Use of the mini-open technique will help to minimize bowel perforations at the incision site. Historically, some surgeons would create the incision lateral to the coccyx and dissect through the soft tissue. It is at this point in the procedure a bowel perforation at the incision site may happen. Dissecting against a hard back stop is the best option. Below are optional types of incisions with the applicable advantages and disadvantages of each (Table 17.1).

After making the initial paracoccygeal skin incision using the mini-open techniques, use an 8″ Curved Kelly clamp turned to the anterior face of the sacrum to bluntly dissect down to the parietal fascia. Penetrating the fascia is necessary to access the retroperitoneal space and the anterior face of the sacrum. Penetrating the fascia can be accomplished using one of the following methods: (1) Finger dissection (2) blunt guide pin dissection, or (3) a combination of the two.

Finger Dissection: Dissect with your index finger to create a pathway to the sacrum while gently pushing the rectum anteriorly from the mesorectal soft tissue plane. While advancing towards the S1-S2 intersection, you can palpate the peritoneal layer of tissue (Waldeyer’s fascia) that runs between the rectum and sacrum [13]. When you palpate this anatomy with your finger, you will note the retro rectal space. Use your index finger to sweep away tissue from the anterior face of the sacrum (Fig. 17.4).

Blunt Dissection: Use the Curved Dissecting Tool to penetrate the fascia immediately below the ligaments. Advance the Curved Dissecting Tool cephalad along the midline, keeping the tip engaged on the anterior cortex of the sacrum to approximately the sacral promontory. Continue to check the A/P and lateral fluoroscopic views. This maneuver is accomplished with “fingertip” control on the handle of the Dissecting Tool and should be completed using fluoroscopic guidance in both A/P and lateral planes (Fig. 17.5).

Extend the dissection bi-laterally taking care to avoid the sacral foramina. This step should be accomplished with guidance from AP fluoroscopy (Fig. 17.6).

Remove the Curved Dissector and insert the Inserter with the attached Bowel Retractor into the dissected presacral space, ensuring the tip of the Inserter/Bowel Retractor is in contact with the sacrum. Deliver the Bowel Retractor to the sacral promontory or the endpoint of the dissection (Fig. 17.7a).

Fill the 30 cc Syringe with a mixture comprised of 10 cc of contrast (intended for enteral use, i.e. Omnipaque, Gastrograffin, etc.) and 20 cc of saline (Fig. 17.7b).

Reposition inflated Bowel Retractor close to promontory (Fig. 17.7c).

Remove Inserter by pulling Inserter while slightly pushing forward at neck of Bowel Retractor (Fig. 17.7d).

Once the dissection has been completed and the bowel retractor is in place, the trajectory is then obtained. Use the dissecting tool to match the trajectory suggested by the template during the preoperative planning session. If the Dissecting Tool cannot match the trajectory suggested by the template, adjust the template to the obtainable trajectory of the Dissecting Tool and verify. Once the trajectory is established, exchange the Dissector Stylet inside the Dissecting Tool for the Beveled Guide Pin then insert the Beveled Guide Pin into the Guide Pin Handle. Insert the Guide Pin Handle through the Dissecting Tool. While maintaining the correct trajectory, the Guide Pin Handle is tapped with the Slap Hammer or a small mallet to dock the Beveled Guide Pin into the sacrum (Fig. 17.8).

After the trajectory has been set and confirmed with the Beveled Guide Pin, a series of instruments are then used to sequentially dilate the soft tissue and sacral corticocancellous bone to create the working channel. Starting with the 6 mm Dilator, slide the Dilator over the Beveled Guide Pin. Use the Slap Hammer to advance the Dilator into the sacrum approximately halfway to the disc space. Remove the 6 mm Dilator, leaving the Beveled Guide Pin in place, and repeat with the 8 mm Dilator. Remove the 8 mm Dilator and repeat with the 10 mm Dilator Assembly. The 10 mm Dilator is assembled together with the 10 mm Dilator Sheath, which slides over the 10 mm Dilator body and engages with a pin and slot configuration. Advance the 10 mm Dilator far enough into the sacrum to ensure the outer diameter of the 10 mm Dilator Sheath is placed completely within the sacral cortex (Fig. 17.10).

Once the dilation of the sacrum is complete, a channel to the L5-S1 disc space is then created by inserting the 9 mm Cannulated Drill over the Beveled Guide Pin through the 10 mm sheath. Create the channel to the L5-S1 disc space by rotating the drill in a clockwise motion. Live fluoroscopy should be used when drilling to ensure both correct trajectory and confirmation of the channel into the L5-S1 disc space. Once the channel has been confirmed, remove the 9 mm Cannulated Drill. When extracting the drill, continue rotating in a clockwise motion. This technique helps to hold pieces of bone in the flutes of the drill. These can be placed aside to be used later in the procedure as supplemental bone graft material (Fig. 17.11).