual content. PM's proficiency was evident in his assistance during the second surgery and in the patient's postoperative evaluation. collectively lent their insights to the manuscript, ensuring its quality and significance. With unanimous approval. all endorsed the final manuscript. They have embraced full accountability for the research, taking the responsibility to thoroughly investigate and resolve any queries regarding its accuracy or integrity. In the collaborative effort of this study. The collaborative writing process involved all four authors. Paraskevas Miltiadou: all played integral roles encompassing the conceptualization and design of the research, the meticulous acquisition, comprehensive analysis, and insightful interpretation of the acquired data. performed the second surgery. collectively lent their insights to the manuscript, ensuring its quality and significance. With unanimous approval. all endorsed the final manuscript. They have embraced full accountability for the research, taking the responsibility to thoroughly investigate and resolve any queries regarding its accuracy or integrity. In the collaborative effort of this study. The collaborative writing process involved all four authors. Charalambos Charalambides: all played integral roles encompassing the conceptualization and design of the research, the meticulous acquisition, comprehensive analysis, and insightful interpretation of the acquired data. performed the second surgery. addition to reviewing the manuscript critically for substantial intellectual input, actively participated in its drafting, further enhancing its intellectual content. PM's proficiency was evident in his assistance during the second surgery and in the patient's postoperative evaluation. collectively lent their insights to the manuscript, ensuring its quality and significance. With unanimous approval. all endorsed the final manuscript. They have embraced full accountability for the research, taking the responsibility to thoroughly investigate and resolve any queries regarding its accuracy or integrity. In the collaborative effort of this study. The collaborative writing process involved all four authors. Ioannis Orfanos: all played integral roles encompassing the conceptualization and design of the research, the meticulous acquisition, comprehensive analysis, and insightful interpretation of the acquired data. who was the primary clinician for the patient, conducted the clinical examination and performed the initial surgery. performed the second surgery. assumed the responsibilities of drafting the manuscript and conducting the necessary diagnostic tests. collectively lent their insights to the manuscript, ensuring its quality and significance. With unanimous approval. all endorsed the final manuscript. They have embraced full accountability for the research, taking the responsibility to thoroughly investigate and resolve any queries regarding its accuracy or integrity, In the collaborative effort of this study, The collaborative writing process involved all four authors.