Causes of Low Back Arthritis
Low back arthritis in adults over 50 is primarily caused by age-related degenerative changes, with additional contributions from genetic predisposition, prior trauma, obesity, and occupational factors. 1
Primary Etiological Factors
Age-Related Degeneration
- Aging is the single greatest risk factor for osteoarthritis (OA), though it is not an inevitable consequence of growing old. 2
- Cell senescence develops with aging, resulting in a senescent secretory phenotype that contributes to joint degeneration. 2
- Advanced glycation end-products form in the joint matrix with aging, affecting the mechanical properties of joint tissues and increasing susceptibility to arthritis. 2
- Osteoarthritis affects 50% of those aged 65 and older, increasing to 85% in those 75 and older. 3
Genetic Predisposition
- There is a significant genetic component to the prevalence of knee and spinal OA, with heritability estimates from twin studies ranging from 0.39 to 0.65, independent of environmental or demographic factors. 1
- More than 300 genomic loci have been identified as associated with OA at different joints. 4
- The genetic influence on OA has been recognized for over 80 years and continues to be a major area of investigation. 4
Trauma and Mechanical Factors
- Prior joint trauma is a well-established local mechanical factor that increases the risk of developing arthritis in the affected area. 1
- Occupational and recreational overuse patterns contribute to mechanical stress on spinal joints. 1
- Anatomical factors that affect joint mechanics, including spinal alignment abnormalities, increase susceptibility to degenerative changes. 1
Obesity
- Obesity is a major constitutional risk factor for OA development, acting through both mechanical loading and systemic inflammatory mechanisms. 1
- Weight is critical enough that weight loss is recommended as a first-line intervention for overweight patients with symptomatic OA. 3
Multifactorial Nature
Constitutional vs. Local Factors
- The etiology of low back arthritis is multifactorial, including both generalized constitutional factors (aging, sex, obesity, heredity, reproductive variables) and local adverse mechanical factors (trauma, occupational usage, alignment). 1
- The joints affected and the severity of disease are most closely related to specific OA risk factors such as joint injury, obesity, genetics, and anatomical factors rather than age alone. 2
Important Clinical Considerations
- Radiographic changes of OA are common in the aged population, but symptoms of joint pain may be independent of radiographic severity in many older adults. 2
- Degenerative changes on lumbar imaging correlate poorly with symptoms and are usually considered nonspecific. 5
- Nearly 50% of Americans aged 65 and above have been diagnosed with arthritis, and an estimated 80% of adults experience low back pain. 6
Common Pitfalls to Avoid
- Do not assume that radiographic degenerative changes automatically explain a patient's symptoms, as the correlation between imaging findings and clinical symptoms is often poor. 5, 2
- Avoid attributing symptoms solely to spinal pathology without considering referred pain from hip osteoarthritis, especially if spinal radiographs are unremarkable. 3, 7
- Do not dismiss symptomatic osteoarthritis as simply "normal aging"—the American Geriatrics Society explicitly rejects this notion. 3