Curves in the spine are called scoliosis. They need to be detected & treated in childhood, before growth stops in mid-teens. Large curves that had not been found, or were treated with older methods, may keep curving into adulthood.
However, such curves don’t tend to cause much back pain, though they can interfere with lung function. The spine can also curve from fractures due to osteoporosis, or injuries. We suspect Scoliosis on physical exam, standing behind the patient and watching them bend forward. If one shoulder rises, the test is positive. Diagnosis is easy by x-ray. Surgical treatment only works well if done before growth stops, in mid-teenage years. In very rare cases, they can compress the spinal cord, which requires emergency surgery (see Spinal Cord Diseases).