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The effect of contouring on fatigue resistance of three types of fracture fixation plates

View Article: PubMed Central - PubMed

ABSTRACT

Background: Metallic reconstruction plates used for fracture stabilization typically require intraoperative contouring for patient-specific anatomical fit. Despite this, characterization of plate mechanical properties after contouring has previously been limited.

Background: The objective of this study was to assess whether contouring affects fatigue resistance for three types of Stryker seven-hole stainless steel (SS) 316LVM fracture fixation plates. The hypothesis was that for each plate type, more contouring repetitions would result in lower fatigue resistance.

Methods: Plates were contoured using a bench-top plate bender to ±20° either 0×, 3×, 6×, or 9× (n = 5 per group) and tested in the straight configuration. Cyclic four-point bending was applied in an incremental stepwise staircase approach (one step = 100,000 cycles, 10 Hz) until failure (defined as brittle fracture or plastic deformation of 10° permanent bend). Moment-cycle product (MCP) was computed as the summation of maximum moment × number of cycles and used as the primary measure of fatigue resistance.

Results: No significant differences in fatigue resistance were detected between contouring groups for Basic Fragment Set (BFS) Reconstruction Plates. Significantly lower fatigue resistance was measured for 9× contoured Matta Pelvic System (MPS) Straight Plates compared to 0× contoured plates (p = 0.023). MPS Flex Plates contoured 3× had greater fatigue resistance than 0× contoured (p = 0.031) and 9× contoured plates (p = 0.032).

Conclusions: This work provides fatigue resistance-based evidence that clinicians should avoid high repetitions of contouring for MPS Straight Plates. Meanwhile, BFS Reconstruction Plates and MPS Flex Plates are not negatively affected by contouring. These results allow for improved intraoperative decisions about using or discarding plates after multiple contouring repetitions.

No MeSH data available.


Boxplots depict median moment-cycle product (MCP) values, 1st and 3rd quartiles, and whiskers indicate maximum and minimum values (n = 5 for each group). a BFS Reconstruction Plates: no significant differences in MCP between groups. b MPS Straight Plates: plates contoured 9× exhibited significantly lower MCP to failure than those contoured 0× (*p = 0.023). c MPS Flex Plates: 3× contoured plates exhibited significantly higher MCP to failure than 0× ($p = 0.031) and 9× (†p = 0.032)
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Fig3: Boxplots depict median moment-cycle product (MCP) values, 1st and 3rd quartiles, and whiskers indicate maximum and minimum values (n = 5 for each group). a BFS Reconstruction Plates: no significant differences in MCP between groups. b MPS Straight Plates: plates contoured 9× exhibited significantly lower MCP to failure than those contoured 0× (*p = 0.023). c MPS Flex Plates: 3× contoured plates exhibited significantly higher MCP to failure than 0× ($p = 0.031) and 9× (†p = 0.032)

Mentions: For each step endured until failure, the maximum moment produced during that step was multiplied by the number of cycles in that step, and these values were summed to compute a total moment-cycle product (MCP) to failure. This parameter was used as the primary measure of cyclic fatigue resistance, similar to the moment-cycle integral metric used in Schmidt et al. for testing locking fixation plates [12], as it included considerations for geometry and total cycles endured whereas other fatigue property measures did not represent the combination of these factors as completely. Boxplots were generated to depict MCP median values, 1st and 3rd quartiles, and minimum and maximum values (Fig. 3).Fig. 3


The effect of contouring on fatigue resistance of three types of fracture fixation plates
Boxplots depict median moment-cycle product (MCP) values, 1st and 3rd quartiles, and whiskers indicate maximum and minimum values (n = 5 for each group). a BFS Reconstruction Plates: no significant differences in MCP between groups. b MPS Straight Plates: plates contoured 9× exhibited significantly lower MCP to failure than those contoured 0× (*p = 0.023). c MPS Flex Plates: 3× contoured plates exhibited significantly higher MCP to failure than 0× ($p = 0.031) and 9× (†p = 0.032)
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC5037585&req=5

Fig3: Boxplots depict median moment-cycle product (MCP) values, 1st and 3rd quartiles, and whiskers indicate maximum and minimum values (n = 5 for each group). a BFS Reconstruction Plates: no significant differences in MCP between groups. b MPS Straight Plates: plates contoured 9× exhibited significantly lower MCP to failure than those contoured 0× (*p = 0.023). c MPS Flex Plates: 3× contoured plates exhibited significantly higher MCP to failure than 0× ($p = 0.031) and 9× (†p = 0.032)
Mentions: For each step endured until failure, the maximum moment produced during that step was multiplied by the number of cycles in that step, and these values were summed to compute a total moment-cycle product (MCP) to failure. This parameter was used as the primary measure of cyclic fatigue resistance, similar to the moment-cycle integral metric used in Schmidt et al. for testing locking fixation plates [12], as it included considerations for geometry and total cycles endured whereas other fatigue property measures did not represent the combination of these factors as completely. Boxplots were generated to depict MCP median values, 1st and 3rd quartiles, and minimum and maximum values (Fig. 3).Fig. 3

View Article: PubMed Central - PubMed

ABSTRACT

Background: Metallic reconstruction plates used for fracture stabilization typically require intraoperative contouring for patient-specific anatomical fit. Despite this, characterization of plate mechanical properties after contouring has previously been limited.

Background: The objective of this study was to assess whether contouring affects fatigue resistance for three types of Stryker seven-hole stainless steel (SS) 316LVM fracture fixation plates. The hypothesis was that for each plate type, more contouring repetitions would result in lower fatigue resistance.

Methods: Plates were contoured using a bench-top plate bender to ±20° either 0×, 3×, 6×, or 9× (n = 5 per group) and tested in the straight configuration. Cyclic four-point bending was applied in an incremental stepwise staircase approach (one step = 100,000 cycles, 10 Hz) until failure (defined as brittle fracture or plastic deformation of 10° permanent bend). Moment-cycle product (MCP) was computed as the summation of maximum moment × number of cycles and used as the primary measure of fatigue resistance.

Results: No significant differences in fatigue resistance were detected between contouring groups for Basic Fragment Set (BFS) Reconstruction Plates. Significantly lower fatigue resistance was measured for 9× contoured Matta Pelvic System (MPS) Straight Plates compared to 0× contoured plates (p = 0.023). MPS Flex Plates contoured 3× had greater fatigue resistance than 0× contoured (p = 0.031) and 9× contoured plates (p = 0.032).

Conclusions: This work provides fatigue resistance-based evidence that clinicians should avoid high repetitions of contouring for MPS Straight Plates. Meanwhile, BFS Reconstruction Plates and MPS Flex Plates are not negatively affected by contouring. These results allow for improved intraoperative decisions about using or discarding plates after multiple contouring repetitions.

No MeSH data available.