The aim of the trial is comparison of the effectiveness of three methods of conservative treatment in partial thickness rotator cuff injury (PTRCI): collagen with PRP injections, PRP injections alone and collagen injections alone.

BACKGROUND: Rotator cuff injury (RCI) occupy third place in the population among the musculoskeletal system pathologies (16%) after low back pain (25%) and knee pain (19%). Partial thickness RCI (PTRCI) is the sum of degenerative, overload and microtrauma processes and their incidence increases significantly with age (up to 30% over 60). One of the factors contributing to the injury is a negative collagen balance and slowed tendon metabolism in proportion to its blood supply disorders. Conservative treatment of PTRCI of degenerative origin is the first choice management, but there are no clear guidelines. External supply of collagen and PRP could potentially counteract these processes.

AIM: Comparison of the effectiveness of three treatment concepts: collagen with PRP, PRP alone, collagen alone in the treatment of PTRCI.

DESIGN: Randomized prospective trial without blinding SETTING: Open study for outpatients, single center study POPULATION: local population METHODS: Three groups of patients (each group 30 patients) with PTRCI confirmed by ultrasound (N=90). The assessment of the supraspinatus tendon (SSP) in standard position of internal rotation of the upper limb for ultrasound examination, assessment of the thickness of the RC in cross-section (mm). Each group treated by three ultrasound guided injections into the shoulder bursa every consecutive week: Group A - collagen (3 amp Collagen MD Shoulder) together with PRP (2ml); Group B - collagen alone (3 amp Collagen MD Shoulder); Group C - PRP alone. All patients were allowed to continue rehabilitation protocol. Primary control tools: NRS, QuickDash, EQ-5D-5L in control points: IA (initial assessment), 6, 12 and 24 weeks after last injection. Secondary control tools: percentage of patients where the RC continuity were preserved and percentage of patients who had ultrasonographic signs of RC regeneration (crossection width increase, improvement of echogenicity) during the observation period between W0 and 24 weeks.

Inclusion Criteria:

• clinical signs and symptoms of rotator cuff pathology
• an adult person consenting to injections
• partial thickness rotator cuff injury confirmed by ultrasound examination without coexisting severe pathologies (systemic inflammatory disease, malignancy, severe stage OA)
• no traumatic event
• no injections or any other local treatment in previous 1 month

Exclusion Criteria:

• full thickness rotator cuff injury
• acute, traumatic injuries requiring surgical treatment
• coexisting injuries of the shoulder joint requiring other intervention
• severe pathologies of the shoulder of another origin (systemic inflammatory disease, malignancy, severe stage OA)
• no consent