Background: Although the results are generally good following pin
fixation of supracondylar humeral fractures in children, occasionally there is
postoperative displacement. The purposes of the present study were to identify
the causes leading to loss of fixation after pin fixation and to present
methods for prevention.
Methods: We evaluated 322 displaced supracondylar humeral fractures
that had been treated with percutaneous pin fixation. We examined fracture
classification, pin configuration, intraoperative alignment after fixation,
change in alignment after fixation, details of additional procedures, and
final radiographic and clinical outcomes.
Results: Adequate radiographs were available for 279 of the 322
fractures. Eight (2.9%) of the 279 fractures were associated with
postoperative loss of fixation; all eight were Gartland type-III fractures.
Seven of these eight fractures initially had been treated with two
lateral-entry pins, and one had been treated with two crossed pins. In
patients with Gartland type-III fractures, loss of fixation was successfully
avoided more often when three pins were used (with fixation being maintained
in thirty-seven of thirty-seven patients) as opposed to when two lateral-entry
pins were used (with fixation being maintained in thirty-five of forty-two
patients) (p = 0.01). In all cases, loss of fixation was due to technical
errors that were identifiable on the intraoperative fluoroscopic images and
that could have been prevented with proper technique. We identified three
types of pin-fixation errors: (1) failure to engage both fragments with two
pins or more, (2) failure to achieve bicortical fixation with two pins or
more, and (3) failure to achieve adequate pin separation (>2 mm) at the
Conclusions: Postoperative displacement following pin fixation of
supracondylar humeral fractures in children is uncommon. In the present
series, loss of fixation was most likely to occur when Gartland type-III
fractures were treated with two lateral-entry pins. There were no failures
when three pins were used. In all cases of failure, there were identifiable
technical errors in pin placement.
Level of Evidence: Therapeutic Level III. See
Instructions to Authors for a complete description of levels of evidence.