Effect of Cranial Flexion of Pelvic Limbs on Interlaminar Length of the Lumbosacral Space in Sternally and Laterally Recumbent Juvenile Duroc and Adult Yucatan Pigs.

Epidural puncture in swine is technically challenging. Several combinations of limb and body positions have been suggested to increase lumbosacral interlaminar space (LSS) and lumbosacral angle (LSA). This study investigated whether cranial hyperflexion of pelvic limbs increased LSS and LSA in laterally and sternally recumbent juvenile Duroc and adult Yucatan pigs and assessed which position produced the largest LSS. Juvenile Duroc (n = 7) and adult Yucatan (n = 7) pigs were euthanized and randomly placed in 4 positions: sternal with neutral limbs, sternal with cranially hyperflexed limbs, lateral with neutral limbs, and lateral with hyperflexed limbs. LSS and LSA were measured on transverse axial CT images of the spine and compared by using multivariate ANOVA and the Student t test. In both age groups, LSS was greater in lateral flexed (juvenile, 7.0 ± 0.7 mm; adult, 15.9 ± 1.1 mm) and sternal flexed (juvenile, 7.5 ± 1 mm; adult, 17.1 ± 1.1 mm) positions than in lateral neutral (juvenile, 5.4 ± 0.9 mm; adult, 9.6 ± 1.6 mm) position. In addition, in both age groups, LSS and LSA in lateral neutral position were smaller than lateral flexed, sternal neutral, and sternal flexed positions. In adults, LSS was greater in lateral flexed and sternal flexed than in sternal neutral position. Hyperflexion of pelvic limbs increases LSS and LSA in sternally recumbent adult Yucatan pigs and laterally recumbent adult Yucatan and juvenile Duroc swine. Increased LSS from positioning pigs with pelvic limbs flexed in sternal or lateral recumbence may facilitate epidural puncture compared with neutral limb positioning.