Hind limb weight-bearing
The weight bearing test is based on the animal’s tendency to avoid pain by shifting its weight from the (right) hind limb with the painful, MIA-injected knee to the contralateral (left) limb with the healthy knee. Changes in weight distribution between the limbs were measured with an incapacitance tester (Incapacitance Tester Librae - for Mice and Rats, Ugo Basile, Milan, Italy). Rats were placed in an angled Plexiglas chamber that allowed them to lean on their hind paws via two separate force pads. Once the animal had settled, five measurements of the forces exerted by the hind limbs (in grams) were recorded and the average value was used in the analysis. The results were presented as a percentage of the weight distributed on the ipsilateral hind paw, calculated according to the following equation: [weight on the right hind paw/(weight on the right hind paw + weight on the left hind paw)] × 100.