IntroductionRotator cuff tendinopathy is a progressive disorder of the shoulder which begins with an acute tendinitis, progresses to tendinosis with degeneration and partial thickness tears, and results in full thickness rupture [1]. Rotator cuff tendinopathy has multifactorial etiology [2]. According to intrinsic factors, tendon degeneration would result from the combination of natural process of aging, poor vascularity, altered biology, and inferior mechanical properties. Constitutional risk factors have been shown to be associated with rotator cuff tendinopathy, including diabetes mellitus, obesity, smoking, and hyperlipidemia [3][4][5][6]. Whereas, extrinsic factors include hooked acromion, mechanical overuse, anterior glenohumeral dislocations and fractures of great tuberosity [7].Non-steroid anti-inflammatory drugs (NSAIDs) and physical therapy are commonly recommended to restore shoulder function in rotator tendinopathy [8,9]. Diercks et al.[10] also recommended home exercises of low intensity and high frequency, combining eccentric training with stabilization training of the scapula and focusing on relaxation and proper posture.If the results of the conservative treatment fails, corticosteroid or anesthetics injection is often used in the management of persistent shoulder pain [11]. The potential mechanism of corticosteroids include decreased inflammation, inhibition of cellular proliferation, scarring and adhesion, and anti-nociceptive action [12]. However, their effectiveness is ascertained only in the short term follow-up and occurrence of local degradation of tissues has been reported as a result of repeated corticosteroid injection, as well as tendon tearing and corticosteroid arthropathy [11]. Therefore, their use should be restricted to selected cases.Currently, intra-articular hyaluronic acid (HA) is well accepted as a good alternative in the conservative treatment in patients with osteoarthritis [13][14][15]. Furthermore new and effective HA, called mobile reticulm hyaluronic acid, with different molecular characteristics is used Abstract Background: Rotator cuff disease is the most common cause of shoulder pain and weakness. Conservative treatment is the first choice of shoulder pain management. Viscosupplementation of hyaluronic acid (HA) seems to be effective for management of tendon disorders.