Q: Is it possible to have a rotator cuff strain that is not a rotator cuff tear?
A: When it comes to injuries of the rotator cuff, there are actually three possibilities. There can be a strain, muscle tear (partial or full-thickness), and degenerative defects.
A rotator cuff strain has been defined as an intact rotator cuff (no tear) but with edema (swelling) and bone bruises where the rotator cuff attaches to the bone. These are tissue changes that have been observed with MRIs.
Traumatic injury resulting in an acute tear of one or more tendons of the rotator cuff can also be seen on MRIs. Left unrepaired (surgically), the tear or "defect" fills in with fat and scar tissue. This process is called fatty infiltration and granulation.
The third condition, degeneration, is seen more often in older adults. There isn't an inflammatory process like we would normally see with an acute injury. The cells that make up the collagen matrix (basic structure) of the rotator cuff are altered.
As a result, the body's effort to repair and remodel degenerating or defective tissue is unbalanced. The natural break down of tissue occurs without an equal amount of repair and remodeling.
This ongoing process of unbalanced degeneration, repair, and remodeling results in a rotator cuff defect that is referred to as a tendinopathy. The literal translation of tendinopathy is "pathology (disease) of the tendon". The result can be a tearing of the rotator cuff tendon with no trauma or only minor trauma in the older adult.
Studies show that defects in the rotator cuff occur more often than we thought. Up to half of all adults over the age of 70 may have unknown rotator cuff defects. Because many people are asymptomatic (no symptoms and especially no pain), the presence of rotator cuff disease goes unnoticed. Why some people have symptoms while others do not (with equal rotator cuff disease) remains a mystery.
Reference: Neal C. Chen, MD, Asheesh Bedi, MD. Rotator Cuff Defect: Acute or Chronic? In The Journal of Hand Surgery. March 2011. Vol. 36A. No. 3. Pp. 513-516.