Research on other knee conditions 

Knee – Chondromalacia Patella

Treatment of anterior knee pain due to chondromalacia patellae with platelet-rich plasma and hyaluronic acid in young and middle-aged adults, a cohort study

The main results of this study affirm the positive effects of PRP and HA for the treatment of anterior knee pain described by previous research and the subsequent improvement of the quality of life. Relatively little information was found in the literature search regarding the therapeutic effects of PRP on anterior knee pain and chondropathies. While a previous radiologic study found no evidence regarding the effect of PRP, this study found a benefit when comparing PROMs between patient groups.

https://pubmed.ncbi.nlm.nih.gov/38780774/

Knee - Meniscus Tear

There was no association between BMAC or PRP augmentation and the incidence of revision surgery after isolated primary meniscus repair. 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.

https://journals.sagepub.com/doi/full/10.1177/23259671231186990

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 PRFM. PRFM was shown to have no benefit in improving functional outcomes.    

https://pubmed.ncbi.nlm.nih.gov/36209223/

Knee - Cartilage Defect

First case of MRI-proven healing of an osteochondral defect with PRP (without accompanying cartilage restoration surgery). Ongoing treatment with an anabolic therapy like PRP may facilitate symptom improvement and structural healing.

https://pubmed.ncbi.nlm.nih.gov/38002400/

Knee - ACL

Two cases of contact athletes with anterior cruciate ligament injuries who returned to competition early after conservative treatment with PRP therapy

Two high-impact sports athletes with ACL injuries treated with aggressive conservative therapy using PRP returned early to their preinjury play level. Hence, PRP treatment could be utilized for aggressive conservative treatment of ACL injuries.

https://www.sciencedirect.com/science/article/pii/S2210261222005144

Knee - MCL

Platelet-rich plasma (PRP) injections may be used to treat medial collateral ligament (MCL) injuries: Often caused by a blow to the outer side of the knee. PRP injections may be effective for grade 1 and 2 MCL tears, which are partial-thickness and full-thickness tears, respectively. However, people with grade 3 tears, which are full-thickness tears that extend across the ligament and LCL, should avoid PRP injections and may need surgery instead. 

Some say that PRP injections can be an effective treatment for low-grade MCL injuries and chronic MCL injuries. However, others say that there is a lack of high-level evidence to support the efficacy of PRP injections for treating MCL lesions in humans. 

Autologous platelet-rich plasma therapy for refractory pain after low-grade medial collateral ligament injury

52 patients with 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. Magnetic resonance imaging showed that the low-grade MCL injury had completely healed, and no edema was present around the MCL. Conclusions: Intra-articular injection of autologous PRP is an effective treatment for refractory pain after low-grade MCL injury.

J Int Med Res. 2020 Feb; 48(2): 0300060520903636. Published online 2020 Feb 23. doi: 10.1177/0300060520903636,  PMCID: PMC7111026, https://pubmed.ncbi.nlm.nih.gov/32090668/

THE USE OF SERIAL PLATELET RICH PLASMA INJECTIONS WITH EARLY REHABILITATION TO EXPEDITE GRADE III MEDIAL COLLATERAL LIGAMENT INJURY IN A PROFESSIONAL ATHLETE: A CASE REPORT

A 30-year-old professional wrestling athlete presented to the clinic with acute complaints of right medial knee pain resulting from a traumatic valgus force. This athlete had required surgery to reconstruct the ACL and repair the MCL 13 months prior. The subject was successfully treated with a series of three sequential Leukocyte Rich Platelet Rich Plasma (LR-PRP) Injections spaced evenly one week apart in addition to an early physical therapy regimen. The total treatment time was cut down from an expected 35-49 days to 31 days. Conclusion: The results of this case report indicate that the use of LR-PRP and early rehabilitation shows promise in treating an acute grade 3 MCL injury. Future research utilizing randomized controlled trials are needed.

Int J Sports Phys Ther. 2018 Jun; 13(3): 520–525. PMCID: PMC6044600. PMID: https://pubmed.ncbi.nlm.nih.gov/30038838

An Autologous Leukocyte-Reduced Platelet-Rich Plasma Therapy for Chronic Injury of the Medial Collateral Ligament in the Knee: A Report of 3 Successful Cases. 

Some patients complain of chronic persistent medial knee pain after isolated low-grade injuries of medial collateral ligaments (MCL). Insufficient healing of ligaments is believed to be responsible for symptoms. We report on successful treatment of chronically symptomatic MCL injuries in 3 patients using autologous leukocyte-reduced platelet-rich plasma (PRP) injections. There were 3 men with a mean disease duration of 10 months. Magnetic resonance imaging showed discontinuities of superficial layers and thickness of deep layers in the proximal 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.

Clin J Sport Med. 2019;29(1): e4.  https://pubmed.ncbi.nlm.nih.gov/29194097/

Patellar tendinopathy

Evaluation of Patellar Tendon Structural Changes following Biological Treatments: Secondary Analysis of Double-Blinded Clinical Trial of Bone Marrow Mesenchymal Stromal Cells and Leukocyte-Poor Platelet-Rich Plasma

BM-MSC treatment demonstrates a superior capacity to promote tendon regeneration and organization, restore strength, and reduce pain compared to Lp-PRP, after 3, 6, and 12 months in male patients with patellar tendinopathy.

https://www.mdpi.com/2227-9059/12/7/1599

 The Best Current Research on Patellar Tendinopathy: A Review of Published Meta-Analyses

Multiple platelet-rich plasma (PRP) injections appear superior to eccentric exercises and provide lasting improvements compared to eccentric exercises when conservative treatments fail. Extracorporeal shockwave therapy (ESWT) also seems superior to non-operative options and similar to surgery for patellar tendinopathy in the long term. However, evidence for eccentric exercise efficacy remains unclear due to inconclusive findings.

https://www.mdpi.com/2075-4663/12/2/46

Safety and Efficacy of Bone Marrow–Derived Mesenchymal Stem Cells for Chronic Patellar Tendinopathy (With Gap >3 mm) in Patients: 12-Month Follow-up Results of a Phase 1/2 Clinical Trial

The 12-month follow-up outcomes after both groups of patients (n = 20) received BM-MSC treatment indicated that biological treatment was safe, there were no adverse effects, and the participants showed a highly statistically significant clinical improvement (P < .0002), as well as an improvement in tendon structure on MRI (P < .0001). Preinjection of Lp-PRP yielded no advantages.

https://journals.sagepub.com/doi/full/10.1177/23259671231184400

Platelet-rich plasma for jumper's knee: a comprehensive review of efficacy, protocols, and future directions

Jumper's knee is commonly managed conservatively, but there is a lack of consensus on further treatment options. PRP treatment holds promise in promoting tissue healing and repair. However, standardized protocols for PRP preparation and administration, as well as optimal dosage and number of injections, require further investigation to enhance its efficacy. Continued research efforts are necessary to ascertain the precise role of PRP and its refinement in the management of patellar tendinopathy.

https://pubmed.ncbi.nlm.nih.gov/37668753/