patient has received an aequalis® resurfacing head implant as per the manufacturer's instructions (including the recommended indication): degenerative indication such as primary osteoarthritis, secondary osteoarthritis (post-traumatic post instability), avascular osteonecrosis of the humeral head ;

with a functional rotator cuff ;

has clinical and radiographic follow-up data available ;

is informed about the study and has provided informed consent as applicable.

patient with proximal humeral fracture,

previous history of infection,

rotator cuff tear, cuff tear arthropathy,

significant bone loss of the glenoid (more than 25% of the articular surface),

nerve palsy,

revision arthroplasty.