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EP031 Three-dimensional reconstruction of randomly selected ex-vivo spines: Needle insertion angles for spinal anesthesia
  1. Hipólito Labandeyra1,2,
  2. Xavier Sala-Blanch3,4,
  3. Alberto Prats-Galino3 and
  4. Anna Puigdellívol-Sánchez3,5
  1. 1Laboratory of Surgical Neuroanatomy, Human Anatomy and Embryology Unit, Faculty of Medicine and Health Sciencies. Universitat de Barcelona, Barcelona, Spain
  2. 2Servei d’Anestesiologia., Parc Sanitari Sant Joan de Déu, Sant Boi de Llobregat, Spain
  3. 3Laboratory of Surgical Neuroanatomy, Human Anatomy and Embryology Unit, Universitat de Barcelona, Barcelona, Spain
  4. 4Servei d’Anestesiologia., Hospital Clínic de Barcelona, Barcelona, Spain
  5. 5CAP Anton de Borja, Terrassa Health Consortium, Rubí, Spain


Background and Aims A freely available visual guide with optimal angles for paramedian approaches, depending on the skin-dural sac distance (S-DS-d) ( ) and viable paths for needle insertions, perpendicular to the back, below the upper spinous process in a given interspinous space, had been described. Our aim was now to verify needle location applying the guide in ex-vivo samples.

Methods Random selection of ex-vivo samples with flexed lumbosacral spines (n=7), determination of S-DS-d in the interspinous spaces by ultrasound, needle insertions at axial 0°, below the upper spinous process at different interspinous spaces, from L4-L5 to L1-L2 [n=42; median (n=21), 1cm paramedian (n=16) or individualized paramedian, previsualizing the longest interlaminar height, pre-estimating the angle by means of a protractor (n=5)], computed tomography, three-dimensional reconstruction and verification of needle location (figure 1).

Abstract EP031 Figure 1

3D reconstruction of bone structures and needle positions in flexed spines of ex-vivo samples

Abstract EP031 Figure 2

When osteoporotic vertebral compression fractures are present, the contact between adjacent spinal processes impedes the needle penetration in median approaches

Abstract EP031 Figure 3

Median and paramedian approaches at 0° regarding the axial plane, taking the upper spinous process as reference, lead to successful needle insertions within the spinal canal in non-fractured spines

Results When osteoporotic compression fracture was found (38%), the contact between adjacent spinous process impeded the median approach (figure 2), but most needle insertions were located within the spinal canal in the other cases (85.7% median or 81% 1cm paramedian) (figure 3). In 23% the needle remained within the canal beside the dural sac. In 13% a certain bone penetration occurred. Individualization of the paramedian approach led to successful insertions at very variable angles and distances (up to 32,2° and 2,64 cm paramedian, respectively).

Conclusions Ultrasound may indicate if the interspinous space is visible. Then, the insertion of needles at 0° regarding the axial plane, taking the upper process as reference, is viable. If not, the alternative optimal paramedian approach must be individualized in fractured or rotated spines.

  • spinal anesthesia
  • osteoporotic vertebral compression fracture
  • 3D reconstruction
  • needle insertion
  • optimal angles.

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