Bone fractures
In normal bone,
fractures occur as a result of an abnormal load or strain to which the bone
gives way. Fractures can also occur in poor quality bones (osteoporosis). In
this case, a normal tension for a healthy bone is not supported by the diseased
bone, which breaks. In children whose bones are in development, fractures
around growth plates or bone diaphyses may occur. It is characteristic that
these diaphysis fractures result in a partial cortical rupture, similar to that
occurring when a branch of a young tree is torn off. They are therefore
referred to as 'green stem' fractures. After a fracture has occurred, the
natural response to it is the tendency to heal. A blood clot forms between the
edges of the fracture, from which new vessels develop.
A gelatinous
texture matrix is then formed, resulting in further migration of
collagen-producing cells to it. On this soft tissue infrastructure, calcium
hydroxyapatite is accumulated by the action of osteoblasts, insoluble crystals
form of it and the bone matrix is settling. As bone is generated, it is
possible to appreciate the progressive formation of a callus around the
fracture. Treatment of fractures requires a prior reduction of the fracture
line. When it cannot be kept with plaster, it is necessary to proceed to
external fixing with screws and metal rods.
Necrosis avascular
Avascular
necrosis is the cell death of the bone, induced by loss of temporary or
permanent irrigation in a bone. It can be recorded in a number of medical
conditions, some of which are not precisely known. A characteristic location of
avascular necrosis is the fracture of the neck of the femur in elderly
patients. In them there is a loss of continuity of spinal cortical blood flow,
with decreased irrigation of retinalfibers. This reduces the blood supply to
the head of the femur, in which sclerosis and collapse are recorded. In these
patients it is necessary to replace the femoral head with a prosthesis
Osteoporosis
Osteoporosis is a
disease in which bone mineral density is significantly reduced. This causes the
bone to be exposed to an increased risk of fracture. Characteristically,
osteoporotic fractures occur in the neck of the femur, vertebrae and wrist.
Although osteoporosis can occur in men, especially elderly men, typical
patients of this type of picture are postmenopausal women. Several risk factors
predispose to the development of osteoporosis. These include inadequate diet,
steroid use, tobacco use and premature ovarian insufficiency. Treatment focuses
on the correction of risk factors, improving the diet and preventing bone loss
with drug treatments (e.g. based on vitamin D and calcium supplements; new
treatments include drugs that increase bone density)
Descriptions of synovial joints based on shape and
movement
The synovial
joints are described by virtue of their shape and movement:
• Accordingtothe
shape of its joint surfaces, the synovial joints are flat,hinged (gíglims),
pivot, bicondyle (two groups of contact points), condyle ( ellipsoids),in
saddle and sphericals and glenoids.
• Intheir motion,
the synovial joints are uniaxial (motion in one plane), biaxial (movement in
two planes) and multiaxial (movement in three planes). Hinged joints are
uniaxial while spherical and glenoid joints are multiaxial.
Specific types of synovial joints
• Flat joints,
which allow sliding movements when one bone moves on the surface of another
(e.g. in the acromioclavicular joint).TheHinged joints, which allow movement
around a transverse axis to the jointorn; Body systems • Skeletal system
regulate bending and extension movements (e.g. elbow joint [humerocubital])
• Pivoting
joints, which allow movement around an axis that crosses the diaphysis of the
bone longitudinally; regulates rotation (e.g. in the
atlantoaxialjoint).TheJointsbicondyleas, which mainly allow movement around an
axis, with limited rotation around a second axis; formed by two convex condyls
that are articulated with concave or flat surfaces (e.g. on the knee).
Condyle joints
(ellipsoids), which allow movement around two axes that are at right angles to
each other; regulate bending, extension, abduction and circumference movements
(e.g. in the wrist joint).
• Saddle joints,
which allow movement around two axes that are at right angles to each other;
the joint surfaces are shaped like a saddle; regulate bending movements,
extension, abduction, adduction and circumcision (e.g. in the carpometacarpal
joint of the thumb).
•Rich, glenoid
joints, which allow movement around multiple axes; regulate bending, extension,
abduction, adduction, circumference and rotation (e.g. in the hip joint).
Fibrous joints
include sutures, gonphosis and synosmosis:
The sutures are
seen only inthe cráneo, where the adjacent bones are joined by a thin layer of
connective tissue called the suturalligament.
TheThe gonphosis sorit's sitUbetween the teeth and the adjacent bone; in these joints, short fibers of collagen tissue in the periodontal ligament run between the tooth root and the bone cavity.
TheThe gonphosis sorit's sitUbetween the teeth and the adjacent bone; in these joints, short fibers of collagen tissue in the periodontal ligament run between the tooth root and the bone cavity.
Syndesmosis are
joints in which two adjacent bones are attached by a ligament, for example, the
yellow ligament, which connects the adjacent vertebral blades, or an interseal
membrane, which joins, for example, the radius and ulna in the Forearm.
Cartilage joints include syndrosis and symphysis:
Syndrosis appears
where two osifice centersof a developingbone remain separated by a layer of
cartilage, for example, the growth cartilage between the epiphysis and the
diaphysis of the long growing bones, these joints allow bone growth and
eventually fully ossify.
Thesynfisis arise
where two separate bones are interconnected by lakecart,most of these types of
joints appear in the middle line and include pubic symphysis between the two
coxal bones and the discs intervertebrals between adjacent vertebrae.
