Improved clinical outcomes from PRP injections for knee OA may be related to a higher platelet dose.

The administration of three or five injections of platelet-rich plasma is safe, substantially more effective than single injections, and leads to remarkable clinical improvement by significantly reducing knee pain, improving joint stiffness, and enhancing physical function in patients with grade I-III knee osteoarthritis. Furthermore, no significant difference was observed in the efficacy of three or five injections. Therefore, we recommend using three injections of PRP in the treatment of patients with knee osteoarthritis of grade I-III.

The use of PRP for the treatment of knee osteoarthritis has shown statistically significant improvements in some patient-reported outcomes compared with placebo.

There was a statistically significant decrease in the rate of revision meniscus surgery when BMAC or PRP was used to augment meniscus repairs in the setting of concurrent ACLR; however, the overall revision rates were small.

 Although meniscus repairs augmented with PRP led to significantly lower failure rates and better postoperative pain control compared with those of the non-PRP group, there is insufficient RCT evidence to support PRP augmentation of meniscus repair improving functional outcomes. 

Moreover, PRP could be recommended in meniscus repair augmentation compared with platelet-rich fibrin matrix (PRFM). PRFM was shown to have no benefit in improving functional outcomes. 

PRP injections may be effective for grade 1 and 2 MCL tears, which are partial-thickness and full-thickness tears, respectively. 

Refractory pain after low-grade knee MCL injury were treated by intra-articular injection of autologous PRP. Every patient received a 5-mL intra-articular injection of autologous PRP once weekly for 3 weeks. After one injection, the patients’ pain was greatly decreased and they stopped taking nonsteroidal anti-inflammatory drugs. Post completed treatment Magnetic resonance imaging showed that the low-grade MCL injury had completely healed, and no edema was present around the MCL.

Some patients complain of chronic persistent medial knee pain after isolated low-grade injuries of medial collateral ligaments (MCL). After PRP injections, all cases returned to their sport activities at a previous level as without symptoms, and complete healing of proximal ligaments was identified on magnetic resonance images. The outcomes indicated that PRP injections led to successful repair for chronic injuries of MCL in knees.