Review Question - QID 217373

This patient has evidence of infraspinatus atrophy on pre-operative MRI. The presence of pre-operative infraspinatus atrophy has been identified as an independent risk factor for the development of post-operative superior rotator cuff tears following anatomic total shoulder arthroplasty (TSA) (Answer 5).

Anatomic TSA is an attractive surgical solution for patients with glenohumeral osteoarthritis and an intact rotator cuff. Anatomic TSA provides predictive relief of pain in well-indicated patients and demonstrates 93% survival at a ten-year follow-up. An anatomic TSA, unlike a reverse-type prosthesis, is dependent on the presence of intact rotator cuff musculature. Furthermore, secondary rotator cuff dysfunction is a common long-term complication following anatomic TSA.

Somerson et al. report on the complications following TSA. Their study includes 4063 complications split between both anatomic and reverse TSA. They note that the most common mechanisms of failure for anatomic TSAs include glenoid loosening, rotator cuff tear and/or repair failure, instability, and infection.

Young et al. investigated the rate of secondary rotator cuff dysfunction following anatomic TSA. Their study includes 518 patients with a minimum five-year follow-up. They note that the overall rate of secondary rotator cuff dysfunction was 16.8% at a mean 103.6 months follow-up, with no instances occurring before 60 months. The authors conclude that preoperative infraspinatus fatty infiltration and superior tilt of the glenoid component were risk factors for secondary rotator cuff dysfunction.

Werner et al. investigated the association between corticosteroid injection timing and the development of postoperative infection following arthroscopy or arthroplasty in Medicare patients. The arthroplasty cohort consisted of 8420 patients with both three and six-month follow-ups. The authors found that corticosteroid injection within three months of surgery was an independent risk factor for the development of post-operative infection at both three and six months post-operative.

Figure A demonstrates an AP projection of a right shoulder with complete obliteration of the glenohumeral joint space. Figure B is a select T2-weighted sagittal image of the shoulder demonstrating fatty atrophy of the infraspinatus, with a well-preserved subscapularis and supraspinatus.

Incorrect Answers
Answer 1: Acromial stress fractures are a possible complication following a reverse, not an anatomic, total shoulder arthroplasty.
Answer 2: While glenoid wear is a possibility for all TSAs, this patient's preoperative rotator cuff atrophy is an independent risk factor for the development of post-operative rotator cuff dysfunction.
Answer 3: Risk factors for post-operative infection include male gender, young age, and intraarticular corticosteroid injection within three months of surgery.
Answer 4: The patient has no pre-operative signs of subscapularis weakness, and there is no evidence of atrophy on MRI; therefore, she does not face an increased risk of post-operative subscapularis repair failure based on preoperative factors.