External fixator versus elastic stable intramedullary nail for treatment of metaphyseal-diaphyseal junction fractures of the pediatric distal femur: a case-control study

Abstract

Background: Several methods have been used for the treatment of pediatric distal femoral fractures, such as elastic stable intramedullary nail (ESIN), external fixator (EF) and plate osteosynthesis, but there has been no consensus about the optimal method. The purpose of this study was to compare the clinical outcome between EF and ESIN techniques used in metaphyseal-diaphyseal junction (MDJ) fractures of the pediatric distal femur.

Methods: We retrospectively analyzed operatively treated MDJ fractures of pediatric distal femur between January 2015 and January 2022. Patient charts were reviewed for demographics, injury and data of radiography. All of the patients were divided into EF and ESIN groups according to the operation techniques. Malalignment was defined as more than 5 degrees of angular deformity in either plane. Clinical outcomes were measured by Flynn scoring system.

Results: Thirty-eight patients were included in this study, among which, 23 were treated with EF, and 15 with ESIN. The mean follow-up time was 18 months (12-24 months). At the final follow-up, all of the fractures were healed. Although there were no statistical differences between the two groups in demographic data, length of stay, estimated blood loss (EBL), rate of open reduction, time to fracture healing and Flynn score, the EF was superior to ESIN in operative time, fluoroscopic exposure and time to partial weight-bearing. The EF group had a significantly higher rate of skin irritation, while the ESIN had a significantly higher rate of malalignment.

Conclusion: EF and ESIN are both effective methods in the treatment of MDJ fractures of the pediatric distal femur. ESIN is associated with lower rates of skin irritation. However, EF technique has the advantages of shorter operative time, reduced fluoroscopic exposure, and shorter time to partial weight-bearing, as well as lower incidence of malalignment.

Level of evidence: Level III.

Keywords: Children; Distal femur fractures; Elastic stable intramedullary nail; External fixator.

Fig. 1

Definition of distal MDJ of femur. Line A and B represent 1/3 border of the proximal and distal femur, and line C represents the proximal border of metaphysis. We defined the MDJ as the femoral segment that lies completely at the proximal end of the distal 1/3 femur. It is bounded proximally by the junctional line between the middle and distal thirds of the femur and distally by the proximal end of the distal femoral metaphyseal region on the anteroposterior (AP) radiograph of the femur (Region line B-C)

Fig. 2

A 9-year-old girl with distal MDJ fracture caused by motor vehicle accident. Preoperative radiography showed complete displacement of the fracture with significant shortening (A, B); the fracture was treated with EF, and postoperative X-rays showed satisfactory reduction (C, D); with the fracture union after 3 months (E, F), the implant was removed under sedation, and the range of motion of the knee joint and lower limb function were normal at the final follow-up (G, H)

Fig. 3

A 4-year-old girl with brace fixation in emergency department, with X-ray indicating MDJ fracture as a result of motor vehicle accident (A, B); the girl received ESIN treatment, and the intraoperative reduction was satisfactory (C, D). Additional brace was adopted to compensate for instability. With the fracture union after 6 months (E, F), the implant was removed under general anesthesia after 10, the knee activity and lower limb function were normal at the 13-month follow-up (G, H)

Fig. 4

The patient flowchart