The reasons why a rabbit walks with one hind leg hanging in the air:

1. Fracture. A rabbit's hind legs may fracture after suffering trauma, resulting in the rabbit's legs being unable to move normally and causing one hind leg to walk in the air.

2. Soft tissue contusion. Direct or indirect violence to the soft tissue or skeletal muscles of the rabbit's hind legs will cause soft tissue contusion and the phenomenon of walking backwards and hanging in the air.

3. Dislocation. Excessive force when catching a rabbit, intense sports injuries, legs stuck in the cage, etc. can cause dislocation of the hind legs and the behavior of walking in the air.

Solutions to a rabbit walking with one hind leg hanging in the air:

1. The owner needs to take the rabbit to the pet hospital for imaging examination. If it is caused by a fracture, Treatment is by cast immobilization or surgery.

2. If it is caused by soft tissue injury, it needs to be treated with drugs that promote blood circulation and remove blood stasis.

3. If it is a dislocation, massage it back into place and then wrap it up with a towel or gauze.