Tuesday, November 30, 2010
Symptomatic Progression of Asymptomatic Rotator Cuff Tears
A recent study from the major orthopedic journal investigated the progression of painful rotator cuff tendon tears. I have excerpted a portion of the article below. This is a question that I am frequently asked by patients.
The study demonstrates that a substantial proportion of subjects with asymptomatic rotator cuff tears become symptomatic after a short-term follow-up period. Pain development in asymptomatic rotator cuff tears is associated with tear size progression. Collectively, the subjects who developed new shoulder pain showed significant tear size increases compared with baseline measurements, whereas those who remained asymptomatic had no significant change in tear size. Likewise, the rate of tear progression, as defined in this study, for the symptomatic group (23%) was significantly greater than the rate for the asymptomatic group (4%). Tear progression manifested as both enlargement of full-thickness tears as well as conversion of partial-thickness to full-thickness tendon defects. The lack of tear progression seen in the majority of newly symptomatic tears, however, suggests that factors other than tear progression likely play a role in the evolution of symptoms for these patients. Given the high prevalence of asymptomatic rotator cuff disease, especially in individuals older than sixty years or in patients with a painful rotator cuff tear in the contralateral shoulder, these findings are clinically relevant. The onset of shoulder pain in a patient with a known preexisting asymptomatic tear may indicate an increase in tear size, which would potentially affect the clinical management of these patients.
Compared with the group of subjects who remained asymptomatic, the subjects who developed pain were found to have significantly larger tears at the time of enrollment. This suggests that the absolute size of an asymptomatic tear may be a predictor of future pain development. Previously, we reported the average size of symptomatic tears to be 30% larger than that of asymptomatic tears. There may be a cuff tear size threshold that predisposes a subject to future pain development, irrespective of tear progression. Future studies are necessary to define the relationship of absolute tear size and tear progression with pain development in the shoulders with an asymptomatic rotator cuff tear. In addition, a significant difference in predilection toward hand dominance was seen between the shoulders that developed pain (56% were on the dominant side) and those that remained asymptomatic (26% were on the dominant side). This may be explained by the finding that the dominant-side shoulders initially had larger tears than the nondominant shoulders. It is also possible that hand dominance, irrespective of tear size, predisposes a shoulder with an asymptomatic tear to develop symptoms.
This study demonstrates that shoulder function deteriorates as asymptomatic rotator cuff tears became painful. All measures of active range of motion of the shoulder, with the exception of external rotation at 90° of abduction, decreased significantly after pain development. Interestingly, the subjects who remained asymptomatic also showed a decrease in forward elevation and internal rotation in extension. These findings suggest that progressive loss of range of motion of the shoulder may be a consequence of the presence of a rotator cuff tear, regardless of the presence of symptoms. The declines in active range of motion seen in this study were small at this short-term time point and would be difficult to appreciate clinically. Furthermore, the differences seen between symptomatic and asymptomatic shoulders were not clinically important. Further studies are needed to determine if this loss of shoulder motion progresses over time and if specific strategies can prevent or correct the functional changes in this patient cohort.
External rotation strength of the shoulder was not significantly affected by new pain development. This can be explained by the fact that the tears included in this study were relatively small in size. These tears primarily involved the supraspinatus tendon, whereas the majority of the infraspinatus tendon was preserved, thus minimizing external rotation weakness. Furthermore, degenerative changes within the rotator cuff musculature were minimal, likely preserving cuff strength. It is possible that scapular plane abduction strength may have been a more sensitive test for the detection of disease progression in these subjects as this test is more sensitive to detect supraspinatus tears and has been previously correlated to the size of asymptomatic rotator cuff tears.
This study demonstrates that pain development in asymptomatic rotator cuff tears is not associated with progression of fatty degeneration of the rotator cuff muscles. This may be explained by the relatively short time period (one year) between the evaluation time points and the relatively small size of the tears included in this study. Nonetheless, it is notable that progressive fatty degeneration is not associated with pain development or tear enlargement in previously asymptomatic rotator cuff tears.
In summary, the risk of symptom progression for asymptomatic rotator cuff tears after a short-term follow-up interval is substantial. In this study, shoulders that developed pain had significantly larger tears at baseline and demonstrated a higher rate of tear progression than those that remained asymptomatic. Shoulder function and active range of motion deteriorated with symptom onset; however, no significant changes were found in external rotation strength or fatty degeneration of the rotator cuff muscles after pain development. There was an increase of compensatory scapulothoracic motion during early shoulder abduction after pain development; however, no increase in proximal humeral migration was seen.
The message here is that tears that are not treated and repaired will progress and get bigger over time. Bigger tears get worse faster and are more likely to cause pain and impairment. Patients with rotator cuff tears will often have to use their upper back muscles to fully lift the shoulder which is why we examine the neck and upper back (thoracic spine) for shoulder examinations. Further study is needed to follow these tears over longer periods of time.
Reference: The Journal of Bone and Joint Surgery (American). 2010;92:2623-2633.
Posted by Dr. Jim Mazzara at 1:01 PM