It is through several mechanisms that torn rotator cuff tendons get to a stage of being irreparable. An irreparable tear is not the same as a massive tear though it is often confused with each other. The key difference is that an irreparable rotator cuff tear can be massive but all massive tears aren’t necessarily irreparable. In the case of irreparable tears, the tendon tissue will first become weak and thin and easily torn when repair is attempted and following this stage atrophy sets in the muscle to which the tendon is attached.
The muscle ultimately turns fibrotic and infiltrated with fat, making joint movement excruciatingly tougher. Based on their size, retraction, and muscle impairment caused by atrophy and fatty infiltration, the lesions will then be categorized as irreparable. Like everywhere else in our body, muscles and tendons need to work against resistance to maintain strength and form. The muscles and tendons atrophy when this resistance is lacking. This will consequently make the tendon get thinner and weaker and shorter even thereby enlarging the tear even further.