Our study shows that acute completely displaced fractures of the femoral diaphysis in children aged 2 to 6 can successfully be treated by closed reduction and ESIN fixation with good functional outcomes; only a few cases of pin site infection were detected among the patients. These problems, due to prominent hardware at the nail insertion site, were resolved within a few days by giving oral antibiotics and analgesics. In addition, there were equal operating times and radiation exposure in the two groups. There was no clinic-radiological difference in terms of time to fracture site union and full weight bearing between the two groups. The range of motion at the hip and knee was normal in all patients after the removal of the ESINs. There were no patients with angulation deformities in the sagittal plane or coronal plane in either group.
Stable femoral shaft fractures in children have been treated by closed reduction and ESIN fixation in the past based on good results and fewer complications. In recent years, surgeons have preferred these operative techniques for unstable fractures of the femoral shaft; therefore, the majority of paediatric femoral shaft fractures are now treated operatively. The families benefit from shorter hospital stays and have economic and social benefits over conservative treatment, such as traction treatment.
ESIN is often recommended as the best treatment for children aged 6 to 12 years, ideally weighing less than 50 kg [13, 20, 32–34]. There are no previous comparative studies between stable and unstable femoral shaft fractures in preschool-aged patients. In our study, the number of patients in each group with a normal range of motion at the hip and knee joints was the same at the final follow-up. Similar results were obtained by the studies of Khazzam et al. [35], Gyaneshwar et al. [36] and Lohiya et al. [37]. The average duration of progression to full weight bearing in our study was 10.4 weeks in Group 1 and 11.0 weeks in Group 2 (p = 0.479). In the study by Lohiya et al. 10 [37], the mean duration to full weight bearing was 10.5 weeks.
In our research, minor complications were observed in 19.0% of Group 1 and 23.0% of Group 2 with no major complications. In the study by Gyaneshwar et al. [36], the minor complication rate was significantly higher, 47.06% of patients in the titanium group and 35.29% of patients in the stainless steel group. Fewer major complications were found. There was no significant difference in the malunion deformity rate in either group in the sagittal and coronal planes. Wall et al. [38] reported that the malunion rate in the titanium group was 23.2% (13/56), which was much higher than our report. This difference may be because their study did not include the same age group as ours. Moroz et al. and Ho et al. reported that patients older than 10 years of age who underwent ESIN for femoral shaft fractures showed a higher complication rate than younger patients [13, 24]. Canavese F et al. also found that a higher rate of complications was observed in patients aged 13 years or older [39]. All of the patients in our series were younger than 6 years and had a low rate of complications.
ESINs prebent in a double C-type configuration with a degree three times the diameter of the intramedullary canal represent the best treatment for transverse fractures in a diaphyseal long bone fracture. Two prebent “C”-shaped nails are generally thought to be an essential part of the ESIN technique in stable shaft fractures, but no evidence for this is available for unstable fractures, including long oblique and spiral fractures. Kaise et al. [40] demonstrated in vitro that prebent ESINs are important in providing stability in spiral femoral shaft fractures but that the degree of prebending needs to be > 30°. Kaiser et al. [41] also recommended the use of a 3rd nail in ESIN in paediatric femur fractures to improve the stability of the osteosynthesis and to reduce peri- and postoperative complications, especially in long oblique and spiral fractures. This is the first mention of the idea of “stacking” the canal. Busch et al. [42] advised that treatment with four ESINs should be considered for skeletally immature patients presenting with length-unstable femur fractures. The concept of “stacking” the femoral canal is mentioned again.
In our Group 2, all patients were treated by two traditional “C shaped” techniques, with ESINs 2.0–3.0 mm in diameter. None of the 13 patients needed a 3rd or 4th ESIN and they all recovered satisfactorily. In general, there are two reasons that can explain this: first, these patients are in the preschool age, the diameter of their canals is limited, and two ESINs already result in sufficient stiffness and resistance to rotation and axial loading; second, fracture instability leads to malunion due to shortening, recurvatum, or varus, and the retrograde 2C configuration creates a construct that utilizes 6 points of intramedullary contact to create stable fixation[15].
Some researchers reported that children treated with ESIN for femoral shaft spiral fractures required further surgery for either unacceptable varus deformity, shortening, or insufficient stability [43]. Other authors have commented on the unsatisfactory fixation obtained by ESIN alone in spiral or other complex femoral fractures; Kraus et al. [44] reported external fixation for these fractures, and Sink et al. [45] preferred submuscular plating. In our study, the total outcome according to Flynn's criteria [22] was excellent in 91.2% of patients and satisfactory in 8.8%, with no poor results. However, the clinico-radiological results were not significantly different between the two groups at the final follow-up.
The analysis of our results showed some limitations. First, to the best of our knowledge, this is the first retrospective study, with a relatively low number of patients, that has compared the clinical and radiological outcomes of femoral shaft fractures in both stable and unstable types treated by closed reduction and ESIN fixation in preschool-age children. The retrospective nature of our study is prone to selection and observational biases. Second, it represents a single surgeon’s experience. Third, future prospective cohort research would be useful to explore these variables and better define the role of ESIN fixation in length-unstable femur fractures in these children.