engleski

Incidence of aseptic loosening in total knee replacement in rheumatoid arthritis patients

Background: Rheumatoid arthritis (RA) is the most frequent human chronic inflammatory autoimmune disease characterized by chronic synovitis and bone damages. Joint destruction caused by RA predominantly occurs in hands, feet and knee joints. RA is responsible not only for great deformity of the joint, but also affect the bone quality causing the progressive bone resorption and osteoporosis. Progressive changes can affect the quality of every day life in RA patients. The greatest problem during total knee replacement in RA patients proved to be the lack of strong bone of the tibia and femur, as well as necessity of the soft tissue balancing during surgery due to great deformity. Both factors are very important in longevity of the knee prosthesis. Objectives: The purpose of our research was to assess outcome in RA patients undergoing total knee replacement concerning an incidence of early aseptic loosening. Methods: We analysed the 55 knees in 48 patients (37 women and 18 men) in whom total knee replacement was performed due to advanced arthritic changes and deformity. All changes were due to well estabilished and documented rheumatoid arthritis according to American College of Rheumatology criteria. The average age of these patients was 65.4 years (range 54 to 75) and the average follow up period was 6 years (3– 12). Outcome was evaluated clinically in terms of pain relief and range of motion of the knee. On radiological images we analysed the knee axis and signs of loosening of prosthetic component and bone resorption. Results: A bone stock and bone strength are important for supporting the prosthesis component and with propertly performed soft tissue balancing we achieved optimal biomechanical load in knee prosthesis. In all patients we achieved pain relief and flexion of the knee of 90 degrees and greater. During the final radiological analysis there were no signs of bone resorption or aseptic loosening of the prosthesis components. Moreover, we observed no clinical signs of synovitis in all examined knees. Conclusion: Knees affected by rheumatic changes often show reduction of the bone quality and impairment of bone remodeling that can cause great deformity after years of the disease. After implantation of prosthesis all clinical signs of rheumatoid arthritis of the knee disapeared. Despite severe osteoporosis and deformity there were no signs of aseptic loosening during follow up period in the examined group of patients. This can support the hypothesis that the cartilage is important factor in maintaining the inflammation process in RA.

rheumatoid arthritis; osteoporosis; therapy

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