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Updated: May 5, 2026
A Mini-Invasive Internal Fixation Technique for Studying Immobilization-Induced Knee Flexion Contracture in Rats
Published on: May 20, 2019
A novel method for establishing a rat model of knee osteoarthritis: knee joint fixation using medical polyurethane
Xiaowen Lian1,2, Maotao Mu3, Yaxin Zhuang1,2
1Rehabilitation Hospital Affiliated to Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian, China.
Background:
Knee osteoarthritis (KOA) is a leading cause of chronic pain and disability in humans, companion and farm animals, with socioeconomic burden and animal welfare concerns. KOA models are essential for advancing diagnostics, therapies, and preventive strategies. This study aimed to establish a reliable non-invasive rat KOA model and evaluate its translational value for comparative and clinical medicine.
Methods:
Twenty male Sprague-Dawley rats were randomly allocated to two groups: a model group (n = 10) and a control group (n = 10). KOA was induced in the model group by immobilizing the knee joint through circular fixation using a medical polyurethane composite bandage. Following the modeling phase, knee cartilage was macroscopically evaluated. Functional impairment was assessed using the Modified Lequesne MG scale. Imaging analyses comprised 7.0 T magnetic resonance imaging (MRI) and micro-computed tomography (Micro-CT) to examine structural and morphological alterations in the knee joint. The histological assessment included Safranin O-Fast Green staining to assess cartilage degradation using the Osteoarthritis Research Society International (OARSI) scoring system. Chondrocyte apoptosis was identified through terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining.
Results:
The examination of the knee joint cartilage in the model group revealed significant surface irregularities and roughness. Compared to the control group, the model group exhibited a notably higher Modified Lequesne MG score (P < 0.01), indicating compromised joint function. Imaging techniques such as high-field MRI and micro-CT confirmed typical osteoarthritic characteristics. Safranin O-Fast Green staining showed a substantial reduction in proteoglycans in the superficial cartilage layer of the model group, along with a significantly increased OARSI score (P < 0.01). TUNEL staining indicated a marked rise in chondrocyte apoptosis in the model group, with an approximately 4.8-fold higher rate compared to the control group (P < 0.01). The model induction success rate exceeded 95%, with a complication rate below 5%.
Conclusion:
We developed a non-invasive rat KOA model using polyurethane bandage immobilization that recapitulates cross-species progressive OA pathology. This robust, low-cost platform enables early biomarker screening, disease-modifying therapy evaluation, and preventive intervention validation for veterinary/human OA, highlighting its translational value for comparative and clinical medicine.
