The patient was a 24-year-old female who presented with progressive left hip pain. Diagnosticworkup confirmed Ewing Sarcoma, classified as Enneking stage IIB, involving the ilium, superior pubic ramus, ischium, and part of the sacroiliac (SI) joint. She underwent neoadjuvant chemotherapy and radiation therapy, achieving a partial tumor response.
Dr. Sadegh Saberi
- Orthopaedic Oncologist
- Associate Professor of Orthopaedic Surgery
- Tehran University of Medical Sciences (TUMS)
Pre-operative Planning
High-resolution 1-mm CT imaging was used to reconstruct the three-dimensional bony model, and MRI was utilized to accurately define the tumor boundaries and determine the resection planes.
Patient-specific cutting guides were designed based on the anatomic landmarks to ensure precise osteotomy planes corresponding to the custom implant geometry. The implant itself was designed by mirroring the contralateral healthy hemipelvis to restore normal pelvic anatomy.
Careful planning of acetabular version and inclination, fixation screw trajectories, and incorporation of porous surfaces for osseointegration ensured both biomechanical stability and long-term integration. This detailed preoperative workflow allowed a structured intraoperative plan, minimizing uncertainty, facilitating accurate placement of the prosthesis, and contributing to reduced operative time despite the complexity of the surgery. The final implant and guides were manufactured using SLM titanium, followed by post-processing and gamma sterilization.
Surgical Treatment
The procedure was performed under general anesthesia. Tumor resection and reconstruction were performed during a single operative session. Using patient-specific guides, a Type II pelvic resection was completed, achieving safe oncologic margins while preserving neurovascular structures. The patient-specific 3D-printed implant was then anatomically positioned according
to the preoperative plan and secured using the predetermined screw trajectories. 6.5-mm cancellous screws were utilized to achieve fixation to the sacroiliac joint, providing robust mechanical stability. Muscular and soft-tissue attachments were restored through designated suture holes on the prosthesis, contributing to pelvic stability and maintaining hip biomechanics.
Additionally, the implant was intentionally designed based on the surgeon’s planning—to avoid the need for resection of the anterior superior iliac spine (ASIS), preserving critical bony landmarks and soft-tissue attachments while allowing optimal implant placement.
Post-operative Follow-up
During the postoperative course, the patient received parenteral antibiotics for up to 5 days. An abduction brace was applied and maintained for 6 to 8 weeks. Mobilization was initiated with partial weightbearing, and hip range of motion exercises were started as tolerated, with appropriate precautions based on the reconstruction and soft-tissue repair. Partial weightbearing was continued until early radiographic signs of osseous integration and stable implant fixation were confirmed. Weightbearing was then gradually advanced over the following weeks, and strengthening of the surrounding musculature particularly the gluteal muscles was introduced once soft-tissue healing allowed. During follow-up, which extended for approximately 6 months, the patient experienced an early wound complication that was successfully managed without the need for additional surgery. No late complications were observed throughout the remainder of the follow-up period. The patient continued adjuvant chemotherapy as planned. Postoperative imaging demonstrated proper implant positioning and stable fixation. Functionally, the patient showed encouraging early recovery, achieving an MSTS score of 73.3%. Oncologic evaluation revealed no evidence of disease. By the later follow-up visits, the patient demonstrated improved gait stability and increasing independence in daily activities.
Physician’s Conclusion
The management of this complex Type II pelvic defect was successfully achieved using a custom 3D-printed hemipelvic implant, allowing precise tumor resection and faithful restoration of pelvic anatomy. Traditional reconstruction techniques, such as modular prostheses or structural allografts, frequently encounter challenges including imperfect anatomical fit and limited fixation options which can negatively impact both mechanical stability and postoperative function.
In this patient, detailed preoperative planning, combined with patient-specific osteotomy guides and an implant designed with porous interfaces, provided robust initial stability and supported early osseointegration. detailed preoperative workflow allowed a structured intraoperative plan, minimizing uncertainty, facilitating accurate placement of the prosthesis, and contributing to
reduced operative time despite the complexity of the surgery. Beyond the engineering features, this case underscores the importance of close collaboration between orthopedic oncologic surgeons and biomedical engineers, which enabled the prosthesis to be customized to the patient’s unique anatomy and surgical needs.
The result was not only effective oncologic control but also functional restoration, with early rehabilitation facilitated by the precise fit and stability of the implant. This case exemplifies how patient-specific pelvic prostheses can overcome the limitations of conventional reconstruction and deliver favorable outcomes in aggressive pelvic tumors.