Mend Physical Therapy Blog and Injury Information

Ultrasound The Ultimate Placebo Wand

March 12, 2020


Ultrasound is a therapeutic modality designed to attempt to warm injured tissues, increase circulation, and reduce pain through transmission of sound waves into the body. Initially utilized in middle of the 20th century and likely reaching its’ peak use in the 90s before President Clinton signed the balanced budget act (which included enforcement of Medicare and Medicaid reimbursement for Physical Therapy services). This modality can still be found in use today in some Physical Therapy practices often for 8-10 minutes at a time, or the least amount of time required to bill a unit of service. Prior to the advancement of the scientific evidence regarding the treatment of musculoskeletal pain it was understandable why this modality would be chosen to reduce a patient’s symptoms. In current practice, ultrasound and other modalities of its’ kind fall far behind more effective interventions including manual therapy, patient education, and exercise.

Given its’ popularity in clinical practice, educational instruction in our PT schools, and the sheer number of machines across the country it is stunning how little evidence, albeit low quality, has been conducted on its’ use. In particular, ultrasound’s ability to compete against natural history (control group) or a detuned ultrasound machine (placebo). We know the placebo is extremely powerful and can account for a significant portion of an intervention or drug’s therapeutic effect. Teasing out the true therapeutic effect requires the utilization of a three armed trial (intervention, placebo, and control) because if an intervention is truly valuable then it should significantly beat both natural history and the placebo (ex. an effective drug should significantly beat the sugar pill). The reviews on ultrasound in the clinical research call into question both its’ physiological effects and its’ clinical benefits with many authors reporting significant evidence on its’ lack of effectiveness. Given the supporting evidence most experts agree ultrasound adds little to no benefit to patient care. If a clinical effect is found we can attribute most of the benefit to the placebo and the clinician’s wishful thinking.