Resisted Internal Rotation with Axial Pull indicates Subscapularis RTC involvement when pain does which pattern?

• A. Pn decreases = subacromial bursa; increases or stays the same = Subscapularis RTC
• B. Pn unchanged for both
• C. Pn decreases = Subscapularis RTC; increases = subacromial bursa
• D. Pn increases = subacromial bursa; decreases = Subscapularis RTC

Answer: (C)

This test uses a combination of muscle contraction and joint compression to tell apart two common sources of shoulder pain: the subscapularis tendon and the subacromial bursa (and related impingement structures). When you resist internal rotation, you actively recruit the subscapularis. If the tendon is irritated or torn, pain will appear during that contraction.

Now add axial loading by pulling the humerus straight downward into the joint. This compression tends to aggravate subacromial impingement and the subacromial bursa because it narrows the space under the acromion where those structures glide. If the pain mainly comes from subacromial impingement, the added compression will worsen the pain.

If, during the same motion, the pain decreases with the axial pull, that points away from subacromial impingement and toward subscapularis tendon involvement as the primary source. The contraction of the subscapularis is still the driving factor, but the axial load doesn’t elicit as much pain—and may even ease it—because the pain pattern is driven by the tendon pathology rather than the compressed subacromial space.

So, a pattern where pain decreases with the axial load indicates subscapularis rotator cuff involvement, while a pattern where pain increases points to subacromial bursa or impingement as the culprit.