Shoulder is an important joint in the human body that helps in mobility. Any small damage to the shoulder joint can critically affect the day to day functioning of an individual. The ball and socket joint in the shoulder makes it prone to overuse and if not taken care of, can lead to adverse consequences.
The shoulder joint is a ball and socket joint. This ball and socket system is what helps the arm move up and down or in a circular motion. Any injury to the bone like fracture, osteoarthritis, osteonecrosis, rheumatoid arthritis and other inflammatory disorders or torn rotator cuff leads to a situation where shoulder replacement is advised by the doctor. More often the injury occurs to ligaments, tendons or cartilage. In situations where severe pain is accompanied by difficulty in using the arm that restricts the normal routine motion, replacement of the shoulder is recommended.
Types of shoulder replacement surgeries
- Anatomic total shoulder replacement-
- Reverse total shoulder replacement
- Partial shoulder replacement
In total shoulder replacement procedure both the ball and socket are replaced. The ball is replaced with a metal ball and the socket covered by a plastic surface.
When the rotator cuff is totally and severely damaged a reverse replacement is preferred where the ball is attached to the shoulder blade and socket to the upper arm bone (humerus).
As the name suggests the replacement is partial where only the ball of the joint is replaced.
In the total shoulder replacement surgery, the doctor makes an incision at the top and front part of the shoulder running along the deltoid muscle. To enter the shoulder joint, the surgeon cuts deeper into the tissue. The humeral head or the upper arm bone is dislocated from the socket and using a bone saw the humeral head is removed. A prosthesis is then placed in humerus using bone cement or cementless process. Once the stem is in place, the prosthetic ball is attached to the top portion.
In reverse shoulder replacement, the structure of the ball and socket is reversed. An artificial ball is placed on the shoulder blade, and the artificial socket is attached to the top of the humerus bone.
Cemented and Cementless procedure
The prosthesis is fixed in place by two methods: cemented and uncemented.
In cemented method, a fast-drying adhesive part is used to fix prosthesis to the bone.
In uncemented method, which is also called press-fit prosthesis, the prosthetic is placed in such a way that over time the bone grows and integrates with prosthesis.
Hybrid method is where a combination of cemented and the uncemented prosthesis is used.
An acrylic polymer known as poly methyl methacrylate ( PMMA) is used between the prosthetic part and joint to affix the component in place in the cemented method. This dries within 10 -15 minutes. The disadvantage of this method is that over some time the cement may deteriorate and break off, which may cause inflammation.
In uncemented option, the natural bone grows into the prosthesis and offers long term and stronger bond. The press-fit prosthesis can be used only on patients with healthy bones with high density. The natural growth takes up to three to four months.
Risks or complications in shoulder replacement surgeries
- Infection or bleeding in the joint.
- Dislocation, where the ball in the new joint may come out.
- Rotator cuff injuries or damage to the rotator cuff may be seen in some cases.
- Fracture to the bone due to the low bone density of the patient is a possibility
The potential complications are:
After the surgery, the patient will be shifted to a recovery or observation room & vitals of the patient are monitored. In cases of any rare complications, the patient would have to stay under observation for two days. The patient would have to take the support of the immobilizer for some days.
The patient will be administered short-term medications for pain relief. The stitches will be removed after 14 days post-surgery. The patient will be able to resume daily activities within 3 to 6 weeks after surgery. Mild exercises are advised for the healing and healthy functioning of the joint.