Further studies are needed to produce clear guidelines to define the best choice in terms of clinical outcomes, function and complications.

Level III, retrospective comparative study.

VAS and functional score in all trials that we have analyzed. Conclusion: intra-articular injection with HA is effective in reducing pain and improving function in shoulder with rotator cuff tears and without severe adverse reaction. Level of evidence: Level I.KEY WORDS: cuff tears, glenohumeral, hyaluronic acid, hyaluronate, shoulder, viscosupplementation. IntroductionRotator cuff pathology is the main cause of shoulder pain and disability. The causes arises from a multivariate etiology, often due to age-related chronic degeneration in which play a role the decrease in collagen synthesis, increase in free radicals expression and metabolism imbalance in favor of catabolic activity 1 . Classically, the diagnosis is clinical, characterized by pain, mostly during the night, severe disability and functional impairment 2,3 . MRI and US may usefully this diagnosis 4,5 . The first management is conservative, including oral anti-inflammatory drugs, topic agents, cortisone injections, physical therapies, and joint rehabilitation exercises [6][7][8] . In the past, much has been published on the use of steroid and local anesthetic injections, administered alone or in combination to other therapies. On the other hand, many evidences have corroborated their potential effects as negative on the collagen matrix of tendons and ligaments [9][10][11][12][13][14] . In the substance, compared to other treatments, effective in the mid and long term, the benefits after these injections could be valid only in the short-term 15 . Clinical trials have confirmed that HA may be effective for management of tendons disorders. Specifically, in Achilles tendinopathy, the tendon healing process is improved and the formation of adhesions in reduces by the regulation of the expression of vascular endothelial growth factor (VEGF) and type IV collagen 16 . After hand surgery, it improves the motion of fingers lubricating the tendon surface and reducing friction and adhesions 17,18 . Few papers have investigated the effects of HA in rotator cuff disorders, and no systematic review have been performed on this matter. The aim of the present review is to summarize all papers published inherently to the injection of HA for management of cuff tendinopathy, in terms of feasibility, safety, and efficacy. © C I C E d i z i o n i I n t e r n a z i o n a l i Material and methods Criteria for considerationWe included randomized clinical trials, prospective and retrospective studies reporting on clinical and functional outcomes in patients who had undergone sub-acromial or intra-articular injections of HA for management of rotator cuff pathology. Given the linguistic capabilities of the research team, we considered only papers published in English language. We performed a broad search for relevant studies published up to August 2014 in Medline (http://www.ncbi.nlm.nih.gov/sites/entrez/); Ovid (http://www.ovid.com); Cochrane Reviews (http://www.cochrane.org/reviews/), Google Scholar, Enbase database. Combined key words for the search were "cuff tears", "gl...

Further studies are needed to produce clear guidelines to determine how to balance the apoptosis process to reduce the failed healing response found in non-traumatic RC tears.

Fatty degeneration is a degenerative condition of the tendon-muscle unit of rotator cuff muscles, characterized by atrophy of muscle fibers, fibrosis, and fatty accumulation within and around the muscles. Many classification may be useful to stage this pathology, especially on Computed Tomography (CT) and magnetic resonance imaging (Mari) findings. Stem cell-based therapies for repair and regeneration of tendons and muscles may be used to promote healing and to make this condition reversible. Diagnosis and management of this condition is mandatory as in patients undergoing rotator cuff repair, it may influence outcomes, increase the likelihood of re-tearing, and evolve negatively.

IV.

Level III, retrospective comparative study.

The number of patients undergoing revision surgery following failure of anterior cruciate ligament (ACL) reconstruction has increased over the recent past, following the overall increased number of primary ACL reconstruction performed. Failure of primary ACL reconstruction can be attributed to technical errors, biological failures, or new traumatic injuries. Technical errors include femoral and/or tibial tunnels malposition, untreated associated ligaments insufficiencies, uncorrected lower limb malalignment, and graft fixation failures. Candidates for revision surgery should be carefully selected, and the success of ACL revision requires precise preoperative planning to obtain successful results. Preoperative planning begins with the analysis of the mechanisms of ACL reconstruction failure, and information regarding previous surgery, such as the type of graft implanted, and the position of existing hardware. Appropriate imaging is necessary to evaluate the position of the femoral and tibial tunnels, and abnormal tunnel widening. On the basis of clinical examination and imaging, surgeon can perform an ACL revision procedure in 1 or 2 stages.