Effects of Risk Factors on Evoked Pain Patterns in Rat Models of Experimental Knee Osteoarthritis

This study compared evoked pain behaviors and joint pathology across three rat models of knee osteoarthritis driven by distinct risk factors: acute joint trauma, chronic joint instability, and metabolic syndrome. Using longitudinal behavioral testing and detailed histopathological analysis, the authors demonstrated that pain intensity, onset, and distribution varied significantly depending on the initiating risk factor and were inconsistently associated with structural joint damage. Acute mechanical trauma produced the earliest and most severe pain responses, while metabolic syndrome induced delayed but persistent pain despite minimal cartilage degeneration. These findings highlight the complexity of osteoarthritis pain mechanisms and underscore the importance of selecting risk-factor-appropriate preclinical models.