Intraoperative Stability Testing of Lateral-Entry Pin Fixation of Pediatric Supracondylar Humeral Fractures

Author(s): Zenios M, Ramachandran M, Milne B, Little D and Smith N

Source:  J Pediatr Orthop 27:695-702, 2007.

Summary:

The optimal pin configuration for pediatric supracondylar humeral fractures remain controversial.  Crossed medial and lateral pins have been reported to be biomechanically superior to lateral pin entry fixation only.  However, studies have shown increased risks of ulnar nerve problems with medial pin insertion.  At the authors’ institution, they had noted loss of fracture reduction with two lateral entry pins for displaced type-3 fractures.  They hypothesized that the traditional intraoperative lateral image taking in external rotation gives a false impression of rotational stability.  Therefore, the aim of this study was to determine whether rotational stability testing in displaced fractures can be used intraoperatively to assess fracture stability after fixation.

The cohort consisted of patients with a completely displaced type-3 that were prospectively recruited into the study.  After closed reduction, 2 divergent lateral-entry 1.6-mm K-wires were inserted.  The lateral x-ray was assessed in internal and external rotation and 90 degrees of flexion.  The fixation was considered unstable and the image in internal rotation showed opening of the fracture or mismatched diameter of the proximal and distal fragments.  If instability was noted, a third lateral entry pin was inserted and the fracture stability was reassessed.  If rotational instability was still present, a medial pin was inserted.

For a control group, the authors used a retrospective cohort with similar demographics and no uniform protocol for treatment.  Most of these patients had 2 lateral entry wires.  The two groups were compared for maintenance of fracture rotation and need for further surgery.  Standard radiographic measurements were also taken.

Over a four month period, twenty-one patients participated in the study with appropriate inclusion criteria.  Of the 21 fractures, 6 were stable with 2 lateral pins, 10 were treated with 3 lateral pins, 5 were deemed to require additional medial pins.  The retrospective comparison group consisted of 24 patients.  Fourteen of these patients had 2 lateral pins, four had 3 lateral pins and six had lateral and medial pin insertion.  In the prospective group, no patient required further surgery compared to six patients in the retrospective group, because of loss of reduction.  There was significant loss of reduction in the retrospective group compared to the prospective group.

The authors provide an interesting approach to displaced type-3 supracondylar fractures.  This study demonstrates that it is possible to treat some type-3 supracondylar fractures with lateral pins only.  However, intraoperative rotational testing may define persisting instability and require additional pin placement.  The addition of a third lateral pin may further stabilize the fracture and negate medial pin placement.  However, if after 3 lateral pins persisting instability is identified, a medial pin may be necessary with its associated risk.

 

Pediatric, Elbow, Supracondylar, Humerus, Fracture


Related Links