Total shoulder arthroplasty

Last revised by Craig Hacking on 7 Feb 2024

A standard total shoulder arthroplasty, also known as anatomic total shoulder arthroplasty or total shoulder replacement, aims to replace both the glenoid and humeral head to replicate the normal anatomic alignment of the glenohumeral joint and is the commonest form of shoulder replacement surgery.

The placing of a total shoulder arthroplasty into the approximate anatomic position is dependent on the rotator cuff muscles and the state of the in situ bony structures. Thus, a successful outcome relies upon intact rotator cuff muscles and adequate glenoid bone stock to ensure joint functionality and durability postoperatively.

Insufficiency of these structures predisposes the patient to possible hardware malpositioning, failure and prosthetic fractures. If there is preoperative concern for the integrity of any of these structures, it is wise to perform a full preoperative imaging assessment.

  • glenoid component

    • can be metal- or polyethylene-backed

    • PE is radiolucent but it has a radiopaque marker to allow postprocedure identification on imaging

  • humeral component: metal backed with a ball at the end to act as the humeral head

  • both glenoid and humeral components may be either cemented or cementless

The postoperative assessment is usually done using AP, Grashey, axillary and Y projections:

  • humeral head component must be centered within the glenoid cavity

  • humeral shaft component must be centered in the proximal humeral shaft

  • a uniform periprosthetic lucency <2 mm is acceptable

    • periprosthetic lucency is very common (up to 96%) in cemented PE pegged glenoid components 4

If there is concern for rotator cuff abnormality, MRI is recommended as subscapularis muscle insufficiency is the most common rotator cuff complication postoperatively. 

Complications tend to affect the glenoid more than the humeral component 1:

On the immediate postoperative radiographs, periprosthetic radiolucency is commonly noted, which might be related to poor cement penetration into the bone, nevertheless, the persistence of this finding on follow-up images is indicative of total shoulder arthroplasty loosening 1.

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