while cutting a glass tube why shoulder multiple s e a t c h e s be avoided?
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The normal shoulder is a marvel of mobility and stability. It provides more motion than any other joint in the human body. Throughout the wide range of shoulder activities, the humeral head (ball of the shoulder joint) remains precisely centered in the glenoid (the socket of the joint). One of the main stabilizing mechanisms is concavity compression. Concavity compression is the mechanism in which the head of the humerus is held into the glenoid concavity by the action of the rotator cuff (much like a golf ball is held into the concavity of a golf tee).
Figure 1 shows the humeral head, the glenoid, and one of the muscles of the rotator cuff. The concavity of the shoulder socket is deepened by a fibrous ring known as the glenoid labrum (See clip 1, glenoid labrum). The glenoid labrum greatly increases the stability of the shoulder (See clips 2 and 3, suction cup and concavity compression). Another stabilizing mechanism is ligament restraint, in which the motion of the shoulder is kept within the proper range by ligaments that span the joint (See clip 4, glenhumoral capsule).
The glenoid labrum and the ligaments can be torn when the arm is forced backwards, allowing the humeral head to dislocate from the glenoid. If the labrum and the ligaments do not heal, the shoulder may continue to be unstable, allowing the ball to slip from the center of the glenoid even with minimal force.
When recurrent shoulder dislocations or feeling of instability interfere with the comfort and security of the shoulder, a repair of the ligaments and labrum by an experienced shoulder surgeon can usually restore the stability of the joint.
The patient with an unstable shoulder requires a thorough history and physical examination along with proper x-rays.
The most common form of ligament injury is the Bankart lesion, in which the ligaments are torn from the front of the socket. A solid surgical repair requires that the torn tissue be sewn back to the rim of the socket. Failure to secure this lesion solidly can result in failure of the repair.
If the glenoid bone is deficient, the shoulder may benefit from a surgery to restore the lost bony anatomy.
Figure 1 shows the humeral head, the glenoid, and one of the muscles of the rotator cuff. The concavity of the shoulder socket is deepened by a fibrous ring known as the glenoid labrum (See clip 1, glenoid labrum). The glenoid labrum greatly increases the stability of the shoulder (See clips 2 and 3, suction cup and concavity compression). Another stabilizing mechanism is ligament restraint, in which the motion of the shoulder is kept within the proper range by ligaments that span the joint (See clip 4, glenhumoral capsule).
The glenoid labrum and the ligaments can be torn when the arm is forced backwards, allowing the humeral head to dislocate from the glenoid. If the labrum and the ligaments do not heal, the shoulder may continue to be unstable, allowing the ball to slip from the center of the glenoid even with minimal force.
When recurrent shoulder dislocations or feeling of instability interfere with the comfort and security of the shoulder, a repair of the ligaments and labrum by an experienced shoulder surgeon can usually restore the stability of the joint.
The patient with an unstable shoulder requires a thorough history and physical examination along with proper x-rays.
The most common form of ligament injury is the Bankart lesion, in which the ligaments are torn from the front of the socket. A solid surgical repair requires that the torn tissue be sewn back to the rim of the socket. Failure to secure this lesion solidly can result in failure of the repair.
If the glenoid bone is deficient, the shoulder may benefit from a surgery to restore the lost bony anatomy.
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