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Updated: Aug 9, 2025
The Monoiodoacetate Model of Osteoarthritis Pain in the Mouse
Published on: May 16, 2016
Pathological Characteristics of Monosodium Iodoacetate-Induced Osteoarthritis in Rats
Minji Kwon1,2, Dongyeon Nam1, Junesun Kim3,4,5,6
1Rehabilitation Science Program, Department of Health Science, Graduate School, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea.
Background:
This study aimed to identify pain-related behavior and pathological characteristics of the knee joint in rats with monosodium iodoacetate (MIA)-induced osteoarthritis (OA).
Methods:
Knee joint inflammation was induced by intra-articular injection of MIA (4 mg/50 µL, n = 14) in 6-week-old male rats. Knee joint diameter, weight-bearing percentage on the hind limb during walking, the knee bending score, and paw withdrawal to mechanical stimuli were measured to evaluate edema and pain-related behavior for 28 d after MIA injection. Histological changes in the knee joints were evaluated using safranin O fast green staining on days 1, 3, 5, 7, 14, and 28 after OA induction (n = 3, respectively). Changes in bone structure and bone mineral density (BMD) were examined 14 and 28 d after OA (n = 3, respectively) using micro-computed tomography (CT).
Results:
The knee joint diameter and knee bending scores of the ipsilateral joint significantly increased 1 d after MIA injection, and the increased knee joint diameter and knee bending score persisted for 28 d. Weight-bearing during walking and paw withdrawal threshold (PWT) decreased from 1 and 5 d, respectively, and were maintained up to 28 d after MIA. Cartilage destruction started on day 1, and Mankin scores for bone destruction significantly increased for 14 d, as shown by micro-CT imaging.
Conclusion:
The present study demonstrated that histopathological structural changes in the knee joint due to inflammation started soon after MIA injection, which induced OA pain from inflammation-related acute pain to spontaneous and evoked associated chronic pain.
Insights
Monosodium iodoacetate injection in rats rapidly induced osteoarthritis (OA) and associated knee pain. This model shows early inflammation and progressive cartilage destruction, mimicking chronic OA pain development.
Area of Science:
- Biomedical Science
- Orthopedics
- Pain Research
Background:
- Osteoarthritis (OA) is a degenerative joint disease characterized by cartilage breakdown and inflammation.
- Animal models are crucial for understanding OA pathogenesis and evaluating potential treatments.
Purpose of the Study:
- To characterize the pain-related behaviors and pathological changes in the knee joint of rats induced by monosodium iodoacetate (MIA).
- To establish a reliable rat model for studying osteoarthritis and its associated pain.
Main Methods:
- Osteoarthritis was induced in male rats via intra-articular injection of MIA.
- Pain-related behaviors (edema, weight-bearing, mechanical allodynia) and joint pathology (histology, micro-CT) were assessed over 28 days.
Main Results:
- MIA injection led to significant increases in knee joint diameter and bending scores, persisting for 28 days.
- Reduced weight-bearing and paw withdrawal thresholds indicated pain, starting from day 1 and day 5, respectively.
- Histological analysis revealed rapid cartilage destruction from day 1, with significant bone destruction evident by day 14.
Conclusions:
- MIA-induced OA in rats rapidly triggers inflammation and pathological changes in the knee joint.
- This model effectively replicates the transition from acute inflammatory pain to chronic pain associated with osteoarthritis.
