Evaluating the integrity of the subscapularis: it can be difficult.

Correlation between preoperative clinical examination and intraoperatively found subscapularis tendon tear

These authors sought to analyze the diagnostic value for subscapularis (SSC) tendon tears, their correlation between pain and strength on clinical tests, and compare them with intraoperative arthroscopic findings to assess their diagnostic value.

They studied 110 consecutive patients undergoing arthroscopic rotator cuff repair, identifying those with isolated subscapularis (SSC) tendon tears (n = 39) and combined anterosuperior tendon tear (n = 71). Preoperative clinical testing included assessment of pain and weakness on the  belly press (BPT), bear hug (BHT), lift-off (LOT), palm-up (PUT), and Jobe tests (JT). 

The results for the subscapularis tears are shown below.

However the same tests were not uncommonly positive in tears of the supraspinatus as shown below.

Comment: This study touches on the complexity of evaluating the subscapularis in patients who have not had an arthroplasty. The situation in patients post arthroplasty is much more complex. 

Here's an example of a patient who prematurely started external rotation strengthening after an anatomic arthroplasty with resulting increase in passive external rotation from 20 degrees at surgery to 90 degrees and feelings of instability in the area indicated. Even without imaging, the diagnosis of subscapularis failure seems very likely.

In another patient the arm was forcefully externally rotated to 90 degrees at two weeks after arthroplasty. An ultrasound was interpreted as showing an intact subscapularis. However, because of the history, sudden increase in pain and increased swelling and tenderness at the anterior shoulder the shoulder was explored revealing a completely torn subcapularis which was re-repaired. During the rehabilitation from the second surgery the patient became concerned that the tendon had torn again because of increased pain. An MRI was obtained and interpreted as showing a complete retear. 

Again the shoulder was explored. At surgery the re-repair was seen to be solidly intact as seen between the two elevators below.

All this is to demonstrate that the evaluation of the subscapularis, especially after an arthroplasty can be tricky.  Sometimes it may be necessary - especially when injury occurs soon after surgery - to open up the wound and take a look (no matter what imaging shows). 

For more on the subscapularis see this link: Subscapularis and shoulder arthroplasty: repair, failure and reconstruction

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Here are some videos that are of shoulder interest

Shoulder arthritis - what you need to know (see this link)

Shoulder arthritis - x-ray appearance (see this link)

The smooth and move for irreparable cuff tears (see this link)

The total shoulder arthroplasty (see this link).

The ream and run technique is shown in this link.

The cuff tear arthropathy arthroplasty (see this link).

The reverse total shoulder arthroplasty (see this link).