- Pin Diameter and Length:
- pins should be at least 5 mm in diameter (such as the Orthofix 6/5 mm self tapping screws);
- resistance to cephalad displacemnt could be approximately doubled by using 5 mm vs. 4 mm half pins for iliac wing fixation, & is further enhanced by adding a second pin group in each ilium between anteroinferior and superior iliac spines;
- smaller pelves, however, require 4-mm pins to avoid comminution of iliac wing & loss of purchase;
- osteoporotic pelvis in the elderly patient may not hold pins well.
- pin length:
- use pins with adequate length, to allow for postoperative swelling and the need for anteriorization of the frame;
- Frame Type:
- it is helpful to construct the frame prior to surgery;
- consider using a double frame construct;
- this will allow for postoperative manipulation of one frame without losing the reduction (since the second frame is in place);
- avoid placing cross bars between the two frames since this will complicate postoperative frame manipulation;
- care must be taken to avoid placing clamps too close to abdomen, particularly in acute situation in which abdominal distension will cause frame impingement;
- always build into the frame the option of increasing the frame's girth in order to allow for postoperative frame manipulation should swelling occur
Anatomic and radiographic considerations in the placement of anterior pelvic external fixator pins.
Biomechanical testing of new and old fixation devices for vertical shear fractures of the pelvis.