Following the same theme, why does someone need a Reverse total shoulder replacement surgery instead of just the more conventional total shoulder replacement surgery?
The shoulder joint is stabilized and held in place by the rotator cuff. The upper arm, the humerus, is not afixed to the socket. They fit together but are held in place by an intact rotator cuff. In the conventional total shoulder replacement surgery the upper humerus is replaced with a prosthetic metal humerus and the socket is replaced with a polyethylene socket but they are positioned in the same arrangement as the natural elements of the joint. They are dependent on an intact rotator cuff to hold the two parts together.
When the rotator cuff is torn such that it will no longer hold the joint together properly, the top of
the head of the humerus tends to drift upward. As the humerus shifts, it allows the deltoid muscle to go slack. A slack muscle is ineffective in moving or raising the limb. With a torn rotator cuff and a slack deltoid muscle the patient is unable to lift their arm. Replacing the humerus and the socket would not change this.
Reversing the position of the head of the humerus and the shoulder socket allows the muscles of the upper arm and shoulder to squeeze or compress the parts together. They are no longer dependent on the rotator cuff alone. Gravity and time encourage the parts to stay in place. The deltoid muscle is attached to the humerus surgically and becomes the main element in raising the arm. It works!
The road to recovery is a long one. Very conservative physical therapy keeps the joint mobile without risking a dislocation while the muscles recover and knit into the joint. You have to be a patient patient!
The shoulder joint is stabilized and held in place by the rotator cuff. The upper arm, the humerus, is not afixed to the socket. They fit together but are held in place by an intact rotator cuff. In the conventional total shoulder replacement surgery the upper humerus is replaced with a prosthetic metal humerus and the socket is replaced with a polyethylene socket but they are positioned in the same arrangement as the natural elements of the joint. They are dependent on an intact rotator cuff to hold the two parts together.
When the rotator cuff is torn such that it will no longer hold the joint together properly, the top of
the head of the humerus tends to drift upward. As the humerus shifts, it allows the deltoid muscle to go slack. A slack muscle is ineffective in moving or raising the limb. With a torn rotator cuff and a slack deltoid muscle the patient is unable to lift their arm. Replacing the humerus and the socket would not change this.
Reversing the position of the head of the humerus and the shoulder socket allows the muscles of the upper arm and shoulder to squeeze or compress the parts together. They are no longer dependent on the rotator cuff alone. Gravity and time encourage the parts to stay in place. The deltoid muscle is attached to the humerus surgically and becomes the main element in raising the arm. It works!
The road to recovery is a long one. Very conservative physical therapy keeps the joint mobile without risking a dislocation while the muscles recover and knit into the joint. You have to be a patient patient!
Thank you for a very clear and very helpful explanation.
ReplyDeleteAlways nice to see a note from P.B.
ReplyDelete