Table 1 Start and end points for the 3 lateral and 2 posterolateral implant trajectories
Lateral orientation | ||
Trajectory | Start point | End point |
Top implant | Lateral to the middle of the first sacral body, distal to the alar line, following the slope of the ala | 12 o’clock position above S1 foramina |
Middle implant | Lateral to the S2 foramen, between the first and second sacral body, angled approximately 15-20° ventral-to-dorsal from horizontal | 1 cm in advance of the S1 foramen |
Bottom implant | Lateral to the middle of the second sacral body, ensure the implant is roughly parallel with the top and middle implants in an outlet view | Between the S1 and S2 foramen near the lateral border of the S1 foramen |
Posterolateral orientation | ||
Trajectory | Start point | End point |
Top implant (PL1) | At the lateral aspect of the PSIS. Follow the trajectory that is 10-15° lateral-to-medial and 0-10° cranial-to-caudal | At the ala of the sacrum about 1 cm from the anterior sacral cortex |
Bottom implant (PL2) | 2-3 cm posterior of the sacral ala, in line with the S2 pedicle, follow a similar trajectory to the top implant | In the ala of the sacrum about 1 cm from the anterior sacral cortex |