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Mono- versus polyaxial locking plates in distal femur fractures - a biomechanical comparison of the Non-Contact-Bridging- (NCB) and the PERILOC-plate.

El-Zayat BF, Efe T, Ruchholtz S, Khatib S, Timmesfeld N, Krüger A, Zettl R - BMC Musculoskelet Disord (2014)

Bottom Line: The end points were implant failure or relevant loss of reduction.Distribution curves of all samples in both groups, showing the plastic deformation in relation to the axial force, showed no statistically significant differences.Operative stabilization of distal femur fractures can be successfully and equally well achieved using either a monoaxial or a polyaxial locking plate.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopaedics and Rheumatology, University Hospital Marburg, Baldingerstrasse, 35043 Marburg, Germany. elzayat@med.uni-marburg.de.

ABSTRACT

Background: The aim of this cadaveric study was to compare a polyaxial (NCB®, Zimmer) to a fixed-angle monoaxial locking plate (PERILOC®, Smith & Nephew) in comminuted fractures of the distal femur regarding stability of the construct. Up to date there is no published biomechanical data concerning polyaxial plating in cadaveric distal femurs.

Methods: Fourteen formalin fixed femora were scanned by dual-energy x-ray absorptiometry. As fracture model an unstable supracondylar comminuted fracture was simulated. Fractures were pairwise randomly fixed either with a mono- (group A) or a polyaxial (group B) distal femur plate. The samples were tested in a servohydraulic mechanical testing system starting with an axial loading of 200 N following an increase of 200 N in every step with 500 cycles in every sequence up to a maximum of 2 000 N. The end points were implant failure or relevant loss of reduction. Data records included for each specimen time, number of cycles, axial load and axial displacement. Statistical analysis was performed using the exact Wilcoxon signed rank test.

Results: The mean donor age at the time of death was 75 years. The bone mass density (BMD) of the femurs in both groups was comparable and showed no statistically significant differences. Five bones failed before reaching the maximum applied force of 2000 N. Distribution curves of all samples in both groups, showing the plastic deformation in relation to the axial force, showed no statistically significant differences.

Conclusions: Operative stabilization of distal femur fractures can be successfully and equally well achieved using either a monoaxial or a polyaxial locking plate. Polyaxial screw fixation may have advantages if intramedullary implants are present.

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Related in: MedlinePlus

Failure at 1600 N (NCB-plate, sample 11/10) with deformation of the bone due to a cutout of the screws.
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Fig2: Failure at 1600 N (NCB-plate, sample 11/10) with deformation of the bone due to a cutout of the screws.

Mentions: Seven pairs of cadaveric femora were used (2 male, 5 female donors). The mean donor age at the time of death was 75 years (range 45-92 years). The results for the biomechanical testing are shown in Table 1.Five constructs failed before reaching the maximum applied force of 2000 N. In 4 cases, failure was due to a distal loss of reduction (2 × PERILOC, 2 × NCB) due to a cutout of the screws as shown in Figure 2.One sample (PERILOC®) showed at 2000 N a complete failure in the shaft region, whereas the condyles were still stable (Figure 3). All other bones reached the test endpoint of 2000 N without any complication.Figure 4 presents the absolute values of plastic deformation of all samples in relation to the axial force. Both plates are compared for every bone pair. In most samples the curves have a very parallel or similar course.The overall plastic deformation in both groups was comparable. The measured differences were statistically not significant (Figure 5).Table 1


Mono- versus polyaxial locking plates in distal femur fractures - a biomechanical comparison of the Non-Contact-Bridging- (NCB) and the PERILOC-plate.

El-Zayat BF, Efe T, Ruchholtz S, Khatib S, Timmesfeld N, Krüger A, Zettl R - BMC Musculoskelet Disord (2014)

Failure at 1600 N (NCB-plate, sample 11/10) with deformation of the bone due to a cutout of the screws.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4232626&req=5

Fig2: Failure at 1600 N (NCB-plate, sample 11/10) with deformation of the bone due to a cutout of the screws.
Mentions: Seven pairs of cadaveric femora were used (2 male, 5 female donors). The mean donor age at the time of death was 75 years (range 45-92 years). The results for the biomechanical testing are shown in Table 1.Five constructs failed before reaching the maximum applied force of 2000 N. In 4 cases, failure was due to a distal loss of reduction (2 × PERILOC, 2 × NCB) due to a cutout of the screws as shown in Figure 2.One sample (PERILOC®) showed at 2000 N a complete failure in the shaft region, whereas the condyles were still stable (Figure 3). All other bones reached the test endpoint of 2000 N without any complication.Figure 4 presents the absolute values of plastic deformation of all samples in relation to the axial force. Both plates are compared for every bone pair. In most samples the curves have a very parallel or similar course.The overall plastic deformation in both groups was comparable. The measured differences were statistically not significant (Figure 5).Table 1

Bottom Line: The end points were implant failure or relevant loss of reduction.Distribution curves of all samples in both groups, showing the plastic deformation in relation to the axial force, showed no statistically significant differences.Operative stabilization of distal femur fractures can be successfully and equally well achieved using either a monoaxial or a polyaxial locking plate.

View Article: PubMed Central - PubMed

Affiliation: Department of Orthopaedics and Rheumatology, University Hospital Marburg, Baldingerstrasse, 35043 Marburg, Germany. elzayat@med.uni-marburg.de.

ABSTRACT

Background: The aim of this cadaveric study was to compare a polyaxial (NCB®, Zimmer) to a fixed-angle monoaxial locking plate (PERILOC®, Smith & Nephew) in comminuted fractures of the distal femur regarding stability of the construct. Up to date there is no published biomechanical data concerning polyaxial plating in cadaveric distal femurs.

Methods: Fourteen formalin fixed femora were scanned by dual-energy x-ray absorptiometry. As fracture model an unstable supracondylar comminuted fracture was simulated. Fractures were pairwise randomly fixed either with a mono- (group A) or a polyaxial (group B) distal femur plate. The samples were tested in a servohydraulic mechanical testing system starting with an axial loading of 200 N following an increase of 200 N in every step with 500 cycles in every sequence up to a maximum of 2 000 N. The end points were implant failure or relevant loss of reduction. Data records included for each specimen time, number of cycles, axial load and axial displacement. Statistical analysis was performed using the exact Wilcoxon signed rank test.

Results: The mean donor age at the time of death was 75 years. The bone mass density (BMD) of the femurs in both groups was comparable and showed no statistically significant differences. Five bones failed before reaching the maximum applied force of 2000 N. Distribution curves of all samples in both groups, showing the plastic deformation in relation to the axial force, showed no statistically significant differences.

Conclusions: Operative stabilization of distal femur fractures can be successfully and equally well achieved using either a monoaxial or a polyaxial locking plate. Polyaxial screw fixation may have advantages if intramedullary implants are present.

Show MeSH
Related in: MedlinePlus