Targeted care for chronic plantar heel pain: Shockwave therapy for bone marrow lesions (the BALSA trial)

Shockwave & advice Three sessions of radial shockwave, directed at the plantar calcaneus, will be provided at weekly intervals, delivered using the same branded machine (EMS Swiss DolorClast Master Touch). Visualising the bone marrow lesion (BML) location on MRI is not required as all lesions must be in a plantar location and therefore accessible to topical shockwave application. However shockwave application will be directed to the most painful aspect of the plantar heel, marked prior to application with an indelible pen. Each session will last less than 20 minutes and details of treatment (machine settings, total session energy dose, maximum energy intensity, participant response) will be recorded on a treatment log for each participant. Treatment parameters will be as per industry (EMS) and societal recommended guidelines (International Society for Medical Shockwave Treatment, ISMST) with intensity ranging from 2-4 bar pressure for a minimum of 2000 pulses using a 15mm diameter applicator head, at a frequency ranging from 4-10Hz based on comfort. As is standard clinical practice, the intent is to deliver the highest tolerable energy based on a progressive increase in bar pressure, a term referred to by ISMST as ‘pain-adapted dosing’. As well as aiming for maximum bar pressure, we will seek to deliver a minimum total energy treatment dose across all 3 sessions. For this study for the purpose of quantifying a per protocol energy dose, we will target a minimum total energy dose of 500 mJ/mm^2. The Master Touch unit can convert bar pressure into energy flux density (mJ/mm^2), which when multiplied by the number of pulses delivered, computes the total sessional energy dose. To reach 500 mJ/mm^2 across 3 sessions, an average bar pressure above 2.2 is required. This places this dose in a clinically therapeutic range. If it is evident that the cumulative dose is going to be short of the targeted 500 mJ/mm^2, the clinician may increase the number of pulses in subsequent sessions (e.g. to 2500), however the priority is always to deliver the maximum peak energy dose. If participants do not receive the minimum dose across the 3 sessions, a 4th ‘top-up’ session will be offered. If a top-up session is required, this will be matched with a top-up session to an equal number of participants in the sham group. Sessions will be booked in consecutive weeks in advance however we will allow missed sessions to be caught up with treatment gaps not exceeding 2 weeks. An advice sheet detailing flare management, footwear and activity recommendations will be provided to both groups.