Interobserver Concordance in the Classification of Rotator Cuff Calcific Tendinopathy

Purpose: Percutaneous ultrasound-guided needle lavage is a therapeutic alternative for calcific tendinopathy of the shoulder. However, there is no consensus about its indications or validated classifications of calcium types. The objective of this study was to assess the interobserver concordance in the proposed calcification classification by Gartner and Hayer (types I, II, and III).

Methods and Materials: Two musculoskeletal radiologists with > 5 years of experience evaluated in two stages (separated by an interval of 3 months) independently and consecutively the radiographs and ultrasounds of 22 patients with calcific tendinopathy. Data were collected for both techniques regarding the type of calcium (Gartner and Hayer classification) and its size. We included a type IV ultrasound classification type when the calcifications were linear, fragmented, or residual. In the statistical analysis, the interobserver correlation was studied using the κ coefficient for the type of calcium and the intraclass correlation coefficient (ICC) for size.

Results: The analysis of the data revealed good interobserver agreement regarding the type of calcium and size, both in radiography (κ: 0.6; ICC: 0.9) and in ultrasound (κ: 0.5; ICC: 0.9). The results improved in the second evaluation (κ: 0.8; ICC: 0.8, and κ: 0.7; ICC: 0.9 for radiography and ultrasound, respectively).

Conclusion: The Gartner and Hayer method to classify the type and size of calcium offers good interobserver correlation in the hands of experienced radiologists. Thus standardized therapeutics protocols could be accomplished with this classification.

Fig. 1 Ultrasound calcification classification by Gartner and Hayer.

Fig. 2 Contingency table TYPE_RX_B*TIPO_RX_W and symmetric measures.

Fig. 3 Contingency table TYPE_US_B*TIPO_US_W and symmetric measures.

Fig. 4 Case processing summary, reliability statistics, and intraclass correlation coefficient.

No conflict of interest has been declared by the author(s).

Publication History

Article published online:
17 December 2020