Objective    To evaluate the clinical effectiveness of rotatory hinge prosthesis replacement for treatment of giant cell tumors around knee joint.     Methods    Thirty-one patients with giant cell tumors of bone around the knee from January 2001 to January 2008 in our hospital were reviewed. There were 13 males and 18 females. Their ages ranged from 19 to 56 and the mean age was 33.5. The anatomic site for the lesions were the distal femur (20 cases) and proximal tibia (11 cases). Using Companacci’s staging system: 7 patients were classified as grade Ⅱ and 24 as grade Ⅲ. The patients were grouped as follows: the tumor breaking through the cortex with an extraosseous mass in 2 patients

having pathologic fracture in 3

representing more biologicallyaggressive lesions in 5

and having one or more local recurrences in 21. All patients had been treated with en block excision and reconstruction with rotatory hinge prosthesis.     Results    According to the follow-up for 12 to 96 months

all patients had no local recurrence or metastasis. The mean Musculoskeletal Tumor Society (MSTS) score was 24.0±2.5

with an excellent limb function in 23 patients

good in 6 patients

and fair in 2 patients. The overall excellent and good function was obtained in 93.5% of the patients.      Conclusion    Rotatory hinge prosthesis replacement is an effective method to treat giant cell tumors of bone around the knee joint. It also can reduce the local recurrence and obtain better the outcomes.