"Obviously, the skeleton was flattened out when it was in the ground," Appleby said in a statement. "We had a good idea of the sideways aspect of the curve, but we didn't know the precise nature of the spiral aspect of the condition."
Scoliosis can be caused by muscular imbalances that pull the spine out of alignment, but the rest of Richard III's skeleton showed no evidence of such problems, Appleby and her colleagues found. Nor were there any malformed hemivertebrae, which are wedge-shaped vertebrae that can cause the spine to twist and turn.
Instead, the researchers concluded, Richard III likely had adolescent-onset idiopathic scoliosis. Idiopathic means the cause is unknown, which is the case in the majority of people with scoliosis. The abnormal curve probably appeared in Richard after age 10.
The curve itself had a spiral appearance, and an angle that would be considered large today. Doctors use a measurement called the Cobb angle to gauge spine deformity. On an X-ray, they draw a line outward from the top of the highest vertebra on the curve and then do the same for the bottom of the lowest vertebra. They then measure the angle where the two lines meet. Richard III's Cobb angle was between 70 degrees and 90 degrees in life, the researchers determined.