Atypical periprosthetic femoral fractures around cemented stems: Radiographic features and clinical implications from a multicenter study.

Abstract

Atypical periprosthetic femoral fracture (APFF) is a rare but increasingly recognized complication of hip arthroplasty. Although cemented stems are generally considered protective against fractures, APFFs have also been reported around these implants. However, their clinical and radiographic characteristics remain poorly understood. This multicenter retrospective study aimed to clarify the features of APFFs occurring around cemented stems. Twenty hips from 19 patients were identified, based on the revised criteria of the American Society for Bone and Mineral Research Task Force, without excluding periprosthetic fractures. Fracture location was classified by distance from the stem tip: beyond 25 mm proximally as subtrochanteric type, within 25 mm as stem tip-type, and beyond 25 mm distally as femoral shaft type. Stem tip-type fractures were most common (15 hips, 75 %), followed by femoral shaft type (four hips, 20 %) and subtrochanteric type (one hip, 5 %). All varus aligned stems (four hips) and 83 % of neutrally aligned stems (10 of 12 hips) were stem tip-type fractures. Beaking or flaring of the lateral cortex was present in 76 % (13 of 17 hips) with pre-fracture radiographs. Prodromal pain was reported in 40 % (eight hips) and bisphosphonate use was identified in 94 % (16 of 17 hips) with available medication data. Surgical treatment was performed in 85 % (17 hips), including internal fixation (10 hips) and revision arthroplasty (seven hips); 15 % (three hips) were managed conservatively. Cemented APFFs frequently occur around the stem tip and are often preceded by radiographic changes and symptoms. Early recognition may support timely diagnosis and intervention.