Background

Determining the risk and rate of rotator cuff tear progression is important for formulating appropriate surgical indications.  There are many studies that report the prevalence of asymptomatic rotator cuff tears. One study, in 2015, was able to determine the natural history of degenerative rotator cuff tears over time.  That study is reviewed and summarized in this monograph.

The indications for surgical treatment of rotator cuff tears may vary.  Early surgical intervention for painful rotator cuff tears is intended to prevent the tear enlargement and muscle degeneration that can occur with nonoperative treatment as well as the diminished potential for tendon healing with delayed surgery.  An understanding of the natural history of rotator cuff disease can increase the ability to identify patients and shoulders at risk for tear progression and refine surgical indications. Patients can also be more effectively counseled regarding the potential risks of nonoperative treatment.

Asymptomatic degenerative rotator cuff tears are ideal for studying the natural history of rotator cuff disease.  This study looks at the risk of symptom development, tear size progression, and muscle degeneration in patients with an asymptomatic rotator cuff tear and analyze the factors associated with these changes.

Methods

All patients underwent a standardized shoulder ultrasound evaluation.  The dimensions of the rotator cuff tear were documented. The maximum degree of retraction of the rotator cuff was noted.

Tear enlargement was determined on the basis of sequential annual ultrasound evaluations of the rotator cuff tear.  A full-thickness cuff tear was considered to have enlarged if it sized increased by over 5 mm in any dimension compared with the baseline.  Once a tear was confirmed to have increased in size, the new tear size was set as the new baseline for future comparisons. A partial-thickness tear was considered to have enlarged when it had converted to a full-thickness defect defined as a complete disruption of the tendon continuity from the bone.

Individuals with normal rotator cuffs were also included in the study and an enlargement or development of a tear was noted when a partial or full-thickness defect of at least 5 mm was noted on the ultrasound.  Normal patients, called the control group, are always included in these types of studies to see how many individuals with a normal rotator cuff would have developed a tear over the timeframe of the study. This helps the office determine whether or not the presence of rotator cuff tear puts in individual at risk for progression of that tear compared to a normal tendon.

The study evaluated 224 subjects.  53% had a full-thickness tear, 25% had a partial-thickness tear and 22% had a normal rotator cuff.  The age and sex distributions were similar in all categories. Full-thickness rotator cuff tears were typically significantly larger than partial-thickness tears.  A greater proportion of full-thickness tears were associated with degenerative changes in the rotator cuff muscle of the supraspinatus and infraspinatus tendons. These are the two most commonly torn tendons of the rotator cuff. The median duration of follow-up was 5.1 years.

Results

Tear progression was seen in 49% of the shoulders in 2.8 years.  The risk of tear enlargement was significantly influenced by the severity of the rotator cuff tear pattern.  There were tear enlargement rates of 61% in full-thickness rotator cuff tears. Of the partial-thickness rotator cuff tears, 44% progressed over time and only 14% of individuals with normal rotator cuff tears developed tears during the study timeframe.  The risk of an increase in the size of a full-thickness rotator cuff tear was 4.2 times greater than in individuals with normal rotator cuffs. For individuals with partial rotator cuff tears the risk of progression was 1.5 times larger than those with normal rotator cuff tendons. If the shoulder studied was a dominant arm, there was a greater likelihood of tear enlargement.  63% of dominant rotator cuff tears compared with 42% of nondominant rotator cuff tears progressed over the duration of the study.

There were no clinically relevant differences in age, sex or smoking status between stable and enlarged tears.

Full-thickness rotator cuff tears enlarged in a median time of 2.3 years.  Partial rotator cuff tears enlarged in a median time of 3.3 years. Rotator cuff tears that were normal at the beginning of the study (14%) developed a tear a median time of 2.2 years.

Symptom Progression

46% of individuals developed new pain at a median time of 2.6 years.  A greater risk for pain development was associate with a more advanced final rotator cuff tear type.  46% of patients with partial thickness tears and 50% of patients with full-thickness tears developed new pain.

Tear enlargement was a significant risk factor for the development of shoulder pain.  The tear enlarged and 38% of shoulders that remained asymptomatic compared with 63% of shoulders that developed pain.

Muscle Degenerative Changes

Tear enlargement was significantly associate with progressive degenerative changes in the muscle of the torn rotator cuff.

Shoulder Function

Nearly all shoulders with new pain showed a significant decline in function from baseline values.

Conclusion

Full-thickness rotator cuff tears were 4.2 times more likely to enlarge than rotator cuff tears that were initially normal and they were 1.5 times more likely to enlarge then partial thickness rotator cuff tears.  Progressive muscle degeneration is associated with progression of even smaller rotator cuff tears. The study suggest that activity level may influence tear progression given the high rate of enlargement seen in dominant shoulders.  There appears to be a greater risk of increased pain in shoulders in which the tear enlarged compared with those in which the tear remained stable.

(Reference:  A Prospective Evaluation of Survivorship of Asymptomatic Degenerative Rotator Cuff Tears.  JBJS. 2015; 97: 89-98)

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