Performing an Intrameniscal Injection
The menisci are two wedge-shaped fibrocartilaginous structures that are located between the tibia and femur that act as a support structure for the knee (2).
Due to the load across the meniscus with ambulation, they are susceptible to degeneration and tears over time. Degenerative meniscus tears are found in 35% of knees of patients aged 70-90 years old (4). Treatment of a degenerative meniscus tear can range from physical therapy, injection, and arthroscopic surgery. The primary goal in treatment of a meniscus tear is to preserve meniscus cartilage, as arthroscopic removal of meniscus tissue can lead to knee osteoarthritis (1).
Historically, corticosteroid injections are injected into the joint to treat symptoms associated with arthritis and degenerative meniscus tear. However, due to persistent pain in some patients after these injections, intra-meniscal injections have been studied. Studies have found improvements in patient’s functional outcomes and pain levels with a PRP injection into a chronic meniscus tear (1). Other studies have looked at corticosteroid injections into the perimeniscal tissue, which have also been found to lead to pain improvement (5).
A linear transducer is typically used for an intrameniscal injection. The patient will be placed in a side-lying position with the affected side facing upwards (3). For optimal positioning, the knee will be flexed to 30 to 60 degrees and a rolled-up towel can add valgus or varus stress depending on tear location (3). Providers will typically use a 25g needle for anesthesia. Providers should first evaluate for the presence of the saphenous nerve medially and the common fibular nerve laterally (3).
Then, with the probe in long axis to the knee, a short axis view of the meniscus is seen (3). A protruding meniscus will appear to bulge over the bone (5). Then, a 22g needle can be used to inject the PRP. Injection protocols can vary, but the standard is 0.5cc of PRP into the tear if visible.
PRP can also be injected into the meniscal wall and peri-meniscal space. The injection can be done in plane and out of plane.
Ultrasound guided injections of PRP have been found to provide pain relief in patients with degenerative meniscus tears. The injection can be safely done with PRP and providers should avoid damage to the saphenous or common fibular nerve. Surgery is reserved for those patients who have persistent pain.
By Gregory Rubin, DO
– More Knee Pain @ Sports Medicine Review: https://www.sportsmedreview.com/by-joint/knee/
– More about meniscus tears @ Wiki Sports Medicine: https://wikism.org/Meniscus_Tears
1) Kaminski, Rafal, et al. “Short-Term Outcomes of Percutaneous Trephination with a Platelet Rich Plasma Intrameniscal Injection for the Repair of Degenerative Meniscal Lesions. A Prospective, Randomized, Double-Blind, Parallel-Group, Placebo-Controlled Study.” International Journal of Molecular Sciences, vol. 20, no. 4, Feb. 2019, p. 856. PubMed, https://doi.org/10.3390/ijms20040856.
2) Guenoun, D., et al. “Treatment of Degenerative Meniscal Tear with Intrameniscal Injection of Platelets Rich Plasma.” Diagnostic and Interventional Imaging, vol. 101, no. 3, Mar. 2020, pp. 169–76. PubMed, https://doi.org/10.1016/j.diii.2019.10.003
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5) Di Sante, Luca, et al. “Ultrasound Guided Injection of a Painful Knee Osteoarthritis with Medial Meniscus Extrusion: A Case Series Study.” Muscles, Ligaments and Tendons Journal, vol. 7, no. 2, 2017, pp. 331–37. PubMed, https://doi.org/10.11138/mltj/2017.7.2.331.
6) Di Matteo, Berardo, et al. “Ultrasound-Guided Meniscal Injection of Autologous Growth Factors: A Brief Report.” Cartilage, vol. 13, no. 1_suppl, Dec. 2021, pp. 387S-391S. PubMed, https://doi.org/10.1177/19476035211037390.
7) Wilderman, Igor, et al. “Meniscus-Targeted Injections for Chronic Knee Pain Due to Meniscal Tears or Degenerative Fraying: A Retrospective Study.” Journal of Ultrasound in Medicine: Official Journal of the American Institute of Ultrasound in Medicine, vol. 38, no. 11, Nov. 2019, pp. 2853–59. PubMed, https://doi.org/10.1002/jum.14987
8) Coll, Clemence, et al. “Ultrasound-Guided Perimeniscal Injections: Anatomical Description and Feasibility Study.” Journal of Ultrasound in Medicine: Official Journal of the American Institute of Ultrasound in Medicine, vol. 41, no. 1, Jan. 2022, pp. 217–24. PubMed, https://doi.org/10.1002/jum.15700.
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