Reconstruction with megaprosthesis for recurrent nonunion of an atypical periprosthetic femoral fracture in an elderly patient - Yuto Nishiura; Tomohiro Yoshizawa; Tomofumi Nishino; Toshiki Muramatsu; Yohei Yanagisawa; Ryunosuke Watanabe; Yasuhiro Homma (Journal of Surgical Case Reports, 2026)