The patient is kept in an operating room and positioned as per the convenience of the surgeon to insert the arthroscope to get a clear view of the damaged shoulder. The two positions in which arthroscopic shoulder replacement surgery takes place are:
- Beach chair position: In this posture, the patient is made to recline in a semi-seated way.
- Lateral decubitus position: on an operating table the patient is made to lie on his or her side.
Both the positions have their own sets of unique advantages and the surgeon selects the most appropriate one depending on the surgery.
The hair from the region of that shoulder will be removed and an antiseptic may be used to wash and cleanse the area. This region will be further covered with sterile drapes and the forearms will be kept in a holding device to ensure that the arm stays in one position all the while.
In order to inflate the joint, some fluid will be injected and this will further enable the surgeon to see the shoulder structures via the instrument arthroscope. For the insertion of the arthroscope, the surgeon will make a very small puncture. Through the arthroscope, fluid is made to flow to keep the view clear and also prevent any bleeding. Damages and the inside of the shoulder images will be displayed on the screen before the surgeon to understand the next course of action.
Beginning from the top and front of the shoulder the surgeon will make a 6 inches long incision on the shoulder which shall further curve along with the deltoid muscle. The surgeon will further cut deep tissues including the rotator cuff tendons in order to penetrate till the shoulder joint.
The humeral head which is the topmost portion of the upper arm bone is gradually dislocated from the scapula’s socket or the glenoid. The area below the rounded humeral head is the humeral neck, which will now be observed by the surgeon. So as a result of arthritis some bone spurs may have developed on the humeral neck which will now be removed by the surgeon using a device called an osteotome.
With the help of a bone saw, the humeral head is removed by the surgeon. Next, the surgeon will prepare the humerus bone for the prosthetic humeral stem. This new graft or the humeral stem is narrow in shape and basically a tapering metal shaft that fits inside the humerus by several inches below. The shaft’s top is so designed so that it can house a prosthetic ball which can further replace the natural humeral head of the shoulder joint.
The surgeon prepares the shoulder socket to receive the new prosthesis by shaping and smoothing the surface with a reamer tool.
This artificial socket is made of polyethylene and the surface is a bit concave in design and smooth to aid in the movement with the prosthetic humeral head. A flat and straight-edged peg called a keel which is shaped like the keel of a boat is used to back the new socket. This keel is now made to fit the natural bone.
With the help of bone cement, the prosthetics will be made to fit the natural bone. In some cases, the arrangement can be less cement too. This bone cement does not take more than 10 minutes to set.