The disease-modifying effects of intra-articular corticosteroid injection at the freezing phase of frozen shoulder in an animal model

Abstract

Freezing phase of frozen shoulder is characterized by elevated inflammatory response. It is not known if the effects of intra-articular corticosteroid injection during the freezing phase are limited to transient suppression of inflammation, or if it exerts disease-modifying effects to prevent further progresion of the disease towards fibrosis. This study aimed to assess the disease-modifying effects of intra-articular corticosteroid administration at the freezing phase of frozen shoulder at preventing disease progression. 24 Sprague-Dawley rats were randomly divided into four groups (n=6 in each). Unilateral shoulders were immobillized for the first 3 days in all groups, followed by intra-articular corticosteroid injection in Group A, injection and cessation of immobilization in Group B, no further intervention in Group C, and cessation of immobilization in Group D. All rats were sacrificed in Week 3 of study, at which passive shoulder abduction angles were measured, and axillary recess tissues were retreived for histological, immunohistochemical and Western blot analyses. Passive shoulder abduction angles at sacrifice were 138.0° ± 7.8° (Group A), 145.7° ± 5.2° (Group B), 94.8° ± 11.2° (Group C), 132.2° ± 8.1° (Group D), and 157.8° ± 2.3° (Control). Group B did not show significnat difference from Control (P=0.069), showing that intra-articular corticosteroid injection at the freezing phase combined with remobilization restored shoulder range of motion to normal range. Histological assessment showed greater degree of fibrosis and inflammation in groups that did not receive corticosteroid injection (Groups C and D) compared to corticosteroid-injected groups (Groups A and B). Corticosteroid-injected groups showed no significant differences in semi-quantitative histological scores compared to healthy control, Western blot analyses showed similar expression levels of IL-1α and IL-1β in Group B and healthy control. Group A also showed significantly lower expression of IL-1α, IL-1β, TNF-α, TNF-β, and RAGE compared to Group C. These findings demonstrated the long-term anti-inflammatory and disease-modifying effects of corticosteroid injection at the freezing phase of frozen shoulder

Freezing phase of frozen shoulder is characterized by elevated inflammatory response. It is not known if the effects of intra-articular corticosteroid injection during the freezing phase are limited to transient suppression of inflammation, or if it exerts disease-modifying effects to prevent further progresion of the disease towards fibrosis. This study aimed to assess the disease-modifying effects of intra-articular corticosteroid administration at the freezing phase of frozen shoulder at preventing disease progression. 24 Sprague-Dawley rats were randomly divided into four groups (n=6 in each). Unilateral shoulders were immobillized for the first 3 days in all groups, followed by intra-articular corticosteroid injection in Group A, injection and cessation of immobilization in Group B, no further intervention in Group C, and cessation of immobilization in Group D. All rats were sacrificed in Week 3 of study, at which passive shoulder abduction angles were measured, and axillary recess tissues were retreived for histological, immunohistochemical and Western blot analyses. Passive shoulder abduction angles at sacrifice were 138.0° ± 7.8° (Group A), 145.7° ± 5.2° (Group B), 94.8° ± 11.2° (Group C), 132.2° ± 8.1° (Group D), and 157.8° ± 2.3° (Control). Group B did not show significnat difference from Control (P=0.069), showing that intra-articular corticosteroid injection at the freezing phase combined with remobilization restored shoulder range of motion to normal range. Histological assessment showed greater degree of fibrosis and inflammation in groups that did not receive corticosteroid injection (Groups C and D) compared to corticosteroid-injected groups (Groups A and B). Corticosteroid-injected groups showed no significant differences in semi-quantitative histological scores compared to healthy control, Western blot analyses showed similar expression levels of IL-1α and IL-1β in Group B and healthy control. Group A also showed significantly lower expression of IL-1α, IL-1β, TNF-α, TNF-β, and RAGE compared to Group C. These findings demonstrated the long-term anti-inflammatory and disease-modifying effects of corticosteroid injection at the freezing phase of frozen shoulder