Effectiveness of lyophilized growth factors injection for subacromial impingement syndrome: a prospective randomized double-blind placebo-controlled study

BACKGROUND: Platelet-derived lyophilized growth factors (L-GFs) use a standardized number of allogenic pathogen-free platelets instead of autologous platelets used in PRP as a source of growth factors. This study aimed to evaluate the efficacy of L-GF injection versus placebo in subacromial impingement (SIS) treatment. METHODS: The current randomized double-blind placebo-controlled study included sixty patients (40 females and 20 males, aged between 24 and 75 years) diagnosed with SIS (both clinically and sonographically). Patients were randomly assigned to two equal groups. Under ultrasound guidance, group 1 received subacromial saline injection, and group 2 received L-GF injection. Clinical examination, pain visual analogue scale (VAS), shoulder pain and disability index (SPADI) and shoulder ultrasound were performed before and at the 8th week after injection. RESULTS: Follow-up assessment showed statistically significant improvement in the L-GF group regarding active flexion, active and passive internal rotation and extension, SPADI-disability scale, VAS and thickness of the supraspinatus tendon by US. Regression analysis showed that group 1 was approximately 30 times more likely than the L-GF group to experience painful arc at follow-up. Both groups showed statistically significant improvement in SPADI-pain scale and SPADI-total, flexion and abduction (still the mean value of abduction was significantly higher in the L-GF group). CONCLUSIONS: L-GF injection resulted in clinically significant reductions in pain and functional disability outcomes in patients with SIS. An objective significant reduction in the thickness of the supraspinatus tendon, measured by ultrasound, in the L-GF group hopefully encourages proper healing and functioning in SIS. Trial registration: The identification number is NCT04330027, date of first registration (01/04/2020). Unique on 21/11/2019, Protocol ID: 0106178.