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The purpose of this longitudinal study was to clarify the motion characteristics of children who had greatly improved their sprint speed in the middle grades of elementary school over a one-year period. The sprint motions of 23 children (12 boys and 11 girls) in the third and fourth grades were filmed and compared by classifying them into 2 groups: a superior group, who improved their running speed relatively significantly, and an inferior group, who increased their running speed only slightly. The motions of children who had improved their sprinting speed significantly in one year were characterized by an increase in the swing-back angular velocity of the hip joint, the degree of knee joint extension during ground contact, and the angular velocity of the extension. In addition, the whole leg swing speed and the ankle joint angle at ground contact were found to be smaller. Except for the swing-back angular velocity of the hip joint, these motions differed from the rational motions clarified in previous biomechanics research. The findings of this study indicate that some middle-grade elementary school children improve their sprinting speed significantly over the course of a year, even if it is transformed into a motion that is at odds with the rational motion, or the motion to be aimed for, described in previous studies. [ABSTRACT FROM AUTHOR]

The purpose of this study was to clarify the characteristics of twisting motion during a round-off, and its changes resulting from connection to a stretched backward somersault in gymnastics floor exercise. Eight male gymnasts performed a round-off (i.e., round-off trial) and a round-off to a backward stretched somersault (i.e., round-off somersault trial). Each of the trials was videotaped with 4 cameras operating at 120 fps to obtain 3-dimensional coordinate data. The time for a round-off, the center of mass of the hands and feet, the velocity of the center of body mass, the rotation angle about the longitudinal axis of the body (i.e., twist angle of round-off), the torsion angle of the torso, the shoulder joint angle, and the hip joint angle were calculated. The results indicated that the twist angle of round-off increased continually, starting before hand contact with the floor and ending when the hands left the floor. The round-off twist was not only generated by hip abduction at the stepping leg, but also promoted by the upward swing motion of both legs through his back side. The round-off trial temporarily formed a deeply flexed lunging position to increase the velocity of the center of body mass in the frontal direction. Also, the backward upswing of the legs rotated the lower torso, thus restraining the torso torsion. To gain the required rotational magnitude for a somersault, gymnasts flexed the hip in the air so that the feet came closer to the hand. [ABSTRACT FROM AUTHOR]

Purpose: To design an evaluation method for lumbar spine and hip joint function using dynamic radiography using a flat-panel detector (FPD) system., Method: Sixteen healthy subjects (males; age range, 22-60 years; median, 27 years) and 9 patients (7 males and 2 females; age range, 67-85 years; median, 73 years) with L4 degenerative spondylolisthesis were examined using a dynamic FPD system (CANON Inc.). Sequential images were captured with the subjects in the standing position with maximal forward bending followed by backward bending for 10 s. The lateral lumbar radiographs were obtained at 2 frames/s (fps). The flexion-extension angles of L1 and S1 were measured on those images., Results and Discussion: The range of motion (ROM) of the lumbar joints was significantly larger in the healthy group (82.4 ± 8.7°) than in the disease group (50.4 ± 8.5°; p<0.05). The ROM of the pelvic region was significantly smaller in the healthy group (26.9 ± 17.1°) than in the disease group (53.1 ± 17.6°; p<0.05). The healthy subjects exhibited a normal lumbar-pelvic rhythm. In the disease group, hip joint movements tended to be completed earlier compared with those in the healthy group. In the disease group, the loss of lumbar flexibility was compensated by an increase in hip joint motion due to the lumbar disease., Conclusion: The dynamic FPD system is a convenient imaging modality for the diagnosis of lumbar diseases through the assessment of locomotive function in the lumbar spine and hip joints.

The durability of total hip arthroplasty (THA) is affected by patient-related factors such as age, gender, body weight, disease, and bone quality, as well as the materials and design factors of the hip implants, and the surgical technique employed. Bone quality may relate to the longevity of hip implants via the risk of periprosthetic fractures, but nowadays this is not a big issue due to the advancement of materials, designs, and techniques in THA.

Evolution in surgical techniques and prosthetic designs and materials has improved durability of total hip arthroplasty (THA) . As a result, bone quality of the hip joint has become an important risk factor limiting the durability of THA. In preparation of the acetabular bony bed, the subchondral bone or eburnated bone of good bone quality should be preserved. Sockets fixed in joints with atrophic osteoarthrosis were at a higher risk for loosening than those in joints with normotrophic or hypertrophic osteoarthrosis. Femoral components set in the proximal femurs with a stovepipe canal were at a higher risk for loosening than these in the proximal femurs without. To further improve the durability of THA, the issues of poor bone quality and structure of the hip joint should be overcome.

One hundred and twenty-eight aged people were divided into four groups to elucidate the mechanism of senile spinal deformity: extended type, S-shaped type, flexed type and hand-on-the-lap type. Except for S-shaped type, the major cause of anterior stooping of the spine was lumbar disc degeneration. The paraspinal muscles prevent anterior stooping. In case the muscles cannot compensate the anterior stooping, the spine can be taken back straight by posterior pelvic tilting. Posterior pelvic tilting is obtained by extension of the hip joint and flexion of the knee joint. Knee flexion up to 25 or 30 degrees serves to correct this pelvic tilting, but can cause patellofemoral osteoarthritic changes. When the knee of an aged person exceeds this angle, the individual will assume hand-on-the-lap posture. In aged people spinal deformity is thus compensated by the lower extremity. The spine and lower extremity should be regarded as a single musculoskeletal unit.

A three-dimensional analysis of the resultant forces on the hip was carried out using a fresh cadaver of a 40 year old male. A cross sectional area of each of twenty-four muscles around the hip was measured. Markers were fixed at the proximal and the distal insertions of the muscles and the direction of muscular forces was calculated. From these data, three-dimensional resultant forces on the hip and muscular forces around the hip were calculated through the computer in the normal and the postoperative states of Salter pelvic osteotomy, Chiari pelvic osteotomy and rotational acetabular osteotomy. The results showed the resultant forces to be 3.38 times the body weight in the normal specimen, and 3.79 times for the Salter pelvic osteotomy, 2.74 times for the Chiari pelvic osteotomy, and 4.07 times for the rotational acetabular osteotomy. However, as the loaded area on the femoral head also had increased to 1.12 times for the Salter pelvic osteotomy, and 1.20 times for the rotational acetabular osteotomy, the resultant force in each square centimeter was 0.94 times for the Salter pelvic osteotomy, and 0.71 times for the rotational acetabular osteotomy.

The passive range of motion was measured in the shoulder, elbow, forearm, wrist, hip, knee and ankle joints in 624 healthy Japanese persons ranging from the neonatal to 80 years of age, by the method formally decided by the Japanese Orthopaedic Association and the Japanese Association of Rehabilitation Medicine in 1974, followed by a statistical analysis. 1. The joint motions, the range of motion value of which being remarkably different by age, were found among the movements in external rotation and horizontal abduction of the shoulder, extension, abduction, adduction, external rotation, internal rotation of the hip and dorsiflexion of the ankle. 2. Elbow flexion, forearm pronation and supination, wrist dorsiflexion and knee flexion showed little change by age. 3. Extension, external rotation and horizontal abduction of the shoulder, dorsiflexion of the wrist, flexion of the hip, flexion of the knee and dorsiflexion and plantar flexion of the ankle gave values exceeding the normal range indicated by the associations. 4. The fluctuation in the range of joint motion was especially wide in the infant and the aged person.

I measured hip abduction force using a new device of my own design and evaluated the correlation between hip abduction force and electromyographic (EMG) activity of the gluteus medius, gluteus maximus, rectus femoris and adductor longus in 20 normal adults. Hip abduction force showed a maximum value on starting and decreased during abduction of the hip joint. Durability, on the other hand, showed an increase. The attenuation curve was approximated to the exponential function A.e-Kt; A and l/k indicating maximum hip abduction force and durability, respectively. Maximum hip abduction force was about 20 kg and durability was about 160 seconds on starting hip abduction. The regression coefficient between hip abduction force and EMG activity of the gluteus medius, gluteus maximus, rectus femoris and adductor longus was 1.5, 06, 0.6 and 0.2 respectively. From these results, I concluded that although the gluteus medius plays the major role in hip abduction, the rectus femoris and gluteus maximus may act as stabilizers for maintaining the position of hip abduction.

To clarify the function of the menisci, dynamic contact pressure in femoro-tibial joints obtained from postmortem or surgical specimens with intact menisci, following partial and total meniscectomy was measured using transistor pressure transducers and Buldon tube pressure gauges. After meniscectomy, the peak contact pressure increased strikingly and contact area decreased markedly. The lower contact pressure after partial meniscectomy than after total meniscectomy is probably one reason why the results of partial meniscectomy are clinically much better than those of total meniscectomy. With flexion of the knee, the region of peak contact pressure shifted posteriorly and high contact pressure was detected below the posterior segment of the medial meniscus. Stress release in articular cartilage varies from region to region, and occurs remarkably after meniscectomy. These findings suggest that the main function of the menisci is load bearing and protection of the cartilage from overload applied to the knee joint.