Short Proximal Femur ̈Hip Salvage ̈ Endoprosthetic Reconstruction for Children with Bone Sarcomas: A Report of Two Cases

3 The Children’s Hospital of Philadelphia University of Pennsylvania School of Medicine 34th and Civic Center Boulevard 2nd floor Wood Building Philadelphia, PA, 19104-4399 Introduction Historically, the reconstruction options after resection of malignant bone tumors in the lower limb of skeletally immature patients were limited to amputation and biological reconstruction, although rotationplasty has also been described. Limb salvage surgery (LSS) is now the preferred treatment at most institutions, with approximately 90% of patients presenting as suitable candidates. The femur is the most common site for primary malignant tumors of bone in children; however, hip replacement by means of a proximal femoral or a total femur reconstruction is rarely required. When a massive intramedullary extension of a diaphyseal sarcoma is present, total femoral reconstruction is recommended. This reconstruction involves the replacement of both the knee and hip joint. Good functional outcomes have been reported with regards to the knee 6, 8, ; however, few sources address hip related functional outcomes following this type of reconstruction in the skeletally immature. Furthermore, little is known about the development of the acetabulum without a natural femoral head to mold it. Irregular development can result in hip dysplasia and possible superior and lateral migration (subluxation) of the joint. For this reason, maintaining the hip joint may be crucial in ensuring better clinical outcomes. The use of a bipolar hemiarthroplasty in children between six and fourteen years old following tumor resection has been reported to lead to superior and lateral migration of the femoral head, resulting in a 20% revision rate by five years . In another study in patients over 11 years old, the revision rate was 25%, increasing up to 75 % in younger patients in a ten year period of time. We report two cases in which a unique approach was used to preserve the native hip joint in patients with skip lesions as well as extensive involvement of the femur.