Prevalence and characteristics of lumbar ribs: a meta-analysis with anatomical and clinical considerations

Lumbar ribs (LR) are a rare and relatively unknown anatomical abnormality of the lumbar spine. The literature provides better understanding regarding other spinal congenital variations like cervical ribs or lumbosacral transitional vertebrae, which are rather commonly recognised conditions. Thus, this meta-analysis aimed to provide data on prevalence and key characteristics of LR.

Relevant databases were systematically searched for studies reporting the prevalence, laterality and geographic distribution of LR. No exclusion criteria based on language and date of original articles were employed. The pooled prevalence estimates (PPE) were calculated using a random-effects model. To assess the between-study heterogeneity, the I² statistic and Chi-square test were utilized. Throughout the investigation, the PRISMA guidelines were adhered to scrupulously. Evaluation of the included studies' reliability was made with the AQUA tool.

In total, 9 studies were included in this meta-analysis. The pooled prevalence estimate (PPE) of LR was 2.1% (95%CI: 1.0-4.6). In studies based on CT imaging, LR were found in 1.6% (95%CI: 0.6-4.3) of patients and in Xray based studies in 2.1% (95%CI: 0.4-11.1) of patients. Lumbar ribs were bilateral in majority of individuals (65.4%, 95%CI: 39.4-84.6) and could be most frequently encountered in Europe with PPE of 2.8% (95%CI: 3.0-20.0), then in East Asia with PPE of 1.5% (95%CI: 1.0-19.2) and Middle East with PPE of 1.1% (95%CI: 0.6-20.0).

The findings of our study indicate that LR are a common anatomical variation of lumbar spine, contrary to previous beliefs. In a clinical practice, when a patient presents with a non-specific low back pain, a possible occurrence of LR should be taken into consideration. The presence of LR may be misleading for surgeons and result in wrong-level spine surgeries.