Saline is often used as a placebo in pharmacology research. When injected iv, it exerts no effect and functions as a true placebo. But, when saline is used for hydrodissection and used as a placebo in studies of procedures that involve hydrodissection with PRP and other materials, saline is NOT a placebo because saline causes changes in the tissue. Here are studies that explain.
Asghar, Aneela, Zahid Tahir, Aisha Ghias, Usma Iftikhar, and Tahir Jameel Ahmad. “Efficacy and Safety of Intralesional Normal Saline in Atrophic Acne Scars.” Annals of King Edward Medical University 25, no. 2 (June 24, 2019). https://doi.org/10.21649/akemu.v25i2.2867.
Bagherani, Nooshin, and Bruce R Smoller. “Introduction of a Novel Therapeutic Option for Atrophic Acne Scars: Saline Injection Therapy.” Global Dermatology 2, no. 6 (2016). https://doi.org/10.15761/GOD.1000159.
Cass, Shane P. “Ultrasound-Guided Nerve Hydrodissection: What Is It? A Review of the Literature” 15, no. 1 (2016): 3.
“Clinical Benefit of Intra-Articular Saline as a Comparator in Clinical Trials of Knee Osteoarthritis Treatments_ A Systematic Review and Meta-Analysis of Randomized Trials | Elsevier Enhanced Reader.” Accessed April 6, 2022. https://doi.org/10.1016/j.semarthrit.2016.04.003.
El-Amawy, Heba Saed, and Sameh Magdy Sarsik. “Saline in Dermatology: A Literature Review.” Journal of Cosmetic Dermatology 20, no. 7 (2021): 2040–51. https://doi.org/10.1111/jocd.13813.
Popp, Lothar W. “Improvement in Endoscopic Hernioplasty: Transcutaneous Aquadissection of the Musculofascial Defect and Preperitoneal Endoscopic Patch Repair.” Journal of Laparoendoscopic Surgery 1, no. 2 (January 1991): 83–90. https://doi.org/10.1089/lps.1991.1.83.
Saltzman, Bryan M., Timothy Leroux, Maximilian A. Meyer, Bryce A. Basques, Jaskarndip Chahal, Bernard R. Bach, Adam B. Yanke, and Brian J. Cole. “The Therapeutic Effect of Intra-Articular Normal Saline Injections for Knee Osteoarthritis: A Meta-Analysis of Evidence Level 1 Studies.” The American Journal of Sports Medicine 45, no. 11 (September 1, 2017): 2647–53. https://doi.org/10.1177/0363546516680607.
Searle, Tamara, Firas Al-Niaimi, and Faisal R. Ali. “Saline in Dermatologic Surgery.” Journal of Cosmetic Dermatology 20, no. 4 (2021): 1346–47. https://doi.org/10.1111/jocd.13996.
Sharma, ReenaK, Mudita Gupta, and Ritu Rani. “Delineating Injectable Triamcinolone-Induced Cutaneous Atrophy and Therapeutic Options in 24 Patients—A Retrospective Study.” Indian Dermatology Online Journal 13, no. 2 (2022): 199. https://doi.org/10.4103/idoj.idoj_483_21.