Volar versus dorsal latest-generation variable-angle locking plates for the fixation of AO type 23C 2.1 distal radius fractures: A biomechanical study in cadavers

Department of Traumatology, Hand and Reconstructive Surgery, Universitätsklinikum Jena, Erlanger Allee 101, D-07740 Jena, Germany. Electronic address: .
Injury (Impact Factor: 2.14). 04/2013; 44(4):523–526. DOI: 10.1016/j.injury.2012.08.048


IntroductionAnatomicaly preformed variable-angle locking plates are technologically mature and appear to be optimal for the fixation of distal radius fractures. However, there is still much argument about whether volar plating is equivalent to dorsal (buttressing) plating, especially in the management of intra-articular extension fractures. This biomechanical study was performed to determine, in a simple intra-articular fracture model, whether dorsal or volar plate constructs would be more stable.Materials and methodsSix pairs of fresh frozen radii were examined with dual-energy absorptiometry (DXA) to determine their bone mineral density (BMD). An AO type 23 C2.1 fracture was created. Volar fixation was with a 2.4 mm Variable-Angle LCP Two-Column Volar Distal Radius Plate; dorsal fixation was with two orthogonal 2.4 mm Variable-Angle LCP Dorsal Distal Radius Plates (both devices: Synthes, Oberdorf, Switzerland). Biomechanical testing used a proven protocol involving static tests of stiffness, and a cyclic test to obtain range of motion (ROM), maximum deformation, and subsidence data.ResultsNone of the constructs failed during biomechanical testing. The two groups (volar and dorsal plating, respectively) did not differ significantly in terms of initial (pre-cyclic-testing) and final (post-cyclic-testing) stiffness. Equally, there was no significant difference between the subsidence values in the two groups. The post-cyclic-testing ROM was significantly greater in the dorsal-plate group as compared with the volar-plate group. The volar constructs showed a significant decrease in the ROM between pre- and post-cyclic testing.Conclusion
Biomechanically, volar plating with a modern variable-angle locking plate is equivalent to dorsal plating with two modern variable-angle locking plates.

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    • "Distal radius fractures (DRF) are among the most common fractures of the human skeleton and their incidence is anticipated to rise in the future (Nellans et al., 2012). The development of time and cost efficient treatment procedures with minimal complications is essential and was recently addressed in numerous clinical trials (Kawasaki et al., 2014; Aita et al., 2014), experimental studies (Rausch et al., 2013; Crosby et al., 2013) and computer simulations (Lin et al., 2011; Mair et al., 2011). "
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    ABSTRACT: Continuum-level finite element (FE) models can be used to analyze and improve osteosynthesis procedures for distal radius fractures (DRF) from a biomechanical point of view. However, previous models oversimplified the bone material and lacked thorough experimental validation. The goal of this study was to assess the influence of local bone density and anisotropy in FE models of DRF osteosynthesis for predictions of axial stiffness, implant plate stresses, and screw loads. Experiments and FE analysis were conducted in 25 fresh frozen cadaveric radii with DRFs treated by volar locking plate osteosynthesis. Specimen specific geometries were captured using clinical quantitative CT (QCT) scans of the prepared samples. Local bone material properties were computed based on high resolution CT (HR-pQCT) scans of the intact radii. The axial stiffness and individual screw loads were evaluated in FE models, with (1) orthotropic inhomogeneous (OrthoInhom), (2) isotropic inhomogeneous (IsoInhom), and (3) isotropic homogeneous (IsoHom) bone material and compared to the experimental axial stiffness and screw-plate interface failures. FE simulated and experimental axial stiffness correlated significantly (p<0.0001) for all three model types. The coefficient of determination was similar for OrthoInhom (R(2)=0.807) and IsoInhom (R(2)=0.816) models but considerably lower for IsoHom models (R(2)=0.500). The peak screw loads were in qualitative agreement with experimental screw-plate interface failure. Individual loads and implant plate stresses of IsoHom models differed significantly (p<0.05) from OrthoInhom and IsoInhom models. In conclusion, including local bone density in FE models of DRF osteosynthesis is essential whereas local bone anisotropy hardly effects the models׳ predictive abilities.
    No preview · Article · Nov 2015 · Journal of Biomechanics
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    • "Injury procedure with plating is a reliable choice of treatment for displaced intra-articular distal radius fractures [6] [7] [8] defined as unstable according to stability criteria described in the literature [9]. Since the last decade, dorsal plating is no longer considered the best management of unstable dorsal displaced fractures [6] [10]. "
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    ABSTRACT: Small variations within normal range of radiographic parameters, except ulnar variance and volar tilt, do not influence the final functional outcome in distal radius fractures. There are many reports in the literature on the relationship between radiographic variables and their influence on the final outcome of distal radius fractures. Most authors report that a good functional result depends on anatomical restoration of the articular surface and extra-articular alignment. The aim of this study was to verify if it is really necessary to restore anatomic radiographic parameters to obtain satisfactory functional outcome in distal radius fractures treated with volar plate. We retrospectively evaluated 51 patients treated with volar locked plate for articular unstable distal radius fractures from December 2006 to March 2009. Each fracture was evaluated according to the AO classification. The average follow-up was 40.5 months. Radiological measurements were performed considering radial height, radial inclination, volar tilt and ulnar variance, both preoperatively and postoperatively, to estimate the correction value. We examined range of motion (ROM), grip strength with a Jamar(®) dynamometer and Disabilities of the Arm, Shoulder and Hand (DASH) score. The τ Student test was performed for statistical analysis. The persistence of articular step-off was assessed in 35.3% of patients. Normal radial inclination (21-25°) was restored in 74.5% of patients (range 15-27.5°). Normal radial height (10-13mm) was restored in 66.6% of patients (range 6.8-17.3mm). Normal volar tilt (7-15°) was achieved in 90.2% of patients (range 3-17°). Normal ulnar variance (0.7-1.5mm) was restored in 86.3% of patients (range 0.7-4.1mm). There was a statistically significant difference between the preoperative and postoperative radiographic values (p<0.01). The majority of patients showed complete recovery of ROM, with no statistically significant difference (p>0.05) in extension, flexion, supination and pronation compared with the contralateral hand. Eight patients who had postoperative volar tilt and/or ulnar variance out of range had a statistically significant difference (p<0.05) in ROM compared with the non-operated side. At final follow-up, all patients had a statistically significant difference (p<0.05) in grip strength compared with the contralateral side, even with good strength values. The mean DASH score was 12.2 (range 0-61). Our experience suggests that ulnar variance and volar tilt are the most important radiographic parameters to be restored to obtain good functional outcome in distal radius fracture. Small variations of other radiographic parameters seem to not affect the final outcome at minimum 3 years' follow-up. Copyright © 2014 Elsevier Ltd. All rights reserved.
    Full-text · Article · Oct 2014 · Injury
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    ABSTRACT: To evaluate if the use of locking head screws (LHS) in the distal holes of a locking compression plate (LCP) applied to the caudal aspect of the ulna to treat equine ulnar fractures is associated with a risk of injury to the lateral cortex of the radius. Controlled laboratory study. Cadaveric equine forelimbs (n = 8 pair). After transverse ulnar osteotomy, osteosynthesis was performed with a narrow 10-13 hole 4.5/5.0 LCP applied to the caudal aspect of each ulna. The distal 3 holes were filled with 4.5 mm cortex screws (CS) in 1 limb (group 1) and with 5.0 mm LHS contralaterally (group 2). CS were inserted in an angle deemed appropriate by the surgeon and LHS were inserted perpendicular to the plate. Implant position and injury to the lateral cortex of the radius were assessed by radiography, CT, and limb dissection. In group 1, injury of the lateral radius cortex did not occur. In group 2, 4 limbs and 6/24 LHS were associated with injury of the lateral radius cortex by penetration of a LHS. This difference was statistically significant. CS were inserted with a mean angle of 17.6° from the sagittal plane in a caudolateral-craniomedial direction. Use of LHS in the distal part of a LCP applied to the caudal aspect of the ulna is associated with a risk of inadvertent injury to the lateral cortex of the radius.
    No preview · Article · Sep 2013 · Veterinary Surgery
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