- See: Safe Zone of Pin Insertion
- Discussion:
- whether a ring or unilateral fixator is used, there is some evidence that a better regenerate is formed with the use of titanium half pins rather than transfixation wires;
- ref: Limb lengthening by callus distraction (callotasis).
- pin characteristics:
- ilizarov half pins are 4.0 mm, 5.0 mm, and 6.0 mm in size;
- appropriate drill sizes;
- 2.7 mm drill bit for 4.0 mm half pin;
- 3.8 mm drill bit for 5.0 mm half pin;
- 4.8 mm drill bit for 6.0 mm half pin;
- Rancho Cubes:
- allow attachment of 4.0, 5.0, or 6.0 mm half pins to the ring;
- require use of centering sleeves between cubes and half pins;
- hexagonal set screws fit thru threaded extremity holes to lock centering sleeves;
- rancho drill guide and trocar are used to direct drill bits thru cubes;
- oblique pin insertion:
- oblique pin insertion enhances stability, especially when half pins cannot be placed at 90 deg to each other;
- a one hole cube is attached to a post;
- washers are inserted between the cube and the post which prevents the bolt from blocking the hole;
- Technical Pearls:
- consider use of titanium half pins inorder to lower the rate of infection;
- use a small periosteal elevator to carefully elevate the periosteum off the bone surface, so that it does not get caught up in the drill;
- always use new (sharp drills);
- in dense cortical bone, stop the drill every few seconds to allow cooling;
- consider periodically withdrawling the drill to clean out the flutes;
- irrigation may allow some cooling;
- consider insertion of an additional half pin which is left unattached to the ring construct;
- if one pain becomes infected, the extra pin can then be attached to the frame without the need to return to the OR;
- skin incision:
- when the fixator has been placed for limb lengthening, consider incising the skin in front of the path that the pin will take during the lengthening;
- make a larger incision for the pins closer to the osteotomy site;
- the incision will create a weak spot (even after the incision has healed) which will allow the half pins to cut through the skin without creating excessive skin tension