Pin size influences sagittal alignment in percutaneously pinned pediatric supracondylar humerus fractures

No study examining pin constructs has adequately addressed pin size and its role in fracture fixation. Our goal was to review our experience with Wilkins-modified Gartland type-III pediatric supracondylar humerus fractures treated with closed reduction and percutaneous pinning to evaluate the effects of pin size within 2 different pin constructs on maintenance of reduction and on the risk of surgical complications.

We retrospectively reviewed the medical records of pediatric patients with Wilkins-modified Gartland type-III supracondylar humerus fractures that were closed reduced and percutaneously pinned at our institution from March 1999 through December 2008. We grouped those 159 patients by fracture stabilization method (lateral-entry-pin or crossed-pin constructs), by pin size ratio (ie, ratio of pin diameter to the humeral midshaft cortical thickness: small ≤0.9; large >0.9), and then by 4 combinations of pin construct and pin size ratio. For each group, we evaluated radiographs for immediate postoperative reduction (coronal and sagittal alignment), maintenance of reduction at last follow-up, and the number of surgical complications. We used the Student t test, χ² test, Mann-Whitney U test, and Wilcoxon Signed Rank test to examine for significance, which was set at P<0.05.

Although we found no significant differences between the groups immediately after surgery, final follow-up sagittal alignment was significantly more likely to be maintained in the large pin size ratio group than in the small pin size ratio group. For 2 types of surgical complications, infection and nerve palsy, we found no statistically significant differences in these complications between the pin construct or pin size ratio groups.

Large pin sizes improved radiographic sagittal alignment at final follow-up without an increased rate of infection or ulnar nerve palsy.

Level III Therapeutic Study.