Page 57 - Reconstructive Techniques in Musculoskeletal Tumor Surgery

Introduction
Primary sarcomas of the pelvis commonly involve periacetabular bone. Traditionally
these were treated by hindquarter amputation with a poor functional outcome
and quality of life1. Because of the advances in chemotherapy, preoperative
imaging and surgical techniques, limb-salvage surgery has become increasingly
popular. At present, most patients are treated with a type 2 or type 2/32 internal 3 hemipelvectomy, followed by reconstruction of the defect3. These are some of the
most challenging procedures in orthopaedic oncology. First, it is often di cult to achieve adequate margins due to the complex anatomy, size of the tumor and proximity of major neurovascular structures4. Second, reconstruction of a functional and painless limb is demanding, because of the complex biomechanics and extent of the resection. Third, infection is of major concern, with reported rates of up to 40% whichever method of reconstruction is used.5-8
A number of techniques have been described for the reconstruction of a periacetabular defect. Although associated with a signi cant reduction in range of movement, some authors prefer to perform an iliofemoral arthrodesis or pseudarthrosis. However, failure to obtain a solid fusion is a frequent occurrence and results in a painful reconstruction with poor function9. Others have attempted to reconstruct the defect using allografts, irradiated autografts or an allograft- prosthetic composite6,7,10. However, allografts are associated with a high rate of failure because of nonunion, fracture and graft resorption6,7,10,11. If an allograft becomes infected it is di cult to treat and often has to be removed12. An alternative technique, hip transposition, causes signi cant shortening of the limb but may result in reasonable function. It tends to be used as a salvage procedure after failure of other forms of reconstruction13.
Much thought has also been given to endoprosthetic reconstruction of pelvic defects and a number of di erent types of endoprostheses have been employed. Although encouraging results have been reported, mechanical complications are frequent5,8,14,15. Dislocation is reported to occur in 12% to 22%, while 3% to 12% experience aseptic loosening. Reoperations are often needed: secondary rotationplasty, hip transposition or hindquarter amputation may be needed3,4,8,16-18.
Musculoskeletal oncologists generally agree that reconstructing a pelvic defect with an endoprosthesis has the greatest potential to achieve a well-functioning limb3,4,19. Nevertheless, long-term results are limited and little is known about the durability of these reconstructions. Meanwhile, the search continues for new, more successful prostheses.
Pedestal cup endoprosthesis
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