Distal femoral fractures (DFF) account for 3–6% of femoral fractures. Several reports recommend that DFF should be treated surgically to achieve optimal patient outcomes and an earlier return to social activity [1,2].

Recently, retrograde intramedullary nailing (RIMN) has become a treatment option for DFF [3]. Although there have been numerous studies about DFF, few studies have focused on postoperative management, including weight-bearing protocols for DFF after RIMN. Few studies have compared the postoperative outcomes of DFF after RIMN by weight-bearing starting period. Surgeons are sometimes concerned about a loss of reduction and mechanical failure after RIMN for DFF [4]. Femoral alignment is also important for preservation of extremity function [5]. Malalignment in the sagittal plane also affects knee kinematics and range of motion [6]. Healing with >15° of valgus or any degree of varus at the knee after ORIF resulted in posttraumatic arthritis [7].

On the other hand, in the case of femoral shaft fracture, within the last 5–10 years, early weight bearing (EWB) has been reported to be safe, may facilitate fracture healing, and may result in less hospitalization, a decreased need for prolonged inpatient rehabilitation, and decreased cost of care. Another study reported that among patients with EWB following RIMN for femoral shaft fracture, there were no cases of implant failure [8]. Furthermore, elderly people may also not be able to follow instructions for load restrictions because of neurological or physical disorders [9].

It is thus unclear whether the timing of the weight bearing affects the loss of correction in the fracture site and malunion. Therefore, this multicenter study was undertaken to assess, using propensity score matching, differences in the rates of implant failure and bone union, alignment of the lower extremities, and clinical and functional outcomes following RIMN for DFF between an EWB group and a late weight-bearing (LWB) group in elderly patients.