Intramedullary nailing (IMN) is a definitive femoral midshaft fractures surgical management method [19]. The advantages of IMM include the preservation of the haematoma, periosteum and minimal manipulation of the soft tissues around the fracture site, so it does not interfere with the biological process of consolidation [20]. Retrograde femoral nails can be used in all three types of femoral midshaft fractures 32A, 32B and 32C, also in distal shaft fractures (Fig. 4), such as supracondylar types 33A [20, 21], and sometimes in intercondylar type 33C of the AO classification could be used [21].

A 18 year old male patient with distal shaft fractures treated using SFN®, (a, b) preoperative radiographs, (c, d) postoperative radiographs, (e, f) consolidation at the follow up at 12 months

Retrograde IMM indications are polytraumatized patients with bilateral femoral fractures or ipsilateral fractures of the femur and tibia, distal shaft fractures, obesity with femoral midshaft fractures, and pregnancy [22]. In femoral fractures, the use of IMN with image intensifier is the standard technique. However, in LIMC where the image intensifier is not available in all scenarios, the locking targeting device in the SSN® is designed for use without an image intensifier or the availability of the SFN® that does not require distal locking screws is helpful in the treatment of long bone fractures in LIMCs [23].

Adesina et al. [24] compared 84 patients with antegrade nailing to 154 patients with retrograde nailing using the SIGN® program (SSN® and SFN®). They concluded that in low-resourced settings the retrograde nailing approach is more effective, patient positioning is easier, approaches are less complicated, and closed reduction and intramedullary reaming are more straightforward than antegrade nailing for the treatment of femoral midshaft fractures.

In our study, using the retrograde approach, we did not find a statistical difference between closed and open reductions of the fractures between the two nail options (p = 0.69); however, as the SFN® does not require locked screws, it decreases the number of surgical wounds and avoids distal screw loss or mistakes, which is a possible complication of SSN® when the image intensifier is not available.

Birner et al. [25] performed a randomized analysis of 500 patients treated at 110 hospital centers using retrograde femoral nailing with SFN® for femoral midshaft fractures, determining an incidence of malalignment > 5° in 9.4% of the cases and obtained satisfactory postoperative results in the majority of patients, comparable to use the SSN® in the treatment of femoral midshaft fractures in LIMC.

In Ethiopia, Birlie et al. [26] studied postoperative knee pain at six months in 110 patients treated with retrograde femoral nailing using the SSN® and SFN®. They reported that retrograde intramedullary nail fixation is an effective method for femoral midshaft fractures but may cause knee pain at six months in 36.4% of patients. In our study, at six months of follow-up, 9% (11 of 122) of the patients had anterior knee pain: 5% in group A and 12.9% in group B. No statistically significant differences were found between the two groups (p = 0.12).

Liu et al. [14] studied the outcomes of retrograde intramedullary nailing in 57 patients with SSN® and 28 patients with SFN® in Tanzania. At one year of follow-up, both surgical options offered similar radiographic, functional, and clinical results. Authors mentioned that the use of SFN® could decrease the surgical time. In our series, we confirmed that the mean operative time decreased from 104.3 min with SSN® to 78 min with SFN® (p =  < 0.001).

The principal limitation in our study was the loss of follow of the patients, generally in the NGO hospital is estimated that about 30% of the patients are lost to follow-up because they live in provinces far away from Freetown, there is no adequate transportation and many of the patients do not have the financial resources to return to the hospital. In many cases, not only patients treated with SIGN nail program, other patients with any pathology treated in the hospital only return for evaluation if they present complications. Based on this fact observed by the 23-year history of the hospital in Sierra Leone we could assume that patients with loss to follow-up at six months are without complications. Other limitations were the retrospective design of our study and the number of patients in the sub-groups, further studies with a larger number of patients would be needed to confirm our findings.

In conclusion, both options appear equally effective in the treatment of midshaft and distal femoral shaft fractures with excellent results. In our five-year experience using the sing nail program we observed that for patients with complex AO type fractures classifications like 32C2, 32C3, and 33C2 the SSN® offers better stability by using proximal and distal locking screws, in our study complications such as non-union and nail migration reported in the SFN group were patients with complex fracture patterns (32C2, 32C3, and 33C2). In other patterns of fractures, the SFN® is an excellent option (Fig. 5); The SFN® reduces the surgical time, due to this fact, in polytraumatized patients, patients with bilateral femur fracture or patients with ipsilateral tibia fracture, it can be considered as the best option to be used.

A 40 year old female patient with femoral midshaft fractures treated using SFN®, (a, b) preoperative radiographs, (c, d) postoperative radiographs, (e, f) consolidation at the follow up at 12 months