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Biomechanics and Joint Replacement of the Shoulder and Elbow
Published in Manoj Ramachandran, Tom Nunn, Basic Orthopaedic Sciences, 2018
Mark Falworth, Prakash Jayakumar, Simon Lambert
The ulnohumeral (ulnotrochlear) joint consists of the ulnar trochlear notch articulating with the trochlea of the distal humerus and forming a simple hinge joint. The distal humerus is angled anteriorly by 40° in relation to the humeral shaft, and recessed anteriorly and posteriorly to accommodate the coronoid and olecranon processes, respectively. This adaptation improves congruity, stability and optimizes range of movement, allowing a flexion–extension range of around 140°.
Single best answer (SBA)
Published in Tristan Barrett, Nadeem Shaida, Ashley Shaw, Adrian K. Dixon, Radiology for Undergraduate Finals and Foundation Years, 2018
Tristan Barrett, Nadeem Shaida, Ashley Shaw, Adrian K. Dixon
A 38-year-old man presents with elbow pain after a fall. AP and lateral radiographs demonstrate the presence of an 8 mm anterior fat pad and a posterior fat pad. No obvious fracture line can be identified. Which of the following is most likely? Ulna fracture.No fracture.Olecranon fracture.Radial head fracture.Humeral shaft fracture.
Distal humeral fractures
Published in Charles M Court-Brown, Margaret M McQueen, Marc F Swiontkowski, David Ring, Susan M Friedman, Andrew D Duckworth, Musculoskeletal Trauma in the Elderly, 2016
Nathan Sacevich, George S. Athwal, Graham King
The distal humerus can be considered as a divergent two column structure supporting the distal articular surface. The distal humeral shaft is triangular shaped in cross-section with its apex directed anteriorly. The medial column diverges approximately 45 degrees from the shaft in the coronal plane, whereas the lateral column diverges at approximately 20 degrees from the shaft.2 The trochlea connects the columns centrally and forms an articulation with the coronoid and olecranon facets of the ulna. The anatomy of the trochlea is analogous to that of a spool. The capitellum is the distal-most portion of the lateral column, which articulates with the radial head. The trochlea is more distal than the capitellum in the coronal plane, which results in a valgus alignment of 4–8 degrees. The distal articular segment of the humerus is internally rotated 3–8 degrees relative to the epicondyles and has 30–40 degrees of anterior angulation relative to the central axis of the humerus.12 The distal posterior portion of the lateral column is non-articular and permits distal placement of contoured posterolateral plates (Figure 23.1).
Feasibility Analysis and Clinical Applicability of a Modified Type V Resection Method for Malignant Bone Tumors of the Proximal Humerus
Published in Journal of Investigative Surgery, 2020
Qing Liu, Zhibing Dai, Junshen Wu, Suzhi Ji, Jingping Bai, Renbing Jiang
The humerus was truncated at least 5 cm away from the lesion according to the tumor-free principle; then we cut off the humeral shaft using a swing saw or wire saw. With the shoulder joint capsule exposed, we measured a distance of about 4 mm from the medial margin of the articular capsule to the basal outside lateral margin of the coracoid process. In all cases, the medial margin of the articular capsule was visually observed to be unaffected by the tumor. We performed the modified type V resection, resecting the shoulder joint outside the coracoid process, preserving the coracoid process and the coracoacromial ligament. The scapula glenoid fossa was cut at a distance 4 mm from the outside lateral margin of the coracoid process, 15° counterclockwise from the top to the bottom, and then clockwise from the bottom up, creating a nearly concave resection. We completely removed the shoulder joint (including the long-head tendon of the biceps brachii) and the humeral tumor segment.
Modeling the effects of musculoskeletal geometry on scapulohumeral muscle moment arms and lines of action
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2019
Daanish M. Mulla, Joanne N. Hodder, Monica R. Maly, James L. Lyons, Peter J. Keir
Monte Carlo simulations were performed to evaluate sensitivity of model-predicted moment arms and lines of action to muscle attachment location alterations. Univariate normal distributions were generated for each muscle’s attachment locations (Table 1). To construct these normal distributions, current model muscle attachment sites were used as the mean origin and insertion locations. Standard deviations were quantified using cadaveric data (Högfors et al. 1987), and linearly scaled to the model’s anthropometrics. Thus, six muscle input parameters were represented by normal distributions: XYZ location at either the clavicle (Cx/Cy/Cz—anterior deltoid only) or scapula (Sx/Sy/Sz), and XYZ location at the humerus (Hx/Hy/Hz). Wrapping objects were adjusted as a function of humeral attachment location. The humeral head was represented by a spherical wrapping object, with radius set as the distance between the humeral head center and the humeral attachment location of the rotator cuff muscles. A cylindrical wrapping object represented the proximal humeral shaft, with radius set as the distance between the axis and the humeral attachment of the teres major. Based on the normal distributions, each muscle’s attachment locations were randomly sampled and the muscle moment arms and lines of action were quantified. Monte Carlo simulations were run to 1000 iterations for convergence of solutions to steady state.
Prostheses for reverse total shoulder arthroplasty
Published in Expert Review of Medical Devices, 2019
Jillian M. Kazley, Keegan P. Cole, Khusboo J. Desai, Samuel Zonshayn, Andrew S. Morse, Samik Banerjee
In the second generation prostheses, the glenosphere was changed to a half sphere design to further medialize the COR. The glenoid component was changed to cementless fixation with central peg and divergent screws to counteract initial shear forces between the baseplate and glenoid surfaces. Grammont named this design ‘Delta’ due to the effective role of the deltoid for function and stabilization. Further advancements led to the current generation prostheses, Delta III prosthesis (Depuy Inc., Warsaw, Indiana), which has five components: glenoid baseplate, Co-Cr glenosphere, polyethylene humeral cup, humeral neck, and humeral stem [14]. The 36 mm and 42 mm glenospheres with 19 mm offsets are fixed to the baseplate with a Morse taper and reinforced with a central countersunk screw. The humeral neck is threaded to the humeral stem and has a lateral fin for rotational control and both the neck and stem are either polished cemented or hydroxyapatite-coated for cementless fixation [6,11,14]. The humeral component had a neck-shaft angle of 155 component to place the center of rotation (COR) inferior and increase deltoid tension. The humeral shaft was manufactured in three lengths and could be press fit or cemented. The polyethylene liner was press fit into the humeral neck sizes to match the glenosphere [7,11,14]. Boileau et al., retrospectively reviewed 45 patients with the original Delta III prosthesis, found that forward elevation improved from 51° preoperatively to 121° postoperatively and 78% of patients were satisfied or very satisfied at mean 40 month follow up [14,15]. The Delta I and II are hemiarthroplasty and total shoulder arthroplasty designs that share the same humeral stem components.