When a calcium deposit ruptures, acute pain often sets in. The calcium enters the bursa and causes severe inflammation, known as calcific bursitis.
The often large calcium deposits usually have a pasty consistency, similar to toothpaste. Shock wave treatment makes absolutely no sense at this highly acute stage. There's no "crushing" of the plaque, nor does the highly acute dissolution process need to be further fueled by massive inflammation to break down the calcium deposits.