Dataset Information

Accuracy of radiographs in assessment of displacement in lateral humeral condyle fractures.

ABSTRACT:

Purpose

Determining the magnitude of displacement in pediatric lateral humeral condyle fractures can be difficult. The purpose of this study was to (1) assess the effect of forearm rotation on true fracture displacement using a cadaver model and to (2) determine the accuracy of radiographic measurements of the fracture gap.

Methods

A non-displaced fracture was created in three human cadaveric arms. The specimens were mounted on a custom apparatus allowing forearm rotation with the humerus fixed. First, the effect of pure rotation on fracture displacement was simulated by rotating the forearm from supination to pronation about the central axis of the forearm, to isolate the effects of muscle pull. Then, the clinical condition of obtaining a lateral oblique radiograph was simulated by rotating the forearm about the medial aspect of the forearm. Fracture displacements were measured using a motion-capture system (true-displacement) and clinical radiographs (apparent-displacement).

Results

During pure rotation of the forearm, there were no significant differences in fracture displacement between supination and pronation, with changes in displacement of <1.0 mm. During rotation about the medial aspect of the forearm, there was a significant difference in true displacements between supination and pronation at the posterior edge (p < 0.05).

Conclusion

Overall, true fracture displacement measurements were larger than apparent radiographic displacement measurements, with differences from 1.6 to 6.0 mm, suggesting that the current clinical methods may not be sensitive enough to detect a displacement of 2.0 mm, especially when positioning the upper extremity for an internal oblique lateral radiograph.

SUBMITTER: Knutsen A

PROVIDER: S-EPMC3935020 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundLateral humeral condyle fractures are the second most common elbow fracture in children. Displaced and rotated fractures require stabilization and reduction. Kirschner wires (K-wires) are most commonly used in the fixation of these fractures. Here, we introduce a new fixation method that uses an absorbable screw. We aim to determine if it is feasible to treat lateral humeral condyle fractures with an absorbable screw by comparing functional outcomes following absorbable screw fixation vs. K-wire fixation.MethodsBetween May 2007 and September 2010, 86 patients were treated with absorbable screws (43 patients) or K-wire (43 patients). All patients had been diagnosed with lateral condyle fractures that were classified as either Jacob type II (unstable) or III. One absorbable screw (3.5 mm-diameter) was used for fixation in 1 group, while two 1.6 to 1.8 mm K-wires were used in the other group. Patients were followed 6 months about the elbow function according to Broberg and Morrey standard. On 5-7 years, the patients were followed about the carrying angle (valgus deformities and varus deformities), range of motion (flexion loss and extension loss), prominent lateral condyle, symptomatic implants, and fishtail deformity.ResultsAnatomic reduction was achieved in all patients. Each group had one radial nerve injury that were present preoperatively. Nerve function recovered spontaneously within 3 to 4 weeks of surgery in both patients. No patient developed necrosis of the capitulum in both groups. Nine patients in K-wires group and 2 in absorbable screw group developed symptomatic implants (P = .048). On the sixth month, there was no significant difference on elbow function according to Broberg and Morrey standard. On 5 to 7 years (average, 6.7 ± 1.3 years), valgus deformities was 6.8 ± 1.2 vs 5.7 ± 0.8, varus deformities was 7.2 ± 1.5 vs 5.1 ± 1.9, flexion loss was 12.4 ± 2.2 vs 9.5 ± 3.1, extension loss was 11.1 ± 3.1 vs 10.2 ± 2.7, prominent lateral condyle was 27.9% vs 37.2%, fishtail deformity was 7.3% vs 4.9%, no significant difference between these groups.ConclusionsOpen reduction with absorbable screw fixation is feasible and safe for the treatment of lateral condyle fractures of the humerus in children.Level of evidenceTherapeutic III.