The reasons why the patient’s right foot dorsum feels a little numb are as follows: 1. Peripheral nerve injury or entrapment: When the head of the fibula is fractured, the common peroneal nerve can be injured, and the branch of the common peroneal nerve is the superficial scarlet nerve, and the superficial scarlet nerve can innervate the sensation of the skin on the dorsum of the foot, and numbness of the skin on the dorsum of the foot can occur when the common peroneal nerve is injured. When the knee fracture is fixed in a cast, the cast may compress the common peroneal nerve that passes through the head of the fibula if it is not fixed properly, so numbness of the dorsum of the foot and foot drop may also occur. 2, lumbar disc protrusion: when the protruding disc tissue compresses the lumbar 5 nerve root, skin sensation numbness of the dorsum of the foot will occur.