Comparative evaluation of surgical methods in the treatment of chronic irreparable supraspinatus tears: a biomechanical study

Chronic irreparable supraspinatus (SSP) tears are frequently treated using tensor fascia lata (TFL); however, these grafts are prone to recurrent ruptures. A TFL scaffold with seeded mesenchymal stem cells (MSCs) may increase the mechanical strength of the regenerated tendon. In this experimental study the above hypothesis is evaluated and the healing qualities of the MSC embedded scaffold are compared against the ones repaired with only a TFL allograft, from a biomechanical perspective. A number of skeletally mature male rabbits were used to create a chronic retracted SSP tear model. A tendon defect was created at the right shoulder of each specimen and was reconstructed six weeks later using a TFL allograft either with or without MSCs embedded. The rabbits were sacrificed twelve weeks after the operation and their biomechanical evaluation was based on the tendon’s ultimate failure load and stiffness of each group. The results of the biomechanical analysis revealed that the MSC group demonstrated a higher tensile strength than the TFL group. The values of the mean ultimate failure load and the mean stiffness of both TFL and MSC groups were significantly lower compared to the respective values obtained for the intact rotator cuff (RC) group. It seems that bone marrow MSCs increased the mechanical strength of the supraspinatus tendon; however, the stiffness was similar between the operated groups in rabbit models. Based on the results, it could be stated that rotator cuff regeneration using MSCs appears as a promising approach; nonetheless, additional clinical evidence is required, before definite conclusions are drawn.