Shoulder is a "ball-and-socket" joint. A "ball" at the top of the upper arm bone (the
humerus) fits neatly into a "socket," called the glenoid, which is part of the shoulder blade (scapula).
The cartilage cushions the joint, and allows the bones to move on each other with smooth movements. This cartilage does not show up on X-ray, therefore you can see a "joint space" between the head of the upper arm bone (humerus) and glenoid socket of the shoulder blade (scapula).
Three bones, the collarbone (clavicle), the shoulder blade (scapula), and the upper arm bone (humerus) come together to form the shoulder joint.
Humerus: Provides attachment to muscles of the upper arm. The humeral head forms the ball of the ball-and-socket shoulder joint.
Scapula: Scapula (shoulder blade) is a flat, triangular bone providing attachment to the muscles of back and neck.
Clavicle: The clavicle is an S-shaped bone that connects the shoulder girdle to the trunk. It maintains the shoulder in a functional position with the axial skeleton and allows varied arm positions in sports. In addition to its structural function, the clavicle protects major underlying nerves and blood vessels as they pass from the neck to the axilla.
Coracoid Process: The coracoid process is the extension around the shoulder joint at the front.
Acromion: The acromion is the extension of scapula (shoulder blade) around the shoulder joint at the rear to from a roof. This is also called the acromial process.
Glenoid: Glenoid is the depression at the end of scapula that forms the socket of ball-and-socket shoulder joint.
Arthritis is a general term covering numerous conditions where the joint surfaces (cartilage) wear out. The joint surface is covered by a smooth articular surface that allows pain free movement in the joint. This surface can wear out for a number of reasons, often the definite cause is not known. When the articular cartilage wears out, the bone ends rub on one another and cause pain. There are numerous conditions that can cause arthritis and often the exact cause is never known. In general, but not always it affects people as they get older (Osteoarthritis).
Arthritis – Other causes include:
The combinations of these factors make the arthritic shoulder stiff and limit activities due to pain or fatigue.
The surgery is performed under sterile conditions in the operating room under spinal or general anesthesia. An incision is made over the affected shoulder to expose the shoulder joint. The upper arm bone (Humerus) is separated from the glenoid socket of the shoulder blade (Scapula). The humeral head which is arthritic is cut off. The surgeon concentrates on the glenoid (socket). The arthritic part of the socket is removed and prepared to take the glenoid component. The glenoid component is then pressed into the socket. The upper arm bone is prepared to take the new humeral component. The humeral component is then inserted into the upper arm bone. This may be press fit relying on the bone to grow into it or cemented depending on a number of factors such as bone quality and surgeon’s preference. The humeral head component is then placed on the humeral stem. This component is made of metal. The artificial components are fixed in place. The Joint capsule is stitched together. The muscle and tendons are then repaired and the skin is closed.
As with any major surgery there are potential risks involved. The decision to proceed with the surgery is made because the advantages of surgery outweigh the potential disadvantages. It is important that you are informed of these risks before the surgery takes place. Complications can be medical (general) or specific to the shoulder Medical complications include those of the anesthetic and your general wellbeing. Almost any medical condition can occur so this list is not complete. Complications include