RESUMEN
PURPOSE: While the use of bone marrow concentrate (BMC) has been described in the treatment of rotator cuff tears, the impact of a rotator cuff injury on the mesenchymal stem cells (MSCs) content present in the human shoulder has not been determined, especially with regard to changes in the levels of MSCs at the tendon-bone interface. With the hypothesis that there was a decreased level of MSCs at the tendon-bone interface tuberosity in patients with rotator cuff tear, we assessed the level of MSCs in the tuberosity of the shoulder of patients undergoing a rotator cuff repair. METHODS: We analysed the data of 125 patients with symptomatic rotator cuff tears and of 75 control patients without rotator cuff injury. We recorded the following data: size of tear, number of torn tendons, aetiology of the tear, lag time between onset of shoulder symptoms/injury and repair, and also fatty infiltration of muscles. Mesenchymal stem cell content at the tendon-bone interface tuberosity was evaluated by bone marrow aspiration collected in the humeral tuberosities of patients at the beginning of surgery. RESULTS: A significant reduction in MSC content (from moderate, 30-50 %, to severe >70 %) at the tendon-bone interface tuberosity relative to the MSC content of the control was observed in all rotator cuff repair study patients. Severity of the decrease was statistically correlated to a number of factors, including the delay between onset of symptoms and surgery, number of involved tendons, fatty infiltration stage and increasing patient age. CONCLUSION: This study demonstrates that the level of MSCs present in the greater tuberosity of patients with a rotator cuff tear decreases as a function of a number of clinical factors, including lag time from tear onset to treatment, tear size, number of tears and stage of fatty infiltration, among others. This information may help the practices in using biologic augmentation of a rotator cuff repair.