Limb-Salvage Treatment of Malignant Pelvic Bone Tumor in China for the Past 20 Years
The treatment of malignant pelvic bone tumors has undergone significant advancements over the past two decades in China, particularly in the realm of limb-salvage surgery. This progress has been driven by the development of surgical techniques, innovative reconstruction methods, and the integration of multidisciplinary approaches. The Musculoskeletal Tumor Center of Peking University People’s Hospital (PKUPH) has been at the forefront of these advancements, accumulating extensive clinical experience and contributing to improved patient outcomes.
Historical Context and Challenges
Malignant pelvic bone tumors present a unique set of challenges for orthopedic oncologists. These tumors are often large at the time of diagnosis due to their inconspicuous early symptoms and their location in a complex anatomical region. The pelvis is surrounded by critical neurovascular structures, as well as the intestinal and urinary tracts, making surgical resection particularly difficult. Historically, the primary treatment for these tumors was hindquarter amputation, which, while effective in removing the tumor, resulted in significant cosmetic and functional deficits for patients.
The concept of limb-salvage surgery emerged as a more desirable alternative, aiming to preserve the limb while achieving oncological control. However, the low incidence of pelvic bone tumors made it challenging to accumulate sufficient clinical experience at single centers. Additionally, the complexity of pelvic anatomy and the lack of standardized surgical techniques initially led to poor prognosis for many patients.
Evolution of Limb-Salvage Surgery
Hindquarter Amputation
Hindquarter amputation was the standard surgical treatment for malignant pelvic bone tumors until the 1970s. This procedure involves the removal of the entire hemipelvis and the affected limb. It is classified into four types based on the extent of resection: classical hemipelvectomy, modified hemipelvectomy, extended hemipelvectomy, and compound hemipelvectomy. Additionally, the procedure can be categorized into anterior and posterior flaps hemipelvectomy depending on the choice of flaps.
While hindquarter amputation remains necessary for some patients with extensive tumor involvement, the development of internal hemipelvectomy techniques has allowed for limb-salvage surgery in many cases. Internal hemipelvectomy involves the resection of the tumor while preserving the limb, significantly improving the quality of life for patients.
Partial Hemipelvectomy Resection
Partial hemipelvectomy resection has become a cornerstone of limb-salvage surgery for pelvic tumors. This technique is categorized into four types based on the location of the tumor: iliac tumor resection (Type I), periacetabular tumor resection (Type II), pubis and ischium tumor resection (Type III), and resection of tumors involving the sacroiliac joint (Type IV). Most malignant pelvic tumors involve two or more zones of the pelvic bone, necessitating complex surgical planning.
Since the 1980s, orthopedic oncologists in China have adopted partial hemipelvectomy resection techniques, achieving satisfactory surgical margins and improved patient outcomes. For example, a case series reported by PKUPH demonstrated limb-salvage, en-bloc resection, and 5-year survival rates of 90.5%, 61.9%, and 44%, respectively. These rates were superior to those reported in other countries, highlighting the effectiveness of the techniques developed in China.
Reconstruction Techniques
Reconstruction After Type I or I + IV Resection
Resection of Type I or I + IV tumors without reconstruction can lead to complications such as acetabular adduction, pelvic tilt, and scoliosis. Since 2002, PKUPH has utilized pedicle/iliac screws and titanium rods to restore durable stability after resection. Additionally, the defect is reconstructed using fibular or residual iliac bone. The advent of 3D-printed technology has further enhanced reconstruction outcomes. In 2015, PKUPH designed a 3D-printed modular iliac prosthesis (GPS Type I), which features a metal trabecular structure that promotes union with the residual iliac bone. This modular design simplifies implantation and improves long-term stability.
Reconstruction After Type II or II + III Resection
Reconstruction after Type II or II + III resection is particularly challenging due to the involvement of the periacetabular region. The saddle prosthesis, introduced in 1979, was one of the earliest solutions for this problem. However, its use was limited by a high complication rate of 60%, including dislocation, prosthesis shifting, iliac fracture, and heterotopic ossification.
In the 1990s, custom-made hemipelvic endoprostheses were developed, but they also had high complication rates, particularly infections. The Ice-Cream Cone Prosthesis, introduced in 2001, aimed to restore pelvic continuity and hip joint function. However, it was associated with infection and dislocation rates of 20-47% and 20%, respectively.
PKUPH has made significant contributions to this field with the development of the modular hemipelvic endoprosthesis. In 2007, a study of 28 patients reported deep infection and mechanical failure rates of 14.3% and 7.2%, respectively. A larger study of 100 patients demonstrated deep infection, mechanical failure, and dislocation rates of 15%, 5%, and 9%, respectively. The mean Musculoskeletal Tumor Society (MSTS) 93 score was 57.2%, indicating satisfactory functional outcomes.
The introduction of 3D-printed hemipelvic endoprostheses has further improved reconstruction outcomes. In 2016, PKUPH reported on 35 patients who underwent reconstruction with 3D-printed prostheses, confirming their safety and effectiveness. These prostheses offer early stability, individualized matching, and long-term fusion with the host bone. The deep infection rate with 3D-printed prostheses is significantly lower than that of machine-made prostheses, making them a preferred option for pelvic reconstruction.
Reconstruction After Type I + II or I + II + IV or I + II + III Resection
Reconstruction after Type I + II or I + II + IV or I + II + III resection is particularly complex due to the extensive involvement of the pelvis and sacrum. In 2007, PKUPH introduced the translumbar fixation of the hemipelvic endoprosthesis, which achieved satisfactory clinical results. This prosthesis features a bi-axle gear-like structure that allows for adjustable acetabular angles during surgery. The design minimizes the volume of the prosthesis while ensuring mechanical fixation to the sacrum. In 2015, the sacral contact surface of the prosthesis was modified to a 3D-printed metal trabecular structure (GPS Type III), promoting bone growth and reducing complications such as mechanical failure.
Classification and Surgical Management of Pelvic Tumors Involving the Sacroiliac Joint
The surgical management of pelvic tumors involving the sacroiliac joint is particularly challenging due to the large size of the tumors and their extension into critical structures. In 2016, PKUPH developed a classification system for pelvi-sacral tumors based on the extent of sacral involvement and acetabular involvement. This classification, known as the PKUPH classification, divides pelvi-sacral tumors into six types: P-s Ia, P-s IIa, P-s IIIa, P-s Ib, P-s IIb, and P-s IIIb. This system has facilitated standardized surgical treatment and functional reconstruction, improving oncological outcomes and reducing operative risks.
Development of Adjuvant Therapy and Related Disciplines
The management of pelvic bone tumors has also benefited from advancements in adjuvant therapies. Intraoperative blood loss has been a significant challenge in pelvic and sacral tumor resections. The use of aortic balloon occlusion technology has reduced average blood loss from approximately 5000 mL to 2000 mL, making surgery safer and more feasible.
Chemotherapy and radiotherapy have also played critical roles in the treatment of pelvic osteosarcoma and sacral Ewing sarcoma. While the effectiveness of chemotherapy for pelvic osteosarcoma remains controversial, modern radiotherapy techniques have improved local control and survival rates. Additionally, the development of targeted therapies, such as denosumab for giant cell tumors of bone, has provided new treatment options for patients with pelvic and sacral tumors. Denosumab, a monoclonal antibody that inhibits RANKL, has reduced intraoperative blood loss and recurrence rates, offering significant benefits for patients.
Conclusion
Over the past 20 years, the treatment of malignant pelvic bone tumors in China has seen remarkable progress. The development of limb-salvage surgical techniques, innovative reconstruction methods, and advancements in adjuvant therapies have significantly improved patient outcomes. The Musculoskeletal Tumor Center of Peking University People’s Hospital has played a pivotal role in these advancements, contributing to the standardization and optimization of treatment protocols. While challenges remain, the continued integration of multidisciplinary approaches and technological innovations holds promise for further improvements in the management of these complex tumors.
doi.org/10.1097/CM9.0000000000000509
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