Use of the radial groove view intra-operatively to prevent damage to the extensor pollicis longus tendon by protruding screws during volar plating of a distal radial fracture

Evaluation of Ulnar Setting of Volar Locking Plates for Distal Radius Fractures Using Modified Skyline View

Purpose

Volar lunate facet fragments in distal radius fractures are located at the center of the load in the wrist joint and, therefore, should be properly supported by the distal ulnar setting of volar locking plates to obtain better postoperative outcomes. This study evaluated the usefulness of the modified skyline view (MSV) in intraoperative fluoroscopy for the ulnar setting of volar locking plates by comparing it with that of the anteroposterior view (APV).

Methods

Sixty-five patients with distal radius fractures who underwent open reduction and plate fixation as well as follow-up intraoperative fluoroscopy and postoperative computed tomography (CT) at our institution between April 2019 and March 2022 were included. The distance between the ulnar edge of the plate and the distal radius (d-value) was measured retrospectively using intraoperative fluoroscopy (distance measured from MSV and distance measured from APV) or postoperative CT (distance measured using postoperative CT). The distance measured from MSV and that measured from APV were compared with those measured using CT as the true values. Each measurement was performed twice by 2 examiners at an interval of 1 month. The comparison scores were evaluated using the intraclass correlation coefficient.

Results

The distance measured from MSV showed a difference of 0.6 ± 0.5 mm from that measured using CT, which was significantly smaller than that measured from APV (1.2 ± 0.9 mm; P < .001). Neither postoperative volar subluxation nor dislocation of bone fragments was found during the study period. Both intraclass correlation coefficient (1,1) and intraclass correlation coefficient (2,1) reliabilities were substantial to almost perfect.

Conclusions

Modified skyline view is an effective and versatile imaging method for estimating the ulnar setting of volar locking plates; it provides measurements more similar to those provided by postoperative CT compared with APV. The use of MSV may reduce postoperative complications, such as volar subluxation and dislocation of bone fragments, especially in cases with volar lunate facet fragments in which the ulnar setting of the plate is significant.

Type of study/level of evidence

Diagnostic III.

Optimal screw length in volar locking plate osteosynthesis for distal radius fractures: a systematic review

BACKGROUND

Fractures of the distal radius represent the most common fracture of the upper limb, and can be managed surgically with volar locking plate osteosynthesis (VLPO). Uncertainty remains regarding the optimal length of the distal locking screws. The aim of this study was to determine the optimal VLPO screw length which provided adequate stability while minimizing complications.

METHODS

A systematic review of relevant literature published within Cochrane, PubMed, MEDLINE and Embase, including studies up to April 2020, was performed using the Preferred Reporting Items for Systemic Reviews and Meta-analysis (PRISMA) guidelines. Studies were included if they investigated distal radius fracture fixation with VLPO, screw lengths, complications, and associated imaging.

RESULTS

Search results identified 664 relevant studies, of which 14 studies examining 926 radii were included for review. Synthesis revealed that unicortical locking fixation with screws ~75% the depth of the radius, or 2 mm short of the dorsal cortex, provided equivalent stability to bicortical fixation. The lunate may be used as a proxy to determine radial depth at each quartile column. Inadvertent screw protrusion can be assessed by taking four images intra-operatively; anteroposterior (AP), lateral, 45° supinated and dorsal tangential views (DTVs). Radial shaft screws can have up to 2 mm prominence with no clinical significance.

CONCLUSION

Unicortical locking fixation at least 75% the depth of the distal radius provides equivalent stability to bicortical fixation in extra-articular fractures with lower complication rates. Imaging should be used to confirm that penetration of the dorsal cortex has not occurred.

Comparison of a ceiling-mounted 3D flat panel detector vs. conventional intraoperative 2D fluoroscopy in plate osteosynthesis of distal radius fractures with volar locking plate systems

Objectives

To compare intraoperative 3D fluoroscopy with a ceiling-mounted flat panel detector in plate osteosynthesis of distal radius fractures (AO/OTA 2R3C1.2) with volar locking plate systems to conventional 2D fluoroscopy for detection of insufficient fracture reduction, plate misplacement and protruding screws.

Methods

Using a common volar approach on 12 cadaver forearms, total intraarticular distal radius fractures were induced, manually reduced and internally fixated with a 2.4 distal radius locking compression plate. 2D (anterior-posterior and lateral) and 3D (rotational) fluoroscopic images were taken as well as computed tomographies. Fluoroscopic images, Cone Beam CT (CBCT), 360° rotating sequences (so called “Movies”) and CT scans were co-evaluated by a specialist orthopedic surgeon and a specialist radiologist regarding quality of fracture reduction, position of plate, position of the three distal locking screws and position of the three diaphyseal screws. In reference to gold standard CT, sensitivity and specifity were analyzed.

Results

“Movie” showed highest sensitivity for detection of insufficient fracture reduction (88%). Sensitivity for detection of incorrect position of plate was 100% for CBCT and 90% for “Movie.” For intraarticular position of screws, 2D fluoroscopy and CBCT showed highest sensitivity and specifity (100 and 91%, respectively). Regarding detection of only marginal intraarticular position of screws, sensitivity and specifity of 2D fluoroscopy reached 100% (CBCT: 100 and 83%). “Movie” showed highest sensitivity for detection of overlapping position of screws (100%). When it comes to specifity, CBCT achieved 100%. Regarding detection of only marginal overlapping position of screws, 2D fluoroscopy and “Movie” showed highest sensitivity (100%). CBCT achieved highest specifity (100%).

Conclusion

As for assessment of quality of fracture reduction and detection of incorrect position of plate as well as overlapping position of the three diaphyseal screws CBCT and “Movie” are comparable to CT – especially when combined. Particularly sensitivity is high compared to standard 2D fluoroscopy.

Influence of training on dorsal tangential radiographic view to detect screw protrusion after anterior plating of the distal radius: a cadaveric study

In this cadaveric study of anterior plating of the distal radius, we aimed to determine the interobserver agreement and diagnostic performance for detecting dorsally protruding screws using the dorsal tangential radiographic view before and after specific training. Without prior instruction, 13 observers interpreted the dorsal tangential view of cadaveric specimens, in which anterior radial plates were placed. After seeing a training video on the dorsal tangential view, they repeated the task. Though we found that accuracy and interobserver agreement was lower than described in some other clinical series, training led to statistically significant improvements of (1) the interobserver agreement on the decision to exchange screws, (2) the self-confidence of the surgeon in obtaining adequate views, and (3) the number of fluoroscopic images required to obtain these views. After training, the number of protruding screws missed was reduced by 36%, but 7% of dorsally protruding screws was still missed.

A Prospective Cohort Study on Accuracy of Dorsal Tangential Views to Avoid Screw Penetration With Volar Plating of Distal Radius Fractures

OBJECTIVE

To assess diagnostic performance of dorsal tangential views (DTVs) to detect dorsal screw protrusion in clinical practice.

DESIGN

Prospective cohort study.

SETTING

Level-1 trauma center.

PATIENTS

Fifty consecutive patients undergoing volar plating for 50 distal radius fractures were prospectively included.

INTERVENTION

Fluoroscopic DTVs were routinely obtained, and screw revision was documented. Multiplanar reconstructions of postoperative CTs allowed for detection and quantification of dorsal screw penetration using reproducible measuring techniques.

MAIN OUTCOME MEASUREMENTS

Diagnostic performance (sensitivity, negative predictive value, positive predictive value, and accuracy) of DTV.

RESULTS

Intraoperatively, in 16 of 50 patients (32%), screws were revised based on DTV, with 13 of 218 screws (6.0%) being revised due to dorsal prominence. One screw was changed because DTV showed it was in the distal radioulnar joint. Postoperatively, in 10 patients (20%), the computed tomography revealed 12 additional screws penetrating ≥1 mm with an average of 1.8 mm (range 1.0-4.5 mm). DTV had a sensitivity of 52%, a negative predictive value of 95%, and accuracy of 95%. No ≥1-mm protruding screw remained in the third compartment.

CONCLUSIONS

In one-third of our patients, the incidence of protruding screws that can cause iatrogenic extensor tendon rupture was reduced by obtaining additional DTVs. Although DTV reduces the incidence of dorsal screw penetration considerably, this study reveals limited sensitivity. Therefore, one should keep in mind that dorsal screw penetration may go unnoticed on DTVs, and proper surgical technique remains paramount of DTV.

LEVEL OF EVIDENCE

Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.

The Effect of Radial Shaft Dorsal Screw Prominence in Volar Locking Plate Fixation of Distal Radius Fractures

Background: The purpose of this study was to determine whether prominent radial shaft screws in volar locked plating of distal radius fractures increase the risk of tendon irritation, tendon rupture, or hardware removal. Methods: Patients who underwent volar locked plating of distal radius fractures from April 2002 to March 2016 with at least 6 months of follow-up were evaluated. Variables examined included demographics, extensor tendon irritation, extensor tendon rupture, and hardware removal. The most prominent cortical screws on postoperative lateral radiographs were identified and measured from the dorsal cortex of the radial shaft to the tip of the screw. Results: In all, 261 distal radius fractures in 255 patients were identified. Thirty-nine patients (14.9%) underwent subsequent hardware removal at a mean 15.8 ± 18.6 months. Nine patients (3.45%) were found to have clinically significant extensor tendon irritation including one patient (0.38%) with extensor tendon rupture. The average screw was 1.48 mm proud of the dorsal radial cortex. In all, 22.6% of screws were greater than 2 mm proud. Comparing patients who underwent hardware removal with those who did not, there was no statistically significant difference in mean screw prominence or proportion of patients with screws greater than 2 mm. There was no statistically significant difference between shaft screw prominence and extensor tendon irritation. Conclusions: The effect of dorsal screw prominence of radial shaft screws is not significant. This study does not support the downsizing of prominent screws 2 mm or less.

Volar Plating: Imaging Modalities for the Detection of Screw Penetration

Background  Volar plating for distal radius fractures exposes the risk of extensor tendon rupture, mechanical problems, and osteoarthritis due to protruding screws. Purposes  The purpose of this review was to identify the best intraoperative diagnostic imaging modality to identify dorsal and intra-articular protruding screws in volar plating for distal radius fractures. Methods  The Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines were followed for this review. In vitro and in vivo studies that analyzed the reliability, efficacy, and/or accuracy of intraoperatively available imaging modalities for the detection of dorsal or intra-articular screw protrusion after volar plating for distal radius fractures were included. Results  Described additional imaging modalities are additional fluoroscopic views (pronated views, dorsal tangential view [DTV], radial groove view [RGV], and carpal shoot through [CST] view), three-dimensional (3D) and rotational fluoroscopies, and ultrasound (US). For detection of dorsal screw penetration, additional fluoroscopic views show better results than conventional views. Based on small (pilot) studies, US seems to be promising. For intra-articular screw placement, 3D or 360 degrees fluoroscopy shows better result than conventional views. Conclusion  Based on this systematic review, the authors recommend the use of at least one of the following additional imaging modalities to prevent dorsal protruding screws: CST view, DTV, or RGV. Tilt views are recommended for intra-articular assessment. Of all additional fluoroscopic views, the DTV is most studied and proves to be practical and time efficient, with higher efficacy, accuracy, and reliability compared with conventional views. Level of Evidence  The level of evidence is Level III.

Effect of different multiplanar reformation algorithms on image quality of intraoperative three-dimensional fluoroscopy

Different multiplanar reformation (MPR-512 and -256) algorithms of intraoperative acquired 3-D-fluoroscopy data exist without recommendations for use in the literature. To compare algorithms, 3-D-fluoroscopic data sets of 46 radius fractures were blinded and processed using MPR-256 and -512 (Ziehm, Vision-Vario 3D). Each reformatted data set was analysed to evaluate image quality, fracture reduction quality and screw misplacements. Overall image quality was higher rated in the MPR-512 compared with the MPR-256 (3.2 vs. 2.2 points, scale 1-5 points), accompanied by a reduced number of scans that could not be analysed (10 vs. 19%). Interobserver evaluation of fracture reduction quality was fair to moderate (independent of the algorithm). In contrast, for screw misplacements MPR-depended ratings were found (MPR-256: fair to moderate; MPR-512: moderate to substantial). Optimization of post-processing algorithms, rather than modifications of image acquisition, may increase the image quality for assessing implant positioning, but limitations in evaluating fracture reduction quality still exist.

Complications in the Management of Distal Radius Fractures: How Do We Avoid them?

PURPOSE OF THIS REVIEW

Distal radius fractures are one of the most common fractures in the upper extremity. The purpose of this review is to outline common complications that may arise when caring for distal radius fractures and to describe the treatment strategies when faced with such complications.

RECENT FINDINGS

Tendon complications are not uncommon after distal radius fractures. Recent literature highlights new plating technology for dorsal plating techniques. Moreover, new literature has outlined parameters for flexor tendon complications when using volar locking plates in an effort to avoid flexor tendon irritation and rupture. In summary, it is important to understand the various complications that can arise when treating distal radius fractures in an effort to avoid suboptimal outcomes.

Distal locking screw length for volar locking plate fixation of distal radius fractures: Postoperative stability of full-length unicortical versus shorter screws

We compared post-operative distal radius fracture (DRF) displacement after volar locking plate fixation using full-length unicortical and shorter-length distal locking screws. In this non-inferiority, retrospective cohort study, DRFs treated with volar locking plate fixation were evaluated on X-rays. In the full-length group, volar locking plate fixation was performed with full-length unicortical distal locking screws. In the shorter-length group, the distal locking screws were planned pre-operatively to be approximately 75% of the distal radius depth based on the lunate depth, and the same depth was drilled. Three radiographic parameters - ulnar variance, volar tilt, and radial inclination - were measured intra-operatively and at the final follow-up. The displacements were compared between the two groups. Each group contained 34 fractures. The mean ulnar variance between the two periods increased 1.1 mm in the full-length group and 1.3 mm in the shorter group (mean difference, 0.2 mm; 90% confidence interval, -0.3 to 0.6). The shorter group was not significantly inferior to the full-length one. Volar tilt increased 0.6° in the full-length group and -0.1° in the shorter group, while the radial inclination increased 0.1° in the full-length group and 0.2° in the shorter one. The differences in the increases were not significant. The post-operative DRF stability of 75%-length distal locking screws was not inferior to that of full-length unicortical screws. To prevent extensor pollicis longus tendon rupture, shorter distal locking screws and the same drilling depth may be preferable for volar locking plate fixation.

"Island-shape" Fractures of Lister's tubercle have an increased risk of delayed extensor pollicis longus rupture in distal radial fractures: After surgical treatment by volar locking plate

PURPOSE

Weperformed a retrospective case-control study to explore the hypothesis that conditions adjacent to Lister's tubercle (LT) in patients with distal radial fractures (DRFs) exhibiting dorsal comminution would influence the extent of the delayed extensor pollicis longus (EPL) rupture.

METHODS

Among patients treated by volar locking plates (VLPs) were placed between March 2011 and December 2015, 314 met inclusion/exclusion criteria and were analyzed. We designated group 1 as the "EPL rupture" and group 2 as the "no EPL rupture". Basic demographic data, radiological findings, and operative variables were evaluated. The fracture patterns around LT were classified as follows: type I, no fracture line/fragment in LT or the EPL groove (third compartment); type IIA, a fracture of LT or the EPL groove with displacement <2 mm; type IIB, a fracture of LT or the EPL groove with displacement >2 mm; and type III, the presence of an island-shaped fracture fragment of LT (isolated free fragment of LT).

RESULTS

EPL ruptures were found in 18 patients (5.7%). The basic demographic parameters did not differ significantly among the groups. Clinically, neither the time to surgery nor the type of VLP used (of three different types) was not significantly associated with EPL rupture, nor was arthroscopically assisted reduction. In terms of radiological variables, the overall ratio of intra-to-extra-articular fractures did not differ among the groups. However, the fracture type significantly affected the extent of the rupture (P < 0.001), the odds ratio of which increased significantly in the fracture order IIA, IIB, and III, compared to type I (91.9, 220.1, and 342.06, respectively).

CONCLUSIONS

The extent of delayed EPL rupture after treatment of DRFs by VLPs was associated with the fracture pattern around the LT. Especially, an island-shaped LT fracture was associated with a high rupture risk because callus formation narrowed the EPL groove.

LEVEL OF EVIDENCE

Therapeutic Level III.

Intraoperative sonography may reduce the risk of extensor pollicis longus tendon injury during dorsal entry elastic intramedullary nailing of the radius in children

Extensor pollicis longus tendon (EPL) injury is a potential complication of dorsal entry radial elastic nailing technique in children. The aim of this study was to investigate if intraoperative ultrasonographic guidance can reduce the risk of (EPL) injury.Correlation between sonographic and operative findings were examined first in 6 adult cadavers. Position of Lister's tubercle, EPL, and extraosseal end of the elastic nail were detected by ultrasound imaging during a minimally invasive dorsal entry nailing. Radial slope of Lister's eminence was determined as a safe and easily identifiable entry point for opening the medullary canal. Extraosseal ends of the nails were bended in a slight radial direction and cut immediately beneath the skin in a maximally palmar-flexed wrist position. Cadaveric dissections followed our procedures all correlated with ultrasonographic findings, we have not seen tendon damage, obstruction or friction by the implant's end.After cadaveric experiments, we began using intraoperative sonography for monitoring elastic nail insertion in pediatric radial fractures.Between January 2015 and November 2016, 77 pediatric closed diaphyseal radial fractures were operated by dorsal approach ESIN under intraoperative sonographic checking.Procedures were executed by 2 orthopedic surgeons experienced in ESIN technique with basic musculoskeletal ultrasonographic qualifications.Sonographic identification of EPL and Lister's tubercle in the transverse view was possible in all cases. Determination of the position of the nail end to EPL was also possible in all cases. Mean distance of the transverse view center of the EPL and nail was 0.49 cm (range 0.3-0.62 cm, SD = 0.66). Based on the sonographic transverse view, the operator decided repositioning the nails by 2 patients.We have not found EPL injury postoperatively. All patients were followed for at least 12 months after operations. Nails were removed in all children without further complications.Intraoperative sonography helps determining optimal insertion point and the risk of EPL injury may be reduced during dorsal entry approach.Although the procedure is relatively easy, authors take note that surgical and sonoanatomic knowledge, basic sonographic skills and experience in the ESIN technique are equally necessary for its successful application. A greater number of cases is necessary to confirm our initial promising experiences.

Intraoperative three-dimensional imaging in the treatment of distal radius fractures

INTRODUCTION

In operative treatment of distal radius fractures satisfying outcome mainly relies on anatomical fracture reduction and correct implant placement. Examination with two-dimensional fluoroscopy may not provide reliable information about this. The aim of this study was to determine the effectiveness of additional intraoperative three-dimensional imaging in the operative treatment of comminuted distal radius fractures.

MATERIALS AND METHODS

From August 2001 to June 2015, patients with a distal radius fracture who were treated operatively and received intraoperative three-dimensional scan were included. The findings of the three-dimensional scan were documented by the operative surgeon and analyzed retrospectively with regard to incidence and the need for intraoperative revisions. Clinical evaluation included the patient's medical history, the injury pattern of the affected wrist (according to the OTA/AO fracture classification) and concomitant injuries. Intraoperative and postoperative complications and revision surgeries were evaluated as well.

RESULTS

Of 4515 operatively treated distal radius fractures, 307 (6.8%) received additional intraoperative three-dimensional imaging during surgery. 263 of 307 patients (85.7%) had a distal radius fracture type C. Intraoperative three-dimensional imaging revealed findings in 125 patients (40.7%) that were not detected on conventional two-dimensional fluoroscopy. In 54 patients (17.6%) these findings led to an immediate revision. Most commonly, revision was done in the case of remaining steps in the articular surface ≥ 1 mm (n = 25, 8.1%) followed by intra-articular screw placement (n = 23, 7.5%).

CONCLUSIONS

Intraoperative three-dimensional imaging can provide additional information compared to conventional two-dimensional fluoroscopy in the operative treatment of distal radius fractures with the possibility of immediate intraoperative revision.

Use of Computed Tomography in Determining the Occurrence of Dorsal and Intra-articular Screw Penetration in Volar Locking Plate Osteosynthesis of Distal Radius Fracture

Background: The use of volar locking plate in distal radius fracture can lead to extensor tendon rupture due to dorsal screw penetration. The aim of our study was to investigate the occurrence of dorsal and intra-articular screw penetration using CT scan after volar distal radius osteosynthesis for distal radius fractures.

Methods: Thirty patients who underwent distal volar locking plate for distal radius fracture were included in a retrospective study. In all 30 patients no dorsal and intra-articular screw penetration were detected on standard AP and lateral views of a plain radiograph. CT scan of the operated wrist was performed to determine the number of intra-articular and dorsal screw penetrations. Clinical examination was performed to determine the wrist functions in comparison to the normal wrist.

Results: Nineteen wrists were noted to have screw penetration either dorsally or intraarticularly. The highest incidence is in the 2nd extensor compartment where 13 screws had penetrated with a mean of 2.46 mm. Six screws penetrated into the distal radial ulnar joint and five screws into the wrist joint with a mean of 2.83 mm and 2.6 mm, respectively. However, there was no incidence of tendon irritation or rupture.

Conclusions: This study demonstrated a high incidence of dorsal and intra-articular screw penetration detected by CT scan which was not apparent in plain radiograph. We recommend that surgeons adhere to the principle of only near cortex fixation and downsizing the locking screw length by 2 mm.

Sensitivity and Specificity of Skyline and Carpal Shoot-Through Fluoroscopic Views of Volar Plate Fixation of the Distal Radius: A Cadaveric Investigation of Dorsal Cortex Screw Penetration

BACKGROUND

Volar plate fixation of distal radius fractures can result in soft tissue injuries. Abnormal contour of the dorsal cortex of the distal radius provides difficulties in discerning screw penetration on standard radiographs. The skyline and carpal shoot-through views are additional views to improve dorsal cortex visibility. We report on the sensitivity and specificity of determining screw protrusion with these views.

METHODS

Seven fresh frozen cadavers were instrumented with a distal radius volar locking plate. Initial screw length was determined by depth gauge measurement. A dorsal dissection of the wrist was performed to detect screw penetration. Protruding screws were documented and replaced with screws of the appropriate length and deemed as baseline. Screws were then sequentially lengthened by 2 and 4 mm. Skyline and carpal shoot-through views were obtained at baseline, 2 mm, and 4 mm. The images were randomized and compiled into an untimed survey asking orthopedic surgeons to determine whether screws were penetrating through the dorsal cortex.

RESULTS

Based on depth gauge measurements, 4 out of 44 (9.1%) volar plate locking screws penetrated the dorsal cortex, as confirmed with dorsal dissection. Sensitivities for the skyline and carpal shoot-through views were 75% and 86% ( P ≤ .001), respectively, for 2-mm protrusions, and 76% and 89% ( P ≤ .001), respectively, for 4-mm screw protrusions. Specificities were 85% and 84% for the skyline and shoot-through views, respectively.

CONCLUSIONS

We believe that the carpal shoot-through view has utility and can be implemented to augment standard intraoperative views, and may decrease the incidence of screw protrusion resulting in soft tissue injuries.

Detections of Screw Penetration during Volar Plating for Distal Radius Fractures

Background  We evaluated the detection for screw penetration on the dorsal cortex of the radius in serial oblique, dorsal tangential, and radial groove radiographic views in volar plating fixation. Materials and Methods  Eight screw positions were set in each of the four cadaveric radii. Screw 1 was placed in the styloid subregion, whereas screws 2 and 3 were placed just proximal to the styloid and were defined for the radial region of the radius. Screws 4 (distal to the extensor pollicis longus [EPL] groove), 5 (the distal half of the groove), and 6 (the proximal half of the groove) were placed in the central region of the radius. Screws 7 (just medial to the groove) and 8 (sigmoid notch subregion) were positioned in the ulnar region of the radius. The screws were overlengthened by 1 and 2 mm and were evaluated in three radiographic views. Results  Penetrations in the radial region were fully visible in supinated oblique views with 1- and 2-mm overlengthened screws. The penetration of screw 4 was clearly observable over a considerable range of views. However, the 1-mm penetration of screw 5 was not detectable at any angle of projection. Detection of the ulnar region screw was the most difficult among the three regions with oblique views. In the dorsal tangential view, the 1-mm penetration of screw 4 was not observed in any of the four radii, but the penetration of screw 5 was detectable in all the radii. The screws 2, 3, 5, 7, and 8 were readily detectable. The screw 4 was barely seen in the radial groove view, while the screws 5 and 6 were readily detectable. Conclusion/Clinical Relevance  Appropriate combinations of these well-known radiological views are essential for the overall detection of penetrated screws during plating in distal radius fractures.

Two-dimensional Morphological Characteristics of the Distal Radius on Axial Magnetic Resonance Image and the Effects on Distal Screw Length

BACKGROUND

Detection of dorsal cortical penetration of distal locking screws is difficult owing to the irregular shape of the dorsal surface of the distal radius. This study was designed to analyze two-dimensional morphological characteristics of the distal radius on axial magnetic resonance image, and to suggest a guideline for evaluation of screw length in distal radius fractures on the fluoroscopic or plain X-ray true lateral image.

METHODS

Anteroposterior length and lateral width of the distal radius, distance between the highest and the lowest point of the dorsal cortex (deceptive length), and widths of the first to second (hazard zone) and the third to fifth extensor compartments (safe zone) at the Lister tubercle level were measured on 104 axial magnetic resonance images by two hand surgeons.

RESULTS

The mean length and width of the distal radius at the Lister tubercle level were 22.96 mm and 30.42 mm, respectively. The mean hazard zone and safe zone widths were 8.72 mm and 19.43 mm, respectively. The mean deceptive length was 4.07 mm and the deceptive length did not have a relationship with height, sex, and age of subjects.

CONCLUSIONS

We suggest that 4 mm be used as a reference value for the evaluation screw length at the safe zone. If the vertical distance between a distal screw tip and the peak of the Lister tubercle is lesser than 4 mm on a fluoroscopic or plain X-ray true lateral image, dorsal cortical penetration should be suspected. When dorsal cortical penetration at the hazard zone is suspected, both oblique or pro-supination views should be checked.

[Descriptive, radiographic, topographic and functional anatomy applied to distal radius fractures]

Extensive anatomical knowledge is needed in order to correctly treat distal radius fractures: normal and pathological osteology of the distal radius, distal radio-ulnar joint and radiocarpal joint-both on the descriptive and functional level-the neurovascular and muscular environments of the distal radius-which are essential to the surgical approaches-and the angles that need to be restored during the reduction. All of these concepts are broached in this article.

Detecting dorsal screw penetration following volar plate fixation of the distal radius – A validation study in a saw bone model

Background

The fluoroscopic detection of dorsal screw protrusion following volar locking plate fixation of distal radius fractures remains difficult. The carpal shoot through view has recently been reported to result in a 17% intra-operative screw exchange rate. The aim of the current study was to assess the sensitivity of the carpal shoot through view in comparison to conventional fluoroscopic views for detecting dorsal cortical and distal radio-ulnar joint screw penetration.

Methods

A volar locking plate was applied to a saw bone model and fluoroscopic views taken with the distal screws inserted flush or protruding by two full screw threads. Images were then shown to 10 orthopaedic surgeons who were asked to identify excessively long screws.

Results

The CST view demonstrated the greatest sensitivity for detection of dorsal screw penetration (78%). Its inter-observer reliability was 0.66 (substantial agreement) and intra-observer reliability 0.86 (near perfect agreement). The dorsal skyline had a sensitivity of 51%; the elevated lateral view had a sensitivity of only 16%.

Conclusions

The current study confirms that the elevated lateral view cannot be relied upon alone for the detection of dorsal screw penetration. The CST view is a valid technique demonstrating the greatest sensitivity in comparison to established intra-operative views.

Tangential View and Intraoperative Three-Dimensional Fluoroscopy for the Detection of Screw-Misplacements in Volar Plating of Distal Radius Fractures

Background:

Volar locking plate fixation has become the gold standard in the treatment of unstable distal radius fractures. Juxta-articular screws should be placed as close as possible to the subchondral zone, in an optimized length to buttress the articular surface and address the contralateral cortical bone. On the other hand, intra-articular screw misplacements will promote osteoarthritis, while the penetration of the contralateral bone surface may result in tendon irritations and ruptures. The intraoperative control of fracture reduction and implant positioning is limited in the common postero-anterior and true lateral two-dimensional (2D)-fluoroscopic views. Therefore, additional 2D-fluoroscopic views in different projections and intraoperative three-dimensional (3D) fluoroscopy were recently reported. Nevertheless, their utility has issued controversies.

Objectives:

The following questions should be answered in this study; 1) Are the additional tangential view and the intraoperative 3D fluoroscopy useful in the clinical routine to detect persistent fracture dislocations and screw misplacements, to prevent revision surgery? 2) Which is the most dangerous plate hole for screw misplacement?

Patients and Methods:

A total of 48 patients (36 females and 13 males) with 49 unstable distal radius fractures (22 x 23 A; 2 x 23 B, and 25 x 23 C) were treated with a 2.4 mm variable angle LCP Two-Column volar distal radius plate (Synthes GmbH, Oberdorf, Switzerland) during a 10-month period. After final fixation, according to the manufactures' technique guide and control of implant placement in the two common perpendicular 2D-fluoroscopic images (postero-anterior and true lateral), an additional tangential view and intraoperative 3D fluoroscopic scan were performed to control the anatomic fracture reduction and screw placements. Intraoperative revision rates due to screw misplacements (intra-articular or overlength) were evaluated. Additionally, the number of surgeons, time and radiation-exposure, for each step of the operating procedure, were recorded.

Results:

In the standard 2D-fluoroscopic views (postero-anterior and true lateral projection), 22 screw misplacements of 232 inserted screws were not detected. Based on the additional tangential view, 12 screws were exchanged, followed by further 10 screws after performing the 3D fluoroscopic scan. The most lateral screw position had the highest risk for screw misplacement (accounting for 45.5% of all exchanged screws). The mean number of images for the tangential view was 3 ± 2.5 images. The mean surgical time was extended by 10.02 ± 3.82 minutes for the 3D fluoroscopic scan. An additional radiation exposure of 4.4 ± 4.5seconds, with a dose area product of 39.2 ± 14.5 cGy/cm² were necessary for the tangential view and 54.4 ± 20.9 seconds with a dose area product of 2.1 ± 2.2 cGy/cm², for the 3D fluoroscopic scan.

Conclusions:

We recommend the additional 2D-fluoroscopic tangential view for detection of screw misplacements caused by overlength, with penetration on the dorsal cortical surface of the distal radius, predominantly observed for the most lateral screw position. The use of intraoperative 3D fluoroscopy did not become accepted in our clinical routine, due to the technical demanding and time consuming procedure, with a limited image quality so far.

Predicting a safe screw length for volar plate fixation of distal radius fractures: lunate depth as a marker for distal radius depth

PURPOSE

We hypothesized that the lunate depth as measured on plain lateral radiographs can be used to predict distal radius depth radially and ulnarly and serve as a useful reference for intraoperative screw placement in volar plate fixation of distal radius fractures.

METHODS

Plain radiographs and magnetic resonance imaging (MRI) of the wrists of 30 patients were reviewed. The lunate depth and the maximal depth of the distal radius were determined from plain lateral radiographs. Depth of the distal radius, measured in quartiles, was determined from axial MRI images, and the lunate depth was obtained from sagittal MRI images. The depth of the distal radius in each quartile was then calculated related to the lunate depth.

RESULTS

The mean depth of the lunate on plain radiographs and MRI was 17.5 mm and 17.4 mm, respectively. The depth of the distal radius from ulnar to radial was 18.4 mm, 20.2 mm, 19.4 mm, and 15.1 mm for the 1st through 4th quartiles, respectively. The depth of the distal radius is the least radially (4th quartile), with a mean 87% of the lunate depth, and greatest in the 2nd quartile, with a mean 116% of the lunate depth.

CONCLUSIONS

The depth of the lunate as measured on plain radiographs can be used as a marker for drilling and placement of safe screw lengths during volar plate fixation of distal radius fractures. We recommend that surgeons use the lunate depth as an estimate for the length of their longest screw when fixing distal radius fractures with volar plate techniques to avoid extensor tendon irritation and rupture.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic III.

Volar locking plate fixation of distal radius fractures: use of an intra-operative 'carpal shoot through' view to identify dorsal compartment and distal radioulnar joint screw penetration

INTRODUCTION

We report our experience using a 'carpal shoot through' view of the distal radius to identify dorsal compartment screw penetration intra-operatively when performing volar plating of the distal radius.

METHODS

A prospective study of 42 patients (mean age 56 years) with acute distal radius fractures treated with open reduction internal fixation was undertaken. Surgical fixation was performed using a volar locking plate in all patients. After plate application, inclined posteroanterior and lateral radiographs were taken followed by the carpal shoot through view.

RESULTS

In six cases (14 %), the carpal shoot through view revealed dorsal screw protrusion, which was not detectable on standard PA and lateral views. In one case, a screw had penetrated the distal radioulnar joint (DRUJ), which was only apparent on the shoot through view. The overall screw exchange rate was 17 %.

CONCLUSIONS

Using the hand and carpus to minimise the contrast in X-ray penetration, the dorsal cortex of the distal radius may be imaged intra-operatively and dorsal compartment screw penetration detected in cases with significant multifragmentation when screw measurement is difficult. This view potentially reduces the risk of post-operative pain and extensor tendon injury and also provides excellent visualisation of the DRUJ.