Multimodality is the mainstay of osteoarthritis (OA) treatment and intra-articular platelet-rich plasma (PRP) injection is gaining acceptance due to its regenerative properties and being minimally invasive. We present a young woman with Kellgren-Lawrence grade 3 post-traumatic OA in the left knee who refused surgery and opted for pain clinic follow-up. Five PRP injections in intervals of 4 to 9 months were administered in the past 2 years in addition to oral analgesia when necessary. Five ml of PRP was prepared via the double-spin open method and injected under ultrasound guidance to the left knee joint. Visual analogue scale (VAS) for pain was recorded at pre-procedure, and at 1-week and 1-month post-procedure. The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) was recorded at pre-procedure and 1-month post-procedure. PRP injection successfully reduced the VAS from 5 to 3 at both 1-week and 1-month post-procedure, and resulted in a WOMAC reduction of 54% with improvement in all WOMAC subscales at 1-month post-procedure. Our case showed that PRP injection demonstrated a positive effect on pain relief and physical function improvement in traumatic knee OA.