Expandable Endoprosthesis Reconstruction in Skeletally Immature Patients With Tumors

Between September 1984 and January 1996, 32 expandable endoprostheses were used for limb reconstruction after resection of malignant bone tumors in patients who were skeletally immature. The 20 boys and 12 girls ranged in age from 3 to 15 years (mean, 9.7 years). One patient had a Stage IIA tumor, 22 patients had Stage IIB tumors, and seven patients had Stage III tumors according to the classification of the Musculoskeletal Tumor Society. There also were two patients with parosteal osteosarcomas. The histologic diagnosis was osteosarcoma in 23 patients and Ewing's sarcoma in nine. All patients except the patients with parosteal osteosarcoma received standard neoadjuvant therapy. Twenty-two Lewis Expandable Adjustable Prostheses, four modular Wright Medical prostheses, four modular Howmedica prostheses, and two Techmedica expandable prostheses were used. Thirteen patients died, two have no evidence of disease, and 17 are continuously disease free. Sixteen of 32 patients (50%) have not had an expansion procedure because of early death in 10 and early amputation in three. Three patients are waiting to undergo an expansion procedure. Sixteen of the 32 patients (50%) have undergone 32 expansion procedures, to a maximum of 9 cm, without any infection. To maintain range of motion before the expansion procedure, a complete resection of the pseudocapsule was done routinely. Fourteen of the 32 patients did not have complications. Eighteen of the 32 patients had 27 complications. All Lewis Expandable Adjustable Prosthesis endoprostheses and the two nonmodular Techmedica prostheses were associated with a large amount of titanium debris. The children's functional results were similar to the results reported for adults with an average Musculoskeletal Tumor Society rating of good to excellent at the knee, fair to good at the hip, and fair about the shoulder. Rehabilitation of the knee in very young patients (5-8 years) remains problematic and careful selection of patient and family is necessary. The Lewis Expandable Adjustable Prosthesis probably should be reserved for very young patients (5-8 years) and modular systems should be used for large preadolescent and adolescent children.