Everts 2008.

Methods	Randomised controlled trial: participants were allocated after randomisation derived from sealed envelopes. It is not clear how the randomisation sequence was generated. Participants and assessors were blinded to the intervention. Trial conducted: no details available; recruitment: no details available
Participants	Participants: 40 undergoing open surgery for shoulder impingement syndrome Included participants: impingement syndrome (stage II), diagnosed at least 6‐months preoperatively. Participants with typical anterior shoulder pain during elevation, loss of active and passive shoulder motion and positive response to 3 subacromial infiltrations (local anaesthetics and corticoids) performed in a 6‐month period Excluded participants: presence of rotator cuff injury; frozen shoulder; acromioclavicular joint disorder; glenohumeral joint degenerative arthritis; shoulder instability; shoulder and elbow disorders; hand disorders; post‐traumatic disorder; participants with diseases that would affect post‐operative wound healing or who were treated for acute shoulder dysfunction Age: PRT group mean (SD): 52 years (11) No PRT mean (SD): 50 years (14) Gender: PRT group (number of men:women): 7:8 No PRT (number of men:women): 5:10 Sports activity: not available
Interventions	All participants underwent open subacromial decompression PRT (number of participants = 20): single intraoperative platelet‐leucocyte gel application. From 52 mL blood, 12 mL used to prepare intervention. Citrate dextrose and autologous thrombin were used for gel formation PRT preparation: kit: Magellan Autologous Platelet Separator System (MAPS) Quantification of platelet concentrates after preparation: 1183 SD 396/109/L, 5.7‐fold increase from baseline No PRT (number of participants = 20): no platelet‐rich therapy controls Co‐interventions: same rehabilitation protocol both groups
Outcomes	ASES (American Shoulder and Elbow Surgeons scoring system) VAS ADL Shoulder range of motion Use of pain medication
Other quality issues	Sample size: the authors did not calculate the sample size Validation of PRT: quantification reported
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Adequate sequence generation	Low risk	Drew random numbers
Allocation concealment	Low risk	Used sequentially‐numbered, opaque and sealed envelopes
Blinding All outcomes	Low risk	Participants and assessors were blinded to the intervention
Incomplete outcome data addressed All outcomes	Low risk	No participants were lost to follow‐up
Free of selective reporting	Unclear risk	The study protocol was not available. It appears that the study’s prespecified primary and secondary outcomes that are of interest in the review have been reported in the prespecified way
Free of other bias	Low risk	The study appears to be free of other sources of bias