This study will look at patient radiographic and functional outcomes who have or will undergo a reverse, extended peg, shoulder arthroplasty (replacement) that requires the use of glenoid bone grafting.

Glenoid bone loss is a known issue with reverse shoulder implants and can lead to issues with implant fixation and stability over time. To address this issue an extended peg glenoid baseplate is used and area around plate is augmented with bone (auto or allo)graft material to encourage bony callous growth around the implant. This study is to look at this area of concern and determine if glenoid bone loss is occurring in the patients where these measures have been taken to deter its development.

Inclusion Criteria:

1. Adult patients who have undergone a reverse shoulder arthroplasty with the an extended peg baseplate and structural bone graft (autograft humeral head or allograft femoral head).
2. Adult patients who are indicated for a long-pegged baseplate and glenoid bone grafting (autograft humeral head or allograft femoral head) as part of their reverse shoulder arthroplasty in our clinic,
3. bone graft is truly structural involving at least 50% of the glenoid baseplate
4. may be a primary or a revision surgery

Exclusion Criteria:

1. patients with missing baseline (preop) data,
2. patients who are unwilling to participate in a final follow-up evaluation.

Patients with substantial glenoid bone loss in the context of severe glenohumeral arthrosis, advanced cuff tear arthropathy or those who have undergone prior shoulder arthroplasty and have or will undergo a reverse shoulder replacement with structural bone graft to address the problem.