Characterization of a frozen shoulder model using immobilization in rats

Abstract

BackgroundThe objective of this study was to investigate serial changes for histology of joint capsule and range of motion of the glenohumeral joint after immobilization in rats. We hypothesized that a rat shoulder contracture model using immobilization would be capable of producing effects on the glenohumeral joint similar to those seen in patients with frozen shoulder.MethodsSixty-four Sprague-Dawley rats were randomly divided into one control group (n = 8) and seven immobilization groups (n = 8 per group) that were immobilized with molding plaster for 3 days, or for 1, 2, 3, 4, 5, or 6 weeks. At each time point, eight rats were euthanized for histologic evaluation of the axillary recess and for measurement of the abduction angle.ResultsInfiltration of inflammatory cells was found in the synovial tissue until 2 weeks after immobilization. However, inflammatory cells were diminished and fibrosis was dominantly observed in the synovium and subsynovial tissue 3 weeks after immobilization. From 1 week after immobilization, the abduction angle of all immobilization groups at each time point was significantly lower than that of the control group.ConclusionsOur study demonstrated that a rat frozen shoulder model using immobilization generates the pathophysiologic process of inflammation leading to fibrosis on the glenohumeral joint similar to that seen in patients with frozen shoulder. This model was attained within 3 weeks after immobilization. It may serve as a useful tool to investigate pathogenesis at the molecular level and identify potential target genes that are involved in the development of frozen shoulder.

Intraarticular injection of relaxin-2 alleviates shoulder arthrofibrosis

“…4 B, II, black arrows). These results are consistent with those reported by Kim et al (47). The mIA group displayed a return to normal thickness in capsular tissue as well as a reduction in peroxidase intensity in and around the capsular tissue ( Fig.…”

“…In an established arthrofibrotic contracture model (40,47,69), treatment with multiple IA injections of relaxin-2 significantly improves total ROM, returning it to baseline levels measured before limb immobilization. A return to normal ROM is not observed with the sIA and mIV treatment groups, even though the sIA single dose was threefold greater than the single dose of the mIA, and the total mIV treatment dose was 340-fold greater in concentration than that of the total mIA dose.…”

“…Human relaxin-2 is expected to have biological, antifibrotic activity within the rat synovium due to its pleiotropic nature (49,50), its structural homology to rat relaxin-1, and the presence of RXFP1 receptors in the rat shoulder joint and periphery (SI Appendix, Fig. S7) (47,51). This human ortholog binds the rat RXFP1 more selectively and stimulates the antifibrotic cascade at a concentration two orders of magnitude less than its endogenous rat counterpart in vitro (52).…”

Shoulder adhesive capsulitis, treatment with oxygen ozone: Technique and results

“…Kim et al, 4 in a study on rats of 2016, reproduced the onset of adhesive capsulitis by immobilizing the shoulder of the animals for three days, with a molded plaster apparatus, 1, 2, 3, 4, 5, 6 weeks, sacrificing them sequentially and analyzing the samples of the capsule to have an exact verification of the development process of adhesive capsulitis.…”

“…It occurs in 2-5% of the general population, [2][3][4] predominantly among women, most commonly between the ages of 40 and 60. [5][6][7] Commonly, this pathology is considered as a self-limiting condition with a natural history that lasts from 1 to 3 years; 8 in some cases, however, a refractory course is reported, with persistent pain and/or movement limitation, in 15-50% of patients undergoing conservative treatment.…”