Shoulder replacement and osteoarthritis

Shoulder replacement: the osteoarthritis treatment

Shoulder osteoarthritis or « Omarthrosis » is due to a gradual break down of the cartilage that covers the head of the humerus (upper arm bone) and the glenoid (part of the scapula which articulates with the humerus); it is one of the major reasons to opt for a shoulder replacement
The bone surfaces then come into contact resulting in a « friction » of the joint causing pain and / or stiffness.
Osteoarthritis can be primitive as in the hip and knee, i.e. without any obvious cause detected. This is the most common.
It may be also known as secondary due to local pathologies (massive rupture of the rotator cuff +++, necrosis of the humeral head, after-effects of fractures or too numerous dislocations…) or general pathologies (rheumatoid arthritis …)
For the surgeon to decide with his patient whether to carry out a shoulder replacement, there must be both prolonged pain and / or functional discomfort which is resistant to the various medical treatments prescribed as well as x-rays or scans confirming the patient’s advanced and degenerative deterioration of the shoulder.
Before surgery and in order to determine the condition of the bone, tendon and muscle, the surgeon will require a thorough imaging evaluation of the shoulder either by arthrogram, scan or MRI.

A total shoulder replacement allows to replace the joint of the ailing shoulder by an artificial joint made up of two parts, a metal part implanted in the humerus which articulates with a part attached to the shoulder blade.
There are two main types of total shoulder replacements:
- The anatomic total shoulder replacement whose principle is to restore a shoulder normal anatomy: the humerus ends in a ball and the glenoid is fitted with a concave cup, as is the case in a “normal” joint. “The ball is at the upper end of the humerus”.
- The reverse total shoulder replacement has an « inverted » design: the implant on the glenoid is a half-sphere and the implant in the humerus ends in a concave cup. « The ball is on the side of the scapula. » This is a French invention and concept developed by Pr Grammont.
To be functional, the total reverse shoulder replacement needs to rely on a core muscle: the deltoid muscle (muscle of the shoulder girdle). It can therefore be fitted in the absence of the rotator cuff tendons essential for the work of an anatomic total shoulder replacement or in the case of major modifications of the shoulder architecture.

The length of hospital stay is usually 3 to 5 days.
After surgery the shoulder is immobilized by a splint holding the arm against the thorax with elbow flexed. Immobilization length is 4 weeks.
Rehabilitation begins the day after the procedure during hospitalization and continues in a physiotherapy rehabilitation centre or at home with the help of a specialized masseur – physiotherapist. The recovery period following total shoulder replacement is from 3 to 6 months. The functional result cannot be evaluated before the end of this period.
Driving is permitted between the 2^nd and 3^rd month after surgery and gardening activities around the 6th month. Return to sports activities should be discussed with the surgeon on a case by case basis.

Concerning anatomic shoulder replacements:
- On the humerus : Increasing use of prostheses sparing the bone stock of the humerus: resurfacing of the humeral head, corolla or short metaphyseal stem (Photo)
- On the glenoid : Improved anchorage to the bone of the very hard polyethylene implant with new fixing systems requiring little cement.
Concerning reversed prostheses, the very concept of inverted drawing has been one of the greatest advances in prosthetic shoulder surgery over the last twenty years.