Females and males exhibit similar functional, mechanical, and morphological outcomes in a rat model of posttraumatic elbow contracture

Capsule release surgery temporarily reduces contracture in a rat elbow model of arthrofibrosis

Elbow trauma can lead to joint contracture and reduced range of motion (ROM). Nonsurgical interventions can improve ROM, but in some cases capsule release surgery is required. Although surgery can improve ROM, it often does not restore full ROM. Thus, alternatives are needed. One approach is to target activated myofibroblasts, which are commonly associated with fibrotic tissue. Mechanical and biochemical cues drive a feedback loop that can result in normal or pathological healing. We hypothesize that this feedback loop exists in joint contracture and can be manipulated so that myofibroblast activity is reduced, normal healing is achieved, and ROM is improved. We previously demonstrated that blebbistatin can inhibit myofibroblast contractile forces and reduce collagen synthesis in vitro. Thus, the purpose of this study was to assess the use of blebbistatin in an animal model of elbow contracture, which was induced in 7 groups of 4 rats each (n = 28). All elbows were mechanically and histologically tested. The uninjured contralateral elbows of each rat were used as a control group. Capsule release surgery significantly improved (p < 0.01) outcomes 1 week after surgery compared to injury alone and was not significantly different from uninjured elbows. Three weeks after surgery, outcomes worsened, indicating joint stiffening consistent with what is observed clinically. The addition of blebbistatin did not significantly improve outcomes. Future work will investigate relationships among treatment, fibrotic tissue deposition, myofibroblast activity, and biomechanics to determine if blebbistatin is a useful adjunctive therapy for treating joint contracture.

Time-Series Expression Profile Analysis of Post-Traumatic Joint Contracture in Rats at the Early Stages of the Healing Process

Objective

This study aimed to characterize the gene expression profile at the early stages of the healing process of post-traumatic joint contracture (PTJC).

Methods

Twelve rats were used for PTJC model establishment and were divided into four groups according to the sampling time: S0d, S3d, S7d and S2w. Transcriptome sequencing was performed on fibrotic joint capsule samples in four groups followed by bioinformatics analyses including differentially expressed genes (DEGs) screening, Short Time-series Expression Miner (STEM) analysis, network construction, and pathway analysis. Five important genes were validated by qRT-PCR.

Results

A total of 1171, 1052 and 793 DEGs were screened in S3d vs S0d, S7d vs S0d, and S2w vs S0d comparison groups, respectively. A total of 383 overlapping genes were screened out, which were significantly enriched in some inflammatory functions and pathways. Through STEM analysis, three clusters were identified, including 105, 57 and 57 DEGs, respectively. Then, based on the cluster genes, 10 genes, such as Il6, Timp1, Cxcl1, Cxcr4 and Mmp3, were further selected after PPI and pathway analyses. The expression levels of Il6, Timp1, Cxcl1, Cxcr4 and Mmp3 were validated by qRT-PCR.

Conclusion

The present study screened out several genes with significant changes in expression levels at the early stages of the healing process in PTJC, such as Il6, Timp1, Cxcl1, Cxcr4 and Mmp3. Our study offers a valuable contribution to the understanding pathomechanism of PTJC.

Pleiotropic Effects of Simvastatin and Losartan in Preclinical Models of Post-Traumatic Elbow Contracture

Elbow trauma can lead to post-traumatic joint contracture (PTJC), which is characterized by loss of motion associated with capsule/ligament fibrosis and cartilage damage. Unfortunately, current therapies are often unsuccessful or cause complications. This study aimed to determine the effects of prophylactically administered simvastatin (SV) and losartan (LS) in two preclinical models of elbow PTJC: an in vivo elbow-specific rat injury model and an in vitro collagen gel contraction assay. The in vivo elbow rat (n = 3-10/group) injury model evaluated the effects of orally administered SV and LS at two dosing strategies [i.e., low dose/high frequency/short duration (D1) vs. high dose/low frequency/long duration (D2)] on post-mortem elbow range of motion (via biomechanical testing) as well as capsule fibrosis and cartilage damage (via histopathology). The in vitro gel contraction assay coupled with live/dead staining (n = 3-19/group) evaluated the effects of SV and LS at various concentrations (i.e., 1, 10, 100 µM) and durations (i.e., continuous, short, or delayed) on the contractibility and viability of fibroblasts/myofibroblasts [i.e., NIH3T3 fibroblasts with endogenous transforming growth factor-beta 1 (TGFβ1)]. In vivo, no drug strategy prevented elbow contracture biomechanically. Histologically, only SV-D2 modestly reduced capsule fibrosis but maintained elevated cellularity and tissue hypertrophy, and both SV strategies lessened cartilage damage. SV modest benefits were localized to the anterior region, not the posterior, of the joint. Neither LS strategy had meaningful benefits in capsule nor cartilage. In vitro, irrespective of the presence of TGFβ1, SV (≥10 μM) prevented gel contraction partly by decreasing cell viability (100 μM). In contrast, LS did not prevent gel contraction or affect cell viability. This study demonstrates that SV, but not LS, might be suitable prophylactic drug therapy in two preclinical models of elbow PTJC. Results provide initial insight to guide future preclinical studies aimed at preventing or mitigating elbow PTJC.

Computer Intelligent Algorithm in the Recovery of the Elbow Joint Sports Injury Model

In this study, the inverse kinematics mathematics computer intelligent algorithm model is used to study the sports injuries of the elbow joint of adolescents. At the same time, we simulated the movement parameter changes during the rehabilitation training of the patient's wrist and proposed a joint angular velocity function based on cubic fitting. Research has found that when the training scene changes greatly or the target task is changed, the smoothness of the elbow joint movement will change. The research conclusions of this article provide a theoretical basis for the selection of man-machine action points and the formulation of rehabilitation training methods. This article establishes the degree-of-freedom simulation model of the operating arm, which is the number of independent position variables in the operating arm, and these position variables determine the positions of all parts in the mechanism.

Investigating the Effects of Physical Therapy Timing, Intensity and Duration on Post-Traumatic Joint Contracture in a Rat Elbow Model

BACKGROUND

Post-traumatic joint contracture (PTJC), characterized by loss of motion and permanent stiffness, affects up to 50% of patients following elbow joint dislocation or fracture. Mechanisms governing successful conservative treatment methods aimed at preventing elbow PTJC and avoiding operative treatments (e.g., physical therapy) are poorly understood. Using a previously established rat model of elbow PTJC, the purpose of this study was to explore the effect of varying timing, intensity and duration of active, functional exercise on joint motion outcomes.

METHODS

Following a surgically-induced unilateral elbow dislocation in rats, injured limbs were immobilized in bandages for 42 days followed by free mobilization for 42 additional days producing long-term PTJC. This work summarizes several studies (Phases I-III) that investigated the effects of early versus delayed therapy (timing), free mobilization versus forced treadmill walking (intensity), and limited-time versus unlimited use (duration) on elbow PTJC.

RESULTS

Joint motion outcomes in therapy groups showed no improvements compared to non-treated injured animals when therapy began day 14 post-injury or later regardless of timing, intensity or duration. Improved joint range-of-motion was only achieved when bandages were permanently removed at day 3 post-injury, regardless of whether added treadmill walking was performed.

CONCLUSION

Early motion is essential to preserving range-of-motion following traumatic elbow injury in a rat model.