Rotator cuff tears are a common orthopedic issue, especially in an aging population. Despite advances in surgical techniques, the re-tear rates for these injuries remain high, varying from 11% to 90% depending on the size of the tear and patient demographics. This has led to the exploration of various biological adjuvants to improve patient outcomes and repair integrity, especially in patients at higher risk for repair failure due to factors such as age, comorbidities, tendon retraction, and fatty degeneration.

PRP is one of the most studied adjuvants for rotator cuff tears and repairs. PRP is a concentration of growth factors that stimulate the proliferation of local progenitors, direct cell differentiation, and modify local inflammatory responses. Despite the promise shown in initial in vitro studies, the clinical impact of PRP on functional outcomes and repair integrity has been inconsistent. Recent studies suggest that PRP may be more advantageous in smaller tears, and future studies should focus on leukocyte-rich versus poor preparations and the use of PRP in patients that are high risk for repair failure.

Biologic and synthetic patches or augments provide mechanical stability for large and massive rotator cuff tears and decrease re-tear rates. A study by Barber et al. (2012) found that augmentation with a porcine small intestine submucosa (SIS) patch significantly improved structural outcomes in large and massive rotator cuff tears. Another study by Wong et al. (2017) found that augmentation with a human dermal allograft improved structural and functional outcomes in massive rotator cuff tears.

MSCs have demonstrated improved healing rates without an impact on outcomes. MSCs have the potential to differentiate into various cell types, including tenocytes, the primary cell type in tendons. This has led to the exploration of MSCs as a potential adjuvant to improve the healing of rotator cuff tears.

Cytokines and growth factors show promise in animal models, but require human trials to further evaluate. These biologic signals play crucial roles in the healing process, and their modulation could potentially improve the healing of rotator cuff tears.

In conclusion, the use of biological adjuvants such as PRP, patches and augments, MSCs, and cytokines and growth factors show promise in improving the outcomes of rotator cuff repairs. However, more research is needed to determine the optimal use of these adjuvants, especially in patients at higher risk for repair failure. The use of these adjuvants should be considered as part of a comprehensive approach to the management of rotator cuff tears, taking into account the specific characteristics of the tear and the patient.