- Discussion:
- incorrect placement of pins is a common error;
-
superior quadrant of femoral head should be
avoided:
- this is where
retinacular vessels enter, and pin penetration into this area may cause
AVN;
- pins should not be placed superiorly inorder to avoid wt bearing area of femoral head;
- pins should enter anterior aspect of extra-synovial base of femoral neck;
- if pins are placed too posteriorly, they may exit thru lateral femoral neck reenter the head, disrupting vessels along neck;
- from anterior entry point, pins are directed posteromedially to engage epiphysis of femoral head;
- in grade III slip, epiphysis & metaphysis overlap only 25% of width of femoral neck, making accurate pin placement difficult;
-
pin penetration:
- pin penetration may cause
chondrolysis;
- two x-rays taken at 90 degrees don't necessarily r/o penetration, however, addition of oblique views should rule out penetration;
- AP and Lateral Views of Screw Placement:
-
number of screws:
- references:
-
Slip progression after in situ single screw fixation for stable slipped capital femoral epiphysis.
-
In situ pinning on slipped femoral capital epipyhysis with a single cannulated screw.
-
Biomechanical Stability of Single-screw Versus Two-screw Fixation of an Unstable SCFE Model: Effect of Screw Position in the Femoral Neck.
The place of threaded pin fixation in the treatment of slipped upper femoral epiphysis.
Unrecognized pin penetration in slipped capital femoral epiphysis.
Prgression of a slipped captial femoral epiphysis after fixation. JR Denton Vol 75-A. No 3. March 1993.
Biomechanical Comparison of Fully and Partially Threaded Screws for Fixation of Slipped Capital Femoral Epiphysis
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