That is a severe case of Metabolic Bone disease. Poor guy will either die soon or be handicapped and deformed the rest of it's life. Happens from lack of UVB exposure. The animal could not process calcium needed for healthy bone growth and caused the joints in it's spine ad other spots of the skeleton to be malformed. Animals with MBD will usually exhibit tremors, soft jaw, humpback spine, s-curved tails and inability to use some limbs. If caught early most animals can be corrected with extra calcium/d3 and husbandry corrections. Very sad.