Editorial Commentary: Treatment Efficacy Found in Animal Studies May Not Translate to Humans

Abstract

Efficacy of low-intensity pulsed ultrasonography (LIPUS) has been demonstrated in several mammalian models of injury/repair of tendons, ligaments, and soft tissue-bone junctions. But human studies have not demonstrated benefit from such intervention. In addition to innate healing differences between humans and research animals, another reason for this outcome variance may be that animal investigations of LIPUS have so far focused on healing after acute intervention, whereas randomized clinical trials have only looked at treating chronic tendinopathy in symptomatic patients. On the basis of current animal data, potential clinical benefit of LIPUS is most likely to be demonstrated for addressing acute injuries or postoperative scenarios. Yet, a particularly important anatomic difference between humans and experimental land animals regarding ultrasonography is the presence of subcutaneous adipose in the former versus the lack thereof in the latter, especially in the extremities, because overlying adipose attenuates ultrasound waves directed at underlying injured, repaired, or reconstructed tissues.

Effects of Low‐Intensity Pulsed Ultrasound in Tendon Injuries

“…In addition, some of the efficacy of LIPUS has been demonstrated in animal models by reading them in vivo, in vitro (Table 2), and in clinical literature (Table 3), but the effects demonstrated in animals have not been demonstrated in human studies to provide benefits of this intervention. In addition to innate healing differences between humans and animals, another reason for this difference in outcomes may be that animal studies of LIPUS to date have focused on healing following acute interventions, whereas randomized clinical trials have only looked at treating symptomatic patients of chronic tendinopathy 71 . Future clinical trials also need to observe the efficacy of LIPUS on acute tendon injury to verify whether the effect in animal models has a role in clinical treatment, so as to better guide the use of clinical LIPUS.…”

“…In addition to innate healing differences between humans and animals, another reason for this difference in outcomes may be that animal studies of LIPUS to date have focused on healing following acute interventions, whereas randomized clinical trials have only looked at treating symptomatic patients of chronic tendinopathy. 71 Future clinical trials also need to observe the efficacy of LIPUS on acute tendon injury to verify whether the effect in animal models has a role in clinical treatment, so as to better guide the use of clinical LIPUS.…”