• Pelvic radiological parameters could be affected by patient malpositioning. • Biplanar radiograph-based 3D reconstructions were performed at increments of axial rotation. • Trueness, precision and global uncertainty were evaluated for pelvic and hip radiological parameters. • Hip parameters were less affected by rotation compared to pelvic parameters. • Maintaining the pelvis close to the neutral position is recommended to ensure the highest possible accuracy.

ABC of the spine is a pediatric tumor occurring rarely in the CS. Treatment options vary from simple curettage to total resection with or without instrumentation. Recurrence after surgery is highest after curettage alone. The main indications for surgery are rapid progression, despite intracystic injection, and/or the presence of neurological signs or symptoms.

Introduction. Giant cell tumors (GCTs) of bone are known for their local aggressiveness and high recurrence rate. There are rare cases of multicentric GCT and most are synchronous. We herein review metachronous multicentric GCT reported in the literature. Material and Methods. A MEDLINE, Cochrane, and Google Scholar search was done to collect all cases of multicentric metachronous GCT specifying the clinical, radiological, and histological characteristics of each location and its treatment. Results. A total of 37 multifocal giant cell tumors were found in the literature. 68% of cases of multicentric giant cell tumors occur in less than 4 years following treatment of the first lesion. Thirty-seven cases of multifocal metachronous GCT were identified in the literature until 2012. Patients with multicentric GCT tend to be younger averaging 23. There is a slight female predominance in metachronous GCT. The most common site of the primary GCT is around the knee followed by wrist and hand and feet. Recurrence rate of multicentric GCT is 28.5%. Conclusion. Multicentric giant cell tumor is rare. The correct diagnosis relies on correlation of clinical and radiographic findings with confirmation of the diagnosis by histopathologic examination.