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The Hip Joint and Total Hip Replacement
Published in S. M. Sapuan, Y. Nukman, N. A. Abu Osman, R. A. Ilyas, Composites in Biomedical Applications, 2020
N. A. Abu Osman, A. Ataollahi, S. M. Sapuan, Y. Nukman, R. A. Ilyas
This chapter presents a brief on hip joint and total hip replacement (THR). The hip joint is composed of soft and hard tissues. A joint comprises the femoral head, acetabulum, cartilage, and ligaments (Figure 1.1). The hip joint is classified as a ball-and-socket joint (Polkowski & Clohisy, 2010). The ball-and-socket joint provides three rotational movements, namely, flexion–extension, abduction–adduction, and internal–external rotation. The femoral head is connected to the femur via the femoral neck. The cartilage supplies a frictionless joint. The stability of the hip joint is supplied by the ligaments and muscles. This structure provides optimal stability for the stance and bipedal locomotion, but the hip joint endures complex dynamic and static loads (Bowman Jr et al., 2010).
Factors Affecting Mirror Performance
Published in Paul Yoder, Daniel Vukobratovich, Opto-Mechanical Systems Design, 2017
The unit moment analysis is used as a guide for design of the mirror mount. For a semikinematic hard mount of the kind used for diamond turning a metal mirror, the unit moment analysis determines the flatness and parallelism of both mounting and mirror interfaces. For this type of mount, an additional analysis is necessary. It relates the local tilt of the mounting surface to the induced moments in the mirror. The need to reduce moments induced in the mirror by the mount normally requires additional degrees of freedom in rotation between mirror and mount. Additional degrees of freedom can be added using a ball-and-socket joint, which is stiff in translation, or with a flexural two-axis gimbal. Contact stress and friction are issues in a ball-and-socket joint. As indicated in Chapter 10 of Volume 1, a flexural two-axis gimbal is often challenging to design and fabricate.
Natural Flight
Published in Malcolm S. Gordon, Reinhard Blickhan, John O. Dabiri, John J. Videler, Animal Locomotion, 2017
The shoulder joint is an approximate ball and socket joint. It faces laterally and allows the wing large up and down and fore and backward movements as well as some rotation around the length axis. The wing is supported by the humerus, the radius, and ulna and by the skeleton of the hand. The radius and ulna articulate with the humerus at the elbow and with two carpal bones (the radiale and ulnare) in the wrist joint. The wrist is a double joint, where the carpal bones articulate with the carpometacarpus (fused carpals and metacarpals) of the hand skeleton as well. Birds usually only have three digits with one or two phalanges each. The first digit forms the skeleton of the alula or bastard wing. The elbow and wrist joints allow the wing to stretch and fold. Stretching tightens two skin folds, the propatagium between the wrist and the shoulder joint and the metapatagium connecting the elbow with the trunk. The proximal condyle of the humerus articulates with the ends of the scapula and the coracoid. The coracoid is connected to the sternum, and its length fixes the distance with the shoulder joint and counteracts the pulling forces of the main flight muscles. The sternum carries a central bony keel, the carina. Ribs, vertebral column, and sternum form a closed cage. The main flight muscles, the pectoralis and the supracoracoideus, originate on the sternum, the carina, and the coracoid. The main downstroke muscle, the pectoralis, inserts from below on an anterior crest on the humerus. It pulls the wing down and causes forward rotation (pronation) of the wing during the downstroke. The main upstroke muscle, the supracoracoideus, is situated underneath the pectoralis and forms a tendon that passes through the triosseal canal in the shoulder joint to insert from above on the upper part of the humerus. Its action lifts the wing and causes rearward rotation (supination). The canal acts as a pulley for the tendon.
Evolution of different designs and wear studies in total hip prosthesis using finite element analysis: A review
Published in Cogent Engineering, 2022
Chethan K N, Shyamasunder Bhat N, Mohammad Zuber, Satish Shenoy B
Usually, the average male femur is about 480 mm in length with a diameter of 23.4 mm (Nakabayashi et al., 1994; Chethan, Bhat et al., 2019; Portigliatti-Barbos et al., 1987). The hip joint is a classic example of a ball and socket joint where the head of the femur articulates in the acetabulum of the pelvis. The head of the femur and acetabulum are covered by a 63.5 mm thick shiny white hyaline which acts as a smooth cushion to the joint (Chethan, Shyamasunder Bhat et al., 2019). This joint has synovial fluid articulated in the mating surface which allows the joint to flex under different pressures without causing wear and tear. The synovial fluid and the hyaline help the bones move each other at different degrees of freedom without causing pain to the human.