Papers by Author: R. Tsukamoto

Abstract: We studied the long-term wear behaviour of alumina-doped zirconia femoral condyles against ultra-high molecular weight polyethylene (UHMWPE) tibial inserts. The simulator kinematics included 20 degrees of flexion/extension, ± 5 degrees of internal/external rotation, and 6 mm of anterior/posterior translation. All knee components were subjected to 10 million cycles of normal walking (2.6 KN max, freq. 1.8 Hz). Lubricant was 50% alpha-calf serum (20 mg/ml protein) with EDTA. The tibial inserts were from one lot of ram-extruded UHMWPE and sterilized with 3.5-Mrad or 7-Mrad radiation dose. Soak controls were stored unloaded in deionised water for 60 days prior to testing. Implants were studied with high-resolution confocal Raman spectroscopy after 10-Mc duration. The wear of control knees (CoCr/3.5-Mrad) averaged 4.5mm3/Mc while the wear with the ZrO2/7-Mrad combination was unmeasurably low even after 10 million cycle duration. Raman Spectroscopy at 10-Mc duration showed only the presence of the desired tetragonal phase. Thus, the ZrO2/7-Mrad bearing combination should prove excellent for active patients who may otherwise risk high wear rates over many years of use.

Abstract: A survey of confocal Raman/fluorescence microprobe spectroscopic techniques is presented with emphasis placed on surface analysis of artificial hip joints. Suitable instrumental configurations are first explained in some details in order to describe the versatility of the spectroscopic microprobes to biomedical materials analyses. Then, these notions, which represent the foundation for structural and mechanical analyses of joint surfaces, are applied to selected cases of paramount importance in hip arthroplasty.