INTRODUCTION. Femur is one of the bones in humans that exhibit ethnic, racial, and gender difference. Several basic and clinical studies were conducted to explore these variations. Clinical anthropological studies have dealt with the compatibility of femoral prostheses and osteosythesis and materials with the femur. If there is a misalignment between the Total Knee Arthroplasy (TKA) femoral comportment installation position, Range of Motion (ROM) failure and several problems may arise. The aim of this study was to evaluate anterior bowing of the Japanese femur and to assess the adequacy of TKA femoral comportment installation position. METHODS. We analyzed 76 normal Japanese and 97 TKA patients. (June 2014-June 2015) The average age of the normal subjects was 62.0±20.90 (24–88) years old and the average of TKA subjects was 73.6±7.9 (53–89) years old. First we defined and measured the anterior curvature and the posterior condylar offset (PCO) in normal japanese femurs. Then in TKA patients we set the implant as same angle of the component. Third, we measured the post operative anterior curvature and PCO. Then calculated the anterior curvature difference and PCO differences and preformed statistical analysis with ROM. RESULTS SECTION. The average of anterior curvature in normal subjects was 7.87±6.60 degrees. Among 97 TKA patients, pre-operative anterior curvature was 7.58±0.16 degrees. Further, the angle of component which was set the post operatively was 7.32±0.25. The average of Anterior curvature difference and PCO differences had correlation with ROM. DISCUSSION. Gilbert reported that caucasian femurs are straight compared to asian femurs. Chinese and Japanese showed different anterior curvature because of different life style. The chalenges are when operating on different ethnic patients, Orthopedic Surgeons consider many factors. Previous studies yielded different suggestions for the ideal point of entry. We suggest difference between the curves of the femurs should be considered for TKA femoral comportment installation position. SIGNIFICANCE. 1)Our results gave an anatomical characteristics of Japanese femur. 2)These data will give clinical indication for TKA femoral comportment installation position

Objectives. To evaluate the clinical and radiographic outcomes of total knee arthroplasty using Vega® Knee System (B Braun-Aesculap, Tuttlingen, Germany) [Fig. 1] designed to allow high flexion by shortening the length of posterior condylar flange of femoral component after at least 2 year and to assess the occurrence of periprosthetic osteolysis and loosening at final follow-up. Materials and Methods. Of the patients who underwent total knee arthroplasty using Vega® Knee System between April 2011 and May 2013, 40 patients (46 knees) were enrolled. The mean age of the patients at the time of surgery was 72.3 years and the mean follow-up period was 29.4 months. Clinical parameters, including Knee Society Knee score, Knee Society Function score, maximal flexion and range of motion were evaluated. Relationship between postoperative maximal flexion and radiographic factors including the posterior tibial slope, the femoral condylar offset and the change of the posterior flange length of femoral condyle was analyzed. Also, the occurrence of periprosthetic osteolysis and loosening was assessed. Results. The mean preoperative flexion contracture was 4.3° which was reduced to 1.1° at the final follow-up (P < 0.05). The mean preoperative maximal flexion was 121.6° which was increased to 132.7° at the final follow-up (P < 0.05). The mean preoperative range of motion was 122.8° which was increased to 130.5° at the final follow-up (P < 0.05). The mean preoperative knee score and function score were 54.2 and 46.1. At the final follow-up, the mean knee score and function score were improved to 90.2 and 78.6 (P < 0.05). The post operative posterior tibial slope, femoral condylar offset and the change of the posterior flange length of femoral condyle showed no significant relationship with the postoperative maximal flexion angle. (posterior tibial slope; R=0.241, p=0.94 / femoral condylar offset; R=−0.271, p=0.167 / posterior flange; R=−0.074, p=0.623). The periprosthetic osteolysis of the femoral component occurred in two cases, but loosening did not occur at the final follow-up. Conclusions. Total knee arthroplasy using Vega® Knee System provided satisfactory maximal flexion at minimum 2 year follow-up and there was no the periprosthetic loosening. And, there was no significant relationship between postoperative maximal flexion and radiographic factors including the posterior tibial slope, the femoral condylar offset and the change of the posterior flange length of femoral condyle. To view tables/figures, please contact authors directly

Introduction. Revision total knee arthroplasy (TKA) has been often used with a metal block augmentation for patients with poor bone quality. However, bone resorption beneath metal block augmentation has been still reported and little information about the reasons of the occurrence of bone resorption is available. The aim of the current study is to identify a possibility of the potential occurrence of bone resorption beneath metal block augmentation, through evaluation of strain distribution beneath metal block augmentation in revision TKA with metal block augmentation, during high deep flexion. Materials and Method. LOSPA, revision TKA with a metal block augmentation (Baseplate size #5, Spacer size #5, Stem size Φ9, L30, Augment #5 T5) was considered in this study. For the test, the tibia component of LOSPA was implanted to the tibia sawbone (left, #3401, Sawbones EuropeAB, Malmö, Sweden), which was corresponded to a traditional TKR surgical guideline. The femoral component of LOSPA was mounted to a customized jig attached to the Instron 8872 (Instron, Norwood, MA, USA), which was designed specially to represent the angles ranged from 0° to 140° with consideration of a rollback of knee joint (Figure. 1). Here, a compressive load of 1,600N (10N/s) was applied for each angle. Strain distribution was then measured from rossete strain gauge (Half Bridge type, CAS, Seoul, Korea) together (Figure 1). Results and Discussions. The strain distribution on the cortical bone of the tibia was shown in Figure 2. The results showed that the strains on the posterior region were gradually increased from extension to high deep of the knee joint and generally larger than the other regions. In contrast to the results on the posterior region, the strains on the medial region were gradually decreased after 60° or 90° flexion position and relatively lower than the other regions. Particularly, the strains on the medial region were generally lower than 50–100 µstrain, which is known as critical value range able to inducing bone resorption, during high deep flexion. This fact indicate that a possibility of the potential bone resorption occurrence in revision TKA used with a metal block augmentation may be relatively increased in patients who are frequently exposed to a personal lifestyle history with the loading conditions of the high flexion. This study may be valuable by identifying for the first time a possibility of the potential bone resorption occurrence through evaluation of the strain distribution beneath metal block augmentation in revision TKA used with a metal block augmentation during high deep flexion. Conclusion. A possibility of the potential bone resorption occurrence in revision TKA used with a metal block augmentation may be dependent on loading patterns applied on the knee joint related to personal lifestyle history. Particularly, it may be relatively increased in patients who are frequently exposed to a personal lifestyle history with the loading conditions of the high flexion. Acknowledgements. This study was supported by a grant from the New Technology Product Evaluation Technical Research project, Ministry of Food and Drug Safety (MFDS), Republic of Korea