Fig. 5.

Recurrence and pathologic fracture after second endoscopic curettage. A 5-year-old boy had left coxalgia; from the X-ray image (a), simple bone cyst was suspected. The first endoscopic curettage was performed via two portals (b). After 2 months, bone healing had begun with cortical enlargement and consolidation of cancellous bone (c). However, approximately 1 year after the endoscopic curettage, the cystic lesion (white arrow) had become prominent and recurrence was suspected (d). A second endoscopic curettage was performed (e). After discharge with a crutch, the patient fell, and a subtrochanteric fracture was identified (f). Open reduction and internal fixation with a compression hip screw (Ti-VFx II tube plate®, Zimmer Biomet, Warsaw, USA) and artificial bone grafting (OSferion®, OLYMPUS) were performed (g), and after 6 months, bone union was confirmed (h) and the implants removed. Three years after the first endoscopic curettage, no recurrence or complications had occurred (i)