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.

Diagnosis of dorsal screw penetration after volar plating of a distal radial fracture.

AIMS: The aim of this study was to investigate whether intraoperative 3D fluoroscopic imaging outperforms dorsal tangential views in the detection of dorsal cortex screw penetration after volar plating of an intra-articular distal radial fracture, as identified on postoperative CT imaging. METHODS: A total of 165 prospectively enrolled patients who underwent volar plating for an intra-articular distal radial fracture were retrospectively evaluated to study three intraoperative imaging protocols: 1) standard 2D fluoroscopic imaging with anteroposterior (AP) and elevated lateral images (n = 55); 2) 2D fluoroscopic imaging with AP, lateral, and dorsal tangential views images (n = 50); and 3) 3D fluoroscopy (n = 60). Multiplanar reconstructions of postoperative CT scans served as the reference standard. RESULTS: In order to detect dorsal screw penetration, the sensitivity of dorsal tangential views was 39% with a negative predictive value (NPV) of 91% and an accuracy of 91%; compared with a sensitivity of 25% for 3D fluoroscopy with a NPV of 93% and an accuracy of 93%. On the postoperative CT scans, we found penetrating screws in: 1) 40% of patients in the 2D fluoroscopy group; 2) in 32% of those in the 2D fluoroscopy group with AP, lateral, and dorsal tangential views; and 3) in 25% of patients in the 3D fluoroscopy group. In all three groups, the second compartment was prone to penetration, while the postoperative incidence decreased when more advanced imaging was used. There were no penetrating screws in the third compartment (extensor pollicis longus groove) in the 3D fluoroscopy groups, and one in the dorsal tangential views group. CONCLUSION: Advanced intraoperative imaging helps to identify screws which have penetrated the dorsal compartments of the wrist. However, based on diagnostic performance characteristics, one cannot conclude that 3D fluoroscopy outperforms dorsal tangential views when used for this purpose. Dorsal tangential views are sufficiently accurate to detect dorsal screw penetration, and arguably more efficacious than 3D fluoroscopy. Cite this article: Bone Joint J 2020;102-B(7):874-880.

Interpretations of the Term "Watershed Line" Used as Reference for Volar Plating.

Objective The objective of this systematic review is to provide an overview of all interpretations of the definition of the watershed line used in literature. Methods The Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines were followed for this review. A comprehensive search was performed for definitions of the watershed line given in literature. A total of 32 studies giving an explicit interpretation of the definition of the watershed line or anatomical reference for plate positioning in writing and/or imaging were included. Results In 32 studies, we found eight different landmarks used to refer to the watershed line or correct plate positioning. Five studies used two different soft tissue landmarks. Six different bony landmarks were described in 24 studies. These could further be subdivided into three anatomical interpretations, described in seven studies, in which the term "watershed line" is explained as a distinguishable anatomical line, and two surgical interpretations, described in 15 studies, which are purely reflecting the optimal location of the volar plate. One interpretation of the watershed line described in two studies combined both anatomical and surgical landmarks. Conclusion The (mis)interpretation of the definition of the term "watershed line" as described by Orbay is subject to the type of landmarks and purpose used: soft tissue or bony landmarks and an anatomical or a surgical purpose. A clear distinction can be made between interpretations using bony landmarks, as the true watershed line is defined and definitions using soft tissue landmarks, which might represent the reference points surgeons use in clinical practice.

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.

The Watershed Line of the Distal Radius: Cadaveric and Imaging Study of Anatomical Landmarks.

Background Placement of volar plates remains a challenge as the watershed line may not be an easy-identifiable distinct line intraoperatively. Objectives The main objective of this article is to define how anatomical landmarks identifiable upon the volar surgical approach to the distal radius relate to the watershed line. Methods We identified anatomical landmarks macroscopically upon standard volar approach to the distal radius in 10 cadaveric forearms and marked these with radiostereometric analysis (RSA) beads in cadaveric wrists. The RSA beads were then referenced against the volar osseous structures using quantification of three-dimensional computed tomography and advanced imaging software. Results The mean measurements were the radial and ulnar prominences 11.1 mm and 2.1 mm proximal to the joint line of the distal radius, respectively. The interfossa sulcus was 0.3 mm proximal and 3 mm dorsal to the ulnar prominence. The watershed line was between 3.5 (minimal) and 7.6 (maximal) mm distal to the distal line of insertion of the pronator quadratus. Conclusion The watershed line is situated distal to the pronator quadratus, but with a wide variability making it an impractical landmark for plate position. The osseous ulnar prominence is a good anatomical reference for safe plate positioning, as it is located on the watershed line and easily palpated at surgery. One should keep in mind the sulcus-the point on the watershed line where the flexor pollicis longus runs-can be situated just proximal to the ulnar prominence. Clinical Relevance To provide anatomical landmarks that are easy to identify upon surgical approach without the direct need for intraoperative imaging.

MRI Study on the Distance between the Distal Radius and the Flexor and Extensor Tendons: Is There Any Room for Error/Hardware?

Purpose This study aims to quantify the distances between the cortex of the distal radius and flexor and extensor tendons. Methods We analyzed 50 magnetic resonance images (MRI) of intact wrist without pathology. The distances between the volar cortex and the flexor pollicis longs (FPL), index flexor digitorum profunduns (FDPi), flexor digitorum profundus (FDP), and flexor digitorum superficialis (FDS) were measured at the level of the watershed line and 3- and 6-mm proximal to this level. The distances between the dorsal cortex and the extensor carpi radialis longus (ECRL), extensor carpi radialis brevis (ECRB), extensor pollicis longus (EPL), extensor indicis proprius (EIP), and the extensor digitorum communis (EDC) were measured at the level of Lister's tubercle and 5-mm distal to this level. Analysis was descriptive. Results At the watershed line, the FPL, FDPi, FDP, and FDS were located at an average of 3.1, 2.4, 3.6, and 5.1 mm, respectively, volar to the volar cortex. The distances of the FDP and FDS increased at 3-mm proximal to the watershed line and increased for all four tendons at 6-mm proximal to the watershed line. Dorsally, at Listers' tubercle the ECRL, ECRB, EPL, EIP, and EDC were identified at an average of 0.7, 0.5, 0.5, 2.6, and 3.2 mm, respectively, dorsal to the dorsal cortex of the distal radius. At 5-mm more distal, these tendons were located on average 1.2, 1.0, 0.7, 1.9, and 1.8 mm, respectively, dorsal to the dorsal cortex. Conclusion On the volar side, on average there is enough room for a volar plate when staying proximal to the watershed line. On the dorsal side, there is virtually no room for protruding screws as physical anatomical space is limited to a maximum of 0.7 mm from cortex to the closest tendon (the FDP), with screw increments being 2 mm. Level of Evidence This is a Level II Study.

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.

Distal Radius Volar Plate Design and Volar Prominence to the Watershed Line in Clinical Practice: Comparison of Soong Grading of 2 Common Plates in 400 Patients.

PURPOSE: To compare plate positioning in clinical practice of 2 commonly used volar locking plate designs with respect to the watershed line as classified by the Soong grading system. METHODS: For this retrospective study, we included a total of 400 patients who underwent open reduction and internal fixation between May 2013 and February 2018. Cohort 1 was defined as patients treated with distal volar radius (DVR) plates during this period. Cohort 2 comprised 200 patients who had volar plate fixation with variable angle locking compression plates (LCP) during the same period. Standardized lateral wrist radiographs were categorized into Soong grade 0, 1, or 2. RESULTS: In cohort 1, 87 plates (43.5%) were not prominent volar to the watershed line, grade 0; 95 plates (47.5%) demonstrated grade 1 prominence; and 18 plates (9.0%) demonstrated grade 2 prominence. In cohort 2, 63 plates (31.5%) were grade 0; 103 plates (51.5%) were grade 1; and 34 plates (17%) had grade 2 prominence on, and volar to, the watershed line. These radiographic results show a greater incidence of volar plate prominence with respect to the watershed line, as defined as Soong grading, in cohort 2. CONCLUSION: This study shows that the use of the variable angle LCP plate is associated with more prominent volar positioning with respect to the watershed line compared with the DVR plate. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic II.

Volar plating in distal radius fractures: A prospective clinical study on efficacy of dorsal tangential views to avoid screw penetration.

PURPOSE: The purpose of this prospective cohort study of patients treated with volar plating for distal radius fractures is to evaluate the efficacy (defined as detection rate, or the ability to detect dorsally protruding screws) of additional dorsal tangential views (DTV) after obtaining standard anteroposterior (AP) and elevated lateral views by evaluating the change in intraoperative strategy in 100 patients. MATERIALS AND METHODS: 100 patients aged 18 years and older undergoing volar plating for acute extra- or intra- articular distal radius fractures were prospectively enrolled. Intraoperative fluoroscopy views, including AP, elevated lateral and DTV were obtained. Intraoperative -screw- revision frequency for dorsal screw protrusion, screw position relative to volar plate and to dorsal compartment, and screw lengths were evaluated. RESULTS: Additional DTV led to a change of intraoperative management in 31 of 100 (31%) of patients. A total of 35 out of 504 screws (6.9%) were changed. Screws in the two most radial screws in the plate were at the highest risk of being revised; 16 (46%) screws in most radial position and nine (26%) screws in the 2nd from radial position were revised. Furthermore, five (14%) screws in both the 2nd from ulnar and most ulnar screw holes were revised after DTV. No screws were revised in the central hole. The median length of revised protruding screws was 22 mm (range, 12-26 mm), and these were changed to a mean length of 20  mm (range, 10-22 mm). CONCLUSION: In this prospective series of 100 patients, obtaining additional DTV is found to be efficacious as it led to change in intraoperative strategy in one-third of patients. We concur with previous pilot studies that DTV, after obtaining conventional AP and elevated lateral views, is advised to avoid dorsally protruding screws, which could minimise the potential for iatrogenic extensor tendon rupture after volar plating for distal radius fractures. Diagnostic accuracy of DTV is subject of a subsequent prospective cohort study with post-operative CT to serve as the reference standard. LEVEL OF EVIDENCE: .Prognostic I.