It allows the
humeral head to fit more securely into the glenoid socket as well as permit the shoulder to have a wide range of motion.
The shape of the glenoid cavity and the glenoid labrum determines the most remarkable feature of the gleno-humeral joint as they precisely stabilizes the
humeral head in the center of the cavity as well as allowing a vast range of movements (15).
The term glenohumeral instability refers to the condition of pathologic excessive translation of the
humeral head on the articular surface of the glenoid.
The resulting dislocation is nearly always an anterior dislocation, in which the
humeral head moves out the shoulder socket to the front of the body.
Fullness in the posterior region of the shoulder joint is decreased, and the
humeral head cannot be felt by palpating the posterior edge of the acromion.
Neck-shaft angle (NSA) was measured as an indication of displacement of the
humeral head [Figure 1].[18] The change of the NSA from immediate postoperative radiographs to final follow-up was calculated.{Figure 1}
An x-ray of the right shoulder was obtained, which showed evidence of osteopenia and an erosion in the
humeral head (FIGURES 1A and 1B).
The mechanism of AHD narrowing due to the ascension of
humeral head is still not precisely known.
According to the company, the Sidus Stem-Free Shoulder system is a total shoulder arthroplasty solution for patients with good bone stock that have either osteoarthritis, post-traumatic arthrosis, focal avascular necrosis of the
humeral head or who had previous surgeries of the shoulder that do not compromise the fixation.
Strong nonabsorbable sutures are placed in the rotator cuff at the bone-tendon junction for facilitating
humeral head and tuberosities reduction.
The acromiohumeral interval is measured to be 8 mm without signs of superior migration of the
humeral head.