ObjectiveTo evaluate the application and effectiveness of bilateral total hip arthroplasty and total knee arthroplasty in the treatment of severe inflammatory arthropathies. MethodsBetween September 2008 and September 2015, 31 patients with severe inflammatory arthropathies were treated with bilateral total hip arthroplasty and total knee arthroplasty. Of 31 cases, 22 were male and 9 were female with an average age of 30 years (range, 20 to 41 years); there were 15 cases of rheumatoid arthritis and 16 cases of ankylosing spondylitis with an average onset age of 14 years (range, 5-28 years); all 4 ankylosed joints were observed in 11 cases, 3 ankylosed joints in 2 cases, 2 ankylosed joints in 6 cases, 1 ankylosed joint in 1 case, and no ankylosed joint in 11 cases. Before operation, the hip range of motion (ROM) value was (17.82±28.18)°, and the knee ROM value score was (26.45±30.18)°; the hip Harris score was 29.64±11.58, and the hospital for special surgery (HSS) score was 27.07±11.04. The patients were grouped and compared in accordance with etiology and ankylosed joint. ResultsOne-stage arthroplasty was performed in 1 case, two-stage arthroplasty in 22 cases, three-stage arthroplasty in 7 cases, and four-stage arthroplasty in 1 case. The total operation time was 325-776 minutes; the total blood loss was 900-3 900 mL; the total transfusion volume was 2 220-8 070 mL; and the total hospitalization time was 21-65 days. The patients were followed up 12-94 months (mean, 51 months). The hip and knee ROM values, Harris score and HSS score at last follow-up were significantly improved when compared with preoperative ones (P < 0.05). The subjective satisfaction degree was good in 16 cases, moderate in 10 cases, and poor in 5 cases. Periprosthetic infection occurred in 2 cases (3 knees), joint stiffness in 3 cases (6 knees), joint instability in 1 case (1 knee), leg length discrepancy of > 2 cm in 2 cases, and flexion deformity of 10° in 1 case (1 knee). The hip and knee ROM values, Harris score and HSS score showed no significant difference between patients with ankylosing spondylitis and patients rheumatoid arthritis at last follow-up (P > 0.05). The hip and knee ROM values of the patients with ankylosed joint were significantly lower than those of patients with no ankylosed joint (P < 0.05); the Harris score and HSS score of the patients with ankylosed joint were lower than those of patients with no ankylosed joint, but no significant difference was found (P > 0.05). ConclusionA combination of bilateral hip and knee arthroplasty is an efficient treatment for severe lower extremities deformity, arthralgia and poor quality of life caused by inflammatory arthropathies. However, the postoperative periprosthetic infection and stiffness of knee are important complications influencing the effectiveness of operation.