Bone Neoplasms/surgery; Bone Screws; Bone Transplantation/instrumentation; Ilium/transplantation; Plastic Surgery Procedures/instrumentation; Sacrum/surgery; Sarcoma/surgery; Spinal Fusion/instrumentation; Adolescent; Adult; Aged; Biomechanical Phenomena; Bone Neoplasms/diagnostic imaging; Bone Neoplasms/physiopathology; Bone Transplantation/adverse effects; Bone Transplantation/mortality; Female; Humans; Ilium/diagnostic imaging; Ilium/physiopathology; Magnetic Resonance Imaging; Male; Middle Aged; Postoperative Complications/etiology; Radiography; Plastic Surgery Procedures/adverse effects; Plastic Surgery Procedures/mortality; Recovery of Function; Retrospective Studies; Sacrum/diagnostic imaging; Sacrum/physiopathology; Sarcoma/diagnostic imaging; Sarcoma/physiopathology; Spinal Fusion/adverse effects; Spinal Fusion/mortality; Time Factors; Treatment Outcome; Young Adult