Shockwave application in calcifying tendinitis of the shoulder--prediction of outcome by imaging

This prospective study examined 62 patients (65 shoulders) with chronic courses of calcifying tendinitis of the shoulder before and after low-energy extracorporeal shockwave application (ESWA) in order to identify variables associated with the outcome of this treatment. Before ESWA, radiographs and contrast-enhanced magnetic resonance imaging (MRI) of the affected shoulders were obtained in order to document the size and morphology of the calcifications and the contrast media reactions in areas of interest (deposit, synovia, bursae), respectively. In addition, a clinical evaluation was performed. After ESWA (mean follow-up 18.2 months), clinical evaluations of all 65 shoulders revealed an increase in the Constant score from 44% to 78% (p < 0.0001). While size (p = 0.61) and morphology (p = 0.7) of the deposits before ESWA were not associated with the clinical outcome, negative contrast reactions around the deposits (p) = 0.0001), synovia (p = 0.0049) and bursae (p < 0.01) were associated with improved clinical outcomes. After the total study group was divided into two groups, one with Constant scores > or = 75% (n = 43) and the other with scores < 75% (n = 22), the positive predictive value (ppv), specificity (sp) and sensitivity (se) were determined for the negative reaction around the deposit (ppv: 0.94; sp: 0.95; se: 0.38), synovia (ppv: 0.84; sp: 0.82; se: 0.49) and bursae (ppv: 0.86; sp: 0.86; se: 0.44). In 5 cases (7.7%), surgery of the affected shoulder during the follow-up period was performed. No major side-effects were seen in the study group. In conclusion, our results suggest that in patients with chronic calcifying tendinitis, the absence of contrast enhancement, especially around the deposit, is a strong predictive parameter of a positive clinical outcome of ESWA.