抄録
Knee replacement with an artificial joints is ultimately for the purpose of ameliorating extreme pain and dysfunction from devastation of the joint caused by arthritis deformans, chronic rthumatism, injury, etc.
Many types of artificial joints have been developed, and are currently in use, yet we are still at the stage where there has been no conclusion as to which type is superior.
Since 1976 to the present, we have used the Okayama University Type Mark II and Kyocera Type Alumina Ceramic surface replacement type artificial knee joints, on 24 patients for the total of 33 joints. The patients consisted of 17 cases of RA and 7 cases of OA. The age range at the time of the surgery were from 28 years to 72, with the average age being 54 years. Clinical results were determined by comparing the patients' conditions before and after surgery, based on JOA judgement criteria concerning the three items of pain, range of movement and walking capacity. OA and RA were treated separately.
Regarding pain, 6 areas were investigated: no pain, pain when standing up, pain from walking, pain when moving without a load, pain when going up and down stairs and last of all spontaneous pain. For the range of movement 3 items where investigated: extension lag, F. T. A. and quadriceps fermoris muscle strength. Walking capacity was investigated under 5 items: independent walking, walking indoors, climbing and decending stairs, walking outdoors for 10 minutes or longer and normal walking. Concerning the knee joint flexing function when walking after surgery, stick pictures were used for a comparative study of normal patients, patients who had satisfactorily functioning knee joint and patients whose knee joint functions were defective.
1. With both the Mark-II type and the Kyocera Type, we are dissatisfied with the improvment in the knee joint R. O. M. With the Mark-II Type, the tibia component sometimes slips out towards the front in early movements following surgery. Some problems also remain with fixation. Fixation of the femoral component is insufficient and it loosens easily. Care should be taken with the setting angle of the component. Particular consideration is necessary in cases of high bone atrophy, as in RA.
As for settling of the tibia component, in the case of the Kyocera-type, we found 3mm within 3 months on the average; after 6 months, the region around the component catagmatizes. In preventing settling, the Mark-II is the same, but it is important that the component be established completely around the bone cortex.
Different sizes of the component are desirable.
If the angle which the tibia component forms with the longitudinal axis of the tibia is slanted, internal and external opposite deformation will occur, leading to curvature defects, and it will be easy for the components to loosen.
In reference to knee function during walking where stick pictures were used, the cases of knee joint curvature defects were reduced, as well as the angle of the curvature during walking, swing was small and knee extension time during the base period was long.
