Figs. 7-A and 7-B Passing the second drill cannula and tapping it in place.

Fig. 7-A.

Passing the second drill cannula, which is serrated at its end and with a narrower lumen, through the initial drill tube cannula.

Fig. 7B.

The serrated second drill cannula with a narrower lumen is tapped into place to maintain its position and perform its function as the drill guide.