Objective:There are no clear indications and clinical results for total knee arthroplasty for bony ankylosing deformity of the knee.In this paper we report the outcome and complications in 45 knees of 31 patients.Methods:From 1987 to 2006,forty-five total knee arthroplasties of 31 patients with bony ankylosing deformity were performed in our department.For flexional ankylosing deformed knees,the preoperative diagnosises included ankylosing spondylitis in 18 knees of 10 patients,rheumatoid arthritis in 14 knees of 11 patients,hemophilia arthritis in 2 knees and psoriasis arthritis in 2 knees.For extensional ankylosing deformed knees,the original diagnosises were complications following open synovectomy in 3 knees,ankylosing spondylitis in 2,rheumatoid arthritis in 3,tuberculous arthritis in 1.The ROM of all patients preoperative was 0°.KSS preoperative were 30.9 points (-8~56) for flexional knees and 44.1 points (10~68) for extensional knees respectively.