Discussion
pain
To our knowledge, this is the first prospective study to assess the effects of a scaffold-based ACP formulation compared with CSA administered with ultrasound-guided subacromial injections as therapy of SIS. The results present clearly that autologous GF applications are at least as effective, with even greater improvement of the force score, as the injections of CSA. The GF content does not depend on the age and gender of the patients.Our study confirmed that ACP/STR has a therapeutic effect on patients with SIS diagnosis. Combined with a physiotherapeutic counseling, we achieved 79.31% of positive outcome in both pain relief and improvement of functionality. Similar to 72.41% of positive outcome in the second group, suggesting that ACP/STR is at least as beneficial as the well-established therapy including steroid injections [In our study, we did not observe any side effects in both cohorts. However, almost all patients in the ACP/STR group complained about an initial painful and pressure at the site of injection during 4 h post injection. This effect might be explained by the high viscosity of the mixed plasma and collagen scaffold. However, these symptoms resolved completely the day after treatment. An additional dose of local anesthetic to relief the pain sensation is not recommended, because it may stop or decrease the desired pro inflammatory tissue reaction [The level of PDFG, TGF ß, HGF and EGF was determined as this GF can be found in the literature playing major role by tendons healing and regeneration process [Moreover, this study clearly demonstrates that the acromion type is a predictor for the outcome of conservative therapy. 83% of the drop out patients in the ACP/STR group and 62.5% of the drop out patients in the control cohort exhibited an acromion type Bigliani III. Almost all of these patients underwent surgery since the conservative therapy including subacromial injection, either with CSA or ACP/STR, failed to improve the symptoms. The findings of the present study are in accordance with the study of Berná-Mestre et al., who also demonstrates that acromion type Bigliani III is a predictive of unfavorable results in SIS patients treated with platelet rich plasma injections [As a limitation of this study, we included only a small patient number and longer FU as 6 months could tell more about the sustainability of the ACP/STR therapy. Another methodical aspect of this study is that the final FU investigation differed significantly between the groups. However, it can be assumed that these FU difference of about 20 days do not have an essential impact of the given clinical results. Individual reasons were mainly responsible to this FU difference and the design of the present study reflecting therefore more the daily clinical practice.