抄録
Objective: To evaluate clinical results and radiological changes of grafted bone in rheumatoid arthritic knees treated with primary total knee arthroplasty (TKA) with massive bone grafts to tibial defects.
Methods: Seventeen knees of sixteen patients after primary TKA were evaluated. Average age at surgery was 58.7 years old (range 49 to 69 years old) . The average follow-up period was 8.9 years (range 6 to 16 years) . According to Dorr's classification, 11 knees had peripheral defects. The other 6 knees had central defects. In the peripheral defect knees, local bone grafting was performed in 6 knees, iliac bone grafting was performed in 3 knees, and allogenic bone grafting was performed in 3 knees. In all of the central defect knees, local bone grafting was performed. All implants were fixed using bone cement.
Clinical evaluation was performed using the Japanese Orthopaedic Association RA knee score (JOA score) . Radiologically, lower leg alignment, clear zone around the component, and component angles β and δ according to the knee society TKA evaluation system were evaluated. Furthermore, union of grafted bone to tibia, collapse of grafted bone, and absorption of the grafted bone were evaluated.
Results: The mean JOA score improved from 43.5±7.5 to 81.2±12.1. Knee extension improved from a mean of -15.5±14.7° to -1.5±4.9°. Knee flexion improved from a mean of 91.1±18.6° to 117.5±12.8°.All grafted bone was united at an average period of 4.5 months. In one knee with an allogenic bone graft, collapse of grafted bone and component loosening was observed. This resulted in revision TKA. In two knees, absorption of grafted bone was observed radiologically. One of those two knees underwent allogenic bone graft. These three knees had had peripheral defects.
Conclusion: Bone grafting is a viable alternative to modular metal tibial wedges or excess cement, even for large tibial bone defects. On the other hand, the use of allogenic bone graft should be done with caution.
