What factors can lead to nonmodular tapered fluted stem subsidence after revision total hip arthroplasty?

Introduction: The purpose of this study was to examine our experience with a nonmodular tapered fluted stem (NTFS) in revision total hip arthroplasty (RTHA) to determine frequency and cause of re-revisions with stem removal, factors associated with stem subsidence and to determine functional outcomes. Patients and method: We retrospectively analyzed the results of using NTFS in 78 cases. The average follow-up period was 5.1 years. Results: In 14 (17.9%) cases, the patients underwent re-revisions with stem removal. Significant subsidence was observed in 5 (6.4%) cases. Type IV femoral defect as per the Paprosky classification (p=0.01) and bicortical contact 2.0 cm (p=0.02) were risk factors for stem subsidence. In addition, we found that the risk of obtaining a bicortical contact of less than 2 cm is higher in patients with a type IV femoral defect (p=0.05). Patients demonstrated improved functional outcomes. Patients with significant stem subsidence having worse functional outcomes compared to patients without significant subsidence. Conclusions: The use of a NTFS in RTHA shows good results in most patients when the bicortical contact threshold of 2 cm in an anteroposterior radiograph of the femur is reached. This is challenging to obtain in patients with Paprosky type IV femoral defects and therefore, in this type of defect it is advisable to used NTFS with carefully or considered other options for femoral reconstructions.