# Diagnostic Limitations and Aspects of the Lumbosacral Transitional Vertebrae (LSTV)
## 4 Discussion  
Castellvi type I:  
In the initial phase of the examination, the Castellvi type I problem with its enlargement of the L5 transverse process of \(>\)19 mm becomes obvious. The standard radiograph of the lumbar spine, as well as the spinal X-ray for scoliosis clarification, does not result in a reliable orthograde representation of the L5 transverse process. Lordosis and pelvic tilt, as well as scoliosis, prevent standardized imaging. The magnification factor that inevitably occurs in a radiograph as a function of object-film distance and tube distance make the height indication of the L5 transverse process an unsuitable measurement for Castellvi I classification. Only the Ferguson image (30\({}^{\circ}\) angle AP radiograph) serves as a standard method for detecting LSTV. Additional imaging is prohibited for radiation hygiene reasons. However, the problem of the magnification factor remains. The alternative is an MRI examination, which provides additional information in all three planes in space. The standard images for disc assessment (coronal and sagittal) are \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & \multicolumn{2}{c}{Spine patients (all)} & & n-1482 \\ \hline  & LSTV (all) & \(\upalpha\)n-83 & \(\upsigma\)n-32 & & n-115 \\ \hline Castellvi & IIA & n-55 & IIB & n-24 \\ \hline  & IIIA & n-20 & IIIB & n-10 \\ \hline  & & & IV & n-6 \\ \hline  & Lumbalgia (all) & \(\upsigma\)n-46 & \(\upsigma\)n-18 & & n-64 \\ \hline Castellvi & IIA & n-30 & IIB & n-13 \\ \hline  & IIIA & n-11 & IIIB & n-5 \\ \hline  & & & IV & n-5 \\ \hline  & \multicolumn{2}{c}{Scoliosis (all)} & \(\upsigma\)n-58 & \(\upsigma\)n-14 & & n-72 \\ \hline Castellvi & IIA & n-42 & IIB & n-11 \\ \hline  & IIIA & n-14 & IIIB & n-3 \\ \hline  & & & IV & n-2 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Data of the own investigation. \begin{table}
\begin{tabular}{c c c c} \hline \hline  & \multicolumn{2}{c}{**Own Data**} & \multicolumn{2}{c}{**Literature**} \\  & **Type II-IV** & \multicolumn{2}{c}{**Type I-IV**} \\ \hline LSTV total & 7.8\% & 20.9\% (+14.7\% Type I) & [1] \\ \hline  & & 15.8\% & [2] \\ \hline  & & 10.7\% (+21.3\% Type I) & [20] \\ \hline  & & 21.1\% & [24] \\ \hline  & & 12.9\% & [28] \\ \hline  & & 9.3\% (+19.7\% Type I) & [36] \\ \hline  & & 31\% & [37] \\ \hline LBP total & 4.3\% & 4.6\% & [19] \\ \hline Bertolotti syndrome & 55.7\% & 40.0\% & [13] \\ \hline  & & 30\% & [11] \\ \hline  & & 24.9\% & [29] \\ \hline Scoliosis and LSTV & 62.6\% & 18.2\% & [30] \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Own data in comparison to the literature. not sufficient for the assessment of LSTV. The frequently used slice thickness of 3 mm and the quality of the device (<3.5 Tesla) form another uncertainty factor for diagnostics. If in the literature there are reported (in many cases not specified) investigations with a CT and MRI slice thickness of 0.6 mm-3 mm, this should not be considered an insignificant representation and therefore also not an inaccurate measurement [3; 4; 6; 10]. However, the height of the L5 transverse process must also depend on the overall size of the patient, so that a measurement >19 mm is only of limited use for classification. In conclusion, the shape of the L5 transverse process could be more indicative of pathology than the measurement alone. In our own work, because of the intractability of the exact classification of Castellvi type I, we did not work on this type further. This does not mean that Castellvi type I cannot be responsible for complaints [8; 9; 10]. It should be emphasized that the scoliosis outpatient clinic, with its patients and the frequent oblique position of L5 compared to S1, presents an additional problem of presentation [1; 2]. This raises the following questions:  
Is pathology of the ligamentous apparatus (iliolumbar ligament) responsible for the shape of the L5 transverse process? If so, the shape of the L5 transverse process would be the expected identifying feature.