I examined the sphericity and the congruity of the femoral head and the acetabulum in 172 Korean fetuses and in 655 Korean adults. I found that Korean fetal acetabuli and femoral heads are spherical and that the proportion of the head contained in the acetabulum remains constant and congruous throughout the fetal life. Adult actabuli and femoral heads are also spherical in both gender and are there are no visible changes in the shape of the acetabuli and the femoral heads with respect to age. No evidence was found that the congruity of the hip joint is a cause of osteoarthritis of the hip joint. Clinical Relevance: Stable hip joints at the time of birth provide an explantation for the low incidence of congenital dislocation of the hip joint in Koreans. The spherical femoral head and acetabulum (congruous hip joint) seem to be a contributing factor to the low incidence of primary osteoarthritis of the hip in Koreans.
Acetabulum/*anatomy and histology/embryology ; Adult ; Female ; Femur Head/*anatomy and histology/embryology ; Fetus/anatomy and histology ; *Hip Joint/pathology ; Human ; Incidence ; Korea/epidemiology ; Male ; Osteoarthritis, Hip/epidemiology/*etiology/pathology

I examined the sphericity and the congruity of the femoral head and the acetabulum in 172 Korean fetuses and in 655 Korean adults. I found that Korean fetal acetabuli and femoral heads are spherical and that the proportion of the head contained in the acetabulum remains constant and congruous throughout the fetal life. Adult actabuli and femoral heads are also spherical in both gender and are there are no visible changes in the shape of the acetabuli and the femoral heads with respect to age. No evidence was found that the congruity of the hip joint is a cause of osteoarthritis of the hip joint. Clinical Relevance: Stable hip joints at the time of birth provide an explantation for the low incidence of congenital dislocation of the hip joint in Koreans. The spherical femoral head and acetabulum (congruous hip joint) seem to be a contributing factor to the low incidence of primary osteoarthritis of the hip in Koreans.
Acetabulum/*anatomy and histology/embryology ; Adult ; Female ; Femur Head/*anatomy and histology/embryology ; Fetus/anatomy and histology ; *Hip Joint/pathology ; Human ; Incidence ; Korea/epidemiology ; Male ; Osteoarthritis, Hip/epidemiology/*etiology/pathology

The main reason of invalidation of prosthetic hip joint is the prostheses flexibility and shift, dislocation and disjunction. Promoting the long time stability of the prostheses is the key of improving the long term hip joint replacement effect. Former research work was focused on the upper segment of femur, and assumed the acetabulum cup to be a spheric concave, and the external form of acetabulum prostheses was basically semi spheric. This paper presents a method of acquiring the point data on the surface of the hip bone using the reverse engineering technology. By analyzing the acetabulum surface fitting error we use rotating elliptical surface to fit the acetabulum surface, together with the optimal technique to build up the CAD model of acetabulum surface. We compare the fitting error between the sphere fitting and rotating elliptical surface fitting and get the result that the rotating elliptical surface fitting error is smaller than the sphere fitting error, and the rotating elliptical surface can describe the shape of the acetabulum better.
Acetabulum ; anatomy & histology ; Anthropometry ; Arthroplasty, Replacement, Hip ; Computer Simulation ; Computer-Aided Design ; Hip Joint ; anatomy & histology ; Hip Prosthesis ; Humans ; Models, Anatomic ; Prosthesis Design

A non-invasive acoustical system was developed for the measurement of transmission properties of acoustic waves in the hip joints. The instrumentation consisted of three sub-systems. An excitation system employed a vibratory force at the sacrum of the test subjects. A transduction system included a pair of identical microphones installed in the tubes of two stethoscopes, which were placed at the greater trochanters on both sides for picking up the acoustical signals transmitted across the hip joints. The data acquisition and analysis system was a portable signal analyzer with a program of dual channel digital filter for measuring the power of acoustical signal in 1/3-octave frequency bands. 27 normal adults, 20 normal pre-school children and 40 normal neonates were randomly selected for testing. Coherence function (CF) and discrepancy (D) was measured during the testing. Results from the three groups showed that there was a high coherence of the signals (CF > 0.9) and a small discrepancy (D < 3 dB) between bilateral hips in the frequency range of 200-315 Hz. For normal neonates, there was a wider frequency range of 160-315 Hz in which the acoustical signals maintained a high coherence (CF > 0.93) and a smaller discrepancy (D < 2 dB) was observed. This study showed that the development of the acoustical technique provided a practical method with objective parameters. The results obtained in this study can offer a baseline for further investigation of hip disorders particularly those related to structural abnormalities of the hip.
Acoustic Stimulation/*instrumentation ; Age Factors ; Hip Joint/*anatomy & histology ; Sacrum/anatomy & histology ; Signal Processing, Computer-Assisted/*instrumentation ; Sound/*diagnostic use

A non-invasive acoustical system was developed for the measurement of transmission properties of acoustic waves in the hip joints. The instrumentation consisted of three sub-systems. An excitation system employed a vibratory force at the sacrum of the test subjects. A transduction system included a pair of identical microphones installed in the tubes of two stethoscopes, which were placed at the greater trochanters on both sides for picking up the acoustical signals transmitted across the hip joints. The data acquisition and analysis system was a portable signal analyzer with a program of dual channel digital filter for measuring the power of acoustical signal in 1/3-octave frequency bands. 27 normal adults, 20 normal pre-school children and 40 normal neonates were randomly selected for testing. Coherence function (CF) and discrepancy (D) was measured during the testing. Results from the three groups showed that there was a high coherence of the signals (CF > 0.9) and a small discrepancy (D < 3 dB) between bilateral hips in the frequency range of 200-315 Hz. For normal neonates, there was a wider frequency range of 160-315 Hz in which the acoustical signals maintained a high coherence (CF > 0.93) and a smaller discrepancy (D < 2 dB) was observed. This study showed that the development of the acoustical technique provided a practical method with objective parameters. The results obtained in this study can offer a baseline for further investigation of hip disorders particularly those related to structural abnormalities of the hip.
Acoustic Stimulation ; instrumentation ; Adult ; Age Factors ; Child ; Child, Preschool ; Female ; Hip Joint ; anatomy & histology ; Humans ; Infant ; Infant, Newborn ; Male ; Sacrum ; anatomy & histology ; Signal Processing, Computer-Assisted ; instrumentation ; Sound

DLUT4060 piezoelectric multi-component force platforms and DVM8820 three-dimensional infrared image capture system were used to test the sit-to-walk (STW) movements of 11 healthy elderly (72. 6 +/- 12. 2 years old) and 11 healthy young (19. 7 +/-1. 3 years old) individuals. Firstly, we studied the effects of seat-heights on the ground reaction forces, the velocity of the center of mass, and action time duration. Then we discussed the movement strategies and falling risks of the persons in the two age groups respectively. Finally, we decided the best seat height for the two age groups. It was found that the best seat heights for both the two age groups were 100% popliteal height. This height may make the subject get the greatest biomechanical advantages and the lowest falling risks. The popliteal height must be concerned when designing and fixing up the public activity area facilities and daily life of the elderly. To some extent, it can reduce the falling risk of the elderly.
Accidental Falls ; prevention & control ; Aged ; Aged, 80 and over ; Ankle Joint ; physiology ; Buttocks ; physiology ; Hip Joint ; physiology ; Humans ; Interior Design and Furnishings ; Knee Joint ; physiology ; Leg ; anatomy & histology ; physiology ; Male ; Middle Aged ; Movement ; physiology ; Posture ; Weight-Bearing ; physiology ; Young Adult

OBJECTIVETo investigate possible causes of micromotion in distal femoral prosthesis.

METHODSBased on the assumption that the femur and prosthesis were considered as concentric cylinders with completely bonded interface, a theoretical model simulating the interfacial stress transfer was established. The distributions of the interfacial shear and radial stresses with the changing of z were obtained through mathematics and mechanics deducing.

RESULTSThe maximum interfacial shear stress occurred at the position of z=0, namely, the cross section of the femur neck. The interfacial shear stress sharply decreased with the increasing of z and came to nearly zero at the range of z> 0.1 m. While the interfacial radial stress increased with the increasing of z,at the range of z >0.05 m it was constant and reached the maximum.

CONCLUSIONThe micromotion in distal prosthesis is caused by the interfacial radial stress.

Biomechanical Phenomena ; Femur ; anatomy & histology ; physiopathology ; surgery ; Hip Prosthesis ; adverse effects ; Humans ; Joint Instability ; etiology ; physiopathology ; Models, Theoretical ; Motion ; Prosthesis Design ; Shear Strength ; Stress, Mechanical

This study aimed to develop a non-invasive diagnostic technique for the measurement of acoustic transmission in hip joints to reflect the dynamic response of the observed structure. This instrument consists of three sub-systems. An stimulation system applied a vibratory force at the sacrum of the test subject. A transduction system included a pair of identical microphones was installed in the tubes of two stethoscopes, which were placed at the greater trochanters on both sides for picking up the acoustic signals transmitting across the hip joints. The data acquisition and analysis system was a portable frequency analyser with a program of dual channel digital filter for measuring the power of acoustic signals in 1/3-octoscn frequency bands. Twenty-seven normal adults, 20 normal pre-school children and 40 normal neonates were recruited for the testing. Coherence function (CF) of the signal and the discrepancy (D) of bilateral hips were measured during the testing. The results from the three groups showed that there was a high coherence of the signals (CF > 0.9) and a small discrepancy (D < 3 dB) between bilateral hips in the frequency range of 200-315 Hz. For normal neonates, the frequency range (160-315 Hz) was wider in which the acoustic signals maintained a high coherence (CF > 0.94) and a smaller discrepancy (D < 2 dB) were observed between bilateral hips. This study has shown that the development of the acoustical diagnostic technique could provide a practical method with objective parameters. The results obtained in this study can offer a base for further investigation of hip disorders, particularly those related to structural abnormalities of hip joints.
Acoustic Stimulation ; instrumentation ; Adult ; Child, Preschool ; Female ; Hip Joint ; anatomy & histology ; Humans ; Infant, Newborn ; Male ; Signal Processing, Computer-Assisted ; instrumentation ; Sound

OBJECTIVE: To evaluate the association between alpha angle and herniation pit on MRI in asymptomatic hip joints and their associations with demographic variables. MATERIALS AND METHODS: Hip MRI of 185 asymptomatic hip joints of 105 adults (age 18 to 80 years) from September 2011 through December 2012 were retrospectively studied. Alpha angles were measured on oblique axial MR images by 2 observers. Herniation pit was determined by 1 observer. Size measures, prevalence, and statistical analyses were conducted regarding its association with age, gender, laterality (right or left hip). Intra- and inter-observer agreements were determined by intra-class correlation coefficient. RESULTS: The prevalence of herniation pit in asymptomatic hips was 21.6%. The range of alpha angle was 27.6-65.0 degrees. Seventeen and 16 out of 185 (9.1% and 8.6%) hip joints showed alpha angle of ≥ 55 degrees in first and second measurement sessions, respectively. There was no association between alpha angle ≥ 55 and presence of herniation pit. There was no association between alpha angle ≥ 55 and the size of herniation pit. Inter-observer agreement of alpha angle was 0.485 between first measurements of first vs. second observer, respectively. Intra-observer agreement of alpha angle was 0.654, respectively. Forty (21.6%) of 185 hip joints (35 of 105 patients, 33.3%) had herniation pit, with no difference according to age, gender, or laterality of hip joint. CONCLUSION: There is no association between alpha angle ≥ 55 degrees and presence of herniation pit or demographic variables.
Adolescent ; Adult ; Aged ; Aged, 80 and over ; Asymptomatic Diseases ; Female ; Femur Neck/anatomy & histology/radiography ; Hip Joint/anatomy & histology/*radiography ; Humans ; *Magnetic Resonance Imaging ; Male ; Middle Aged ; Prevalence ; Retrospective Studies ; Young Adult