Study of the position of six volar locking plates for distal radius fracture relative to the watershed line.

INTRODUCTION: Volar plate malpositioning in the treatment of distal radial fracture can lead to tendinitis or even tendon tear, especially when the plate position is very distal. We studied the impact of design on plate position in the distal radius. The primary aim was to compare the position of six volar wrist plates relative to the watershed line using the Soong classification. The secondary objectives were to assess the epidemiology of volar locking plate fixation within the administrative Département of Finistère (northwestern France) and to study whether the type of fracture played a role in plate position. HYPOTHESIS: The plate design itself influences positioning relative to the watershed line on the Soong classification. MATERIALS AND METHODS: A total of 2723 volar locking plate fixation cases were analyzed and categorized according to the Soong classification. Plates used were divided into six groups based on design: Zimmer Biomet®, Newclip Technics®, Stryker®, Synthes®, Medartis® and Medartis® Footprint. The number of Soong 0 + 1 plates (i.e., plates graded 0 and 1 taken together) was determined for each design, then compared using the Marascuilo procedure with a significance level of α = 0.05. RESULTS: On the Marascuilo procedure, we found significant differences in the number of Soong grade 0 + 1 plates. The Zimmer Biomet and Newclip Technics® plates were significantly more often proximal to the watershed line than the Synthes and Medartis Footprint plates. Plate position with the Medartis® design was significantly more proximal to the watershed line than for its companion design, the Medartis® Footprint plate. The rate of volar locking plate fixation of distal radial fractures over the past 10 years increased in Finistère. Also, the type of fracture affected the choice of plate when different designs were available within a hospital center (Medartis® Footprint plate used in 2R3A fractures). CONCLUSION: Our study highlights a significant difference in volar locking plate position relative to the watershed line between the various models available. Plate design is a deciding factor when treating distal radial fracture, to avoid impingement when implant removal is not routinely planned.

Higher Soong grade predicts flexor tendon issues after volar plating of distal radius fractures - a retrospective cohort study.

BACKGROUND AND PURPOSE: Soong classification is used to estimate volar locking plate prominence and evaluate the risk for flexor tendon ruptures after surgical treatment of distal radius fractures (DRFs). However, the scientific community has questioned the Soong classification due to lacking evidence. Therefore, this study aimed to evaluate the accuracy of Soong grading as a predictor for flexor tendon issues and plate removal. PATIENTS AND METHODS: We performed a retrospective single-center review of adult distal radius fracture patients treated with a volar locking plate between 2009 and 2019. In total, 2779 patients were included in the study. The primary outcome was a flexor tendon issue (flexor tendon rupture, tendinitis, or flexor irritation), whereas plate removal was a secondary outcome. Using Soong grade 0 as a reference, we used univariable and multivariable logistic regression to calculate odds ratios (OR) with 95% confidence intervals (CI) for flexor tendon issues and plate removal. RESULTS: In total, 756 (27%) patients were graded as Soong 0, 1679 (60%) Soong 1, and 344 (12%) Soong 2, respectively. There were 32 (1.2%) patients with flexor tendon issues, of which 4 were flexor tendon ruptures, 8 tendinitises, and 20 flexor irritations. The adjusted OR for flexor tendon issues was 4.4 (CI 1.1-39.7) for Soong grade 1 and 9.7 (CI 2.2-91.1) for Soong grade 2. The plate was removed from 167 (6.0%) patients. Soong grade 1 had a univariable OR of 1.8 (CI 1.2-2.8) for plate removal, and Soong grade 2 had an OR of 3.5. (CI 2.1-5.8), respectively. CONCLUSION: Flexor tendon ruptures are rare complications after the volar plating of DRFs. A higher Soong grade is a risk factor for flexor tendon issues and plate removal. TRIAL REGISTRATION: The trial was retrospectively registered.

The Interobserver Reliability of Grading of Distal Radius Volar Plate Prominence.

PURPOSE: The 3-category rating of volar plate prominence in relation to the most volar edge of the distal radius (the watershed line) on lateral radiographs was reliable among a small group of surgeons and associated with the probability of flexor tendon irritation and potential rupture. Classifications are often less reliable when tested among a large group of practicing surgeons in different environments. METHODS: In this survey-based experiment, an international group of 115 fracture and upper extremity surgeons viewed 1 of 4 sets of 24 lateral radiographs (96 unique lateral radiographs) of patients with distal radius fractures who underwent volar plating in the practice of a single surgeon using 2 types of plates. Surgeons were asked to rate the following metrics: (1) the grade of plate prominence according to Soong, (2) whether the plate was more prominent than the watershed line, (3) whether the plate was separate from the bone distally, and (4) whether there is more than 5° of dorsal angulation of the distal radius articular surface. RESULTS: The interobserver agreement of the classification was "fair" (κ = 0.32; 95% confidence interval [CI] = 0.27-0.36), and grading was more reliable among surgeons who do not supervise trainees. Volar prominence was less reliable (κ = 0.034; 95% CI = 0.013-0.055) than plate separation from bone (κ = 0.50; 95% CI = 0.42-0.59) and more than 5° of dorsal angulation (κ = 0.42; 95% CI = 0.35-0.48). CONCLUSIONS: Among a large number of international practicing surgeons, the classification of volar plate prominence in 3 categories was fair. CLINICAL RELEVANCE: The diagnosis of plate prominence might develop toward criteria with moderate reliability, such as separation of the plate from the bone and residual angulation of the distal radius.

Intraoperative Fluoroscopy Versus Postoperative Radiographs in Assessing Distal Radius Volar Plate Position: Reliability of the Soong Classification.

Purpose: Fluoroscopic imaging remains the standard intraoperative imaging modality for volar locking plate fixation of distal radius fractures, and correlation with postoperative radiographs remains unclear. The purpose of this study was to assess the reliability of the Soong classification system between intraoperative fluoroscopy and postoperative radiographs for distal radius volar plate position. Methods: Eleven hand surgery resident physicians (3 in postgraduate year 2, 2 in postgraduate year 3, 3 in postgraduate year 4, and 3 in postgraduate year 5) and 4 attending physicians classified images using the Soong classification system. Fluoroscopic and radiographic lateral images from 30 patients were randomized and deidentified. Thirty percent of the images were duplicated for intraobserver reliability. Seventy-eight images were randomized and presented to each observer in 1 consecutive session. Cohen kappa values were calculated for intraobserver reliability, and Fleiss kappa values were calculated for interobserver reliability. Results: Intraobserver reliability demonstrated moderate reliability overall. The intraobserver reliability was highest among postgraduate year 4 residents and attending physicians demonstrating substantial reliability. Lateral intraoperative fluoroscopic and postoperative radiographic imaging demonstrated no difference in intraobserver reliability overall. Interobserver reliability was highest among postgraduate year 5 residents demonstrating moderate reliability and attending physicians demonstrating substantial reliability. Conclusions: There was no difference in the intraobserver reliability of the Soong classification system between the lateral images of intraoperative fluoroscopy and postoperative radiographs. Fluoroscopic analysis using the Soong classification system is a reliable method to determine plate prominence and has demonstrated increasing reliability based on year of training. Fluoroscopic analysis using the Soong classification system and direct visualization during surgery for the assessment of plate prominence is recommended, with the understanding that higher Soong grades are associated with increased rates of complications. Type of study/level of evidence: Diagnostic III.

Changes in the Rate of Postoperative Flexor Tendon Rupture in Patients with Distal Radius Fractures.

Background: Flexor tendon rupture is a major complication after volar locking plating for distal radius fracture (DRF). Few studies have investigated changes in the rate of postoperative flexor tendon rupture in patients with DRFs. The present study aimed to investigate the changes in the rate of postoperative flexor tendon rupture and to assess plate placement and reduction positions. Methods: We retrospectively reviewed patients in whom more than 24 months had passed since DRF surgery. The patients were interviewed by telephone. Forty-nine patients (50 fractures; 2007-2009) from institution A were included in group 1 and 81 patients (84 fractures; 2013-2016) from institution B were included in group 2. The DRF surgery method was similar between the two groups. The rate of flexor tendon rupture, Soong classification grade, and radiological index (i.e., volar tilt [VT], radial inclination [RI], and ulnar variance [UV]) were statistically investigated in both groups. Results: Patient epidemiology was not significantly different between the two groups. The flexor tendon rupture rates were 2% and 0% in groups 1 and 2, respectively, without a significant difference. With regard to the Soong grade, 44 fractures were grade 2 and 6 were grade 1 in group 1, whereas 18 were grade 2, 38 were grade 1, and 28 were grade 0 in group 2, with a significant difference (p < 0.05). With regard to the radiological index, the mean VT values were 5° and 11° in groups 1 and 2, respectively, with a significant difference (p < 0.05). However, RI and UV showed no significant difference. Conclusions: Plate placement and reduction positions, which are risk factors for flexor tendon ruptures after DRFs, have improved recently when compared with previous findings. With these changes, the rate of flexor tendon rupture is presumed to have decreased.

Impact of Soong grading on flexor tendon ruptures following palmar plating for distal radial fractures.

The purpose of this study was to evaluate flexor tendon injuries following palmar plating of distal radial fractures relative to the Soong grade. This retrospective cohort study included 113 patients who underwent palmar plate removal after a distal radial fracture between 2010 and 2016. In 13 patients, a greater than 50% injury of the flexor pollicis longus tendon was observed. Of these, nine patients were classified as Soong grade 2, four as Soong grade 1 and none as grade 0. The difference between the Soong groups was statistically significant (p = 0.006). Flexor tenosynovitis was present in eight patients (7%) and more likely in patients with a higher Soong grade (p = 0.026). We conclude that higher Soong grades are associated with significantly more flexor tendon complications. Therefore, elective removal of the palmar plate after union of the fracture should be considered in patients with Soong grades 1 and 2. Level of evidence: IV.

Intrarater and Interrater Reliability of the Soong Classification for Distal Radius Volar Locking Plate Placement.

Background: The purpose of this study was to analyze the intrarater and interrater reliability of the Soong classification for volar locking plate placement on a randomly selected, consecutive series of radiographs. Our hypothesis was that the classification would be reliable. Methods: Six physicians of differing levels of training (orthopedic surgery intern to fellowship-trained upper extremity staff) were asked to review 40 radiographs in a random order on 2 separate occasions, 4 weeks apart. All observers graded each image (0, 1, or 2) based on the corresponding Soong grade. A weighted κ was used to determine the intrarater agreement. The interrater agreement was determined using an intraclass coefficient: Results: The intrarater reliability using a weighted κ ranged from 0.229 (95% confidence interval [CI]: 0.048-0.411) to 0.946 (95% CI: 0.840-1.051). The interrater intraclass coefficient for Randomization 1 was 0.944 (95% 0.912-0.967) and Randomization 2 was 0.877 (95% CI: 0.797-0.930). Conclusion: The Soong classification is a reliable tool, both interrater and intrarater, for assessing distal radius volar locking plate placement. The classification system remained reliable despite a randomly selected, consecutive series of images and physician observers of varying levels of training.

Positioning of a Volar Locking Plate with a Central Flexor Pollicis Longus Tendon Notch in Distal Radius Fractures.

Background Volar locking plates with a central notch were designed to reduce the risk of flexor pollicis longus (FPL) tendon irritation after volar plating for distal radius fractures. Objective The purpose of this study was to evaluate the course of the FPL tendon after FPL-plate osteosynthesis to identify a plate position that avoids an impingement with the FPL tendon. Patients and Methods Nineteen patients treated with volar plating using an FPL plate for a distal radius fracture were evaluated. Transverse ultrasound images were used to assess whether the profile of the FPL tendon lied within the plate notch. The position of the FPL tendon on transverse ultrasound images was transferred onto postoperative dorsovolar X-ray images to define an FPL tendon corridor for a plate position not interfering with the FPL tendon. Results The FPL tendon was aligned inside the plate notch completely in three cases, partially in 11 cases, and missed the notch in five cases. An FPL corridor was defined at the level of the watershed line with all FPL tendons being completely (74%) or partially (26%) aligned inside that corridor. There was a moderate correlation between the plate notch being positioned inside this corridor and the FPL tendon being positioned inside the plate notch ( r = 0.49; p = 0.033). Conclusion It seems advantageous to place the plate notch within a corridor parallel to the radial shaft between the ulnar edge of the scaphoid tubercle and the scapholunate interval for the FPL tendon protection. Level of Evidence This is Level IV study.

Relationship between plate removal and Soong grading following surgery for fractured distal radius.

The aim of this study was to determine the relationship between volar plate removal and the Soong classification following fixation for fractured distal radius. In this retrospective cohort study, all consecutive patients who had volar plate fixation for a distal radius fracture in 2011-2015 were reviewed. Differences in Soong classification between patients who had plate removal and those who did not were analysed. The total incidence of plate removal was calculated and the indications analysed. A total of 323 patients were included. The incidence of plate removal in all patients was 17%. Soong classification was significantly higher in patients who had plate removal compared with those who did not. For patients with plate placement classified as Soong grade 2, the incidence of plate removal was almost six times higher than those classified as Soong grade 0. The relationship between volar plate removal and a higher Soong grading stresses the importance of accurate plate positioning. LEVEL OF EVIDENCE: IV.

Reliability of the Soong Classification for Volar Plate Position.

PURPOSE: The purpose of the present study was to assess the inter- and intraobserver reliability of the Soong classification system for volar plate position. Our hypothesis was that the Soong grade would be found to be reliable. METHODS: Four physicians (K.F.L., M.R., J.L.M., P.K.B.) were asked to classify lateral wrist radiographs of volar plated distal radius fractures based on the Soong classification on 3 separate occasions. Forty-six distal radius fractures fixed by volar plates were selected from a surgical image database at our institution. Radiographs were selected to ensure that each Soong grade was adequately represented. The physician observers in the current study were blinded to the previously assigned grade and to clinical information regarding the patient. RESULTS: Based upon the average grade of all 4 observers, 17 plates were Soong grade 0, 20 plates were Soong grade 1, and 9 plates were Soong grade 2. The intraobserver reliability among the 4 observers was 0.94 (95% confidence interval [CI], 0.96-0.89), 0.93 (95% CI, 0.96-0.90), 0. 91 (95% CI, 0.94-0.86), and 0.80 (95% CI, 0.87-0.71). The interobserver reliability was 0.78 (95% CI, 0.85-0.69). CONCLUSIONS: We found the Soong classification to be a reliable tool in assessing the degree of plate prominence. We continue to use the Soong classification system in describing volar plate position. CLINICAL RELEVANCE: The use of the Soong classification for determining volar plate prominence is reliable.