A to Z Entries
Clare E. Milner in Functional Anatomy for Sport and Exercise, 2019
The elbow consists of three joints all within the same joint capsule. The major articulation of the elbow is the hinge joint between the humerus of the upper arm and the ulna of the forearm. This ulnohumeral joint is responsible for flexion-extension of the elbow joint. Mediolateral movement at the joint is prevented by its bony structure (see planes and axes of movement). The distal end of the humerus, the trochlea, sits in the trochlear notch at the proximal end of the ulna. The second joint at the elbow is between the radius of the forearm and the humerus. This radiohumeral joint is not constrained by its bony structure. It is the articulation between the capitulum and the head of the radius. The radiohumeral joint would be susceptible to dislocation if the thick annular ligament, which forms a ring around the proximal end of the radius, was not present to stabilize it. The third joint at the elbow, the proximal radioulnar joint, between the radial head and the ulnar notch, enables pronation-supination of the forearm and, therefore, repositions the hand about the long axis of the upper limb.
Anatomy
Peter Houpt in Hand Injuries in the Emergency Department, 2023
In the forearm, the radius rotates around the ulna in the distal radio-ulnar joint (DRU joint). The carpal bones of the hand are connected through intrinsic ligaments. The external capsule of the wrist joint is located around the carpalia. Within the carpus, the proximal and distal rows of carpal bones can be distinguished. The os pisiforme is not part of the wrist joint, but acts as a fulcrum for the FCU tendon. In contrast to the fourth and fifth carpometacarpal (CMC) joints, the mobility of the second and third CMC joints is limited. The MCP and IP joints are stabilized by the volar plate and collateral ligaments. The sesamoid bones are located just volar to the MCP joint of the thumb. They sometimes can be located near other joints. The epiphyseal plate is always based proximally in the phalanges of the fingers and distally in the metacarpals, except the metacarpal of the thumb (Figure 2.8).
Radius and ulnar diaphyseal fractures
Charles M Court-Brown, Margaret M McQueen, Marc F Swiontkowski, David Ring, Susan M Friedman, Andrew D Duckworth in Musculoskeletal Trauma in the Elderly, 2016
Studies looking at angular malalignment have found that forearm rotation is limited with angulation of the ulnar or radius greater than 20 degrees.10 Restoration of the normal bow of the radius helps maintain forearm rotation and grip strength. The radial bow is assessed on an anteroposterior (AP) radiograph with the forearm in neutral rotation, the shoulder abducted 90 degrees and the elbow flexed 90 degrees. The bow is quantified by drawing a line from the radial tuberosity to the most ulnar edge of the distal radius. A perpendicular line is then drawn at the point of maximal radial bow with the length of this line then being measured (Figure 25.1).4 It can be helpful in comminuted fractures involving both bones to obtain radiographs of the uninjured forearm to help guide surgical treatment of the injured side. Determining the appropriate radial bow is essential to properly stabilizing the fracture for functional use of the extremity.
Comparison of bone microstructures via high-resolution peripheral quantitative computed tomography in patients with different stages of chronic kidney disease before and after starting hemodialysis
Published in Renal Failure, 2022
Kiyokazu Tsuji, Mineaki Kitamura, Ko Chiba, Kumiko Muta, Kazuaki Yokota, Narihiro Okazaki, Makoto Osaki, Hiroshi Mukae, Tomoya Nishino
Bone microstructures of the distal radius and tibia of the non-dominant arm and leg were evaluated using HR-pQCT (Xtreme CT II, SCANCO Medical, Brüttisellen, Switzerland). If a patient had an arteriovenous fistula on the non-dominant arm, the evaluation was performed on the dominant arm. We used the data within three months after initiation of hemodialysis in the CKD 5 D group. The radial scan site was an area of the distal radius, 10.2 mm in width, 4% of the forearm length proximal from the hand joint. Furthermore, the tibial scan site was an area of the distal tibia, 10.2 mm in width, and 7.3% of the lower leg length proximal from the talocrural joint. The scanning conditions were as follows [29–31]: voltage, 68 kVp; tube current, 1470 μA; integration time, 4.3 ms; projection number, 900; field of view, 140 mm; matrix, 2304 × 2304; voxel size, 60.7 μm; scan length, 10.2 mm; and scanning time, 120 s. The computed tomography dose index, dose length product, and effective dose were 10.8 mGy, 11.0 mGy·cm, and 5 μSv, respectively. All images were evaluated for motion artifacts, and those with artifacts grade 3 or higher were excluded [32]. The semiautomatic algorithm was used for segmentation. For the periosteum, automatic contouring was performed with almost no manual correction. For the endosteum, however, automatic contouring was often followed by manual correction.
A musculoskeletal model of the hand and wrist: model definition and evaluation
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2018
M. Mirakhorlo, N. Van Beek, M. Wesseling, H. Maas, H. E. J. Veeger, I. Jonkers
The MCP joints have two degrees of freedom, allowing for flexion–extension and abduction–adduction. The PIP and distal interphalangeal (DIP) joints have one degree of freedom (flexion–extension). The thumb carpal-metacarpal (CMC) joint is modeled as a saddle joint connecting metacarpal bones to the carpals with two degrees of freedom (flexion–extension and abduction–adduction). The carpal segment, linked to the ulna as a saddle joint, allows the flexion–extension and radial/ulnar deviation relative to the wrist. This simplified modeling of wrist, in contrast to more realistic modeling (Fischli et al. 2009; Majors and Wayne 2011) that accounts for complex kinematics of the human wrist, may affect the outcomes of the model, as elaborated in the limitation section of discussion. A joint with one degree of freedom connects the ulna and radius enabling forearm pronation/supination.
Distraction plating for bilaterally severely comminuted distal radius fracture: a case report
Published in Case Reports in Plastic Surgery and Hand Surgery, 2023
Yuta Izawa, Hiroko Murakami, Tetsuya Shirakawa, Kazuo Sato, Toshiki Yoshino, Yoshihiko Tsuchida
The goal of treating distal radius fractures is to obtain a stable and movable wrist joint. Various treatment options are available, including conservative treatment, but open reduction and internal fixation are required in cases with severe instability or high disposition. The gold standard for internal fixation is volar locking plate fixation [1,2], and fragment-specific fixation is recommended when the articular surface is severely comminuted [3,4]. However, high-energy trauma may be accompanied by severe comminution and soft tissue damage, which are difficult to treat using a traditional internal fixation strategy. In such cases, external fixation is generally regarded as the next best treatment option [5,6]. External fixation spans the wrist joint continuously to maintain alignment until bone union; however, pin site infection and inconvenience owing to the fixation apparatus that the patient has to wear are common problems with this approach. Distraction plating is a method of bridging fixation from the radial shaft to the third metacarpal bone subcutaneously on the dorsal side and is used as an alternative to external fixation [7–10]. Although there is concern that the limitation of range of motion will remain due to the fixation of the wrist joint until implant removal, it has been reported that an acceptable range of motion of the wrist joint will eventually be obtained. Herein, we report a case in which distraction plating was performed for a bilateral highly comminuted distal radius fracture, with acceptable results obtained in the wrist joint’s range of motion and function.