Morphological Changes in the Lumbar and Abdominal Muscles in Individuals with Sacralization

Although sacralization is one of the most common congenital anomalies of the spine, its effect on surrounding muscles is still not well known. This study was conducted to determine the size of the lumbar and abdominal muscles of the individuals with sacralization and to compare with the control group. Eighty-five participants with sacralization phenomena and fifty-six asymptomatic participants were included in this study. Sacralization was classified according to the Castellvi classification. The cross-sectional area of the multifidus lumborum, erector spinae and rectus abdominis muscles, and the section thicknesses of external abdominal oblique, internal abdominal oblique and transversus abdominis muscles were measured bilaterally on axial computed tomography images at the L1-2 and L4-5 levels. ANCOVA revealed that there is no any significant group*side interaction effect regarding muscles sizes in terms of two groups in L1-L2 and L4-L5. In addition, ANCOVA revealed a both side effect [(P=0.020; η2p=0.038)] and group*side interaction effect [(P=0.010; η2p=0.049)] regarding length of the L5 transverse process (P˃0.05). Regardless of low back pain, muscle sizes are not associated with the sacralization phenomenon.