|
Year |
2007 |
|---|---|
|
Question Number |
75 |
|
Category |
Pediatric Orthopaedics |
Question
An 11-year-old boy with a stable slipped capital femoral epiphysis is treated with in situ screw fixation. The postoperative radiographs are shown in Figures 22a and 22b. Which of the following problems is most likely to occur?
1- Chondrolysis
2- Osteonecrosis
3- Significant limb-length discrepancy
4- Growth of the capital epiphysis off the screw
5- Slip of the contralateral hip
Figures
Answer (click for answer)
The correct answer is 5 – Slip of the contralateral hip
In a decision tree analysis of prophylactic pinning of contralateral normal hips in pts with SCFE, Schultz, et al (JBJS 2002) reviewed the available literature on probabilities of outcomes following prophylactic pinning vs. serial observation of the unaffected hip. They reported an overall 14% chance that a contralateral SCFE would be detected during the adolescent period prior to physeal closure and that 50% of those pts remaining would have a missed SCFE detected at some point after physeal closure.
Chondrolysis (choice 1) and osteonecrosis (choice 2) are the major complications associated with pinning of a SCFE, with a rate of approximately 1% each in pinned hips, much less common than a slip of the contralateral hip. Significant limb-length discrepancy (choice 3) is unlikely to occur considering the overall yearly contribution of the proximal femoral physis (~3mm/yr) and the fact that this pt has about 5 years until his physes will naturally close (5y x 3mm/yr = 1.5cm LLD). LLD is not considered significant until >2cm. Choice 4, growth of the capital epiphysis off the screw, is considered a very rare problem and is therefore not the best answer to this question
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