frozen shoulder in one's 40s; shoulder pain around age 40
Commonly used to describe shoulder pain or stiffness that appears around the age of 40, often due to aging or overuse. Similar to 五十肩 (frozen shoulder in one's 50s).
I can't lift my arm because of frozen shoulder in my 40s.
The pain from my shoulder condition is so bad I can't even sleep at night.
Compound of 四十 (forty) and 肩 (shoulder), referring to shoulder problems that commonly start around age 40.