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

ABSTRACT

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: Large pin sizes improved radiographic sagittal alignment at final follow-up without an increased rate of infection or ulnar nerve palsy. LEVEL OF EVIDENCE Level III Therapeutic Study.