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Rotator cuff tears are frequent shoulder problems that are usually dealt with surgical repair. Despite improved surgical techniques, the tendon-to-bone healing rate is unsatisfactory due to difficulties in restoring the delicate transitional tissue between bone and tendon. It is essential to understand the molecular mechanisms that determine this failure. The study of the molecular environment during embryogenesis and during normal healing after injury is key in devising strategies to get a successful repair. Mesenchymal stem cells (MSC) can differentiate into different mesodermal tissues and have a strong paracrine, anti-inflammatory, immunoregulatory and angiogenic potential. Stem cell therapy is thus a potentially effective therapy to enhance rotator cuff healing. Promising results have been reported with the use of autologous MSC of different origins in animal studies: they have shown to have better healing properties, increasing the amount of fibrocartilage formation and improving the orientation of fibrocartilage fibers with less immunologic response and reduced lymphocyte infiltration. All these changes lead to an increase in biomechanical strength. However, animal research is still inconclusive and more experimental studies are needed before human application. Future directions include expanded stem cell therapy in combination with growth factors or different scaffolds as well as new stem cell types and gene therapy.

IV.

Background:A Hill Sachs lesion is a posterior-superior bony defect of the humeral head caused by a compression of the hard glenoid rim against the soft cancellous bone in the context of an anterior instability episode. The presence of these humeral defects increases with the number of dislocations and larger lesions are associated with a greater chance of development of recurrent instability and recurrence after surgery. Also its location and pattern, in particular the so-called engaging Hill-Sachs, are associated with poor prognosis.Methods:There is a lack of consensus in terms of classification and management algorithm, although lesions greater than 25% of the humeral head had been suggested to need more than a simple Bankart repair to avoid recurrence. The concept of glenoid track has turned the attention to location and shape and not only size of the humeral defect. Moreover, the glenoid bone loss is crucial when choosing a treatment option as it contributes to decrease the glenoid track as well. A thorough revision of treatment options has been performed.Results:Numerous treatment options have been proposed including remplissage, glenoid or humeral head augmentation, bone desimpaction, humeral rotational osteotomy and arthroplasty.Conclusion:Humeral defects treatment should be individualized. Determination of size and location of the defect and its relation with glenoid track is mandatory to achieve satisfactory results.

Background:The clinical evaluation of the patient with shoulder instability can be challenging. The pathological spectrum ranges from the straightforward “recurrent anterior dislocation” patient to the overhead athlete with a painful shoulder but not clear instability episodes. Advances in shoulder arthroscopy and imaging have helped in understanding the anatomy and physiopathology of the symptoms. The aim of this general article is to summarize the main examination manoeuvres that could be included in an overall approach to a patient with a suspicion of instability.Material and Methods:In order to achieve the above-mentioned objective, a thorough review of the literature has been performed. Data regarding sensibility and specificity of each test have been included as well as a detailed description of the indications to perform them. Also, the most frequent and recent variations of these diagnostic tests are included.Results:Laxity and instability should be considered separately. For anterior instability, a combination of apprehension, relocation and release tests provide great specificity. On the other hand, multidirectional or posterior instability can be difficult to diagnose especially when the main complain is pain.Conclusion:A detailed interview and clinical examination of the patient are mandatory in order to identify a shoulder instability problem. Range of motion of both shoulders, clicking of catching sensations as well as pain, should be considered together with dislocation and subluxation episodes. Specific instability and hyperlaxity tests should be also performed to obtain an accurate diagnosis.