抄録
Kinematic total knee replacements were performed on 96 joints in 68 cases from October 1981 to September 1985. Out of these 68 cases, tibial component breakage occurred in one knee after surgery.
The patient was a 65-year-old man who had rheumatoid arthritis associated with long-standing pain in the right knee. The knee was replaced in July 1982 with a Kinematic total knee of the anteriorly joined type. After the surgery he was free of pain and his right lower extremity showed a straight alignment. But 32 months after the surgery the right knee began to have varus deformity and he suffered from knee pain again. Radiography revealed bone resorption under the medial part of the tibial component and breakage there.
The right knee was revised. Under the tibial component, medial tibial plateau erosion was found, filled with granulation tissue. The breakage surfaces of the tibial component showed partly a wavy area and partly a shiny area. It was concluded that the component breakage was almost certainly due to fatigue under stress on the medial portion of tibial component. This fatigue fracture of the tibial component of Kinematic anteriorly joined type was caused by a weak point in its structure between the anterior flange and the medial component, and by bone absorption under the medial component.
