What is Mild degenerative changes of the lumbar spine?

Mild degenerative changes of the lumbar spine will usually be in reference to disk space narrowing, but can also include the presence of osteophytes around the vertebral bodies or at the facet joints or hypertrophy of the facets.

This is a normal part of aging, and "mild degenerative changes" are found in almost everyone over the age of 60, but can also be commonly found in people somewhat younger.

Sometimes these changes can cause back pain, but it is difficult to attribute back pain to these changes directly because so many people have this degeneration. For example, 90% of people over the age of 60 years old will display some mild degenerative changes in their spine when viewed on x-ray or MRI, but only 10% of those people will have pain at a given point in time. Thus, is it the degeneration causing the pain? or another cause?