From the Guidelines
The lumbar region of the spinal column is the most prevalent area for bulges and protrusions, with a significant increase in disc protrusion prevalence from 29% in those 20 years of age to 43% in those 80 years of age, as reported in a systematic review of 33 articles 1.
Prevalence of Disc Abnormalities
The lumbar spine is more prone to disc abnormalities due to its larger vertebrae, greater weight-bearing capacity, and increased mechanical stress. The L4-L5 and L5-S1 levels are particularly susceptible to bulges and protrusions because they allow for significant movement while bearing substantial loads.
Age-Related Degeneration
Age-related degeneration is a significant factor in the development of disc abnormalities, with studies showing an increasing prevalence of degenerative spine findings in asymptomatic patients of increasing age 1. A prospective study by Carragee et al found that among patients with lumbar imaging abnormalities before the onset of LBP, 84% had unchanged or improved findings after symptoms developed, highlighting the complexity of diagnosing and managing disc abnormalities 1.
Clinical Implications
The high prevalence of disc abnormalities in the lumbar region has significant implications for clinical practice, with routine imaging providing no clinical benefit in patients with acute, uncomplicated low back pain 1. The majority of disc herniations show some degree of reabsorption or regression by 8 weeks after symptom onset, further emphasizing the importance of conservative management and careful consideration of imaging studies 1.
From the Research
Prevalence of Bulges and Protrusions in the Spinal Column
- The region of the spinal column most prevalent for bulges and protrusions is the lumbar region, as evident from various studies 2, 3, 4, 5.
- A study published in 2015 found that lumbar disc protrusion is common, and its clinical manifestations and treatments are closely related to the pathological changes 2.
- Another study published in 1994 found that 52% of asymptomatic subjects had a bulge at at least one level, and 27% had a protrusion, with the prevalence of bulges increasing with age 3.
- A 2023 study compared the effectiveness of epidural steroid injections in patients with disc bulging and disc protrusion, and found that both conditions benefited from the treatment, with significant decreases in VAS and ODI scores 4.
Anatomical Factors Involved in Lumbar Region
- The integrity of the vertebral body in the lumbar region is multifactorial, involving morphology, development, genetics, microscopic examination, structural architecture, blood supply, neuromuscular control, and biomechanics 6.
- The lumbar lordosis and the design of the vertebral body provide optimal load transfer by maximal strength with minimal weight, and bone mineral density, bone quality, microarchitecture, and material properties contribute to bone strength 6.
- A study published in 1999 found that loss of intervertebral height or abnormal signal intensity on magnetic resonance imagery was significantly associated with disc disruptions extending into or beyond the outer anulus on discograms 5.
Differentiating Lumbar Disc Protrusions and Bulges
- Disc bulges and disc protrusions do not represent discs with significantly different internal architecture, based on the findings of discography, and are no more suggestive of symptomatic tears than discs showing normal contour but decreased height or abnormal signal intensity 5.
- The validity of the nomenclature used to describe lumbar disc protrusions, disc bulges, and discs with normal contour but abnormal signal intensity remains unknown, with moderate interobserver agreement reported when using morphologic terms 5.