Kalli has been having back stiffness and pain. She has recently noticed that she is having trouble turning her neck from side to side. Which disorder does Kalli most likely have?

Ankylosing spondylitis causes inflammation and stiffness in the spine, which can limit movement over time. Kalli’s back pain and difficulty turning her neck fit this pattern. Fibrous dysplasia, psoriasis, and osteoporosis do not typically cause this combination of spinal stiffness and reduced neck mobility.

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