Castor oil decreases pain during extracorporeal shock wave application

In a prospective single-blind study the contact media ultrasound gel, vaseline and castor oil were examined for their effect on surface pain caused by extracorporeal shock waves used for tendinosis calcarea (n = 25), radiohumeral epicondylitis (n = 23) and plantar heel spur (n = 12). A total of 60 patients was divided into six groups. Using a Compact S shockwave source (Dornier MedTech), an energy flux density up to 0.12 mJ/mm2 was applied three times within 3 weeks. Independent of the diagnosis, there was a statistically significant influence of the contact medium on the intensity of application pain. In this comparison castor oil was best. For the diagnosis of tendinosis calcarea and plantar heel spur, castor oil was significantly better than the other two contact media, while for epicondylitis there was no significant difference. Castor oil was found to have an advantage over ultrasound jelly and vaseline in all indications used with regard to application pain. The positive effect of castor oil can be explained by its cavitation-free quality.