This study was designed to validate the functional evaluation system after surgery of malignant musculoskeletal tumors by ISOLS (International Symposium On Limb Salvage).

The reliability, content and criterion validities of the ISOLS system were investigated using the Nottingham Health Profile, the Medical Outcome Study 36-item Short-Form Health survey and the EuroQol instrument to measure the quality of life of patients with malignant musculoskeletal tumors. Forty nine patients were evaluated Osteosarcoma around knee joint was most commonly. Prosthetic reconstruction was performed in 55.1%.

In content validity analysis, no social and psychological domains was found in ISOLS and the domains for functions of the lower extremities had a strong Cronbach's coefficient (0.88). ISOLS exhibited strong correlation in criterion validity. Convergent validity was good but the discriminative validity was poor. ISOLS has reliability with a strong correlation with other golden standard outcome measures.

Overall reliability and validity of the ISOLS system appeared to be acceptable. However, this system may need further development of its appropriate domains to evaluate the quality of life in patients with malignant musculoskeletal tumors.