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* These authors contributed equally
This protocol presents an in vivo rat model of adhesive capsulitis. The model includes an internal fixation of the glenohumeral joint with extra-articular suture fixation for an extended time, resulting in a decreased rotational range of motion (ROM) and increased joint stiffness.
This proposal aims to create an in vivo rat model of adhesive capsulitis for researching potential treatment options for this condition and other etiologies of comparable arthrofibrosis. The model includes extra-articular fixation of the shoulder in rats via scapular to humeral suturing, resulting in a secondary contracture without invading the intra-articular space and resulting in decreased rotational ROM and increased joint stiffness.
We used 10 Sprague-Dawley rats for the purpose of this study. Baseline ROM measurements were taken before glenohumeral immobilization. The rats were subjected to 8 weeks of immobilization before the fixation sutures were removed and changes in ROM and joint stiffness were evaluated. To evaluate whether immobilization resulted in a significant reduction in ROM, changes in kinematics were calculated. ROM was measured at each time point in the follow-up period and was compared to the baseline internal and external ROM measurements. In order to evaluate the stiffness, joint kinetics were calculated by determining the differences in torque (text and tint ) needed to reach the initial external rotation of 60° and initial internal rotation of 80°.
After the removal of the extra-articular suture fixation on follow-up day 0, we found a 63% decrease in total ROM compared to baseline. We observed continuous improvement until week 5 of follow-up, with the progress slowing down around a 19% restriction. On week 8 of follow-up, there was still an 18% restriction of ROM. Additionally, on follow-up day 0, we found the torque increased by 13.3 Nmm when compared to baseline. On week 8, the total torque was measured to be 1.4 ± 0.2 Nmm higher than initial measurements. This work introduces a rat model of shoulder adhesive capsulitis with lasting reduced ROM and increased stiffness.
Adhesive capsulitis of the shoulder is frequently referred to as frozen shoulder or shoulder contracture. It is characterized by restricted glenohumeral motion and pain, presumably as a result of advanced fibrosis and joint contracture1,2,3. The condition involves fibroblast and myofibroblast cell recruitment with a resultant dense collagen matrix (types I and III) in the joint capsule2,3. There are many possible risk factors for developing a joint contracture, including gender, diabetes mellitus, hyperthyroidism, traumatic injury, and prolonged immobilization4,5,6.
Effective treatment options are lacking and mostly include physical therapy, with intervention in the form of surgical release in extreme cases that have not improved with conservative care. The best treatment method remains undetermined and has been a subject of great interest for years in the medical field7,8. Development of novel therapeutic options will require a reproducible animal model for the condition that does not rely on intra-articular induced trauma. The optimal adhesive capsulitis model should involve the two main characteristics of the disease: contracture of the shoulder capsule and a prolonged reduction in range of motion (ROM). Schollmeier et al.9 described one of the first joint contracture models by using a cast to develop shoulder contracture in canines. They also reported that changes in ROM and intra-articular pressure returned to normal levels after cessation of immobilization9. However, an important limitation mentioned in the study is the variation in limb position between animals because of the use of a cast technique.In order to obtain a more reproducible model, Kanno et al.10 later presented an adhesive capsulitis rat model using rigid internal fixation of the shoulder. However, although they achieved a significant reduction in ROM with their model, they did not state whether these changes were temporary or long lasting. The aim of our study was to create a suitable in vivo shoulder contracture rat model by investigating the effect of prolonged extra-articular glenohumeral joint immobilization on ROM and joint stiffness.
The study was approved by the Institutional Animal Care and Use Committee at Beth Israel Deaconess Medical Center. Care was taken to avoid unnecessary prolonged anesthesia and also to avoid hypothermia. Animals were weighted at each ROM measurement session and monitored for weight loss.
1. Study Subjects
2. Surgical Procedure
3. Closing the Incision
4. Suture Removal 8 Weeks After Immobilization
5. Range of Motion and Joint Stiffness Measurements
6. Post-mortem Immunohistologic Analysis
Range of motion
On follow-up day 0, we found a 63% decrease in total ROM compared to baseline (P < .001). We observed a gradual improvement of ROM until week 5 of follow-up, when progression stopped at 19% restriction (P <0.001). The remaining restriction, 18% of total ROM, was still apparent at 8 weeks of follow-up (P <0.001).
Stiffness
This study presents a rat model of adhesive capsulitis of the shoulder through internal fixation of the glenohumeral joint. Furthermore, it shows an extended reduction of total ROM for at least 8 weeks after removal of the fixation. In order to calculate the alterations in ROM at different time points, measurements were compared to animal specific baselines. Conversely, Kanno et al.10 used a standardized torque for all of the animals in order to determine ex vivo ROM changes...
None
The Authors would like to acknowledge Mr. and Mrs. Tom and Phyllis Froeschle for providing financial support towards this project.
Name | Company | Catalog Number | Comments |
Sprague-Dawley rats | Charles River Laboratories, Wilmington, MA, USA | 250-300 g | |
Surgical tool: | |||
Injection needle | BD 1' 30 guage | ||
Needle holder | |||
5% isoflurane | |||
2% isoflurane | |||
Nose cone | |||
Skalpel and skalpel holder | No. 11 scalpel | ||
Curved hemostat forceps | |||
Staright hemostat forceps | |||
Tissue retractor | |||
Toothed tissue forceps | |||
Plain tissue forceps | |||
Dissecting scissors | |||
Suture scissors | |||
Skin clip applicator | Any standard staples for wound closure | ||
Immobilization material | Ethicon | No. 2-0 braided polyester ethibond suture was used for immobilization | |
Other materials: | |||
Costumized device for ROM: 1)Sensor assembly, 2)pivoting axle, 3)arm clamp | Assembly that is described in relaxin paper and adhesive capsulitis paper | ||
Orientation sensor (part of sensor assembly) | MicroStrain Inc., Williston, VT, USA | 3DM-GX3-15 | |
Reaction torque sensor (part of sensor assembly) | Futek Inc., Irvine, CA, USA | TFF400 | |
Stepper Motor | SparkFun Electronics, Niwot, CO 80503 | https://www.sparkfun.com/products/13656 | |
Microcontroller | Torino, Italy). | Arduino UNO, R3 | |
MATLAB code | MATLAB 7.13.0.564, Natick, Ma, USA | ||
Weight Scale | Ohaus |
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