Review Question - QID 217843

The most common complication after anatomic total shoulder arthroplasty (aTSA) is loosening of the glenoid component and the risk for this increases with glenoid morphology abnormalities such as biconcavity and excessive retroversion.

aTSA is used to treat glenohumeral arthritis and typically leads to an improvement in shoulder pain and function. Most patients do quite well and implant longevity is thought to be >10 years in over 90% of patients. However, complications are possible and glenoid loosening is the most common of these complications. Patients who have preoperative glenoid abnormalities, such as biconcavity (Walch B2 glenoid) or excessive retroversion, are at higher risk for glenoid loosening. In order to address these bony deficits, the glenoid can be eccentrically reamed, although this can lead to excessive medialization of the glenoid which can compromise fixation. Metal augments or bone graft can also be used to supplement glenoid fixation. In cases where glenoid morphology is not able to be addressed with aTSA, rTSA may provide surgeons an additional avenue to maximize glenoid fixation.

Dillon et al. examined the outcomes of total shoulder arthroplasty in the Kaiser Permanente Shoulder Arthroplasty Registry. They looked at all kinds of shoulder arthroplasty including hemiarthroplasty, aTSA, and rTSA, noting that osteoarthritis was the most common indication for aTSA and rotator cuff arthropathy was the most common indication for rTSA. They noted that in cases of aTSA and rTSA, issues with glenoid component fixation were prevalent.

Matsen et al. looked at factors affecting length of stay (LOS), readmission and revision after shoulder arthroplasty in >17,000 primary arthroplasty cases. They noted that longer LOS was associated with female sex, older age, medicaid insurance, arthroplasty for fracture, higher hospital case volumes and lower surgeon case volumes. Revision was associated with younger age and was most commonly necessary in cases of mechanical implant complications, loosening, instability, rotator cuff tearing and infection.

Figures A & B demonstrate AP & axillary radiographs of the left shoulder showing significant glenohumeral osteoarthritis and a biconcave glenoid with posterior humeral head subluxation.

Incorrect Answers:
Answer 1: Use of a stemless humeral component would not increase the risk of glenoid loosening, the most common complication after aTSA.
Answer 2: Prior arthroscopic rotator cuff repair may raise concerns for rotator cuff integrity, although rotator cuff tear in the setting of aTSA is not as common as glenoid loosening.
Answer 3: History of diabetes may place patients at a higher risk for infection in general, but this would not increase the risk of glenoid loosening.
Answer 4: Both pegged and keeled glenoid components are acceptable for use, with some studies demonstrating no difference in glenoid loosening rates and others showing a higher rate of loosening in keeled components.