Salvage treatment for failed subtrochanteric fracture fixation is challenging. Re-osteosynthesis with internal fixation or plates and conversion to hip replacement is accepted surgical salvage options. Elderly patients with metal failure of subtrochanteric fractures usually have poor bone quality in the proximal femur. In this situation, refixation will prolong their bed-rest period and prevent early ambulation, often necessitating replacement surgery . Some previous studies have reported that THA could provide a higher level of function and favorable results than hemiarthroplasty [19, 20]. We also preferred THA over hemiarthroplasty because patients often experience pain associated with acetabular cartilage destruction after hemiarthroplasty. Besides, in our series, most patients with failed fixation had experienced long-term non-weight-bearing conditions of the hip joints, which could lead to poor cartilage conditions.
Several authors have reported the results of THA in failed fixation of proximal femur fracture patients [7, 9,10,11,12,13,14,15, 20, 21]. Most of these studies focused on failed fixation of intertrochanter fracture but fewer studies on the subtrochanteric fracture. In a series of 88 patients treated with a salvaged hemiarthroplasty or THA after failed fixation of trochanteric or subtrochanteric fractures , standard femoral stems or long stems were used in all patients. During a 5–11 year of follow-up duration, the revision rate was 16% (14/88 hips). Using long length stems could reduce the risk for reoperation due to bridge previous bone defects. Weiss et al.  reported 30 salvaged THAs using a modular cementless stem for failed trochanteric or subtrochanteric fractures with a mean follow-up period of 4 years. Twenty patients from their study had subtrochanteric fractures. Revisions were conducted for one case of recurrent dislocation, five cases of infection, one case of periprosthetic fracture, and the rate of reoperation was 23% (7/30 cases). In our study, most of the cases showed good pain relief and ambulated independently with or without support, consistent with previous findings from other published literature [7, 10, 15, 22]. Besides, most of the proximal femur fractures were united, except for one delayed union. Only one patient received stem revision due to bone in-growth failure.
In our series, we found that patients previously treated with an intramedullary nail had a significantly shorter surgical duration, lesser intraoperative blood loss, and fewer blood transfusions than those previously treated with plate and screws. We believe that intramedullary nails might be a better initial implant of choice for the treatment of subtrochanteric fractures, particularly as they can easily be converted to THA in cases of failure. When performing salvaged THA for subtrochanteric fracture with failed external plate fixation, we should pay special attention to increased operation duration, blood loss, and complications.
Dislocation is another severe problem seen after the salvage procedure, often as a result of poor hip joint stability. Zhang et al.  reported that the overall dislocation rate of rescue hip replacement after the failure of proximal femoral internal fixation was 15.8%. Archibeck et al.  reported that dislocation occurred in five of 102 patients who treated with conversion THA, and reoperation was performed in one patient because of instability. However, only closed reduction was required for one patient in this study, which can be attributed to the well-orientated position of the components and sufficient repair of the short external rotators and abductor mechanism reconstruction. In the present study, four patients with failed fixation of a subtrochanteric fracture did not have undergone revision fixation due to insufficient bone stock. It was challenging and unlikely for severe bone loss to obtain sufficient fixation and guarantee union through re-osteosynthetic surgery alone.
In the present study, the Wagner femoral stems (Zimmer, Warsaw, USA) were used in all patients. The Wagner conical stem is a tapered, fluted, grit-blasted cementless femoral prosthesis. This femoral stem was designed for treating complex primary THA or revision cases. Sandiford et al.  reported 104 femoral revisions using the Wagner SL stem, with a follow-up of 24–46 months and found no femoral stems had failed due to aseptic loosening; only one patient with the stem and cup infection required operation . Previous studies have shown that the Wagner conical femoral stems have excellent survival rates and favorable results in revision and complex primary THA [26, 27], potentially making it a better choice. The Wagner stem showed good implant survival in the present study, with only one stem revision due to the bone in-growth failure.
Subsidence of the femoral stem could be a common complication in cementless stems and can lead to osseointegration failure, especially in complex THA. In this study, nine patients (50%) showed stem subsidence within 3 months of THA, but the amount of stem subsidence had no influence on clinical outcomes, such as thigh pain, HHS, or patient satisfaction. The subsidence rate observed in this cohort is comparable to previously reported rates of subsidence for femoral stems [28, 29]. Of the cases included in this study, only one stem was revised because the previous instrumentation had negatively impacted the medullary canal and femoral stem fixation. Great care should be taken to avoid undersize the cementless femoral stems selection during operation.
There are some limitations to this study. First, we did not set up a control group to compare the outcomes, and the study was retrospective. Second, there were a limited number of sample cases, and the follow-up duration was also relatively short. However, to the best of our knowledge, only two other studies have reported on more than 18 cases of failed THA for subtrochanteric fractures [7, 22] and ours appears to be the first study to evaluate the effect of a salvage cementless THA using the Wagner stem for failed subtrochanteric fracture. Third, the patients included in this study were operated on for rare diseases with different types of cups for a long period of up to 16 years, which could prove to be a confounding factor for this study.