Comparison of two methods of reconstruction for primary malignant tumors at the knee: A sequential cohort study

Background and Objectives: The purpose of this study was to compare the com plications and functional outcome associated with the use of an irradiated allograft-implant composite or a bone-ingrowth modular tumor prosthesis for replacement of the knee joint after resection of a bone sarcoma from the d istal femur or proximal tibia. Methods: Eleven patients initially received an allograft reconstruction, fo llowed by 64 treated with a tumor prosthesis. The primary analysis concerne d reconstructive failure, defined by the requirement for removal of the ori ginal construct. Functional outcome was assessed by using the 1987 Musculos keletal Tumor Society rating system. Results: Reconstructive failure occurred in 6 of 11 (55%) allograft constru cts compared with 10 of 64 (16%) tumor prostheses (P = 0.009). Failures wer e due to infection (2 of 11 allografts versus 4 of 64 prostheses; P = 0.2) or mechanical complications (4 of 11 allograft fractures versus 5 of 64 bro ken prosthetic stems and 1 aseptically loose prosthesis; P = 0.03). The lim b salvage rate was 95% (61 of 64) for patients with a tumor prosthesis comp ared with 64% (7 of 11) for those with an allograft (P=0.007). Patients wit h a tumor prosthesis had a better functional outcome with a mean score of 7 5% compared with 57% for those with an allograft reconstruction (P = 0.006) . Conclusions: This comparative study suggests that limb salvage surgery at t he knee has a better and more predictable outcome with a tumor prosthesis t han with an allograft-implant reconstruction. J. Surg. Oncol. 2001;77:89-99 . (C) 2001 Wiley-Liss, Inc.