Locking versus nonlocking T-plates for dorsal and volar fixation of dorsally comminuted distal radius fractures: a biomechanical study

Biomechanical Comparison of 5 Different Fixation Constructs in a Trapeziometacarpal Joint Arthrodesis Model

PURPOSE

Trapeziometacarpal joint (TMC) arthrodesis has a high rate of nonunion. This biomechanical analysis sought to determine the stiffness of 5 fixation methods in a TMC joint arthrodesis model.

METHODS

Five fixation constructs were tested in a validated porcine model: crossed 1.1-mm K-wires, crossed 1.6-mm K-wires, crossed headless compression screws (HCSs), compression plating (CP), and locked compression plating (LCP). The cantilever bending stiffness was measured in abduction, adduction, flexion, and extension. Samples were loaded to failure in extension, and the mode of failure was examined.

RESULTS

The crossed HCSs performed consistently well in all tests. Loading to failure resulted in screw pullout. In abduction and adduction, HCS and 1.6-mm K-wires were significantly stiffer than the other constructs. The mean load to failure in extension was similar in the HCS, CP, and LCP groups (304 N/mm, 311 N/mm, and 293 N/mm, respectively). There were no differences between CP and LCP in any biomechanical tests, and the mode of failure was through plate bending. The crossed 1.1-mm K-wires performed poorly in all tests.

CONCLUSIONS

Crossed HCS displayed the greatest overall stability. Standard plating in compression mode and LCP had a similar biomechanical performance.

CLINICAL RELEVANCE

The ideal construct stiffness required for the successful union after TMC joint arthrodesis is unknown, but HCS has the best overall biomechanical performance and, therefore, might be considered the best choice for this clinical setting.

Biomechanical performance of talon cannulated compression device in pauwels type III fractures: a comparative study

INTRODUCTION

Pauwels Type III fractures are unstable and frequently treated with cannulated screws (CS) or dynamic hip screws (DHS). The newly developed talon-cannulated compression devices (TCCD) have the potential to provide rotational stability, mainly through their talon. The study investigates whether TCCD has mechanical advantages over conventional screws or can be as stable as DHS in a reverse triangle configuration for an unstable femoral neck fracture.

MATERIAL AND METHODS

After creating a standard Pauwels Type III unstable femoral neck fracture in 36 synthetic femur bones in cortical/hard cancellous bone density, 18 were reserved for dynamic-static tests, and 18 were used for torsional tests. Each group containing 18 synthetic bones was divided into three groups to apply three different fixation materials (CS, DHS, and TCCD), with six models in each group. The displacement amounts after dynamic-static tests were measured using the AutoCAD program according to the reference measurement criteria. During the dynamic tests, a series of photographs were taken. During the static tests, the beginning and post-test photographs were taken. Finally, torsional tests were performed until implant failure occurred in the synthetic femur.

RESULTS

In static axial loading tests, TCDD was found to be statistically superior to conventional CS in AL-BL distance (p = 0,014) and CL distance (p = 0,013) measurements, and there was no significant difference between the other groups. There was no significant difference between all groups in dynamic axial compression tests in any points of interest. In torsional tests, TCCD outperformed cannulated screws in stiffness (p = 0,001) and maximum torque (p = 0,001) categories, and they provided statistically significant superiority to DHS in yield torque (p<0,001) category.

CONCLUSIONS

Biomechanically, TCCD predominates conventional cannulated screws in femoral neck fractures. TCCD also has superior torsional properties than DHS in the yield torque category. Therefore, TCCD could be the implant of choice for unstable femoral neck fractures.

Biomechanics of Subcutaneous Locked Plating Versus Burke Plate and External Fixator for Comminuted Distal Radius Fractures

Background External fixators that span the wrist have been the historical norm in treating distal radius fractures. We have modified a dorsal distraction approach by using a subcutaneously applied locked bridge plate through two small incisions superficial to the extensor tendons and outside the extensor compartment. The purpose of this study was to biomechanically evaluate this modified method of fixation for comminuted distal radius fractures in comparison with two established constructs. Methods Matched cadaver specimens were used to model an AO Type 23-C3 distal radius fracture. Biochemical testing for stiffness during axial compressive loading was done on three constructs: a conventional Burke distraction plate, the subcutaneous internal fixation plating technique, and an external fixator. All specimens were cyclically loaded for 3000 cycles and then retested. Results The modified construct was found to be stiffer than the external fixator (p=0.013). When compared to the Burke plate, the modified construct was significantly less stiff before axial cycling (p=0.025). However, the difference was not maintained after cycling, and the post-axial loading stiffness difference was non-significant (p=0.456). Conclusion Our data demonstrate the biomechanical integrity of the subcutaneous plating technique for the fixation of comminuted distal radius fractures. It is stiffer than an external fixator and has the theoretical advantage of avoiding pin-tract infections. In addition, it is subcutaneous and not a cumbersome external construct. Our construct is minimally invasive, and it does not violate the dorsal extensor compartments. This allows for finger movement even while the construct is in place.

Evaluating the biomechanical performance of Ti6Al4V volar plates in patients with distal radius fractures

Purpose: This study aimed to investigate the biomechanical performance of three Ti6Al4V volar plates with the latest designs using a finite element model. Methods: An AO type 23-A3 distal radius fracture and the models of T plate (2.4 mm LCP Volar Distal Radius Plate), V plate (2.4 mm LCP Two-Column Volar Distal Radius Plate) and π Plate (2.4 mm Volar Rim Distal Radius Plate) (all from Depuy Synthes, West Chester, PA, USA, Ti6Al4V) were built in 3D-matic software. After assembling the internal fixation and fractures, we imported these models into the finite element analysis software (ABAQUS). An axial loading of 100 N was added to the distal end of each model. The displacements of total models and implants, the principal strains and the von Mises stresses in the plates were calculated and compared to capture the biomechanical features of the three plates. Results: The T plate, V plate and π plate represented a model displacement of 0.8414 mm, 1.134 mm and 1.936 mm, respectively. The T plate was with the implant displacement of 0.7576 mm, followed by the V plate (0.8802 mm) and the π plate (1.545 mm). The T plate had the smallest principal strain of 0.23%, the V plate showed an intermediate level of 0.28%, and the π plate had a value of 0.72%. The least peak von Mises stress was observed in the V plate with 263.6MPa, and this value was 435.6 MPa and 1050 MPa in the T plate and π plate, respectively. Conclusion: The biomechanical features of three Ti6Al4V volar locking plates in an AO type 23-A3 fracture were described in our analysis. The T plate and the V plate showed similar biomechanical performance while the π plate represented worse performance than the other two plates.

Volar versus combined dorsal and volar plate fixation of complex intraarticular distal radius fractures with small dorsoulnar fragment - a biomechanical study

Complex intraarticular distal radius fractures (DRFs), commonly managed with volar locking plates, are challenging. Combined volar and dorsal plating is frequently applied for treatment, however, biomechanical investigations are scant. The aim of this biomechanical study was to investigate volar plating versus double plating in DRFs with different degrees of lunate facet comminution.Thirty artificial radii with simulated AO/OTA 23-C2.1 and C3.1 DRFs, including dorsal defect and lunate facet comminution, were assigned to 3 groups: Group 1 with two equally-sized lunate facet fragments; Group 2 with small dorsal and large volar fragment; Group 3 with three equally-sized fragments. The specimens underwent volar and double locked plating and non-destructive ramped loading in 0° neutral position, 40° flexion and 40° extension.In each tested position, stiffness: (1) did not significantly differ among groups with same fixation method (p ≥ 0.15); (2) increased significantly after supplemental dorsal plating in Group 2 and Group 3 (p ≤ 0.02).Interfragmentary displacements between styloid process and lunate facet in neutral position were below 0.5 mm, being not significantly different among groups and plating techniques (p ≥ 0.63).Following volar plating, angular displacement of the lunate facet to radius shaft was significantly lower in Group 1 versus both Group 2 and Group 3 (p < 0.01). It decreased significantly after supplemental dorsal plating in Group 2 and Group 3 (p < 0.01), but not in Group 1 (p ≥ 0.13), and did not differ significantly among the three groups after double plating (p ≥ 0.74).Comminution of the lunate facet within its dorsal third significantly affected the biomechanical outcomes related to complex intraarticular DRFs treated with volar and double locked plates.Double plating demonstrates superior stability versus volar plating only for lunate facet comminution within its dorsal third. In contrast, volar plating could achieve stability comparable with double plating when the dorsal third of the lunate facet is not separated by the fracture pattern. Both fixation methods indicated achievable absolute stability between the articular fragments.

Mechanical Comparison of a Novel Hybrid and Commercial Dorsal Double Plating for Distal Radius Fracture: In Vitro Fatigue Four-Point Bending and Biomechanical Testing

This study compares the absolute and relative stabilities of a novel hybrid dorsal double plating (HDDP) to the often-used dorsal double plating (DDP) under distal radius fracture. The “Y” shape profile with 1.6 mm HDDP thickness was obtained by combining weighted topology optimization and finite element (FE) analysis and fabricated using Ti6Al4V alloy to perform the experimental tests. Static and fatigue four-point bending testing for HDDP and straight L-plate DDP was carried out to obtain the corresponding proof load, strength, and stiffness and the endurance limit (passed at 1 × 10⁶ load cycles) based on the ASTM F382 testing protocol. Biomechanical fatigue tests were performed for HDDP and commercial DDP systems fixed on the composite Sawbone under physiological loads with axial loading, bending, and torsion to understand the relative stability in a standardized AO OTA 2R3A3.1 fracture model. The static four-point bending results showed that the corresponding average proof load values for HDDP and DDPs were 109.22 N and 47.36 N, that the bending strengths were 1911.29 N/mm and 1183.93 N/mm, and that the bending stiffnesses were 42.85 N/mm and 4.85 N/mm, respectively. The proof load, bending strength and bending stiffness of the HDDPs were all significantly higher than those of DDPs. The HDDP failure patterns were found around the fourth locking screw hole from the proximal site, while slight plate bending deformations without breaks were found for DDP. The endurance limit was 76.50 N (equal to torque 1338.75 N/mm) for HDDP and 37.89 N (equal to torque 947.20 N/mm) for DDP. The biomechanical fatigue test indicated that displacements under axial load, bending, and torsion showed no significant differences between the HDDP and DDP groups. This study concluded that the mechanical strength and endurance limit of the HDDP was superior to a commercial DDP straight plate in the four-point bending test. The stabilities on the artificial radius fractured system were equivalent for novel HDDP and commercial DDP under physiological loads in biomechanical fatigue tests.

Does posterior configuration have similar strength as parallel configuration for treating comminuted distal humerus fractures? A cadaveric biomechanical study

BACKGROUND

The posterior plating technique could be used as a clinical alternative to parallel plating for treating comminuted distal humerus fractures (DHFs) successfully with good clinical results. However, the biomechanical characteristics for posterior fixation are still unclear. The purpose of this study is to evaluate the biomechanical properties of the posterior fixation and to make comparisons between the parallel and the posterior fixation systems.

MATERIALS AND METHODS

We performed a cadaveric biomechanical testing with two posterior plating systems (a posterior two plating and a single posterior pre-contoured Y plating system) and one parallel two plating system to treat AO/OTA type-C2.3 DHFs. Among three groups, we compared construct stiffness, failure strength, and intercondylar width changes after 5000-cycle fatigue loading and failure loads and failure modes after destructive tests in both the axial compression and (sagittal) posterior bending directions. The correlations between construct failure loads and bone marrow density (BMD) were also compared.

RESULTS

In axial direction, there were no significant differences in the stiffness and failure load between the posterior and the parallel constructs. However, in sagittal direction, the two-plate groups (posterior two plating and parallel plating group) had significant higher stiffness and failure loads than the one-plate group (single posterior Y plating). There was no fixation failure after 5000-cyclic loading in both directions for all groups. Positive correlation was noted between BMD and failure loads on parallel fixation.

CONCLUSIONS

We found that when using two plates for treating comminuted DHFs, there were no significant differences in terms of most biomechanical measurements between posterior and parallel fixation. However, the single pre-contoured posterior Y plate construct was biomechanically weaker in the sagittal plane than the parallel and the posterior two-plate constructs, although there was no fixation failure after the fatigue test for all groups regardless of the fixation methods.

LEVEL OF EVIDENCE

Biomechanical study.

Locking Screws With a Threaded Degradable Polymer Collar Reduce Construct Stiffness Over Time

OBJECTIVES

The stiffness of locking plates provide increased stability for early fracture healing but may limit late interfragmentary motion (IFM) necessary for secondary bone healing. An ideal plating construct would provide early rigidity and late flexibility to optimize bone healing. A novel screw plate construct utilizing locking screws with a degradable polymer locking mechanism is a dynamic option.

METHODS

Conventional locked plating constructs (group A) were compared with locking screws with a threaded degradable polymer collar before (group B) and after polymer dissolution (group C). Monotonic axial compression, monotonic torsion, cyclic axial load to failure, and IFM at the near and far cortices were tested on synthetic bone models.

RESULTS

One-way analysis of variance and post hoc Tukey-Kramer testing demonstrated similar axial stiffness in group A (873 ± 146 N/mm) and B (694 ± 314 N/mm) but significantly less stiffness in group C (379 ± 59 N/mm; F(2,15) = 9.12, P = 0.003). Groups A and B also had similar IFM, but group C had significantly increased IFM at both the near (F(2, 15) = 48.66, P = 2.76E-07) and far (F(2, 15) = 11.78, P = 0.0008) cortices. In cyclic axial load to failure, group A (1593 ± 233 N) and B (1277 ± 141 N) were again similar, but group C was significantly less (912 ± 256 N; F(2, 15) = 15.00, P = 0.0003). All failures were above the 500-N threshold seen in typical weight-bearing restrictions for fracture care. Torsional stiffness demonstrated significant differences between all groups (F(2, 15) = 106.64, P = 1.4E-09).

CONCLUSIONS

Use of locking plates with a degradable polymer collar show potential for in vitro construct dynamization. Future in vivo studies are warranted to assess performance under combined loading and the effects of decreasing construct stiffness during the course of bony healing.

Volar Locking Plate Fixations for Displaced Distal Radius Fractures: An Evaluation of Complications and Radiographic Outcomes

BACKGROUND

A volar locking plate (VLP) is the most frequently used form of implant used for open reduction and internal fixation of distal radius fractures. They are known to have a complication rate of up to 27%. We hypothesized that plate design could influence complication rates.

METHODS

We performed a review of patients undergoing VLP fixation for distal radius fracture. A total of 228 patients underwent fixation with the Distal Volar Radial Anatomical (DVR) plate; 388 patients underwent fixation with the VariAx plate. Independent observers performed blinded case note and radiographic review, to assess for the quality of reduction, and complications for the inserted VLP.

RESULTS

Mean time to surgery was 6.0 days; mean follow-up was 17.5 weeks. Mean age was 56.5 years. The quality of reduction was classified as anatomical (46%), good (36.3%), moderate (13.0%), or poor (3.9%). Complications were identified in 109 patients (17%). Plate prominence was seen in 133 patients (21%). The DVR plate was less prominent ( P < .001) and had better overall radiographic appearances ( P = .025). Flexor tendon complications were related to plate prominence ( P = .005). Inferior reduction was associated with increased time to surgery ( P = .020).

CONCLUSIONS

This study highlights the importance of prompt surgery, effective fracture reduction, and careful plate positioning to avoid volar prominence.

A biomechanical comparison of four fixed-angle dorsal plates in a finite element model of dorsally-unstable radius fracture

PURPOSE

To compare the finite element models of two different composite radius fracture patterns, reduced and stabilised with four different fixed-angle dorsal plates during axial, dorsal and volar loading conditions.

METHODS

Eight different plastic models representing four AO/ASIF type 23-A3 distal radius fractures and four AO/ASIF 23-C2 distal radius fractures were obtained and fixed each with 1 of 4 methods: a standard dorsal non-anatomical fixed angle T-plate (3.5mm Dorsal T-plate, Synthes), anatomical fixed-angle double plates (2.4mm LCP Dorsal Distal Radius, Synthes), anatomical fixed angle T-plate (2.4mm Acu-Loc Dorsal Plate, Acumed) or anatomical variable-angle dorsal T-plate (3.5mm, Dorsal Plate, Zrinski). Composite radius with plate and screws were scanned with a 3D optical scanner and later processed in Abaqus Software to generate the finite element model. All models were axially loaded at 3 points (centrally, volarly and dorsally) with 50 N forces to avoid the appearance of plastic deformations of the models. Total displacements at the end of the bone and the stresses in the bones and plates were determined and compared.

RESULTS

Maximal von Mises stress in bone for 3-part fracture models was very similar to that in 2-part fracture models. The biggest difference between models and the largest displacements were seen during volar loading. The stresses in all models were the highest above the fracture gap. The best performance in all parameters tested was with the Zrinski plate and the most modest results were with the Synthes T-plate.

CONCLUSION

There was no significant difference between 2-part (AO/ASIF type 23-A3) and 3-part (AO/ASIF 23-C2) fracture models. Maximal stresses in the plates appeared above the fracture gap; therefore, it is worth considering the development of plates without screw holes above the gap.

Volar Locking Plate Breakage after Nonunion of a Distal Radius Osteotomy

We report a 38-year-old male with a nonunion followed by plate breakage after volar plating of a distal radius osteotomy. Volar locking plates have added a new approach to the treatment of distal radius malunions, due to a lower morbidity of the surgical approach and the strength of the final construction, allowing early mobilization and return to function. Conclusion. Plate breakage is an uncommon complication of volar locking plate fixation. To our knowledge, few cases have been described after a distal radius fracture and no case has been described after a distal radius corrective osteotomy. In the present case, plate breakage appears to have occurred as a result of a combination of multiple factors as the large corrective lengthening osteotomy, the use of demineralized bone matrix instead of bone graft, and the inappropriate fixation technique as an unfilled screw on the osteotomy site, rather than the choice of plate.

The Effect of Osteoporosis on Healing of Distal Radius Fragility Fractures

Although the decision for operative versus nonoperative treatment of distal radius fractures remains subjective and is performed on a case-by-case basis, evaluation and treatment of patients with concomitant osteoporosis requires understanding of the behavior of this injury as a distinct subset of distal radius fractures. Age, infirmity, and osteoporosis affect every aspect of the fracture. Understanding what makes these fractures unique assists surgeons in more effective and efficient treatment. The authors present the current understanding of osteoporotic fragility fractures of the distal radius, focusing on epidemiology, biomechanics of bone healing, and its implication on strategies for management.

Distal radius fractures in athletes: approaches and treatment considerations

Fractures of the distal radius are common injuries in both athletes and nonathletes. Management is dictated by the nature of the fracture and the patient's level of competition, age, and sport-specific demands. Treatment strategies range from nonoperative treatment for stable injuries to primarily operative treatment for unstable fractures, particularly in active athletes. Once the decision has been made to treat a distal radius fracture operatively, a wide variety of fixation options are available. However, no technique has proven superior to all others, and no single method of fixation will lead to acceptable results in all types of distal radius fractures. This study will highlight important considerations when treating distal radius fractures in athletes, describe the various fixation options available, and discuss our method for determining the fixation needs of each fracture.

Biomechanical comparison of osteoporotic distal radius fractures fixed by distal locking screws with different length

Objectives

To evaluate the postoperative stability of osteoporotic distal radius fractures fixed with distal locking screws with different length.

Methods

A comminuted extra-articular dorsally unstable distal radius fracture, treated with volar locking plate system, was created. The 18 specimens were randomized into 3 groups based on distal locked screws with different length: Group A had unicortical screws with 50% length to the dorsal cortex. Group B had unicortical screws with 75% length to the dorsal cortex. Group C had bicortical screws. Axial compression and bending loads were imposed on the models before and after cycling testing as well as load to clinical and catastrophic failure.

Results

Minimum change in stiffness was observed before and after fatigue for all groups. The final stiffness to bending forces was statistically similar in all groups, but stiffness to axial compression was statistically significant different: Group A approached significance with respect to groups B and C (P = 0.017, 0.009), whereas stiffness in group B and C was statistically similar (P = 0.93). Load to clinical failure was significantly less for group A (456.54±78.59 N) compared with groups B (580.24±73.85 N) and C (591.07±38.40 N). Load to catastrophic failure was statistically similar between groups, but mean values for Group A were 18% less than means for Group C.

Conclusions

The volar locking plate system fixed with unicortical locking screws with at least 75% length not only produced early stability for osteoporotic distal radius fractures, but also avoided extensor tendon complications due to dorsal screw protrusion.

A descriptive study on wrist and hand sensori-motor impairment and function following distal radius fracture intervention

STUDY DESIGN

Descriptive cross-sectional design.

INTRODUCTION

Wrist and hand sensori-motor impairment have been observed after distal radius fracture (DRF) treatment. This impairment and its relationship to function lack research.

PURPOSE OF THE STUDY

The primary aim of this exploratory study was to determine the magnitude of wrist and hand sensori-motor impairment following surgical and non-surgical treatment among older patients following DRF. Secondary aims were to determine the relationship between wrist and hand sensori-motor impairment with function and pain as well as the relationships among wrist and hand sensori-motor impairment and function and age following DRF.

METHODS

Ten Test (TT), active joint position sense (JPS), electromyography (EMG), computerized hand-grip dynamometer (CHD), and the Patient-Rated Wrist Evaluation (PRWE) were used to assess twenty-four female participants 8 weeks following DRF treatment and their 24 matched-control healthy counterparts on wrist and hand sensibility, proprioception, muscle recruitment, grip force, muscle fatigue, and functional status.

RESULTS

Participants following DRF demonstrated significantly (p < .05) greater sensory (i.e., JPS, TT), and motor (i.e., EMG, CHD) deficits than their control counterparts. A significantly higher functional deficit (i.e., PRWE) also existed among participants following DRF than the control group. Participants following surgical and non-surgical DRF treatment were found to be statistically different only on total grip force. Group differences on JPS and total grip force revealed the strongest effect size with the highest correlations to PRWE. EMG and muscle fatigue ratio group differences revealed a weaker effect size with a fair degree of correlation to PRWE. Pain significantly correlated with sensori-motor function. Age did not correlate with any measured variable.

CONCLUSIONS

Significant wrist and hand sensori-motor impairment and functional deficits among older females 8 weeks following DRF surgical and non-surgical interventions were revealed. JPS and total grip force were the most clinically meaningful tests for assessing the sensori-motor status as well as explaining functional disability and pain levels for these patients.

LEVEL OF EVIDENCE

2c.

FLEXOR POLLICIS LONGUS TENDON ENTRAPMENT AFTER PERFORMING MINIMALLY INVASIVE PLATE OSTEOSYNTHESIS OF A DISTAL RADIUS FRACTURE: A CASE REPORT

In this study, we report a case of a 60-year-old woman with diabetes mellitus, who had a left distal radius fracture and could not flex the interphalangeal joint of her left thumb after we performed an open reduction and internal fixation procedure using minimally invasive plate osteosynthesis. Nine days after the first operation, we explored her wrist. We observed that the flexor pollicis longus tendon was compressed by the inserted plate. Then revision surgery and tendon repair were performed. Three months later, the fracture was healed and flexor pollicis longus function recovered well without sequelae. Approach through the interval between flexor carpi radialis and radial artery is preferred to prevent tendon entrapement.

Biomechanical comparison of axial load between cannulated locking screws and noncannulated cortical locking screws

The goal of this study was to compare the biomechanical stability of cannulated locking screws and noncannulated cortical locking screws in a periarticular locking plate. Twelve fresh-frozen porcine tibias with a 1-cm gap created distal to the tibial plateau were used to simulate an unstable proximal tibial fracture. All specimens were fixed with a periarticular proximal lateral tibial locking plate and divided into 2 groups based on whether the proximal metaphyseal screw holes of the plate were inserted with either cannulated locking screws or noncannulated cortical locking screws. An axial compressive load was applied to cause failure in each specimen using a materials testing instrument. The axial stiffness and maximum failure strength in axial loading were recorded. Axial stiffness of the constructs using noncannulated cortical locking screw was significantly higher than that of the constructs using cannulated locking screws (P=.006). Axial failure strength of the constructs using noncannulated cortical locking screw was significantly higher than that of the constructs using cannulated locking screws (P=.002). The failure mode observed in all specimens was a permanent screw-bending deformity over the head-shaft junction of proximal metaphyseal screws, irrespective of whether they were cannulated or noncannulated cortical locking screws. Fixation with noncannulated cortical locking screws offered more stability than cannulated locking screws with regard to axial stiffness and failure strength in a porcine model with unstable proximal tibial fractures.

Comparison of a new intramedullary scaffold to volar plating for treatment of distal radius fractures

OBJECTIVES

To compare the biomechanical properties of a new nitinol intramedullary (IM) scaffold implant with those of volar plates for the treatment of dorsally comminuted extra-articular distal radius fractures using an established model.

METHODS

A dorsal wedge osteotomy was performed on a bone model to simulate a dorsally comminuted extra-articular distal radius fracture. This model was used to compare stiffness of 3 different distal radius fixation devices--an IM scaffold implant, a commercially available titanium volar locking plate, and a stainless steel non-locking T-plate. Six constructs were tested per group. Tolerance for physiological loading was assessed by applying 10,000 cycles of axial loading up to 100 N applied at 2 Hz. Axial and eccentric load stiffness were assessed before cyclic loading and axial stiffness again after cyclic loading. Groups were compared using analysis of variance.

RESULTS

Initial axial stiffness (in Newton per millimeter) was significantly (P = 0.011) different only between the volar locking plate (427 ± 43) and non-locking T-plate (235 ± 69). After cyclic loading, axial stiffness was not significantly different between the volar locking plate (392 ± 67) and IM scaffold implant (405 ± 108), but both were significantly (P < 0.001) stiffer than the non-locking T-plate (187 ± 53). Eccentric loading stiffness was not significantly different between the IM scaffold implant (67 ± 140) and volar locking plate (63 ± 5), but both were significantly (P < 0.001) stiffer than the non-locking T-plate (25 ± 4).

CONCLUSIONS

Stiffness of the IM scaffold implant and volar locking plate fracture model constructs was equivalent. Biomechanical testing suggests that this novel IM scaffold provides sufficient stability for clinical use, and further testing is warranted.

Fixation of distal radius fractures in adults: a review

In patients for whom function is a priority, anatomic reduction and stable fixation are prerequisites for good outcomes. Several therapeutic options exist, including orthopedic treatment and internal fixation with pins (intra- and extrafocal), external fixation which may or may not bridge the wrist, and different internal fixation techniques with dorsal or palmar plates using or not, locking screws. Arthroscopy may be necessary in case of articular fracture. In the presence of significant metaphyseal bone defects, filling of the comminution with phosphocalcic cements provides better graft stability. The level of evidence is too low to allow recommending one type of fixation for one type of fracture; and different fixation options to achieve stable reduction exist, each with its own specific complications. With the new generations of palmar plate, secondary displacement is becoming a thing of the past.

Design optimisation and experimental evaluation of dorsal double plating fixation for distal radius fracture

This study determines the relative effects of changes in osteoporosis condition, plate/screw design factors (plate angle/length/width/thickness and screw diameter) and fixation methods (screw number and screw length) on the biomechanical response of dorsal double plating (DDP) fixation at a distal radius fracture to determine the optimal design and evaluate its biomechanical strength using the dynamic fatigue test. Eighteen CAD and finite element (FE) models corresponding to a Taguchi L18 array were constructed to perform numerical simulations to simulate the mechanical responses of a DDP fixed in a simply distal radius fracture bone. The Taguchi method was employed to determine the significance of each design factor in controlling bone/plate/screw stress and distal fragment displacement under axial (100 N), bending (1 N m) and torsion (1 N m) loads. Simulation results indicated that the order rank to determine the mechanical response was the plate thickness, plate width, screw diameter, and number of screws. Dorsal intermediate (L) plate with 60 mm length, 1.8 mm thickness, 6.0 mm width and 2.8 mm diameter, 20 mm length dual-thread locking screw can be found for optimisation. The DDP, including an L plate with 0°, 30° and 60° angles and a straight I plate, were made with Ti6Al4V to fix onto the sawbones with three corresponding radius fractures to perform the dynamic testing. The specimens were oscillated with loads between 10 N and 150 N at 5 Hz for 20,000 cycles. The average stiffness in 20,000 test cycles was 425.7 N/mm, 461.1 N/mm and 532.1N/mm for the 0°, 30° and 60° constructs, respectively. No difference in stiffness was found in the same angled constructs throughout the 20,000 cycles of testing (p > 0.05). Lack of gross construct failures during cyclic testing and reasonable stiffness corroborated that our new constructs tested to date seem stable enough to support restricted post-operative loads.

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

INTRODUCTION

Anatomicaly 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 METHODS

Six 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 2.4mm 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.

RESULTS

None 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.

Locking versus nonlocking palmar plate fixation of distal radius fractures

This study compared functional and radiological outcomes after treatment of extension-type distal radius fractures with conventional titanium nonlocking T-plates or titanium 1.5-mm locking plates. A total of 60 patients were included and followed for 4 to 7 years after receiving nonlocking T-plates (group A; n=30) or locking plates (group B; n=30) with and without dorsal bone grafting. Bone grafting was significantly more often performed in the nonlocking group to increase dorsal fracture fixation and stability (P<.003). Pre- and postoperative and follow-up values for palmar tilt, radial inclination, radial shortening, and ulnar variance were recorded. Age, sex, and fracture type were similarly distributed between the 2 groups. Postoperative and follow-up evaluation revealed equal allocation of intra-articular step formation and osteoarthritic changes to both groups. The overall complication rate was 25%. Compared with the nonlocking system, patients undergoing locking plate fixation presented with statistically significantly better values for postoperative palmar tilt (5.53° vs 8.15°; P<.02) and radial inclination (22.13° vs 25.03°; P<.02). However, forearm pronation was significantly better in group A (P<.005). At follow-up, radial inclination tended to approach a statistically significant difference in favor of group B. All clinical assessment, including Mayo wrist score, Disabilities of the Arm, Shoulder, and Hand score, Green and O'Brien score, Gartland and Werley score, visual analog scale score, and grip strength, yielded no statistically significant difference between the 2 groups. Locking plates seem to provide benefits regarding surgical technique and comfort, improvement in implant anchorage (especially in osteoporotic bone), and reduce the necessity of additional bone grafting.

Volar fixed-angle plating of distal radius fractures: screws versus pegs--a biomechanical study in a cadaveric model

OBJECTIVES

The purpose of this biomechanical study was to determine whether a multidirectional fixed-angle plate with locking screws or with locking pegs in the distal fragment would optimize fixation of Orthopaedic Trauma Association (OTA) type A3 distal radius fractures.

METHODS

Eight pairs of fresh-frozen human distal radii were used. Extra-articular distal radius fractures were created and stabilized with a multidirectional volar fixed-angle plate. The radii were randomized into 2 matched-paired groups. The distal fragment in Group I was stabilized with 7 locking screws. The distal fragment in Group II was fixed with 7 locking pegs. The proximal fragment in both groups was fixed with 3 screws. The specimens were tested under torsion and axial compression during static and cyclic tests. Finally, load-to-failure tests were performed under torsion.

RESULTS

After 1000 cycles, 99% of the median torsional stiffness remained in the group using screws, whereas only 76% of the median stiffness under torsion remained in the group using pegs (P = 0.018). Under axial compression, median stiffness remained at 93% in the group using screws after 1000 cycles compared with a median of 0% in the group using pegs (P = 0.018).

CONCLUSIONS

This biomechanical study showed a statistically significant difference between the locking screw and locking smooth peg configuration with regard to stiffness of the constructs after 1000 cycles. The use of locking screws as opposed to smooth locking pegs for OTA type A3 extra-articular distal radius fractures optimizes construct stability.

Treatment of complex fractures of the distal radius: a prospective randomised comparison of external fixation 'versus' locked volar plating

The traditional treatment of severely impacted fractures of the distal radius involves bridging external fixation and maintaining reduction by applying continuous traction. The recent technique using fixed-angle screws within volar plates is reported restore the radial length and the articular profile whilst avoiding joint distraction. It is also believed to produce better and quicker clinical results. To test these claims, we carried out a randomised controlled comparison of the efficiency of external fixation (EF) 'versus' open reduction and internal fixation (ORIF) in treating severely impacted fractures of the distal radius. A total of 39 patients were treated with EF, eventually associated with percutaneous pinning, whereas 36 underwent ORIF with a locked volar plate. There was no significant difference in the two groups with regard to changes in the ulnar variance. Articular reduction was poor in two patients in the EF group with residual step-offs exceeding 2mm; another patient of the EF group suffered a secondary loss of reduction, healing with a severe articular malunion (>2mm). By contrast, articular reduction was satisfactory in all the patients of the ORIF group. The clinical results on the Green and O'Brien rating were significantly better in the ORIF group than in the EF group (p<0.01 at 6 weeks, p<0.05 at 6 months). Nevertheless, open reduction and volar plating did not yield better subjective results than EF. However, although not statistically significant, patients treated by ORIF seemed to resume their usual activities quicker than those treated with EF, suggesting that this technique may be adapted to a greater extent in the case of active, young individuals.

Union of an intra-articular distal radius fracture after successive failures of three locking plates: a case report

We report a case of a 30-year old male, who presented with a right distal radius intra-articular fracture complicated by compartment syndrome. He was treated with fasciotomies and fracture fixation with a 3.5 mm LCP (Synthes^™), followed 7 days later by skin graft. Repeat radiographs 8 weeks later showed a break across the plate at the level of an unfilled screw hole over the fracture. He underwent exchange plating with a 2.4 mm LCP Distal Radius Plate (Synthes^™). This revision was complicated by an infected wound dehiscence 2 weeks later requiring multiple procedures. Radiographs at 20 weeks showed broken distal screws. A second revision was performed. At 12 months, the fracture had healed clinically and radiologically, but the three distal screws had broken. We discuss the multifactorial failures of the these three attempts at osteosynthesis, and which factors helped achieve osseous union. We also discuss the literature on volar locking plate breakage and conclude with the recommendations to avoid this rare complication.

Evaluation of a polyaxial angle-stable volar plate in a distal radius C-fracture model--a biomechanical study

INTRODUCTION

Polyaxial angle-stable plating is thought to be particularly beneficial in the management of complex intra-articular fractures of the distal radius. The purpose of the present study was to investigate whether the technique provides stability to match that of conventional (fixed-angle) angle-stable constructs.

MATERIAL AND METHODS

In seven pairs of human cadaver radii, an Arbeitsgemeinschaft für Osteosynthese (AO) 23 C2.1 intra-articular fracture was created. One radius of each pair received a juxta-articular 2.4-mm locking compression plate (LCP) Volar Distal Radius Plate, whilst the contralateral one received a 2.4-mm Variable Angle Locking Compression Plate (LCP) Two-Column Volar Distal Radius Plate (both plates: Synthes, Oberdorf, Switzerland). Parameters tested were construct stiffness (static axial loading with 150 N), range of motion and secondary loss of reduction (dynamic 150 N axial loading over 5000 cycles). Stiffness and range of motion were measured both pre- and post-cycling.

RESULTS

The polyaxial constructs were significantly stiffer, both before and after cyclic testing. However, the two-column plates showed a significant loss of stiffness during cyclic testing. The range of motion was significantly greater, both initially and at the end of cyclic testing, in the fixed-angle constructs. The conventional constructs had significantly greater secondary loss of reduction.

CONCLUSION

The polyaxial two-column plate tested in this study provides a biomechanically sound construct for the management of intra-articular fractures of the distal radius.

Multidirectional volar fixed-angle plating using cancellous locking screws for distal radius fractures--evaluation of three screw configurations in an extra-articular fracture model

INTRODUCTION

Volar fixed-angle plating is a popular treatment for unstable distal radius fractures. Despite the availability of plating systems for treating distal radius fractures, little is known about the mechanical properties of multidirectional fixed-angle plates. The aim of this study was to compare the primary fixation stability of three possible screw configurations in a distal extra-articular fracture model using a multidirectional fixed-angle plate with metaphyseal cancellous screws distally.

MATERIAL AND METHODS

Eighteen Sawbones radii (Sawbones, Sweden, model# 1027) were used to simulate an extra-articular distal radius fracture according to AO/OTA 23 A3. Plates were fixed to the shaft with one non-locking screw in the oval hole and two locking screws as recommended by the manufacturer. Three groups (n = 6) were defined by screw configuration in the distal metaphyseal fragment: Group 1: distal row of screws only; Group 2: 2 rows of screws, parallel insertion; Group 3: 2 rows of screws, proximal screws inserted with 30° of inclination. Specimens underwent mechanical testing under axial compression within the elastic range and load controlled between 20 N and 200 N at a rate of 40 N/s. Axial stiffness and type of construct failure were recorded.

RESULTS

There was no difference regarding axial stiffness between the three groups. In every specimen, failure of the Sawbone-implant-construct occurred as plastic bending of the volar titanium plate when the dorsal wedge was closed.

DISCUSSION

Considering the limitations of the study, the recommendation to use two rows of screws or to place screws in the proximal metaphyseal row with inclination cannot be supported by our mechanical data.

Dorsal and volar 2.4-mm titanium locking plate fixation for AO type C3 dorsally comminuted distal radius fractures

PURPOSE

In this retrospective, nonrandomized, single-surgeon study, we evaluated the clinical outcomes of dorsal and volar locking plate fixation for AO type C3 dorsally comminuted distal radius fractures.

METHODS

We treated 41 consecutive patients who had sustained AO C3 dorsally comminuted fractures of the distal radius with 2.4-mm titanium locking plates between 2006 and 2008. Patients in group 1 (n = 22) were treated with dorsal locking plates, and those in group 2 (n = 19) with volar locking plates. We evaluated clinical outcomes at an average of 37 months and performed statistical analysis using the Mann-Whitney U test and Fisher's exact test.

RESULTS

No significant difference was noted between the 2 groups in terms of radial inclination, volar tilt, and ulnar variance. At the 3- and 6-month follow-up, group 1 showed better clinical results with respect to wrist extension, grip strength, and Gartland and Werley score, whereas group 2 showed better wrist flexion during this period. The range of motion and grip strength progressively leveled out between the 2 groups, and no significant differences were observed at the 9- and 12-month assessments. One patient in group 1 had short-term complex regional pain syndrome, and 4 patients in group 2 had temporary median nerve numbness.

CONCLUSIONS

Treatment with dorsal or volar locking plates can provide satisfactory radiographic and functional outcomes for AO type C3 dorsal comminuted distal radius fractures. The dorsal plate group showed an earlier recovery of wrist extension, grip strength, and functional score at the 3- and 6-month follow-up owing to direct reduction as well as fragmental-specific fixation of the dorsal fracture fragments.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Comparison of angle stable plate fixation approaches for distal radius fractures

INTRODUCTION

The aim of the study was to compare radiological and functional outcomes between volar and dorsal surgical fixation of distal radius fractures using low-profile, fixed-angle implants.

PATIENTS AND METHODS

A total of 305 distal radius fracture patients were treated with Synthes locking compression plate (LCP) 2.4- or 3.5-mm fixation using either a volar (n=266) or dorsal (n=39) approach. The patients were examined at 6 months, 1 and 2 years for radiological assessment of fracture healing, alignment, reduction and arthritis, as well as the determination of various functional outcome scores.

RESULTS

Both groups were comparable with respect to baseline and injury characteristics. The complication rate was higher for the volar approach (15%). No significant differences were observed for Disabilities of the Arm, Shoulder and Hand (DASH) and Short Form (36) Health Survey (SF-36) scores, pain, arthritis grade, grip strength and radiological measurements. However, a significantly better functional outcome represented by a low mean Gartland and Werley score was observed for the volar approach after 6 and 12 months. Significantly higher percentages of dorsal extension, palmar flexion, ulnar deviation and supination angle (relative to the mean contralateral healthy wrist) were also reported for volar approach patients at the 6-month follow-up.

CONCLUSIONS

Volar internal fixation of distal radius fractures with LCP DR implants can result in earlier and better functional outcome compared with the dorsal approach, yet is associated with a higher incidence of complications. After 2 years, these differences are no longer observed between the two surgical methods.

Outcome of dorsally comminuted versus intact distal radial fracture fixed with volar locking plates

OBJECTIVE

Distal radial fractures are common. Modern trends favour operative treatment in many instances, providing stable fixation and early functional recovery. Recent biomechanical evidence suggests that volar locking plates (VLPs) enable adequate stability for dorsally displaced fractures, both in dorsally intact (DI) and in dorsally comminuted (DC) fractures. The aim of the study was to compare the clinical outcome of these two fracture groups treated with a VLP.

METHODS

Retrospective case-control analysis of 91 distal radial fractures treated surgically using VLP by a single surgeon between the years 2006 and 2008 was carried out. Fractures were classified according to the Arbeitsgemeinschaft für Osteosynthes/Orthopaedic Trauma Association (AO/OTA) classification. Based on initial pre-reduction X-rays and computed tomography (CT) scans, fractures were classified into two groups of DI and DC fractures. The patients were re-evaluated at 2 and 6 weeks, 3 and 6 months and 1 year.

RESULTS

Forty-one fractures (45%) were dorsally comminuted. Patients in the DC group were significantly older (mean 59 vs. 46 years, p<0.01) and included more female patients, as well as significantly more C3 type fractures than the DI group (p<0.04). The mean Disabilities of the Arm, Shoulder and Hand (DASH) score at 1 year postoperatively was 6.3±2.3 for the DC group, as compared with 6.6±2.02 for the DI group (p=0.64). Average time to return to work was longer in the DC group (81.2 vs. 63.6 days, p=0.05). Range of motion, volar tilt, and radial inclination were within clinically acceptable values and did not differ significantly among the two groups.

CONCLUSIONS

VLP fixation of DC distal radial fractures results in the maintenance of reduction and comparable functional and radiographical outcome with respect to DI fractures.

Biomechanical comparison of locking versus nonlocking volar and dorsal T-plates for fixation of dorsally comminuted distal radius fractures

OBJECTIVES

The purpose of this study was to gain insight into the effect of plate location and screw type for fixation of extra-articular distal radius fractures with dorsal comminution (Orthopaedic Trauma Association Type 23-A3.2).

METHODS

Sixteen pairs of cadaver radii were randomized to four plating configurations: dorsal locking, dorsal nonlocking, volar locking, and volar nonlocking. A standard 1-cm dorsal wedge osteotomy was used. Cyclic axial loads were applied for 5000 cycles. Stiffness and fragment displacement were recorded at 500 cycle-intervals. Pre- and postcyclic loading radiographs were analyzed. An axial load to failure test followed and construct stiffness and failure strength recorded. Biomechanical data were analyzed using a two-way analysis of variance (P < 0.05). Failure modes were descriptively interpreted.

RESULTS

Cyclic testing data revealed no difference between constructs at any interval. Within all construct groups, displacement that occurred did so within the first 500 cycles of testing. Pre- and postcyclic loading radiographic analysis showed no differences in construct deformation. Load to failure testing revealed no differences between groups, whereas volar constructs approached significance (P = 0.08) for increased failure strength. Dorsal constructs failed primarily by fragment subsidence and fragmentation, whereas volar constructs failed by plate bending.

CONCLUSIONS

No difference in all measured biomechanical parameters supports equivalence between constructs and surgeon discretion in determining operative method. Minimal fragment displacement and construct deformation during physiological testing support previous data that early postoperative motion can be recommended. Fragment displacement that occurs does so in the early periods of motion.

Number and locations of screw fixation for volar fixed-angle plating of distal radius fractures: biomechanical study

PURPOSE

To compare the biomechanical properties of different numbers and locations of screws in a multidirectional volar fixed-angle plate in a distal radius osteotomy cadaver model.

METHODS

We created an extra-articular fracture in 16 pairs of fresh-frozen human cadaver radiuses. The 32 specimens were randomized into 4 groups. All fractures were fixated with a multidirectional volar fixed-angle plate. We tested 4 different screw-placement options in the distal fragment. The distal fragment was fixed with 4 locking screws in the distal row of the plate in group a, and with 4 locking screws alternately in the distal and proximal rows in group b. In group c, 3 locking screws were used in the proximal row; in group d, 7 locking screws were used, filling all screw holes in the distal and proximal rows of the plate. The proximal fragment was fixed with 3 screws. The specimens were loaded with 80 N under dorsal and volar bending and with 250 N axial loading. Finally, load to failure tests were performed.

RESULTS

Group d had the highest mean stiffness, 429 N/mm under axial compression, and was statistically significantly stiffer than the other groups. Group b had a mean stiffness of 208 N/mm, followed by group a, with 177 N/mm. Group c showed only a mean stiffness of 83 N/mm under axial compression. There were no statistically significant differences under dorsal and volar bending.

CONCLUSIONS

In this model of distal radial fractures, there was a difference regarding the stiffness and the placement of screws in the distal rows of a volar fixed-angle plate. Inserting screws in all available holes in the distal fragment offered the highest stability. Using only the proximal row with 3 screws created an unstable situation. Based on these findings, we recommend placing at least 4 screws in the distal fragment and assigning at least 2 screws to the distal row of the multidirectional screw-holes.

A biomechanical comparison of a biodegradable volar locked plate with two titanium volar locked plates in a distal radius fracture model

BACKGROUND

Volar plating is commonly used in the management of distal radius fractures; bioresorbable plates have attractive features. We compared a bioresorbable plate with a latest generation and an established locked titanium plate.

METHODS

Twenty-four fresh-frozen radii (12 pairs) were assigned to three mean bone mineral density-matched groups of eight radii each. A standardized extraarticular distal radius fracture was created and plated using one implant type per group. Postplating stiffness and displacement were studied in a first axial-loading test (15 cycles at 250 N). Next, biodegradation was simulated by 4 weeks' immersion in phosphate-buffered saline, followed by a second axial test. Finally, the specimens underwent cyclic loading (2,400 cycles at 250 N).

RESULTS

It is clear from the initial test that the LCP plate was significantly stiffer and displaced less than the bioresorbable plate. The outcome of the postimmersion tests is that one bioresorbable plate failed early on after 4 weeks' immersion, and the remaining bioresorbable plates and the T plates did not differ significantly. Cyclic tests conclude that the LCP plate was significantly superior to the other systems. One T plate and four of the bioresorbable plates failed, but none of the LCP plates failed. In the bioresorbable constructs, stability, time to failure, and bone mineral density were significantly correlated.

CONCLUSIONS

The LCP plate was biomechanically superior and may be generally recommended for the volar plating of distal radius fractures. Except one plate failure, the bioresorbable plate was similar to the T plate in the quasi-static tests and should, therefore, be considered for clinical studies, with patient selection confined, initially, only to candidates with good bone stock quality.

Stability of volar locking plate systems for AO type C3 fractures of the distal radius: biomechanical study in a cadaveric model

BACKGROUND

The purpose of the present study was to compare the relative stability of five volar locking plates (all of which are available for the treatment of intraarticular fractures of the distal radius) under loading conditions simulating the physiological forces that occur during early active mobilization.

METHODS

Five plating techniques were applied to surgically simulated AO type C3.2 distal radius fractures in formalin-fixed cadavers. The specimens were tested with a servohydraulic materials testing machine with 250 N of axial compression load for 3000 cycles. After cyclic loading, the specimens were loaded until they demonstrated failure in axial compression. The five fixation systems studied included a DRV locking plate (group 1), a Stellar plate (group 2), an Acu-Loc plate (group 3), AO Locking Distal Radius System 2.4 (group 4); and a Matrix SmartLock plate (group 5).

RESULTS

None of the plate fixations tested failed during the cyclic loading. Group 2 had a higher elastic limit than groups 4 and 5. There were no significant differences among the five groups for the failure load. Failure occurred at the distal portion of the fixation system, at the ulnar side locking pin, or the locking screw was bent (groups 1, 2, 3); the ulnar side locking screw was broken (groups 3, 4); the locking screw became loose (group 4); and the ulnar side locking screw was uncoupled from the screw hole (group 5).

CONCLUSIONS

All of the five volar plate fixation systems provided sufficient stability to permit 3000 repeated motions of the digits after surgery for AO type C3 distal radius fractures.

A novel non-bridging external fixator construct versus volar angular stable plating for the fixation of intra-articular fractures of the distal radius--a biomechanical study

Non-bridging external fixation has recently been introduced as an alternative to volar angular stable plating for the fixation of unstable intra-articular distal radial fractures. The purpose of this study was to biomechanically compare a new non-bridging external fixator construct to volar angular stable plate fixation in a dorsally comminuted intra-articular fracture model of the distal radius.

MATERIALS AND METHODS

Five pairs of fresh frozen human cadaveric radii were randomly supplied with either a non-bridging external fixator or a stainless steel volar locking plate. A three-fragmental AO 23-C2.1 fracture was created by removing a 15 degrees dorsal wedge with remaining volar cortical contact and by an intra-articular osteotomy lateral to the lister-tubercle. Physiological load transfer via the wrist was simulated by means of a custom-made seesaw. For biomechanical testing, the bones were loaded in cyclic axial compression. Starting at 100N, the load was monotonically increased at 0.025 degrees N per cycle until failure of the construct. Motion of the lunate and scaphoid fragments with respect to the radial diaphysis was acquired by optical three-dimensional (3D) motion tracking. Plastic wedge deformation was determined after 2000, 4000 and 6000 cycles.

RESULTS

The amplitude of wedge motion at the beginning of the test as a measure for construct stiffness was significantly lower for the fixator group (P=0.003, power=0.99). Plastic wedge deformation after 2000, 4000 and 6000 cycles was found significantly lower for the external fixator (repeated measures analysis of variance (ANOVA), P=0.009, power=0.86). Displacement of the intra-articular gap was found below 0.6mm (mean) for both groups (P>0.05).

CONCLUSION

The study revealed superior biomechanical properties of the proposed non-bridging external fixation compared to volar locked plating in an unstable intra-articular fracture model with volar cortical support. However, both fixation techniques seem to apply sufficient stabilisation to restore and retain anatomy after fracture of the most distal part of the radius and should be individually chosen according to distinct criteria.

Influence of an additional locking screw on fracture reduction after volar fixed-angle plating-introduction of the "protection screw" in an extra-articular distal radius fracture model

BACKGROUND

Though, volar fixed-angle plating has become increasingly popular to treat distal radius fractures no studies are available comparing the mechanical properties of different screw configurations to fix the plate to the shaft. The aim of the present study was to evaluate the effect of an additional locking screw directly proximal to the fracture site and to assess if such a screw might be protective against secondary loss of reduction after volar fixed-angle plating.

METHODS

Ten Sawbones radii were used to simulate an extra-articular distal radius fracture model (AO/OTA 23-A3). In the first group (n = 5), volar fixed-angle plates (Aptus Radius 2.5, Medartis, Switzerland) were fixed to the radius shaft with a single nonlocking cortex screw in the oval hole and with two locking screws in the holes proximal to the long hole (LLNx); in the second group, the plates were fixed identically as in the first group, but an additional locking screw was inserted into the plate-hole distal to the oval hole, proximal to the fracture site (LLNL). After embedding, specimens were tested with a servohydaulic material testing machine under cyclic axial loading with 800 N for 2,000 cycles. Axial stiffness, elastic axial deformation (elastic dorsal tilt angle), and plastic deformation (plastic dorsal tilt angle) were recorded.

RESULTS

After 2,000 cycles, stiffness was 761.6 (+/-59.5) N/mm in group LLNx and 628.9 (+/-37.6) N/mm in group LLNL without significant difference. Elastic deformation and elastic tilt angle were 1.05 (+/-0.08) mm and 3.9 (+/-0.3) degree in group LLNx. In group LLNL, elastic deformation and elastic tilt angle were 1.27 (+/-0.08) mm and 4.7 (+/-0.3) degree, respectively. Plastic deformation and plastic tilt angle were significantly higher in group LLNx (p < 0.001). After 2,000 cycles, dorsal tilt angle was 1.9 (+/-0.3) degree in group LLNx and 0.7 (+/-1.0) in group LLNL.

CONCLUSION

This study showed the mechanical superiority of volar fixed-angle plates with a "protection screw" in an extra-articular fracture model. Further clinical investigation is needed to verify the results.

Biomechanical stability of four fixation constructs for distal radius fractures

Implants available for distal radius fracture fixation include dorsal nonlocked plating (DNLP), volar locked plating (VLP), radial-ulnar dual-column locked plating (DCPs), and locked intramedullary fixation (IMN). This study examines the biomechanical properties of these four different fixation constructs. In 28 fresh-frozen radii, a wedge osteotomy was performed, creating an unstable fracture model and the four fixation constructs employed (DNLP, VLP, DCPs, and IMN). Dorsal bending loads were applied and bending stiffness, load to yield 5 mm displacement, and ultimate failure were measured. Bending stiffness for VLP (16.7 N/mm) was significantly higher than for DNLP (6.8 N/mm), while IMN (12.6 N/mm) and DCPs (11.8 N/mm) were similar. Ultimate load to failure occurred at 278.2 N for the VLP, 245.7 N for the IMN, and 52.0 N for the DNLP. The VLP was significantly stronger than the DNLP and DCPs, and the IMN and DCPs were stronger than the DNLP. The VLP has higher average bending stiffness, ultimate bending strength, and resistance to 5 mm displacement than the other constructs and significantly higher ultimate bending strength than the DCPs and DNLP. There was no statistically significant difference between the VLP and IMN. VLP and IMN fixation of distal radius fractures can achieve comparable stability.

Indications and limitations of locked plating

The goal of fracture fixation is to achieve bone healing and restore the function of the injured limb in the shortest possible time without compromising safety. Newer technologies such as the locking compression plate (LCP) and its derivatives are valuable additions to the orthopaedic traumatologist's armamentarium. As with any emerging technology, the indications will be extended until a threshold is reached and the limitations of the technology are seen. It is vital that surgeons involved in fracture care are aware of when locked plating is superior to other methods and also when they should use another treatment modality. This paper reviews the use of locked plating as a fixation method. Five topics covered in this review are: a historical perspective on locked plating, general indications, specific modes and techniques, patterns of failure, and an anatomical overview of current indications for locked plating.

Early breakage of a titanium volar locking plate for fixation of a distal radius fracture: case report

This report presents a case demonstrating the early breakage of a titanium volar locking plate implanted for internal fixation of a dorsally displaced distal radius fracture in which the dorsal cortex was severely comminuted. Careful selection of the proper plate and appropriate surgical technique and postoperative management are necessary to avoid this complication.

Does a volar locking plate provide equivalent stability as a dorsal nonlocking plate in a dorsally comminuted distal radius fracture?: a biomechanical study

OBJECTIVES

The purpose of this study was to compare the fixation afforded by a dorsal nonlocking plate with a volar locking plate in a fracture model simulating an extra-articular distal radius fracture with dorsal comminution (OTA [Orthopaedic Trauma Association] type 23-A3.2).

METHODS

In 10 matched pairs of fresh-frozen cadaveric arms, a comminuted extra-articular dorsally unstable distal radius fracture (OTA type 23-A3.2) was created. The fractures were fixed with either dorsally placed nonlocking T-plate or volarly placed locking plate within matched pairs. The precycling stiffness with axial and torsional loading of the specimens was determined. The specimens were then loaded axially for 5000 cycles, and postcycling axial and torsional stiffness and load to failure were determined.

RESULTS

The mean axial and torsional stiffness before and after cyclic loading of fractures stabilized with dorsal nonlocking plate was not significantly different than fractures fixed with volar locking plate. Although the mean load to failure was greater for the volar locking plate group than dorsal nonlocking plate group, the difference was not significant.

CONCLUSIONS

This study suggests that the fixation obtained with volar locking plates is as stable as fixation with a dorsal plate in acute healing period and can withstand the functional demands of the immediate postoperative period in dorsally comminuted unstable extra-articular distal radius fractures. Elimination of dorsal tendinopathy by using volar locking plates may lead to fewer long-term complications. Locking plates provided better stability in specimens with osteoporosis.

The current status of locked plating: the good, the bad, and the ugly

Locked plate technology has evolved in an effort to overcome the limitations associated with conventional plating methods, primarily for improving fixation in osteopenic bone. The development of screw torque and plate-bone interface friction is unnecessary with locked plate designs, significantly decreasing the amount of soft tissue dissection required for implantation, preserving the periosteal blood supply, and facilitating the use of minimally invasive percutaneous bridging fixation techniques. The locked plate is a fixed-angle device because angular motion does not occur at the plate screw interface. The use of locked plate technology allows the orthopaedic surgeon to manage fractures with indirect reduction techniques while providing stable fracture fixation. The secure 'feel' of locked plates, ease of application, and the low incidence of complications noted in early clinical reports have contributed to the proliferation of this technology. Along with reports of clinical successes, as the use of fixed angle/locked plates has increased, clinical failures are being noticed. This review will focus on the biomechanics of locked plate technology, appropriate indications for its use, laboratory and clinical comparisons to conventional plating techniques, and potential mechanisms of locked plate failure that have been observed.

Prospective study of distal radius fractures treated with a volar locking plate system

PURPOSE

To prospectively determine the results of treatment of distal radius fractures with a volar locking plate system with no bone graft and early mobilization.

METHODS

Internal fixation and early mobilization of dorsally displaced, unstable fractures of the distal radius using a volar locking plate system without bone grafting was investigated in a prospective series of 49 fractures in 49 consecutive patients. All patients were allowed to move the wrist joint immediately after surgery. Physical examination at 5 weeks, 3 months, 6 months, and 1 year after the operation were performed. Radiographic parameters on preoperative, postoperative, and 1-year postoperative radiographs were compared. At 1-year review, the final clinical functions were evaluated with the Gartland and Werley functional scoring system, a modified Green and O'Brien system, and the Disabilities of the Arm, Shoulder, and Hand questionnaire.

RESULTS

The average radiographic results at 1 year were 9 degrees of volar tilt; 22 degrees of radial inclination; 1 mm of ulnar variance, and 0 mm of articular incongruity. At 1-year review, an excellent or good result was found according to the system of Gartland and Werley and a modified Green and O'Brien system with scores of 100% and 98%, respectively. The Disabilities of the Arm, Shoulder, and Hand score averaged 6, indicating a high degree of patient satisfaction. There were no cases of infection, complex regional pain syndrome, tendon rupture, tendon irritation, nerve injury, or implant failure.

CONCLUSIONS

The volar locking plate fixation without bone grafting and early mobilization is a safe and effective treatment for dorsally displaced, unstable fractures of the distal radius.

Evaluation of a novel, nonspanning external fixator for treatment of unstable extra-articular fractures of the distal radius: biomechanical comparison with a volar locking plate

PURPOSE

To compare the stability of a novel, nonspanning external fixator with a standard volar locked plate for treatment of unstable distal radius fractures.

METHODS

A simulated, unstable, extra- articular distal radius fracture was created in six matched pairs of fresh frozen human distal radii. One of each pair was treated with a nonspanning external fixator [Mirza Cross Pin Fixator (CPX), A.M. Surgical Inc. Smithtown, NY] and the other was treated with a volar locked plate [Distal Volar Radial Plate (DVR), Hand Innovations, Miami, FL]. Each specimen was axially loaded in central, dorsal, and volar locations, loaded in cantilever bending in volar to dorsal, dorsal to volar, and radial to ulnar directions and loaded in torsion. Load-displacement curves were generated to determine the construct stiffness for each loading schema, with comparisons made between the two treatment groups. Specimens were then cyclically loaded with 50 N axial loads applied for 1,000 and 10,000 cycles. Measurement of construct stiffness was repeated and comparisons made both between the two treatments and within treatments to their precycling stiffness.

RESULTS

There was no significant difference in the mechanical stiffness of the nonspanning external fixator and the volar locking plate after axial loading in any of the loading modalities. Cyclic loads of 1,000 and 10,000 cycles resulted in no significant difference in construct stiffness between the nonspanning external fixator and volar locked plate. However, the nonspanning external fixator demonstrated decreasing stiffness after cyclic loading with 10,000 cycles (p < 0.02).

CONCLUSION

This study demonstrated no significant difference in the mechanical stiffness of the CPX nonspanning external fixator and volar locked plate in a cadaveric fracture model. Both constructs appear to be biomechanically equivalent in this experimental model; however, this is only one factor in the choice of fixation device for the management of unstable distal radius fractures.

Biomechanical evaluation of volar locking plates for distal radius fractures

PURPOSE

Fixed-angle devices have been a major advancement in orthopedic fracture care and have become an attractive option for fixation of distal radius fractures. Several volar locking plates exist, but there is insufficient literature comparing the strengths of these plates. This study compares the biomechanical strength of two popular volar locking plate systems (Synthes LCP and Hand Innovations DVR-A) along with a nonlocking volar T-plate (Synthes).

METHODS

Twenty-three formalin-fixed cadaveric forearms were divided into three groups with similar ages and bone densities. An unstable extra-articular fracture was created using a standardized osteotomy. Each group was fixed with one of the three plates. Each specimen was loaded in axial compression for 2000 cycles at a force of 400 N. Each specimen that completed cyclic testing was loaded to failure. Stiffness, yield point, and ultimate strength were recorded for each construct.

RESULTS

Each fixed-angle construct completed all 2000 cycles. The nonlocking plates failed at an average of 560 cycles. The mean stiffness of the DVR-A, LCP, and the volar T-plates were 277.00, 343.17, and 175.67 N/mm, respectively. There was a statistically significant difference between both fixed-angle plates and the nonlocking plate (p < 0.05). The difference between each fixed-angle construct did not reach significance. Yield point and ultimate strength could only be determined for the two fixed-angle devices. There was no statistically significant difference between the constructs for both yield point (DVR-A = 855.56 N, LCP = 894.15 N) and ultimate strength (DVR-A = 1,021.97 N, LCP = 1,114.87 N).

CONCLUSIONS

Given our data, fixed-angle constructs withstand cyclical loading representing normal physiologic forces encountered during post-operative rehabilitation. There was no significant biomechanical difference between the two fixed-angle constructs. Our results support that volar fixed-angle locking plates are an effective treatment for unstable extra-articular distal radius fractures, allowing early postoperative rehabilitation to safely be initiated.

Avaliação do posicionamento de parafusos subcondrais utilizados em placas para tratamento das fraturas distais do rádio

As fraturas distais do rádio são as mais freqüentes do membro superior. São classificadas em estáveis e instáveis. As instáveis requerem tratamento cirúrgico. Não está definido na literatura qual o melhor método de fixação, mas existe atualmente uma tendência à utilização das placas com parafusos bloqueados. Um dos aspectos técnicos importantes é o posicionamento dos parafusos distais junto ao osso subcondral, proporcionando suporte mais adequado. A avaliação da localização desses parafusos é feita com radioscopia e radiografias, mas freqüentemente existem dúvidas quanto ao correto posicionamento. Os objetivos deste estudo são: avaliar se é possível determinar com precisão por meio de radiografias, a localização dos parafusos distais no rádio e se a experiência do avaliadorinfluencia nesta análise. Foram utilizados punhos de cadáveres. Cada rádio recebeu três parafusos junto à superfície articular distal. Por meio de incidências radiográficas clássicas e anguladas, médicos especialistas e não-especialistas em cirurgia da mão avaliaram a posição de cada parafuso, se intra ou extra-articular. Os índices de acerto foram submetidos à análise estatística.As radiografias provaram ainda ser um bom método de avaliação, não havendo melhora da precisão na localização dos parafusos com as incidências anguladas. A experiência profissional do avaliador não teve influência nos resultados.