Angle Stable Nails Provide Improved Healing for a Complex Fracture Model in the Femur

Document Type

Article

Publication Date

9-19-2013

Publication Title

Clinical Orthopaedics and Related Research

Abstract

Background

Conventional nails are being used for an expanding range of fractures from simple to more complex. Angle stable designs are a relatively new innovation; however, it is unknown if they will improve healing for complex fractures.

Questions/purposes

When comparing traditional and angle stable nails to treat complex open canine femur fractures, the current study addressed the following questions: do the two constructs differ in (1) radiographic evidence of bone union across the cortices; (2) stability as determined by toggle (torsional motion with little accompanying torque) and angular deformation; (3) biomechanical properties, including stiffness in bending, axial compression, and torsional loading, and construct failure properties in torsion; and (4) degree of bone tissue mineralization?

Methods

Ten hounds with a 1-cm femoral defect and periosteal stripping were treated with a reamed titanium angle stable or nonangle stable nail after the creation of a long soft tissue wound. Before the study, the animals were randomly assigned to receive one of the nails and to be evaluated with biomechanical testing or histology. After euthanasia at 16 weeks, all operative femora were assessed radiographically. Histological or biomechanical evaluation was conducted of the operative bones with nails left in situ compared with the nonoperative contralateral femora.

Results

Radiographic and gross inspection demonstrated hypertrophic nonunion in all 10 animals treated with the nonangle stable nail, whereas six of 10 animals treated with the angle stable nail bridged at least one cortex (p = 0.023). The angle stable nail construct demonstrated no toggle in nine of 10 animals, whereas all control femora exhibited toggle. The angle stable nail demonstrated less angular deformation and toggle (p ≤ 0.005) and increased compressive stiffness (p = 0.001) compared with the conventional nonangle stable nail. Histology demonstrated more nonmineralized tissue in the limbs treated with the conventional nail (p = 0.005).

Conclusions

Angle stable nails that eliminate toggle lead to enhanced yet incomplete fracture healing in a complex canine fracture model.

Clinical Relevance

Care should be taken in tailoring the nail design features to the characteristics of the fracture and the patient.

Volume

472

Issue

4

First Page

1300

Last Page

1309

DOI

10.1007/s11999-013-3288-9

ISSN

ISSN: 0009-921X, Online ISSN: 1528-1132

Rights

© The Association of Bone and Joint Surgeons ® 2013

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