Factors associated with resorption of calcific deposits in the shoulder with extracorporeal shock wave therapy

Focused extracorporeal shock wave therapy (FSWT) is effective for treating calcific tendinitis of the shoulder. However, only a few reports exist on the factors related to calcium resorption after FSWT. Thus, this study aimed to investigate the factors associated with calcium resorption. In 117 shoulders with chronic calcific rotator cuff tendinitis, FSWT was administered 9 times once every 2 weeks (a total of 16 weeks). After 9 sessions of FSWT, the shoulders were radiographed and categorized into complete resorption (CR) and incomplete resorption (ICR) groups. Evaluated parameters included age; duration of disease; Gärtner classification; size of calcium deposits; presence of blood flow around calcium deposits using the Doppler function of the ultrasound imaging system; Japanese Orthopaedic Association score; University of California at Los Angeles (UCLA) score; Disability of the Arm, Shoulder, and Hand score; and tenderness. The CR group included 93 shoulders (79.4%) and the ICR group included 24 shoulders (20.6%). In the two-arm comparison, CR showed significantly longer disease duration (P = .012) and high tenderness (P = .0013). Blood flow around calcium deposits was observed in 79.5% of shoulders in the CR group (P