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

Effect of Screw Length in Volar Plating for Intra-articular Distal Radius Fractures: A Biomechanical Study

PURPOSE

The purpose of this study was to compare the effect of varying screw lengths on load to failure and retention of the dorsal ulnar corner fragment after fixation of comminuted intra-articular distal radius fractures in a cadaveric model.

METHODS

Twenty-four fresh frozen cadaveric forearms were subjected to a standardized distal radius osteotomy to mimic an intra-articular fracture pattern. Dual X-ray absorptiometry scans were performed to ensure minimal variability in bone density. All fractures were fixed with a volar locking plate and distal locking screws. Three different lengths of distal locking screws were used in each group of eight specimens to simulate the clinical decision of different distal screw lengths. The screw lengths tested were bicortical, 100% of the width of the bone but unicortical, and 75% of the width of the bone and unicortical. All specimens were preconditioned with cyclic axial loading and then axially loaded using matching acrylic resin molds to clinical failure and fragment displacement as detected by a motion analysis system. Retention or loss of the dorsal ulnar corner fragment during loading was recorded as a binary variable.

RESULTS

Between the three groups, there were no statistically significant differences in precycling stiffness, postcycling stiffness, load at 2 mm displacement of the dorsal ulnar corner, or force at failure. The group with 75% length screws had a significantly higher loss of reduction of the dorsal ulnar corner (86%) compared with the other groups (0%).

CONCLUSIONS

Varying screw lengths did not affect the stiffness or overall loads to failure of axially loaded specimens. However, the 75% length screws did not reliably secure the dorsal ulnar corner fragments. Although this did not significantly affect the overall load to failure of the construct, displacement of this fragment may have implications for rotation of the forearm through the distal radioulnar joint.

CLINICAL RELEVANCE

Surgeons should consider the utilization of full-length unicortical locking screws to ensure adequate fixation of the dorsal ulnar corner.

TYPE OF STUDY/LEVEL OF EVIDENCE

Biomechanical study V.

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.

Distal radius fracture fixation using volar plate: A comparative study evaluating the biomechanical behavior of uni and bicortical distal screws

Extensor tendon ruptures caused by bicortical screws impingement following distal radius fracture fixation with volar plates are extensively reported in the literature. Thus, a biomechanical study comparing unicortical and bicortical fixations in intra-articular distal radius fracture models is critical in decision-making regarding distal radius fracture management. Forty-two synthetic radius models were fixed using a variable angle volar distal locking plate with seven screws. They were divided into 6 groups (n = 7): G1/G3/G4 unicortical fixation (75% of anteroposterior distal radius lenght); G2/G4/G6 bicortical fixation. Each group underwent a different mechanical test: axial compression (G1/G2), dorsal flexion (G3/G4), and volar flexion (G5/G6). The load application rate was 5 mm/min and 1000 cycles of 50 to 250 N at 1 Hz were performed between both static tests. Comparative results in the first static test, in the second static test, and in failure generally showed a very similar behavior. Models depicted similar behavior in the second static test when cyclic load was performed. Therefore, one can realize that stiffness differed during dorsal flexion only in the first static test. Maximum force to break the model in axial compression was greater in bicortical than in unicortical construct. Since biomechanical properties are similar, we recommend using unicortical distal locking screws in distal radius fracture fixation with volar plates to prevent extensor tendon ruptures.

Biomechanical evaluation of the stability of extra-articular distal radius fractures fixed with volar locking plates according to the length of the distal locking screw

Surgeons usually used short screws to avoid extensor tendon problems during volar locking plate fixation in distal radius fracture. However, the stability according to the length of distal locking screws have not been fully understood. We investigated this issue through finite element analysis and compression test using synthetic radius. Our results demonstrated that the bi-cortical full-length fixation does not contribute to the stiffness increase in the axial compression direction, and a reduction in length of up to more than 50% length can still provide similar stability to full-length screws. Our data can support that surgeon should undersize the distal screw.

Functional Outcome of Intraarticular Fracture of Distal Radius Managed by Volar Locking Plate

Objective

This study's main purpose is to determine the functional outcome of volar locking plates in the management of intraarticular fracture of the distal radius.

Methodology

This cross-sectional study was conducted from August 2016 to August 2019. Forty-nine patients with the intraarticular distal radius fractures managed by the volar locking plate were included in the study. Patients with open fractures, ipsilateral other limb injuries, polytrauma patients, pathological fractures, and patients having neurovascular injuries were excluded from the study. AO Classification was used to classify fractures. The fracture was approached through the volar approach and fixed by the volar locking plate. A modified mayo wrist score evaluated the functional outcome. All the data were recorded on predesigned performa, and Statistical Package for the Social Sciences (SPSS), version 20 (IBM Corp., Armonk, NY) was used to analyze the data.

Results

A total of 49 patients with intraarticular fractures of the distal radius were included in the study. The mean age of the patient was 37.20 ± 10.05 years. Out of 49 patients, 29 (59.2%) were males, and 20 (40.8%) were females. Union was achieved in almost all fractures except one case, which went into non-union despite the adequate initial reduction, and the mean time of union was 11.98 ± 1.64 weeks. With respect to the stratification of functional outcome very good and good functional outcome was achieved in 46 patients (93.8%) in both the groups, the satisfactory outcome was achieved in two (4.1%) cases and one patient had a bad outcome in which union was not achieved and went into non-union.

Conclusion

Open reduction and internal fixation of intraarticular fracture of the distal radius using a volar locking plate is a good option for managing these fractures as it provides stable fixation, and good to excellent outcomes can be achieved by using these plates.

Unstable Distal Radius Fractures Treated by Volar Locking Anatomical Plates

INTRODUCTION

Fracture of the distal end of radius represents the most common fracture of the upper extremity accounting for 16-20% of all fractures. Plating is now emerging as the gold standard for management of distal radius fractures due to increased rate of complications such as malunion, subluxation/dislocation of distal radio-ulnar joint or late collapse of fracture. Procedures such as closed reduction and cast immobilization, ligamentotaxis with external fixator and percutaneous pin fixation are no longer acceptable.

AIM

The purpose of the study was to evaluate the functional and radiological outcome of unstable distal radius fractures treated with the volar locking plate.

MATERIALS AND METHODS

We reviewed 53 patients from January 2011 to December 2015, treated for unstable distal radius fractures using a volar locking compression plate. Standard radiographic and clinical assessment after 12 months (range 12-16 months) were measured and final functional and radiological outcome were assessed using the Modified Mayo wrist scoring system and Sarmiento's modification of Lindstorm criteria respectively.

RESULTS

There were 42 males and 11 females with an average age of 39.12±31.78 years (18-71 years). At the end of 12 months, 36 patients had an excellent radiological outcome and 10 patients had good radiological outcome as per Sarmiento's modification of Lindstorm criteria. Eleven patients had an excellent functional outcome and 26 patients had a good functional outcome as per modified Mayo wrist scoring system. There was one case of superficial wound infection which subsided with intravenous antibiotics.

CONCLUSION

The volar locking plate fixation helps in early mobilization of the wrist, restores anatomy, allows early return to function, prevents secondary loss of reduction and hence is an effective treatment for unstable fractures of the distal radius.

The Detection of Prominent Hardware in Volar Locked Plating of Distal Radius Fractures: Intraoperative Fluoroscopy Versus Computed Tomography

OBJECTIVES

To assess the utility of the dorsal tangential view (DTV) in detecting intraoperative dorsal screw penetration in distal radius fractures treated with volar locked plating.

DESIGN

Retrospective cohort study.

SETTING

Academic level 1 trauma center.

PATIENTS/PARTICIPANTS

Skeletally mature patients where open reduction internal fixation with volar locked plating was the definitive treatment. A total of twenty-six patients were evaluated.

INTERVENTION

Intraoperative anteroposterior, lateral, 20 degree tilted lateral, and DTVs were obtained through fluoroscopy in all wrists. Screw exchange and position by fluoroscopic view was recorded. A computed tomography (CT) was taken postoperatively to identify residual prominent screws.

MAIN OUTCOME MEASURES

Data points included frequency of screw exchange by standard fluoroscopic views, the DTV, and residual prominent screws detected by CT.

RESULTS

Eight constructs of thirty (27%) had prominent screws evident on the DTV but not seen on standard fluoroscopic analysis. CT identified 5 additional screws with ≥1 mm dorsal penetration not identified by the DTV. All except 1 screw was in the second dorsal wrist compartment. The DTV was 67% sensitive with a negative predictive value of 97%.

CONCLUSION

It is risky and unnecessary to place bicortical screws in the distal part of a volar plate. Given that the DTV view was not sufficient to avoid dorsal screw prominence, distal screws should be intentionally 2-4 mm shorter than measured. Recent studies propose bicortical distal locking screws are not needed for sufficient construct stiffness in volar locked plating. We suggest caution when using this view to verify acceptable placement of screws in proximity to the second dorsal compartment.

LEVEL OF EVIDENCE

Diagnostic level III. See Instructions for Authors for a complete description of levels of evidence.

Is there a benefit of proximal locking screws in osteoporotic distal radius fractures? - A biomechanical study

INTRODUCTION

The distal radial fracture is a common fracture and frequently seen in geriatric patients. During the last years, volar plating has become a popular treatment option. While the application of locking screws at the distal fragment is widely accepted, there is no evidence for their use at the radial shaft.

MATERIALS AND METHODS

In six osteoporotic pairs of matched human cadaver radii an extra-articular model creating an AO 23-A2.1 fracture was employed. Osteosynthesis were performed using the APTUS 2.5 Adaptive TriLock Distal Radius System (Medartis AG) with locking (LS) or non-locking screws (NLS) for proximal fixation. Biomechanical testing was performed in a staircase fashion: starting with 50 cycles at 200N, the load was continuously increased by 50N every 80 cycles up to a maximum force of 400N. Finally, load to failure was analyzed with failure defined as sudden loss of force measured (20%) or major deformation of the radii (10mm).

RESULTS

At 200N, 250N, 300N, 400N and load to failure, the NLS group showed a higher degree of elastic modulus. In contrast, the LS group showed higher elastic modulus at 350N. Maximum force was higher in the LS group without reaching statistical significance. Reasons for loss of fixation were longitudinal shaft fractures, horizontal peri-implant fractures and distal cutting out. No difference was seen between the two groups concerning the development of the above mentioned complications.

CONCLUSION

Our study did not show biomechanical superiority for distal radius fracture fixation by using locking screws in the proximal holes in an osteoporotic cadaver study. At load to failure, longitudinal shaft fractures and peri-implant fractures seemed to be a more relevant problem rather than failure of the proximal fixation.

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.

Redisplacement of Distal Radius Fracture after Initial Closed Reduction: Analysis of Prognostic Factors

BACKGROUND

To evaluate risk factors of redisplacement and remind surgeons of key factors regarding conservative treatment of distal radius fracture.

METHODS

A total of 132 patients who received conservative treatment for distal radius fractures between March 2008 and February 2011 were included in this study. Radial inclination, radial length, volar tilting angle, ulnar variance, fragment translation, and presence of dorsal metaphyseal comminution were measured on the X-rays taken immediately after reduction, one week after injury during the first follow-up outpatient clinic visit, and after the gain of radiological union. Secondary displacement was defined as a loss of reduction during the follow-up period, and was divided into 'early' and 'late' categories. We analyzed the influence of initial displacement radiologic variables, dorsal cortex comminution, and patient age on the development of secondary displacement.

RESULTS

Development of secondary displacement was significantly associated only with initial displacement radiologic variables (p < 0.001), development of the late secondary displacement was significantly associated with age (p = 0.005), and initial displacement radiologic variables were associated significantly with a serial increase in ulnar variance (p = 0.003).

CONCLUSIONS

Greater displacement on the initial radiographs indicates a higher possibility of development for secondary displacement, and older patients had a higher probability of late secondary displacement development. Furthermore, dorsal comminutions did not affect secondary displacement directly.

Redisplacement of Distal Radius Fracture after Initial Closed Reduction: Analysis of Prognostic Factors

BACKGROUND

To evaluate risk factors of redisplacement and remind surgeons of key factors regarding conservative treatment of distal radius fracture.

METHODS

A total of 132 patients who received conservative treatment for distal radius fractures between March 2008 and February 2011 were included in this study. Radial inclination, radial length, volar tilting angle, ulnar variance, fragment translation, and presence of dorsal metaphyseal comminution were measured on the X-rays taken immediately after reduction, one week after injury during the first follow-up outpatient clinic visit, and after the gain of radiological union. Secondary displacement was defined as a loss of reduction during the follow-up period, and was divided into 'early' and 'late' categories. We analyzed the influence of initial displacement radiologic variables, dorsal cortex comminution, and patient age on the development of secondary displacement.

RESULTS

Development of secondary displacement was significantly associated only with initial displacement radiologic variables (p < 0.001), development of the late secondary displacement was significantly associated with age (p = 0.005), and initial displacement radiologic variables were associated significantly with a serial increase in ulnar variance (p = 0.003).

CONCLUSIONS

Greater displacement on the initial radiographs indicates a higher possibility of development for secondary displacement, and older patients had a higher probability of late secondary displacement development. Furthermore, dorsal comminutions did not affect secondary displacement directly.

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.

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.

Dorsally comminuted fractures of the distal end of the radius: osteosynthesis with volar fixed angle locking plates

Background. Dorsally comminuted distal radius fractures are unstable fractures and represent a treatment challenge. The objective of this study was to evaluate the functional and radiological outcome of dorsally comminuted fractures of the distal radius fixed with a volar locking plate. Patients and Methods. Thirty-three consecutive patients with dorsally comminuted fractures of the distal end of the radius were treated by open reduction and internal fixation with AO 2.4 mm (n = 19)/3.5 mm (n = 14) volar locking distal radius plate (Synthes, Switzerland, marketed by Synthes India Pvt. Ltd.). There were 7 type A3, 8 type C2, and 18 type C3 fractures. The patients were followed up at 6 weeks, 3 months, 6 months, and 1 year postoperatively. Subjective assessment was done as per Disabilities Arm, Shoulder, and Hand (DASH) questionnaire. Functional evaluation was done by measuring grip strength and range of motion around the wrist; the radiological determinants were radial angle, radial length, volar angle, and ulnar variance. The final assessment was done as per Demerit point system of Saito. Results. There were 23 males and 10 females with an average age of 44.12 ± 18.63 years (18-61 years). Clinicoradiological consolidation of the fracture was observed in all cases at a mean of 9.6 weeks (range 7-12 weeks). The average final extension was 58.15° ± 7.83°, flexion was 54.62° ± 11.23°, supination was 84.23° ± 6.02°, and pronation was 80.92° ± 5.54°. Demerit point system of Saito yielded excellent results in 79% (n = 26), good in 18% (n = 6), and fair in 3% (n = 1) patients. Three patients had loss of reduction but none of the patients had tendon irritation or ruptures, implant failure, or nonunion at the end of an one-year followup. Conclusion. Volar locking plate fixation for dorsally comminuted distal radius fractures results in good to excellent functional outcomes despite a high incidence of loss of reduction and fracture collapse.

Assessment of a novel biomechanical fracture model for distal radius fractures

Background

Distal radius fractures (DRF) are one of the most common fractures and often need surgical treatment, which has been validated through biomechanical tests. Currently a number of different fracture models are used, none of which resemble the in vivo fracture location. The aim of the study was to develop a new standardized fracture model for DRF (AO-23.A3) and compare its biomechanical behavior to the current gold standard.

Methods

Variable angle locking volar plates (ADAPTIVE, Medartis) were mounted on 10 pairs of fresh-frozen radii. The osteotomy location was alternated within each pair (New: 10 mm wedge 8 mm / 12 mm proximal to the dorsal / volar apex of the articular surface; Gold standard: 10 mm wedge 20 mm proximal to the articular surface). Each specimen was tested in cyclic axial compression (increasing load by 100 N per cycle) until failure or −3 mm displacement. Parameters assessed were stiffness, displacement and dissipated work calculated for each cycle and ultimate load. Significance was tested using a linear mixed model and Wald test as well as t-tests.

Results

7 female and 3 male pairs of radii aged 74 ± 9 years were tested. In most cases (7/10), the two groups showed similar mechanical behavior at low loads with increasing differences at increasing loads. Overall the novel fracture model showed a significant different biomechanical behavior than the gold standard model (p < 0,001). The average final loads resisted were significantly lower in the novel model (860 N ± 232 N vs. 1250 N ± 341 N; p = 0.001).

Conclusion

The novel biomechanical fracture model for DRF more closely mimics the in vivo fracture site and shows a significantly different biomechanical behavior with increasing loads when compared to the current gold standard.

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.

Management of distal radius fractures from the North American perspective

In North America, the rate of nonoperative management of displaced distal radius fractures has declined as the rate of internal fixation has increased. Volar locking plate fixation has increased in popularity despite a lack of supportive level 1 evidence. Issues of cost-effectiveness are relevant because there is no best-practice treatment at this stage. Clinicians should be aware of the goals of treatment and challenges, particularly in managing elderly patients with distal radius fractures. Large, randomized controlled trials or meta-analyses may provide answers about when operative intervention is favored over nonoperative management and which operative intervention provides the best outcomes.

The effects of screw length on stability of simulated osteoporotic distal radius fractures fixed with volar locking plates

PURPOSE

Volar plating for distal radius fractures has caused extensor tendon ruptures resulting from dorsal screw prominence. This study was designed to determine the biomechanical impact of placing unicortical distal locking screws and pegs in an extra-articular fracture model.

METHODS

We applied volar-locking distal radius plates to 30 osteoporotic distal radius models. We divided radiuses into 5 groups based on distal locking fixation: bicortical locked screws, 3 lengths of unicortical locked screws (abutting the dorsal cortex [full length], 75% length, and 50% length to dorsal cortex), and unicortical locked pegs. Distal radius osteotomy simulated a dorsally comminuted, extra-articular fracture. We determined each construct's stiffness under physiologic loads (axial compression, dorsal bending, and volar bending) before and after 1,000 cycles of axial conditioning and before axial loading to failure (2 mm of displacement) and subsequent catastrophic failure.

RESULTS

Cyclic conditioning did not alter the constructs' stiffness. Stiffness to volar bending and dorsal bending forces were similar between groups. Final stiffness under axial load was statistically equivalent for all groups: bicortical screws (230 N/mm), full-length unicortical screws (227 N/mm), 75% length unicortical screws (226 N/mm), 50% length unicortical screws (187 N/mm), and unicortical pegs (226 N/mm). Force at 2-mm displacement was significantly less for 50% length unicortical screws (311 N) compared with bicortical screws (460 N), full-length unicortical screws (464 N), 75% length unicortical screws (400 N), and unicortical pegs (356 N). Force to catastrophic fracture was statistically equivalent between groups, but mean values for pegs (749 N) and 50% length unicortical (702 N) screws were 16% to 21% less than means for bicortical (892 N), full-length unicortical (860 N), and 75% length (894 N) unicortical constructs.

CONCLUSIONS

Locked unicortical distal screws of at least 75% length produce construct stiffness similar to bicortical fixation. Unicortical distal fixation for extra-articular distal radius fractures should be entertained to avoid extensor tendon injury because this technique does not appear to compromise initial fixation.

CLINICAL RELEVANCE

Using unicortical fixation during volar distal radius plating may protect extensor tendons without compromising fixation.