Original research
Fixation of Osteoporotic Distal Fibula Fractures: A Biomechanical Comparison of Locking Versus Conventional Plates

https://doi.org/10.1053/j.jfas.2006.09.009Get rights and content

The increased use of locking plates to treat difficult fracture scenarios has been advocated in patients that have reduced bone mineral density. One of these difficult fracture patterns, fixation of the distal fragment of a distal fibula fracture, may depend on unicortical and cancellous bony purchase. This study investigated the construct stiffness afforded by using locking and conventional plating schema in a cadaveric model. Overall, the data indicate that a locking plate construct with two distal unicortical screws was mechanically equivalent to standard plating with 3 distal screws. In addition, fixation with the standard plates was dependent on bone mineral density (BMD) whereas the locking plate fixation was independent of BMD. The clinical implication of this study is that locking plates may be advantageous in patients with the most severe osteoporosis.

Section snippets

Methods

Eight matched pairs of elderly female cadaver ankles were used for this study (age, 73–94; mean, 85). All specimens were evaluated with anteroposterior and lateral plain radiographs to determine if any gross bony abnormality existed. In addition, dual-energy x-ray absorptometry scans were performed on the distal metaphyseal tibia to quantify bone mineral density (BMD). Specimens were dissected to remove the associated soft tissues. All bony and ligamentous structures in the ankle were left

Results

We did not detect any gross osseous abnormalities in any of the 16 tibiae using visual inspection and plane radiographs. As expected, given the matched, paired study design, there was no difference in BMD between the experimental groups. Both groups had a mean BMD of 0.52 g/cm3 in the distal metaphyseal tibia. After hardware application, the locking plate and screw had a lower radial direction height (3.2 mm) than the conventional plate and screw (4.0 mm), indicating a reduced profile for the

Discussion

We have established a cadaveric model to assess fixation in elderly ankle fractures. Using this fracture model, the biomechanical properties of locking plates were compared with those of conventional plates on the distal fibula. Our locking-plate construct with 2 distal unicortical screws was mechanically equivalent to the standard plate with 3 distal screws. We found, as expected, that the fixation with the standard plates was dependent on BMD. The locking-plate fixation, however, was

Conclusion

In summary, we have demonstrated that in the setting of elderly ankle fractures, locking plates are at least equivalent biomechanically to standard plates. In contrast to the standard plates, the locking-plate construct was not dependent on BMD. Clinically, locking plates may be advantageous in patients with the most severe osteoporosis. However, exactly which patients may benefit and the cost-effectiveness of using more expensive implants remains unclear.

References (11)

There are more references available in the full text version of this article.

Cited by (139)

  • Devices for traumatology: Biomechanics and design

    2022, Human Orthopaedic Biomechanics: Fundamentals, Devices and Applications
View all citing articles on Scopus

Implant hardware provided by Synthes, Inc.

1

Chief Resident, Department of Orthopaedic Surgery, University of California, San Francisco, San Francisco, CA.

2

Graduate Research Assistant, Department of Mechanical Engineering, Colorado State University, Fort Collins, CO.

3

Assistant Professor, Department of Orthopaedic Surgery, University of California, San Francisco, San Francisco, CA.

4

Professor, Department of Orthopaedic Surgery, University of California, San Francisco, San Francisco, CA.

5

Assistant Professor, Department of Mechanical Engineering, Colorado State University, Fort Collins, CO.

View full text