Internal fixation of dorsally comminuted fractures of the distal part of the radius: a biomechanical analysis of volar plate and intramedullary nail fracture stability

Effect of uncertain clinical conditions on the early healing and stability of distal radius fractures

BACKGROUND AND OBJECTIVES

The healing outcomes of distal radius fracture (DRF) treated with the volar locking plate (VLP) depend on surgical strategies and postoperative rehabilitation. However, the accurate prediction of healing outcomes is challenging due to a range of certainties related to the clinical conditions of DRF patients, including fracture geometry, fixation configuration, and physiological loading. The purpose of this study is to investigate the influence of uncertainty and variability in fracture/fixation parameters on the mechano-biology and biomechanical stability of DRF, using a probabilistic numerical approach based on the results from a series of experimental tests performed in this study.

METHODS

Six composite radius sawboneses fitted with titanium VLP (VLP 2.0, Austofix) were loaded to failure at a rate of 2 N/s. The testing results of the elastic and plastic behaviour of the VLP were used as inputs for a probabilistic-based computational model of DRF, which simulated mechano-regulated tissue differentiation and fixation elastic capacity at the fracture site. Finally, the probability of success in early indirect healing and fracture stabilisation was predicted.

RESULTS

The titanium VLP is a strong and ductile fixation whose flexibility and elastic capacity are governed by flexion working length and bone-to-plate distance, respectively. A fixation with optimised designs and configurations is critical to mechanically stabilising the early fracture site. Importantly, the uncertainty and variability in fracture/fixation parameters could compromise early DRF healing. The physiological loading uncertainty is the most adverse factor, followed by the negative impact of uncertainty in fracture geometry.

CONCLUSIONS

The VRP 2.0 fixation made of grade II titanium is a desirable fixation that is strong enough to resist irreparable deformation during early recovery and is also ductile to deform plastically without implant failure at late rehabilitation.

Appropriately Matched Fixed-Angle Locking Plates Improve Stability in Volar Distal Radius Fixation

Purpose

Size options for volar locking plates may provide value for distal radius fixation. We compared excessively narrow plates with plates that were appropriately matched in width for fixation of an multifragmented distal radius fracture model.

Methods

Eighteen matched pairs (right and left wrists) of large, cadaveric male distal radii specimens, prepared with a simulated Arbeitsgemeinschaft für Osteosynthesefragen type C-3 distal radius fractures, were tested. One specimen from each matched pair was randomized to receive a plate that was appropriately matched in width to the distal radius. The contralateral limb received a narrow plate, which in all cases was undersized in width. Fixation stability was tested and compared to the contralateral matched specimen. Specimens were preloaded at 50 N for 30 seconds before cyclic loading from 50–250 N at 1 Hz for 5000 cycles then loaded to failure.

Results

Loss of fixation under cyclic loading was significantly greater in the specimens fixed with excessively narrow plates compared with plates of appropriate width. When loaded to failure, the plates of appropriate width were stiffer, with higher force at failure and compressive strength than narrow plates. The primary mode of failure was displacement of the distal lunate facet fragment.

Conclusions

These findings suggest that optimally matching the volar locking plate width to the radius may provide advantages for stability of the fixation construct and fragment capture. This may be due to reduced stress concentration from the distribution of forces across a larger surface area.

Clinical relevance

Optimizing the plate width to the radial width may improve fracture stability and may carry additional importance in comminuted fractures, where narrow plates may not completely capture small bone fragments.

An Adaptable Computed Tomography-Derived Three-Dimensional-Printed Alignment Fixture Minimizes Errors in Radius Biomechanical Testing

Biomechanical testing of long bones can be susceptible to errors and uncertainty due to malalignment of specimens with respect to the mechanical axis of the test frame. To solve this problem, we designed a novel, customizable alignment and potting fixture for long bone testing. The fixture consists of three-dimensional-printed components modeled from specimen-specific computed tomography (CT) scans to achieve a predetermined specimen alignment. We demonstrated the functionality of this fixture by comparing benchtop torsional test results to specimen-matched finite element models and found a strong correlation (R2 = 0.95, p < 0.001). Additional computational models were used to estimate the impact of malalignment on mechanical behavior in both torsion and axial compression. Results confirmed that torsion testing is relatively robust to alignment artifacts, with absolute percent errors less than 8% in all malalignment scenarios. In contrast, axial testing was highly sensitive to setup errors, experiencing absolute percent errors up to 50% with off-center malalignment and up to 170% with angular malalignment. This suggests that whenever appropriate, torsion tests should be used preferentially as a summary mechanical measure. When more challenging modes of loading are required, pretest clinical-resolution CT scanning can be effectively used to create potting fixtures that allow for precise preplanned specimen alignment. This may be particularly important for more sensitive biomechanical tests (e.g., axial compressive tests) that may be needed for industrial applications, such as orthopedic implant design.

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.

Minimally invasive internal fixation for extra-articular distal radius fracture: Comparison between volar plate and intramedullary nail

INTRODUCTION

There are numerous internal fixation techniques for distal radius fracture, using pins, plates or nails. Some authors have developed minimally invasive procedures. The aim of the present study was to compare two minimally invasive internal fixation techniques for unstable extra-articular distal radius fracture in women over 50 years of age: volar plate (minimally invasive plate osteosynthesis: MIPO), and intramedullary nail.

HYPOTHESES

The main study hypothesis was that the incision scar left by minimally invasive internal fixation is smaller using MIPO than an intramedullary nail. The secondary hypotheses were that the two techniques do not differ in terms of pain, functional score, strength, range of motion and radiologic indices.

MATERIAL AND METHOD

The series comprised nineteen A2.2 and one A2.1 fractures in 20 female patients with a mean age of 72 years. The first 10 (group 1) received minimally invasive internal fixation of the distal radius by MIPO, and the other 10 (group 2) by intramedullary nail locked onto the distal radius epiphysis and diaphysis.

RESULTS

The main study hypothesis was confirmed: the incision scar left by minimally invasive internal fixation was smaller using MIPO than an intramedullary nail (mean, 14.3mm vs. 32.8mm). Some of the secondary hypotheses were also confirmed: there were no differences between the two techniques in terms of pain at 6 months, QuickDASH, PRWE (Patient-Reported Wrist Evaluation), range of motion or ulnar variance; two were not confirmed: pain at 6 weeks was less with intramedullary nails, and palmar slope was better with MIPO.

DISCUSSION AND CONCLUSION

The main study hypothesis was confirmed: the incision scar left by minimally invasive internal fixation was smaller using MIPO than an intramedullary nail. In conclusion, the present findings showed that internal fixation of unstable extra-articular fracture in over 50-year-olds gave better clinical results at 6 weeks using an intramedullary nail, while MIPO required smaller incision.

LEVEL OF EVIDENCE

III, retrospective study.

Minimally Invasive Plate Osteosynthesis for Extra-articular Distal Radius Fracture in Postmenopausal Women: Longitudinal versus Transverse Incision

Background  This work aimed to compare two mini-invasive palmar approaches (longitudinal and transverse) to osteosynthesize fractures of the distal radius. The main hypothesis was that the longitudinal technique gave smaller incisions. The secondary hypothesis was that the longitudinal technique would be better for the recovery of pain, functional scores, strength, and mobility. Materials and Methods  The series included 30 extra-articular distal radius fractures in 30 patients (average age: 74 years) fixed with volar locking plate using a mini-invasive technique. Fifteen of these patients had a single longitudinal surgical approach (Group I), and 15 had a transverse approach that was completed with a longitudinal incision for the proximal screws (Group II). Results  The combined average incision size was 14.73 mm in Group I and 19.8 mm in Group II. After 6 months, the pain was on average 1.4/10 (Group I) and 0.46/10 (Group II), the quick Disability of the Arm, Shoulder, and Hand was 13.63/100 (Group I) and 2.8/100 (Group II), Patient-Related Wrist Evaluation was 11.8/100 (Group I) and 5.97/100 (Group II), grip strength was 81.06% (Group I) and 72.13% (Group II), flexion was 88.13% (Group I) and 75% (Group II), extension was 86% (Group I) and 64.6% (Group II), ulnar inclination was 89% (Group I) and 78.67% (Group II), radial inclination was 89.73% (Group I) and 79.93% (Group II), pronation was 96.67% (Group I) and 81.46% (Group II), and supination was 91.93% (Group I) and 79.87% (Group II). Clinical Relevance  The longitudinal technique gave smaller incisions than the transverse technique. Among the secondary hypotheses, all the variables were better with the longitudinal technique, except the pain, although without any significant difference.

Fracture Gap Reduction With Variable-Pitch Headless Screws

PURPOSE

Fully threaded, variable-pitch, headless screws are used in many settings in surgery and have been extensively studied in this context, especially in regard to scaphoid fractures. However, it is not well understood how screw parameters such as diameter, length, and pitch variation, as well as technique parameters such as depth of drilling, affect gap closure.

METHODS

Acutrak 2 fully threaded variable-pitch headless screws of various diameters (Standard, Mini, and Micro) and lengths (16-28 mm) were inserted into polyurethane blocks of "normal" and "osteoporotic" bone model densities using a custom jig. Three drilling techniques (drill only through first block, 4 mm into second block, or completely through both blocks) were used. During screw insertion, fluoroscopic images were taken and later analyzed to measure gap reduction. The effect of backing the screw out after compression was evaluated.

RESULTS

Drilling at least 4 mm past the fracture site reduces distal fragment push-off compared with drilling only through the proximal fragment. There were no significant differences in gap closure in the normal versus the osteoporotic model. The Micro screw had a smaller gap closure than both the Standard and the Mini screws. After block contact and compression with 2 subsequent full forward turns, backing the screw out by only 1 full turn resulted in gapping between the blocks.

CONCLUSIONS

Intuitively, fully threaded headless variable-pitch screws can obtain compression between bone fragments only if the initial gap is less than the gap closed. Gap closure may be affected by drilling technique, screw size, and screw length. Fragment compression may be immediately lost if the screw is reversed.

CLINICAL RELEVANCE

We describe characteristics of variable-pitch headless screws that may assist the surgeon in screw choice and method of use.

Is intramedullary nailing better than the use of volar locking plates for fractures of the distal radius? A meta-analysis of randomized controlled trials

We conducted a meta-analysis of randomized controlled trials that compared the use of intramedullary nails and volar locking plates in distal radial fractures. PubMed, EMBASE and the Cochrane Collaboration Central database were used to find randomized controlled trials that met the eligibility criteria. Two reviewers screened the studies, extracted the data, evaluated the methodological quality and analysed the data with RevMan 5.1 software. No statistically significant differences were detected in the disability of the arm, shoulder and hand and the Gartland and Werley scores, radiographic parameters, wrist range of motion, grip strength, total complication rate and incidence of tendon rupture between the two groups. However, carpal tunnel syndrome occurred less often after intramedullary nailing. The two fixation methods achieved equal clinical, functional and radiological outcomes for primary fixation of the indicated types of distal radial fractures.

LEVEL OF EVIDENCE

Therapeutic/LevelI.

When is the stability of a fracture fixation limited by osteoporotic bone?

This article is concerned with the search for threshold values for bone quality beyond which the risk of fixation failure increased. For trochanteric fractures we recognized a BMD lower than 250mg/cm(3) as an additional risk for cut out. For medial femoral neck fractures since joint replacement surgery is available and produces excellent functional results, we see no indication for further differentiation or analysis of bone quality in relation to fracture fixation. In the area of osteoporotic vertebral body fractures, there are many experimental studies that try to identify BMD limits of screw fixation in the cancellous bone on the basis of QCT analysis. However, these values have not yet been introduced for application in clinical practice. In case of indication for surgical fixation, we favor minimally invasive, bisegmental, fourfold dorsal instrumentation with screw-augmentation for a T-value less than -2.0 SD (DXA analysis, total hip or total lumbar spine). For proximal humerus fractures, BMD value of 95mg/cm(3) could be seen as a threshold value below which the risk of failure rises markedly. In relation to osteoporotic distal radius fractures, based on our clinical experience and scientific analyses there are virtually no restrictions as far as bone quality is concerned on the application of palmar locking implants in the surgical management of distal radius fractures. Optimization of preoperative diagnostics might help to revise the treatment algorithm to take bone density into account, thus reducing the risk of failure and, at the same time, acquiring additional data for future reference.

Biomechanical comparison of different external fixator configurations for stabilization of supracondylar humerus fractures in children

BACKGROUND

Currently, closed reduction and percutaneous pinning are considered the treatment of choice for displaced supracondylar humerus fractures. However, indications exist for the use of external fixation with Schanz screws. In this in vitro study, we evaluate the biomechanical properties of a new variation for external fixation and compare them to an established construct.

METHODS

Twenty distal cadaver humeri (10 pairs) were allocated to 2 groups. The humeri of the first group were fixed by an external fixator consisting of Schanz screws and an oblique K-wire inserted from the distal radial cortex of the humerus, those of the second group were fixed by a new variation with the oblique K-wire inserted from the distal ulnar cortex of the humerus. Displacement and stiffness in static loading in internal and external rotation, as well as in extension and flexion were evaluated and compared.

FINDINGS

The variation of the external fixator of the second group proved to be statistically significantly superior to the variation of the first group in internal rotation loading (p>0.05). In sagittal loading conditions and external rotation loading, the variations were equally stable (p>0.05). There was no significant effect of the samples' bone density on displacement and stiffness values in any direction of loading.

INTERPRETATION

In cases of pediatric supracondylar humerus fractures when an external fixator is used for osteosynthesis, the insertion of an additional ulnarly inserted anti-rotation K-wire should be preferred to a radially inserted one as it reduces secondary displacement of the distal fragment.

Volar, Intramedullary, and Percutaneous Fixation of Distal Radius Fractures

Background The management of extra-articular distal radius fractures is highly variable, with no clear consensus regarding their optimal management. Purpose To assess comparatively the biomechanical stability of Kirschner wire (K-wire) fixation, volar plating, and intramedullary nailing for unstable, extra-articular distal radius fractures with both (1) constant and (2) cyclical axial compression, simulating forces experienced during early postoperative rehabilitation. Methods Twenty-six volar locking plate, intramedullary nail, and K-wire bone-implant constructs were biomechanically assessed using an unstable extra-articular distal radius bone model. Bone implant models were created for each type of construct. Three samples from each construct underwent compressive axial loading until fixation failure. The remaining samples from each construct underwent fatigue testing with a 50-N force for 2,000 cycles followed by repeat compressive axial loading until fixation failure. Results Axial loading revealed the volar plate was significantly stiffer than the intramedullary nail and K-wire constructs. Both the volar plate and intramedullary nail required greater than 300 N of force for fixation failure, while the K-wire construct failed at less than 150 N. Both the volar plate and intramedullary nail demonstrated less than 1 mm of displacement during cyclic loading, while the K-wire construct displaced greater than 3 mm. Postfatigue testing demonstrated the volar plate was stiffer than the intramedullary nail and K-wire constructs, and both the volar plate and intramedullary nail required greater than 300 N of force for fixation failure while the K-wire construct failed at less than 150 N. Conclusions Volar plating of unstable extra-articular distal radius fractures is biomechanically stiffer than K-wire and intramedullary fixation. Both the volar plate and intramedullary nail demonstrated the necessary stability and stiffness to maintain anatomic reduction during the postoperative rehabilitation period. Clinical Relevance Both the volar plate and intramedullary nail demonstrated the necessary biomechanical stability to maintain postoperative reduction in extra-articular distal radius fractures, warranting further clinical comparison.

Defining the role of intramedullary nailing for fractures of the distal radius

This article is a systematic review of the published literature about the biomechanics, functional outcome and complications of intramedullary nailing of fractures of the distal radius.

We searched the Medline and EMBASE databases and included all studies which reported the outcome of intramedullary (IM) nailing of fractures of the distal radius. Data about functional outcome, range of movement (ROM), strength and complications, were extracted. The studies included were appraised independently by both authors using a validated quality assessment scale for non-controlled studies and the CONSORT statement for randomised controlled trials (RCTs).

The search strategy revealed 785 studies, of which 16 were included for full paper review. These included three biomechanical studies, eight case series and five randomised controlled trials (RCTs).

The biomechanical studies concluded that IM nails were at least as strong as locking plates. The clinical studies reported that IM nailing gave a comparable ROM, functional outcome and grip strength to other fixation techniques.

However, the mean complication rate of intramedullary nailing was 17.6% (0% to 50%). This is higher than the rates reported in contemporary studies for volar plating. It raises concerns about the role of intramedullary nailing, particularly when comparative studies have failed to show that it has any major advantage over other techniques. Further adequately powered RCTs comparing the technique to both volar plating and percutaneous wire fixation are needed.

Cite this article: Bone Joint J 2015;97-B:1370–6.

Randomized comparison of volar locking plates and intramedullary nails for unstable distal radius fractures

PURPOSE

To compare minimally invasive intramedullary nails (IMN) and volar locking plates (VLP) for the treatment of unstable distal radius fractures by evaluating postoperative subjective, radiographic, and functional outcomes. The hypothesis was that IMN patients would have less pain and required less pain medication in the early postoperative period and returned to work earlier than VLP patients.

METHODS

Sixty patients with closed, displaced, unstable, extra-articular, metaphyseal fractures of the distal radius were randomized to receive a VLP or an IMN for internal fixation. Functional outcomes (Quick Disabilities of the Arm, Shoulder, and Hand, Michigan Hand Questionnaire), radiographic measurements (ulnar variance, radial height, inclination, and volar tilt), and range of motion were assessed until final follow-up at 2 years after surgery. Narcotic pain medication use was documented for 5 weeks following surgery.

RESULTS

There were 2 groups of 30 patients with IMN (mean age, 55 ± 14 y) or VLP (mean age, 55 ± 16 y) with similar demographics and comorbidities. Patients with IMN regained extension earlier but had similar range of motion to patients with VLP at final follow-up. There was similar improvement in Michigan Hand Questionnaire, Quick Disabilities of the Arm, Shoulder, and Hand, and strength between groups. Five weeks after surgery, fewer IMN patients required narcotic pain medication (13%) than VLP patients (33%). Radiographic outcomes were similar at final follow-up. There were 3 failures with IMN versus 1 failure with VLP. All 10 employed patients with IMN returned to previous work compared with 10 of the 12 employed patients with VLP. Time to return to work was similar for both groups.

CONCLUSIONS

In a cohort of similar patients, IMN and VLP provided comparable improvement in functional and radiographic outcomes. Patients with IMN required less narcotic pain medication after surgery than VLP patients.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic II.

Biomechanical evaluation of two innovative locking implants for comminuted olecranon fractures under high-cycle loading conditions

INTRODUCTION

The relatively high complication rate after fixation of olecranon fractures has led to an increasing application of anatomically pre-contoured locking plate systems. The purpose of the present study was to conduct a biomechanical comparison of olecranon osteosyntheses by applying the Olecranon VA-LCP and the 3.5mm LCP Hook Plate (LCP, locking compression plate) to an unstable fracture model under high-cycle loading conditions.

METHODS

After creating an unstable fracture (Schatzker type B), osteosynthesis was performed on eight pairs of fresh-frozen cadaveric ulnae by application of either the Olecranon VA-LCP (Synthes, Solothurn, Switzerland) or the 3.5mm LCP Hook Plate (Synthes, Solothurn, Switzerland). Loading (50,000 alternating loads, cyclic and sinusoidal 10-300 N) was conducted by application of tensile load with the elbow in 90° flexion to simulate the tensile strength of the triceps brachii. For statistical analysis, angular displacement in the region of the humeral trochlea was taken as a measure of olecranon dislocation.

RESULTS

In Group 1 (Olecranon VA-LCP), a median angular displacement of 0.36° (minimum 0.10°; maximum 0.80°) was observed after 500 alternating loads. In Group 2 (3.5-mm LCP Hook Plate), the medial displacement was 0.80° (minimum 0.13°; maximum 2.72°). The difference was nonsignificant (p = 0.128). The mean value for angular displacement in Group 1 after 50,000 cycles was 0.80° (minimum 0.31°; maximum 1.99°), whereas in Group 2 a mean angular displacement of 2.02° (minimum 0.71°; maximum 6.40°) was recorded. The difference was statistically significant (p = 0.017). In Group 2, implant failure in the form of proximal plate pullout occurred in one construct after 756 cycles.

CONCLUSION

A significantly higher biomechanical stability can be achieved in the fixation of unstable olecranon fractures by application of the Olecranon VA-LCP rather than the 3.5mm LCP Hook Plate.

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.

Comparative study of the closed reduction percutaneous cannulated screw fixation and open reduction palmar locking plate fixation in the treatment of AO type A2 distal radius fractures

INTRODUCTION

The present study was designed to demonstrate the efficacy of standard 4.0 mm cannulated screw fixation by comparing it with palmar locking plate fixation in the treatment of acute, unstable, simple extra-articular distal radius fractures.

MATERIALS AND METHODS

We prospectively collected and retrospectively analyzed outcomes data for 65 patients aged between 18 and 60 with AO type A2 fractures treated with closed reduction, percutaneous cannulated screw fixation (CRPCS n = 34) or open reduction palmar locking plate fixation (ORPLP n = 31). Range of motion, grip strength, Gartland-Werley and QuickDASH scores were compared at 2 months after surgery, and final follow-up (mean 32 months, range 12-90). Deterioration in radiographic parameters were measured and compared. Operative time and return to preinjury activity were evaluated.

RESULTS

Parameters did not differ significantly between the groups at either time point with respect to grip strength or range of motion, except pronation and supination; they were better in the CRPCS group (p = 0.005 and 0.025, respectively) at 2 month follow-up. The Gartland-Werley and QuickDASH scores obtained at final follow-up were similar for each group and lacked statistical significance. Group comparison for the deterioration of radiologic parameters showed no significant difference. CRPCS group had significantly shorter operative time (p = 0.001) and there was no significant differences between the groups regarding the return to preinjury activity (p = 0.129).

CONCLUSIONS

CRPCS group was found to be as successful as ORPLP group and it may be suitable in the case of young, active individuals with AO type A2 distal radius fractures.

Distal radius fixation through a mini-invasive approach of 15 mm. PART 1: a series of 144 cases

The volar Henry approach is becoming the gold standard for distal radius fracture fixation. It decreases the incidence of nonunion, limits complications especially complex regional pain syndrome (CRPS) type I, and allows early mobilization of the wrist. Nonetheless, it has some disadvantages such as the size of the incision, which is not esthetically pleasing, and the loss of ligamentotaxis. This is why some authors have developed a mini-invasive approach. The aim of this work was to evaluate the feasibility of the anterior mini-invasive approach of 15 mm in a clinical series of 144 cases of distal radius fracture. All patients were operated under regional anesthesia using the same techniques by five surgeons of the same team. According to the AO classification, there were 83 type A fractures, 2 type B, and 59 type C. A volar plate (Step One(®), Newclip Technics™, Haute-Goulaine, France) was used in all cases. The 2 proximal metaphyseal screws and the 2 distal central epiphyseal screws were monoaxial locking. The 2 distal ulnar and radial epiphyseal screws were placed in polyaxial locking at 20° angulation maximum. Skin closure without drainage was performed. No postoperative immobilization was prescribed, and patients were encouraged to use their upper limb immediately postoperative. No postoperative physiotherapy was prescribed. The mean follow-up was 4.1 months. The final size of the incision was on average 16.1 mm. Mean pain score was 1.8. The Quick DASH score was average 25. Average range of motion was more than 85 %, and global force of the hand was 67 % compared with contralateral side. On X-ray, the mean radial slope was 22°, the mean radial tilt was 8.3°, and the mean radioulnar variance/index was -0.4 mm. There were nine cases of CRPS type I, which all resolved. Specific complications included two secondary displacements and nine tenosynovitis cases. No tendon rupture was noted. Two intra-articular distal radioulnar joint screws had to be removed at 3 months. One epiphyseal screw required removal 1 month postoperative due to loosening. There were no intra-articular radiocarpal screws. Distal radius fracture fixation using a mini-invasive approach is a reliable and reproducible procedure with few complications. It allows anatomical reduction in the distal radius fractures including intra-articular ones. It can be associated with arthroscopy, scaphoid screw fixation or even percutaneous pinning. Thus, most traumatic lesions of the wrist bony or soft tissue can be treated through this mini-invasive approach.

Percutaneous cannulated screw fixation in the treatment of distal radius fractures

PURPOSE

The aim of this study was to determine the results of closed reduction and percutaneous fixation of distal radial fractures with standard 4.0-mm cannulated screw.

METHODS

We collected prospective outcomes data for 20 patients between 18 and 60 years of age (mean 39) with acute, displaced, extraarticular and unstable fractures of the distal radius treated with closed reduction, percutaneous cannulated screw fixation and early mobilization. The visits at months 2, 6 and 12 were specified as index follow-up visits and assessments of motion, grip strength and standard radiographs were performed. The Gartland Werley functional scores and the Disabilities of the Arm, Shoulder and Hand (QuickDASH) scores were recorded.

RESULTS

Mean values of flexion, extension, pronation and supination on the injured side were up to 70 % of those on the uninjured side at 2 months postoperatively. By 12 months, range of motion values on the injured side showed continuous and significant improvement and flexion, extension, pronation, supination and ulnar deviation reached up to 90 % of those on the uninjured side. A large and significant improvement was seen from 2 to 6 months in the QuickDASH score. A smaller improvement was seen from 6 to 12 months, which was judged not to be significant. Radiographic values were close to anatomic parameters, and the alignment was maintained at 12 months follow-up. No complications occurred.

CONCLUSIONS

Cannulated screw fixation appears to be an effective means of allowing immediate range of motion of the wrist, resulting in a rapid and comfortable functional recovery while maintaining alignment to bone healing.

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.