Biomechanics and Joint Replacement of the Shoulder and Elbow
Manoj Ramachandran, Tom Nunn in Basic Orthopaedic Sciences, 2018
The humerus is composed of the head, neck (surgical and anatomical) and the shaft. The head is superiorly inclined and eccentrically placed in relation to the shaft, with a neck–shaft angle of around 130–140° and positioned 9 mm posterior to the central shaft axis, respectively. It is retroverted by around 30° in relation to the trans-epicondylar axis. The angle of inclination, posterior offset and version must be replicated during prosthetic replacement to achieve optimal biomechanics and limit early failure.
History taking and clinical examination in musculoskeletal disease
Professor Sir Norman Williams, Professor P. Ronan O’Connell, Professor Andrew W. McCaskie in Bailey & Love's Short Practice of Surgery, 2018
The elbow is a hinge joint formed by the articulation of the ulna and radius with the humerus.
Musculoskeletal system
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha in Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
The shoulder joint is a synovial ball-and-socket joint formed between the head of the humerus and the glenoid cavity of the scapula (Fig. 3.18a). The glenoid cavity is shallow, which makes the joint unstable. It has a wide range of movements and relies on muscle support for stability. The joint capsule is lax to permit the wide range of movements available at the joint. It attaches close to the margin of the head of humerus, except inferiorly where it attaches 2–3 cm distally. The capsule is strengthened by four muscles, subscapularis, supraspinatus, infraspinatus and teres minor, which are known collectively as the rotator cuff. Subscapularis originates on the anterior aspect of the scapula and inserts into the lesser tuberosity of the humerus. Supraspinatus originates from the supraspinous fossa of the scapula and inserts into the superior aspect of the greater tuberosity of the humerus. Infraspinatus originates from the infraspinous fossa on the scapula and inserts into the middle portion of the greater tuberosity. Teres minor originates from the upper two-thirds of the axillary border of the scapula (posterior surface) and inserts into the inferior aspect of the greater tuberosity. Intrinsic features include the glenoid labrum, which is a ring of fibrocartilage attached to the periphery of the glenoid fossa to deepen the articular surface.
Experimental and simulated flexion tests of humerus
Published in International Journal of Crashworthiness, 2007
Sonia Duprey, Karine Bruyere, Jean-Pierre Verriest
To enhance car occupant protection during lateral impacts, experimental shoulder impacts have been realised. The simulation of these tests with a finite element method allows a better understanding of the shoulder response. Nevertheless, to simulate shoulder impacts, shoulder bone models have to be validated first. Thus, the aims of this study were firstly, to perform experimental dynamic tests on humerus, and then, to reproduce these tests by simulation in order to assess humerus models. Twelve humerus bones from six subjects (four males, two females, average age = 76) were submitted to flexion tests until failure. Drop tests were carried out with a 6 kg-mass at velocities from 1 to 2 m/s. Impact forces were recorded, and displacements were calculated through video analysis. Then, simulations were performed to compare humerus model responses under loading and experimental force–deflection data. Thus, this work provides experimental results that are used for the assessment of humerus models. The validated humerus bones could be integrated into global shoulder models for further applications such as simulation of car lateral impacts.
The second mamenchisaurid dinosaur from the Middle Jurassic of Eastern China
Published in Historical Biology, 2020
Xin-Xin Ren, Jian-Dong Huang, Hai-Lu You
ABSTRACT A new mamenchisaurid dinosaur, Anhuilong diboensis gen. et sp. nov. from the Middle Jurassic of Eastern China is reported here. The holotype consists of complete left humerus, ulna and radius of an individual. Comparative study and cladistic analysis shows this new taxon belongs to Mamenchisauridae and bears a unique combination of characters, such as low ratios of the average of the greatest widths of the proximal end, mid-shaft and distal end of the humerus/length of the humerus, total length of ulna to humerus and total length of radius to humerus; the lateral edge of the deltopectoral crest directs caudolaterally, the lateral accessory condyle on the craniodistal edge of humerus is more robust than the medial one, and the cross-sectional shape of the ulna at mid-shaft is elliptical with highest ratio of transverse to craniocaudal diameter among mamenchisaurids. Phylogenetically, Anhuilong is the sister taxon of Huangshanlong, and with Omeisaurus they together form the sister clade to all other members of Mamenchisauridae. Including Huangshanlong, two mamenchisaurids have been found in eastern China, and indicates that Mamenchisauridae was already a diverse sauropod clade in China by the Middle Jurassic.
Evaluation and Management of Proximal Humerus Fractures
Published in The Physician and Sportsmedicine, 2011
Jaicharan J. Iyengar, Julianne Ho, Brian T. Feeley
Fractures of the proximal humerus occur frequently, and are primarily insufficiency fractures that occur in the elderly. Thorough clinical evaluation is essential in identifying associated neurovascular injury, which warrants emergent surgical referral. Good quality radiographs remain a necessary diagnostic tool in the evaluation of proximal humerus injuries. An appreciation of the relevant anatomy and predictable patterns of deformation aid in understanding the basic classification of proximal humerus fractures. Most of these fractures are minimally displaced and can be treated nonoperatively with acceptable clinical outcomes. Familiarity with the basic surgical treatment modalities is helpful to physicians involved in the pre- and postoperative management. Significantly displaced proximal humerus fractures are typically treated with surgical reduction and internal fixation. Complex fractures in the elderly and fracture dislocations are indications for humeral head prosthetic replacement. Proximal humerus fractures are strongly associated with decreased bone mineral density and future fracture risk, and should prompt a referral for medical management of osteoporosis.