Preserving subacromial bursa in rotator cuff repair may improve patient outcomes, finds study

Over 500,000 surgeries are performed every year in the US to repair rotator cuff injuries, but a significant number of these procedures do not achieve the desired outcomes. A recent research published in the Science Translational Medicine journal suggests that a reevaluation of surgical practices like the routine removal of the subacromial bursa may be required.

The subacromial bursa is a synovial-like tissue located between the rotator cuff and the acromion. Traditionally, it has been removed during rotator cuff surgeries due to its perceived role in contributing to shoulder pathologies. However, this study utilized proteomic profiling of bursa samples from patients with rotator cuff injuries provides compelling evidence that the bursa actually plays a beneficial role in the healing process.

The study analyzed the response of bursa to tendon injuries in both human patients and a rat model and found that the bursa not only helped to maintain the mechanical properties of the intact infraspinatus tendon which lies next to the injured supraspinatus tendon, but also protected the underlying humeral head by preserving bone morphometry. This protective mechanism suggests that the bursa has a more complex and constructive role than previously understood.

Further experiments in the rat model revealed that the bursa stimulated an inflammatory response that is pivotal for wound healing in the injured tendon. This was marked by the initiation of genes associated with healing processes like the Cox2 and Il6. The positive influence of the bursa was also observed in rat bursa organ cultures by reinforcing the findings from live animal models.

This study involved the use of polymer microspheres loaded with dexamethasone which were delivered to intact bursae of rats after a tendon injury. The release of dexamethasone from the microspheres effectively reduced the expression of inflammatory markers like Il1b in the injured tendon. This research highlights the potential of the subacromial bursa as a novel target for drug delivery systems to enhance the healing process by modulating inflammation directly at the injury site. Overall, the study suggest that preserving the subacromial bursa during rotator cuff repairs could improve patient outcomes by utilizing the natural protective and healing properties of bursa. 

Reference:

Marshall, B. P., Ashinsky, B. G., Ferrer, X. E., Kunes, J. A., Innis, A. C., Luzzi, A. J., Forrester, L. A., Burt, K. G., Lee, A. J., Song, L., Lisiewski, L. E., Soni, R. K., Hung, C. T., Levine, W. N., Kovacevic, D., & Thomopoulos, S. (2024). The subacromial bursa modulates tendon healing after rotator cuff injury in rats. In Science Translational Medicine (Vol. 16, Issue 744). American Association for the Advancement of Science (AAAS). https://doi.org/10.1126/scitranslmed.add8273