Choice of approach

The choice of suprailiac or transiliac approach was made on the basis of the proposed radiological classification and was performed accordingly. In type II/II relationships, approach was determined on the basis of the type of herniation. In the authors experience, central or superiorly migrated herniations may be best approached with the transiliac approach, whereas paracentral or foraminal herniations may be preferably accessed by suprailiac approach. The ratio of pedicle-iliac crest distance and pedicle spinous process distance (PI:PS) is of importance during this assessment. It is defined as a horizontal line passing through the middle of the L5 pedicle joining the L5 spinous process to medial margin of iliac crest. If the distance from the lateral pedicular line to iliac crest (PI) is more than the lateral pedicular line to spinous process (PS), the suprailiac approach can be attempted considering type of herniation as well (Figure 4). Intermediate cases may exist and the authors recommend to make the choice of preferred approach on the basis of all clinical factors including the type of herniation and its location. Representative case examples are shown in Figures 5 and 6​6 for either approach.

Ratio between the distances PI and PS on the AP radiograph. A horizontal line (IPS) is drawn through the middle of L5 pedicle joining spinous process in the midline and laterally where it touches the ilium. I, P & S are the points marked on this solid line. P is the point at lateral margin of the pedicle. I is the point where horizontal line meets ilium. S is the spinous process point on midline. Dotted line shows type II/II relationship. If PI distance is greater than PS then suprailiac approach is recommended & vice versa for transiliac.

A case of 48 years male presented with left S1 radicular pain. Pre-operative axial MRI (A) showing large central extruded L5–S1 disc herniation. Plain radiographs of lumbosacral (B,C) spine showing Type III/III relationship on AP and Lateral views. Intra-operative images (D,E,F) of transiliac approach with reamers passing through the ilium and foramen. A post-operative axial MRI (G) in the bottom right panel shows complete decompression of both the nerve roots.

A case of 48 years male presented with left S1 radicular pain. Plain radiographs (A & B) of the lumbosacral spine show type II/II relationship on AP and Lateral views. Pre-operative axial (C) and sagittal (D) MRI shows a large central extruded L5–S1 disc herniation. An axial CT image was used to aid in pre-operative planning of skin entry point selection (E). Intraoperative fluoroscopic image (G) of the transiliac approach show reamers passing through the ilium and foramen. The intraoperative endoscopic view (H) confirms adequate decompression of the S1 nerve root. A postoperative MRI (F) shows adequate decompression of traversing nerve root.