Can the Use of Variable-Angle Volar Locking Plates Compensate for Suboptimal Plate Positioning in Unstable Distal Radius Fractures? A Biomechanical Study

Hart, Adam; Collins, Melissa; Chhatwal, Dane; Steffen, Thomas; Harvey, Edward J.; Martineau, Paul A.

doi:10.1097/bot.0000000000000146

Cited by 22 publications

(9 citation statements)

References 29 publications

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“…Previous setups vary in almost every aspect, i.e. boundary conditions, the fracture model, and the specimens used [ 17 – 20 ]. All of these have a pronounced impact on the biomechanical outcome parameters.…”

Section: Discussionmentioning

confidence: 99%

“…Constrained axial compression also results in considerable shear forces and moments and is therefore believed to simulate all relevant forces occurring within the construct [ 39 , 40 ]. Moreover, while some studies applied fatigue testing [ 39 , 11 ], our goal was the assessment of primary stability, following previous studies [ 34 , 17 , 13 ]. Finally, the influence of distal screw length was only assessed for the most common distal radius fracture (AO-23 A3) using a biomechanical fracture model.…”

Section: Discussionmentioning

confidence: 99%

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The influence of distal screw length on the primary stability of volar plate osteosynthesis—a biomechanical study

et al. 2015

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BackgroundExtensor tendon irritation is one of the most common complications following volar locking plate osteosynthesis (VLPO) for distal radius fractures. It is most likely caused by distal screws protruding the dorsal cortex. Shorter distal screws could avoid this, yet the influence of distal screw length on the primary stability in VLPO is unknown. The aim of this study was to compare 75 to 100 % distal screw lengths in VLPO.MethodsA biomechanical study was conducted on 11 paired fresh-frozen radii. HRpQCT scans were performed to assess bone mineral density (BMD) and bone mineral content (BMC). The specimens were randomized pair-wise into two groups: 100 % (group A) and 75 % (group B) unicortical distal screw lengths. A validated fracture model for extra-articular distal radius fractures (AO-23 A3) was used. Polyaxial volar locking plates were mounted, and distal screws was inserted using a drill guide block. For group A, the distal screw tips were intended to be flush or just short of the dorsal cortex. In group B, a target screw length of 75 % was calculated. The specimens were tested to failure using a displacement-controlled axial compression test. Primary biomechanical stability was assessed by stiffness, elastic limit, and maximum force as well as with residual tilt, which quantified plastic deformation.ResultsNine specimens were tested successfully. BMD and BMC did not differ between the two groups. The mean distal screw length of group A was 21.7 ± 2.6 mm (range: 16 to 26 mm), for group B 16.9 ± 1.9 mm (range: 12 to 20 mm). Distal screws in group B were on average 5.6 ± 0.9 mm (range: 3 to 7 mm) shorter than measured. No significant differences were found for stiffness (706 ± 103 N/mm vs. 660 ± 124 N/mm), elastic limit (177 ± 25 N vs. 167 ± 36 N), maximum force (493 ± 139 N vs. 471 ± 149 N), or residual tilt (7.3° ± 0.7° vs. 7.1° ± 1.3°).ConclusionThe 75 % distal screw length in VLPO provides similar primary stability to 100 % unicortical screw length. This study, for the first time, provides the biomechanical basis to choose distal screws significantly shorter then measured.Electronic supplementary materialThe online version of this article (doi:10.1186/s13018-015-0283-8) contains supplementary material, which is available to authorized users.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

The influence of distal screw length on the primary stability of volar plate osteosynthesis—a biomechanical study

et al. 2015

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“…Same results were found by Penzkofer et al9) We chose to use three distal screws in this model. Hart et al10) did a biomechanical study that compared dual plating of the distal humerus with either one or three screws in the distal ulna column for AO/OTA A3 type fractures. This study showed that the constructs with three distal screws had a higher stiffness in axial loading and bending.…”

Section: Discussionmentioning

confidence: 99%

Biomechanical Comparison of Fixed- versus Variable-Angle Locking Screws for Distal Humerus Comminuted Fractures

et al. 2019

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Background To compare the stability of fixed- versus variable-angle locking constructs for the comminuted distal humerus fracture (AO/OTA 13-A3). Methods Eight pairs of complete humeri harvested from eight fresh frozen cadavers were used for the study. We fixed the intact humeri using 2.7-mm/3.5-mm locking VA-LCP stainless steel distal humerus posterolateral (nine-hole) and medial (seven-hole) plates. An oscillating saw was used to cut a 1-cm gap above the olecranon fossa. The specimens were loaded in axial mode with the rate of 1 mm per 10 seconds to failure, and stress-strain curves were compared in each pair. The mode of failure was recorded as well as the load needed for 2- and 4-mm displacement at the lateral end of the gap. Results The stiffness of the constructs, based on the slope of the stress-strain curve, did not show any difference between the fixed- versus variable-angle constructs. Likewise, there was no difference between the force needed for 2- or 4-mm displacement at the lateral gap between the fixed- and variable-angle constructs. The mode of failure was bending of both plates in all specimens and screw pull-out in four specimen pairs in addition to the plate bending. Conclusions Our results did not show any difference in the biomechanical stability of the fixed- versus variable-angle constructs. There was not any screw breakage or failure of the plate-screw interface.

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“…VLDRP dohave a distinct advantage over any other treatment method as they allow immediate postoperative mobilisation[ 11 ], provided optimal placement of the plate/screw construct is achievedintraoperatively. Biomechanical studies[ 12 - 15 ] and clinical observations[ 16 - 20 ] indicate the best placement of the distal locking screws is as close as possible to the subchondral area of the joint to prevent loss of postoperative reduction. The aim of our study was to evaluate the relationship between distal screw placement and postoperative radial shortening in a large consecutive cohort of dorsally displaced distal radius fractures plated with VLDRP.…”

Section: Introductionmentioning

confidence: 99%

Screw placement is everything: Risk factors for loss of reduction with volar locking distal radius plates

Drobetz

Black

Davies

et al. 2018

WJO

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AIMTo determine factors correlated with postoperative radial shortening in patients with distal radius fractures treated with volar locking distal radius plates.METHODSA total of 250 patients with a distal radius fracture stabilised with volar locking plates between January 2010 and December 2014 were included in a multicentre retrospective cohort study. We measured the distance of the distal locking screws to the joint line immediately postoperatively and then measured radial shortening after six to eight weeks using the change in ulnar variance.RESULTSMultivariate linear regression analysis showed that there was a significant linear association between the distance of the screws from the joint line and radial shortening. No other patient, injury, or treatment-related characteristic significantly influenced radial shortening in multivariate analysis.CONCLUSIONDistal locking screws should be placed as close as possible to the subchondral joint line to prevent postoperative loss of reduction.

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Can the Use of Variable-Angle Volar Locking Plates Compensate for Suboptimal Plate Positioning in Unstable Distal Radius Fractures? A Biomechanical Study

Abstract: In this experimental model, variable-angle screws provided a leeway of 3 mm in both the sagittal and coronal directions without sacrificing construct strength, which may considerably facilitate fixation of these difficult fractures.

Cited by 22 publications

References 29 publications

The influence of distal screw length on the primary stability of volar plate osteosynthesis—a biomechanical study

The influence of distal screw length on the primary stability of volar plate osteosynthesis—a biomechanical study

Biomechanical Comparison of Fixed- versus Variable-Angle Locking Screws for Distal Humerus Comminuted Fractures

Screw placement is everything: Risk factors for loss of reduction with volar locking distal radius plates

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