RESUMEN
OBJECTIVES: To compare the effects of ultrasound-guided platelet-rich plasma (PRP) and whole blood (WB) injections in patients with chronic hamstring tendinopathy. METHODS: In a prospective double-blind randomized controlled trial, PRP or WB was injected under ultrasound guidance into the proximal hamstring tendon in a cohort of patients with clinically suspected hamstring tendinosis. Questionnaires were administered before injection and 2, 6, and 12 weeks and 6 months after injection. Pain and function outcomes were measured via the Modified Harris Hip Score (MHHS), Hip Outcome Scores for activities of daily living (ADL) and sport-specific function, and International Hip Outcome Tool 33 (IHOT-33). Diagnostic ultrasound was used to compare preinjection and 6-month postinjection tendon appearances. RESULTS: The WB group showed greater improvements in pain and function over the PRP group before 12 weeks, whereas the PRP group showed improved outcomes over WB at 6 months. None of these between-group outcome measures, except 6-week IHOT-33, showed statistical significance. Comparing preinjection and 6-month scores, the PRP group showed significant improvements in ADL (P = .018) and IHOT-33 (P = .28) scores, whereas the WB group showed no significant improvements from baseline. The WB group showed significantly decreased pain with 15-minute sitting (P= .008) at 6 months. Ultrasound imaging showed no significant differences between PRP and WB group tendon appearances. CONCLUSIONS: Both PRP and WB groups showed improvements in all outcome measures at 6 months. The PRP group showed significant improvements in 6-month ADL and IHOT-33 scores. The WB group reached significance in 15-minute sitting pain. No significant between-group differences were observed at any time point.