Background: Displaced lateral malleolar fractures are often treated with reduction and surgical stabilizaiton. However, there has not been a comprehensive laboratory comparison to determine the most appropriate device for treating these patients. This study subjected a range of contemporary lateral fibular plates to a series of mechanical tests designed to reveal performance differences.
Methods: Forty fresh frozen lower extremities were divided into 4 groups. A Weber B distal fibula fracture was simmulated with an osteotomy and stabilized using 1 of 4 plate systems: a standard Synthese one-third tubular plate with interfragmentary lag screw, a Synthes LCP locking plate with lag screw, an Orthohelix MaxLock Extreme low-profile locking plate with lag screw, or a TriMed Sidwinder nonlocking plate. Controlled monotonic bending and cyclic torsinal loading were applied and bending stiffness, torsional stiffness, and fracture site motion were quantified. Resistance to cyclic torsional loading was determined by quantifying the number of loads withstood before excessive rotation occurred. Correlation between bone mineral density and each of the mechanical measures was determined.
Results: There was no difference in angulation or bending stiffness between plates. All plates except the LCP showed greater lateral deflection than in the other beding directions. Bending stiffness was lowest in lateral distal fragment deflection for all 4 plates. There was a positive correlation between bone mineral density and bending stiffness for all plate types. There was no difference in fracture site rotation between plate types in internal or external torsioni, but internal rotation fo the distal fragment consistensly exceeded external rotation. Torsional stiffness in external rotation exceeded stiffness in internal rotation in nearly all specimens. LCP plates perfmoed relatively poorly under cyclic torsion.
Conclusions: Significant differences in plate performance were not demonstrated. The effects of bone quality variability and differences in interfragmentary screw purchase resulted in data dispersion that confounded absolute ranking of plate performance.
Clinical Relevance: Indentification of an optimal lateral fibular plating system has the potential in improve the clinical outcome of malleolar fracture fixation, particularly when patient conditions are unfavorable.