Abstract

Background. The Shoulder Pain and Disability Index (SPADI) is a common patient-reported outcome for frozen shoulder. However, the correlation between SPADI and objective range of motion (ROM), especially during the frozen stage, is not fully understood. Clarifying these relationships can enhance clinical assessment and rehabilitation.

Methods. This cross-sectional study investigated patients with frozen-stage frozen shoulder. Passive ROM (flexion, extension, abduction, external rotation [ER] at 0° and 45°, internal rotation [IR] at 45°) and SPADI total, pain, and function subscale scores were assessed. Pearson correlation coefficients determined the strength and significance of associations between SPADI and ROM.

Results. Significant moderate to strong negative correlations were found between higher SPADI total scores and reduced ROM: ER at 0° (r = −0.458, p = 0.002), IR at 45° (r = −0.507, p < 0.001), flexion (r = −0.567, p < 0.001), abduction (r = −0.380, p = 0.010), and extension (r = −0.298, p = 0.047). The SPADI function subscale showed similarly strong correlations across all ROM directions, notably ER at 45° (r = −0.572, p < 0.001). SPADI pain had weaker correlations, significant only with IR at 45° (r = −0.308, p = 0.040) and flexion (r = −0.459, p = 0.001). ER at 45° strongly correlated with ER at 0° (r = 0.852, p < 0.001), indicating its broader relevance.

Conclusions. The observed correlations generally support the construct validity of SPADI as a functional measure sensitive to physical limitations in patients with frozen shoulder.

Key words

frozen shoulder, SPADI, shoulder ROM