China 
Africa 
Explore chapters and articles related to this topic
The Anatomy of Joints Related to Function
Published in Verna Wright, Eric L. Radin, Mechanics of Human Joints, 2020
Rotation of the head to left and right is achieved by a very elegant mechanism involving the atlantooccipital and atlantoaxial joints. The vulnerability of the spinal cord to mechanical trauma makes it of paramount importance that the range and direction of these movements be rigorously controlled. In particular, the dens of the axis must be absolutely secure. This is achieved at the atlantoaxial joint by its firm enclosure within the fibroosseous ring formed by the anterior arch of the atlas and its transverse ligament. This in itself is a very stable arrangement (133,134) and determines that the axis of rotation at the atlantoaxial joint is approximately vertical, passing through the dens (135,136).
Atlantoaxial instability
Published in Benjamin Joseph, Selvadurai Nayagam, Randall Loder, Ian Torode, Paediatric Orthopaedics, 2016
Children with a Grisel’s syndrome should be treated as an emergency with stabilisation using a halo and traction under close observation. The definitive treatment is a posterior fusion of C1 and C2. If there is an accompanying myelopathy careful documentation is required followed by an attempted reduction. The best decompression is by reduction of the subluxation or dislocation. It may be necessary to perform an open reduction by a lateral approach to the atlantoaxial joint.10 An alternative approach is by anterior transoral release of the dislocated and fixed atlantoaxial joint followed by posterior fixation and fusion of C1 and C2.11
The movement systems: skeletal and muscular
Published in Nick Draper, Helen Marshall, Exercise Physiology, 2014
The different types of synovial joint are shown in Figure 5.6. Gliding joints, such as between the vertebrae in the spine or the sternoclavicular joint as illustrated, are formed when the flat surfaces of bones come together. The amount of movement in a gliding joint is minimal. The elbow, knee and ankle are examples of hinge joints that enable flexion and extension of the arm and leg along with dorsiflexion and plantar flexion of the foot. The atlanto-axial joint in the spine is an example of a pivot joint which enables the head to rotate and is formed between the odontoid peg or dens of the axis bone and the ring of the atlas. An example of ellipsoid or condyloid joints can be found between the arm and hand at the wrist which are called the radiocarpal joints. The wrist enables movement in two planes and is formed where a convex surface fits in to a concave surface.
Bow hunter’s syndrome after cervical laminoplasty in a patient with rheumatoid arthritis with bony ankylosis in the cervical spine: a case report
Published in Modern Rheumatology Case Reports, 2020
Sho Dohzono, Ryuichi Sasaoka, Kiyohito Takamatsu, Hiroaki Nakamura
Cervical laminoplasty for patients with cervical bony ankyloses can led to rotational spinal instability. RA often affects the cervical spine, as well as the hand and wrist joints, and the prevalence of bony ankyloses of the cervical spine is reportedly 9–26% [8–10]. Biomechanically, the atlantoaxial joint is the most rotatable joint in the cervical spine, with a normal range of rotation of 40–45° [20,21]. The present patient had bony ankyloses at the atlantoaxial joint and the C4–C5 facet joints before laminoplasty, and the C3 vertebral posterior slippage deteriorated and osteosclerosis appeared at the C3–C4 vertebrae after laminoplasty. Therefore, rotational mechanical stress on the C3 vertebra, which was the segment adjacent to the ankylosed joints, may increase after cervical laminectomy at C3 with C4–C7 laminoplasty.
Unilateral lag screw fixation of isolated non-union atlas lateral mass fracture: a new technical note
Published in British Journal of Neurosurgery, 2019
Majid Reza Farrokhi, Arash Kiani, Hamid Rezaei
Atlas fractures are usually stable which can also be unstable if they are associated with atlantoaxial ligamentous complex injury that may necessitate surgical intervention. Various conditions such as trauma, arthritis, infection or congenital malformations could make the atlantoaxial joint unstable.11,13 If cervical spinal column injuries are treated improperly, they could cause chronic pain, limitation of motion and even cervical cord injuries resulting in severe neurological impairment. The lateral mass screw fixation of atlas is a well-known described technique.19,20 This procedure is usually being performed bilaterally in combination with C2 pedicular screw fixation,21 resulting in favorable fusion outcomes. There are no reports of unilateral lag screw fixation of atlas lateral mass fracture in the literature. In this report, we successfully fixed the lateral mass fracture of atlas via a single lag screw using standard posterior approach. An important point in this study was that the distance between the fracture’s edges was significant and thus spontaneous healing and fusion could not be achieved even after immobilization. Using a lag screw provided us with the ability to successfully reduce and approximate the fracture’s edges. Considering the large fracture gap, the screw had to be inserted in full length so that the gap could be totally reduced that caused 3 mm extrusion of the screw’s tip from the anterior border of atlas.
Validity of eyeball estimation for range of motion during the cervical flexion rotation test compared to an ultrasound-based movement analysis system
Published in Physiotherapy Theory and Practice, 2018
Axel Schäfer, Kerstin Lüdtke, Franziska Breuel, Nikolas Gerloff, Maren Knust, Christian Kollitsch, Alex Laukart, Laura Matej, Antje Müller, Thomas Schöttker-Königer, Toby Hall
One method of measuring upper cervical movement impairment is the cervical flexion-rotation test (FRT) (Takasaki et al, 2011). In this procedure, the cervical spine is placed in end-range flexion and passive rotation to each side is measured. It is postulated that rotation in end-range cervical flexion occurs predominantly at the atlanto-axial joint (C1-C2) (Hall and Robinson, 2004; Ogince, Hall, Robinson, and Blackmore, 2007; Takasaki et al, 2011). If a firm resistance is encountered, pain provoked, and range is limited before the expected end range, then the test is considered positive. Normal range of motion is approximately 44° to both sides (Hall and Robinson, 2004). Range of motion less than 34° to one side is rated as abnormal based on ROC analysis in various studies (Hall, Briffa, and Hopper, 2010; Hall, Briffa, Hopper, and Robinson, 2010a, 2010b; Ogince, Hall, Robinson, and Blackmore, 2007).