Wear of polyethylene liner and osteolysis appear to be topical problems after long-term follow-up in total hip arthroplasty(THA). Age and activity of patients, manufacturing procedure of polyethylene liner, thickness of the liner, position of acetabular cup, and material of artificial femoral head have of effects on the degree of wear. In addition, conformity, congruency and micromotion between liner and metal cup are likely to be related to the wear. The purpose of this study is 1) to determine the stress caused by contact between metal and polyethylene components, 2) to evaluate the effects of conformity, congruency, and fixation between metal and polyethylene components, on contact stress in acetabular cups and 3) to identify the design parameters of the commercial acetabular cup within the constraints imposed by the overall functional requirements of total joint replacement. The specimens applied to six different commercial cups made in five companies. The methods was performed on dynamic test and static test to rely on load conditions, estimated the gap between the components through LM. The results showed H-G II cup had the most excellent congruency because of the narrowest interval between two components.
Acetabulum ; Head ; Hip ; Humans ; Joints ; Osteolysis ; Polyethylene*

PURPOSE: This study validated the musculoskeletal model of the human lower extremity by comparative study between calculated muscle parameters through simulation using modified hill-type model and measured muscle parameters through isokinetic exercise. The relationship between muscle forces and moments participated in motion was quantified from the results of simulation. MATERIALS AND METHODS: For simulation of isokinetic motion, a three-dimensional anatomical knee model was constructed using gait analysis. The EMG-force model was used to determine muscle activation level exciting muscles. The modified Hill-type model was used to calculate individual muscle force and moment in dynamic analysis. This method was validated by comparing analytical data with experimental data. RESULTS: The results showed that there was a significant correlation between calculated torques from simulation and measured torque from isokinetic motion experiments (R=0.97). We also found that muscle forces and moments during knee flexion and extension have nonlinearly proportional or inversely proportional relationship, since lower extremity muscles were simultaneously involved in flexion/extension motion and inner/outer rotation. CONCLUSION: We concluded that the simulation by using musculoskeletal model may be a useful mean to predict and recover musculoskeletal-related diseases, and analyze complicated experiment such as clash condition.
Gait ; Humans ; Knee Joint* ; Knee* ; Lower Extremity ; Muscles ; Torque

Using three different types of the ankle joint, i.e., the fixed, single-axis, and multi axis type, the gait characteristics of transfemoral amputees were investigated to understand the biomechanics of ankle joint motion during gait of transfemoral amputees with a SNS (swing and stance phase) control prosthesis controlling the flexion-extension of knee in the stance phase unlike conventional swing control prostheses. The socket pressure was measured to explain the resulting gait characteristic of the transfemoral amputees for different ankle joint components. Based on the results from the gait characteristics, socket pressure, knee flexion-extension behavior, and ground reaction vector, the fixed type ankle joint could be considered as the most appropriate ankle joint for the transfemoral amputees using the SNS control prosthesis.
Amputees* ; Ankle Joint ; Ankle* ; Axis, Cervical Vertebra ; Freedom* ; Gait* ; Humans ; Knee ; Prostheses and Implants*

Using three different types of the ankle joint, i.e., the fixed, single-axis, and multi axis type, the gait characteristics of transfemoral amputees were investigated to understand the biomechanics of ankle joint motion during gait of transfemoral amputees with a SNS (swing and stance phase) control prosthesis controlling the flexion-extension of knee in the stance phase unlike conventional swing control prostheses. The socket pressure was measured to explain the resulting gait characteristic of the transfemoral amputees for different ankle joint components. Based on the results from the gait characteristics, socket pressure, knee flexion-extension behavior, and ground reaction vector, the fixed type ankle joint could be considered as the most appropriate ankle joint for the transfemoral amputees using the SNS control prosthesis.
Amputees* ; Ankle Joint ; Ankle* ; Axis, Cervical Vertebra ; Freedom* ; Gait* ; Humans ; Knee ; Prostheses and Implants*

Tinea incognito (TI) is a dermatophytic infection which has lost its typical clinical appearance because of improper use of steroids or calcineurin inhibitors. The incidence of TI is increasing nowadays. We conducted retrospective review on 283 patients with TI from 25 dermatology training hospitals in Korea from 2002-2010 to investigate the demographical, clinical, and mycological characteristics of TI, and to determine the associated risk factors. More than half (59.3%) patients were previously treated by non-dermatologists or self-treated. The mean duration of TI was 15.0 +/- 25.3 months. The most common clinical manifestations were eczema-like lesion, psoriasis-like, and lupus erythematosus-like lesion. The trunk and face were frequently involved, and 91 patients (32.2%) also had coexisting fungal infections. Among 67 isolated strains, Trichophyton rubrum was the most frequently detected (73.1%). This is the largest study of TI reported to date and the first investigational report concerning TI in Korea. We suggest that doctors should consider TI when a patient has intractable eczema-like lesions accompanied by tinea pedis/unguium. Furthermore, there should be a policy change, which would make over-the-counter high-potency topical steroids less accessible in some countries, including Korea.
Adolescent ; Adult ; Aged ; Aged, 80 and over ; Child ; Child, Preschool ; Demography ; Eczema/pathology ; Face/pathology ; Female ; Humans ; Lupus Erythematosus, Cutaneous/pathology ; Male ; Middle Aged ; Psoriasis/pathology ; Republic of Korea ; Retrospective Studies ; Risk Factors ; Tinea/*diagnosis/microbiology ; Trichophyton/isolation & purification ; Young Adult