An in-vitro three-dimensional surgical simulation technique to predict tibial tunnel length in transtibial posterior cruciate ligament reconstruction.

BACKGROUND: During the transtibial posterior cruciate ligament (PCL) reconstruction, drilling depth excessively longer than the tibial tunnel length (TTL) is an important reason to cause popliteal neurovascular bundle injury when preparing the tibial tunnel. This study aims to develop an in-vitro three-dimensional surgical simulation technique to determine the TTL in anteromedial (AM) and anterolateral (AL) approaches. METHODS: A total of 63 knees' 3-dimensional (3D) computed tomography models were included in this study. The SuperImage system was used to reconstruct the 3D knee model and locate the tibial PCL site. The established 3D knee model and the coordinates of the tibial PCL site were imported into Rhinoceros 3D modeling software to simulate AM and AL tibial tunnel approaches with different tibial tunnel angles (TTA). The TTL and the tibial tunnel height (TTH) were measured in this study. RESULTS: In AM and AL tibial tunnel approaches, the TTL showed a strong correlation with the TTA (for AM: r = 0.758, p < 0.001; for AL: r = 0.727, p < 0.001). The best fit equation to calculate the TTL based on the TTA was Y = 1.04X + 14.96 for males in AM approach, Y = 0.93X + 17.76 for males in AL approach, Y = 0.92X + 14.4 for females in AM approach, and Y = 0.94X + 10.5 for females in AL approach. CONCLUSION: Marking the TTL on the guide pin or reamer could help to avoid the drill bit over-penetrated into the popliteal space to damage the neurovascular structure.

Accuracy of detecting burst of the lateral wall in intertrochanteric hip fractures with plain radiographs: Is postoperative CT necessary?

Background: Postoperative burst of the lateral femoral wall is thought to be the main predictor of reoperation for intertrochanteric fractures, which is routinely evaluated using plain radiographs. We retrospectively compared computed tomography (CT) scans and radiographs regarding the ability to detect burst of the lateral wall. We also investigated whether intramedullary nails may cause iatrogenic burst of the lateral wall. Methods: From January 2010 to December 2021, patients aged 65 years and older who undergone intertrochanteric fractures treated with the proximal femoral nail antirotation 2 (PFNA-Ⅱ) were included. The incidence of burst of the lateral wall was evaluated with two different imaging modalities by two observers. Two rounds of evaluation were performed: (1) with plain radiographs alone; and (2) with CT scans combined with radiographs. Interobserver and intraobserver agreement (κ value) for evaluation of the lateral wall burst was assessed. Results: A total of 1507 patients were included (362 males and 1145 females). Compared with radiographs alone (12.0 %, 181/1507 patients), a higher rate of lateral wall burst was found by CT scans combined with radiographs (72.9 %, 1098/1507 patients) for observer 1 at first reading (P < 0.001). Similar results were seen in other evaluations. Interobserver and intraobserver agreement was substantial for radiographs alone (κ, 0.659-0.727) and almost perfect for CT scans combined with radiographs (κ, 0.847-0.926). Conclusions: Computed tomography combined with radiographs is superior to radiographs alone for detecting burst of the lateral wall after intertrochanteric fracture fixation. Additionally, PFNA-Ⅱ could cause iatrogenic burst of the lateral wall for intertrochanteric fractures in the elderly.

Mercury pollution risks of agricultural soils and crops in mercury mining areas in Guizhou Province, China: effects of large mercury slag piles.

The historical large mercury slag piles still contain high concentrations of mercury and their impact on the surrounding environment has rarely been reported. In this study, three different agricultural areas [the area with untreated piles (PUT), the area with treated piles (PT), and the background area with no piles (NP)] were selected to investigate mercury slag piles pollution in the Tongren mercury mining area. The mercury concentrations of agricultural soils ranged from 0.42 to 155.00 mg/kg, determined by atomic fluorescence spectrometry of 146 soil samples; and mercury concentrations in local crops (rice, maize, pepper, eggplant, tomato and bean) all exceeded the Chinese food safety limits. Soil and crop pollution trends in the three areas were consistent as PUT > PT > NP, indicating that mercury slag piles have exacerbated pollution. Mercury in the slag piles was adsorbed by multiple pathways of transport into soils with high organic matter, which made the ecological risk of agricultural soils appear extremely high. The total hazard quotients for residents from ingesting mercury in these crops were unacceptable in all areas, and children were more likely to be harmed than adults. Compared to the PT area, treatment of slag piles in the PUT area may decrease mercury concentrations in paddy fields and dry fields by 46.02% and 70.36%; further decreasing health risks for adults and children by 47.06% and 79.90%. This study provided a scientific basis for the necessity of treating large slag piles in mercury mining areas.

Design of well-matched end-structure of anatomical proximal femoral locking plate based on computer-assisted imaging combined with 3D printing technology: a quality improvement study.

BACKGROUND: The extramedullary locking plate system was the common internal fixation method for hip fractures. However, common plates were poorly matched to femur, which was because they were designed based on anatomical parameters of the Western populations. Therefore, the aim was to design an end-structure of the anatomical proximal femoral locking plate that closely matched the anatomy of the Chinese population. MATERIALS AND METHODS: From January 2010 to December 2021, consecutive patients aged 18 years and older who underwent a full-length computed tomography scan of the femur were included. The end-structure (male and female model) of the anatomical proximal femoral locking plate was designed based on anatomical parameters of femurs that were measured in three-dimensional space using computer-assisted virtual technology. The match degree between the end-structure and femur were evaluated. Inter-observer and intra-observer agreement for the evaluation of match degree was assessed. The matching evaluation based on a three-dimensional printing model was regarded as the gold standard to assess the reliability. RESULTS: A total of 1672 patients were included, with 701 men and 971 women. Significant differences were seen between male and female for all parameters of the proximal femur (all P <0.001). All match degree of end-structure was over 90%. Inter-observer and intra-observer agreement was almost perfect (all kappa value, >0.81). The sensitivity, specificity, and percentage of correct interpretation of matching evaluation in the computer-assisted virtual model was all greater than 95%. From femur reconstruction to completion of internal fixation matching, the process takes about 3 min. Moreover, reconstruction, measurement, and matching were all completed in one system. CONCLUSIONS: The results showed that based on the larger sample of femoral anatomical parameters, a highly matching end-structure of anatomical proximal femoral locking plate for Chinese population could be designed with use of computer-assisted imaging technology.

Incorporating soil mercury species and fractions into multi-objective risk assessment of a residue disposal site in China.

Environmental problems in soil and water caused by solid waste dumps have become a growing concern. This study proposes an integrated risk assessment model aimed at multi-objectives including human, ecology and groundwater and develops remediation target values at different tiers associated with soil mercury species and fractions in a typical residue disposal site of China. The results show that the residue disposal site was severely contaminated with mercury, with the maximum mercury content in the soil reaching 579.14 mg/kg. The average concentration of vapour mercury, bioaccessible mercury, bioavailable mercury and leachable mercury tested in laboratory was 87.65 mg/kg, 3.15 mg/kg (intestinal phase), 1.654 mg/kg and 0.045 mg/L, respectively. The hazard index calculated using total mercury, bioaccessible mercury and vapour mercury was 7.43 E + 01, 4.42 E + 01, and the remediation target values were7.79 mg/kg and 13.1 mg/kg, respectively. The ecological risk for total mercury and bioavailable mercury was calculated using measured site soil mercury background values of 6390.92 and 94.52, and the remediation target was 0.7 mg/kg and 47.33 mg/kg, respectively. Under Class IV water conditions, the measured and three-phase equilibrium model simulations of leachable mercury resulted in remediation targets of 6 mg/kg and 10 mg/kg for soil mercury. Compared to total mercury, the remediation target values calculated using mercury species and fractions were significantly larger under human health protection, ecology protection and groundwater protection. This results in a reduction in the area of soil to be remediated by 20.3-85.7%, resulting in significant savings in remediation costs. It was concluded that when conducting risk assessment and reuse of mercury-contaminated sites, it is important to consider the species and fractions of mercury in the soil in order to reasonably determine the remediation criteria and scale of remediation to avoid over-remediation and incomplete remediation. At the same time, a comprehensive protection target remediation mechanism should be established by combining different receptors.

Characteristics, sources and risk assessments of heavy metal pollution in soils of typical chlor-alkali residue storage sites in northeastern China.

In this study, thirty-four soil samples from a typical chlor-alkali slag residue storage site near the city of Qiqihar in northeastern China were collected and their arsenic, cadmium, chromium, copper, mercury, nickel, lead and zinc concentrations were determined. Sources of these heavy metals were analyzed with a positive matrix factorization model, and the health risks associated with different pollution sources were calculated. The results showed that mercury was the main heavy metal pollutant at the site (maximum concentration of 112.19 mg.kg-1) and the soil was also contaminated with arsenic, copper and lead. The sources of eight heavy metals were: mixed oil refinery wastewater and parent material (arsenic, chromium, copper and lead), vinyl chloride waste source (mercury), parent material (cadmium, nickel and zinc). The average potential ecological risk of the soil was 22344.39, with vinyl chloride waste source contributing 99.85% of this risk. The average carcinogenic risk of a mixture of oil refinery wastewater and parent material for children and adults was 9.06×10-6 and 6.36×10-6, respectively, accounting for 99.9% (children) and 99.48% (adults) of the total average carcinogenic risk. The average hazard index of vinyl chloride waste source for children and adults was 0.6 and 0.38, respectively, which accounted for 64.13% (children) and 52.34% (adults) of the total hazard index. These results provide a reference for soil pollution risk assessments at this type of site.

Source Apportionment of Heavy Metals Based on Multiple Approaches for a Proposed Subway Line in the Southeast Industrial District of Beijing, China.

Apportioning the sources of heavy metals (HMs) in soil is of great importance for pollution control. A total of 64 soil samples from 13 sample points at depths of 0-21 m were collected along a proposed subway line in the southeast industrial district of Beijing. The concentrations, distribution characteristics, and sources of eight HMs were investigated. The results showed that the concentrations of Hg, Cd, Cu, Pb, As, and Zn in the topsoil (0-2 m) exceeded the Beijing soil background values. Three sources were identified and their respective contribution rates calculated for each of the HMs using multiple approaches, including correlation analysis (CA), top enrichment factor (TEF), principal component analysis (PCA), and positive matrix factor (PMF) methods. As (63.11%), Cr (61.67%), and Ni (70.80%) mainly originated from natural sources; Hg (97.0%) was dominated by fossil fuel combustion and atmospheric deposition sources; and Zn (72.80%), Pb (69.75%), Cu (65.36%) and Cd (53.08%) were related to traffic sources. Multiple approaches were demonstrated to be effective for HM source apportionment in soil, whilst the results using PMF were clearer and more complete. This work could provide evidence for the selection of reasonable methods to deal with soils excavated during subway construction, avoiding the over-remediation of the soils with heavy metals coming from natural sources.

Association of the lateral wall integrity with clinical outcomes in older patients with intertrochanteric hip fractures treated with the proximal femoral nail anti-rotation-Asia.

PURPOSE: The purpose of this study is to assess the role of the lateral wall in post-operative clinical outcomes in patients with intertrochanteric fractures treated with the proximal femoral nail anti-rotation-Asia (PFNA-II). METHODS: A cohort of 466 patients (OTA type 31A1 or A2) was divided into two groups: one was intact lateral wall group, and the other was fractured lateral wall group. Radiographic outcomes were measured by using the loss of neck-shaft angle (NSA), femoral neck shortening (FNS), and offset shortening (OS). Functional outcomes were assessed by using the Harris score and SF-36 Physical Component Summary (SF-36 PCS). Post-operative complications were recorded. RESULTS: The fractured lateral wall group had a greater loss of NSA (mean [SD], fractured group (8.7°) [2.7°] vs intact group (4.8°) [2.8°]; mean difference, 3.3° [95% CI 2.9 to 3.8]; P < 0.001) compared with the intact lateral wall group. Similar results were found for FNS and OS. The fractured lateral wall group had a worse Harris scores at the three month follow-up (mean [SD] score, fractured group (66.6) [5.2] points vs intact group (71.3) [5.8] points; mean difference, - 3.3 points [95% CI - 3.9 to - 2.7]; P < 0.001) compared with the intact lateral wall group. Similar results were observed for Harris scores at the three and 12-month follow-ups and SF-36 PCS at the three, six and 12-month follow-ups. The fractured lateral wall group had a higher risk of post-operative complications compared with the intact lateral wall group. CONCLUSION: Among older patients with intertrochanteric fractures, the fractured lateral wall was associated with worse clinical outcomes compared with the intact lateral wall. Clinicians should pay attention to the lateral wall integrity in patients with intertrochanteric fractures treated with the PFNA-II.

Anchoring Water Soluble Phosphotungstic Acid by Hybrid Fillers to Construct Three-Dimensional Proton Transport Networks.

Phosphotungstic acid (HPW)-filled composite proton exchange membranes possess high proton conductivity under low relative humidity (RH). However, the leaching of HPW limits their wide application. Herein, we propose a novel approach for anchoring water soluble phosphotungstic acid (HPW) by polydopamine (PDA) coated graphene oxide and halloysite nanotubes (DGO and DHNTs) in order to construct hybrid three-dimensional proton transport networks in a sulfonated poly(ether ether ketone) (SPEEK) membrane. The introduction of PDA on the surfaces of the hybrid fillers could provide hydroxyl groups and secondary amine groups to anchor HPW, resulting in the uniform dispersion of HPW in the SPEEK matrix. The SPEEK/DGO/DHNTs/HPW (90/5/5/60) composite membrane exhibited higher water uptake and much better conductivity than the SPEEK membrane at low relative humidity. The best conductivity reached wass 0.062 S cm-1 for the composite membrane, which is quite stable during the water immersion test.

Influence of Timing of Postoperative Weight-Bearing on Implant Failure Rate Among Older Patients With Intertrochanteric Hip Fractures: A Propensity Score Matching Cohort Study.

Introduction: The purpose of this study was to determine whether immediate weight-bearing as tolerated increased the risk of implant failure and decreased functional outcomes compared with restricted weight-bearing. Methods: From January 2010 to December 2018, 1,125 consecutive patients (≥65 years) with intertrochanteric fractures were identified. Of them, 130 patients were excluded, resulting in 995 patients in final cohort (563 receiving immediate weight-bearing and 432 receiving restricted weight-bearing). Propensity score (PS) matching yielded 403 patient pairs. Primary outcome was implant failure at 12 months. Secondary outcomes were implant failure at 3 months, functional outcomes at 12 months, and time to full weight-bearing. Results: Among 806 patients who were matched by PS, the mean age was 77.8 years (SD, 7.6), and 603 patients (74.8%) were women. After matching, there was no significant difference between immediate (10.0% [39/389]) and restricted (9.1%, [35/385]) weight-bearing for implant failure at 12 months (absolute risk difference, 0.93% [95% CI, -3.26 to 5.13%]; RR, 1.11 [95% CI, 0.69 to 1.80]; p = 0.66). Additionally, no significant difference was seen for implant failure at 3 months and functional outcomes at 12 months. Patients with immediate weight-bearing had shorter time to full weight-bearing (mean [SD], 87.6 days [7.5] vs. 121.3 days [11.0]; mean difference, -33.7 [95% CI, -35.0 to -32.3]; p < 0.001). Conclusions: Among older patients with intertrochanteric fractures, receipt of immediate weight-bearing as tolerated did not increase risks of implant failure or worsen functional outcomes compared with receipt of restricted weight-bearing. However, patients receiving immediate weight-bearing had a shorter time to full weight-bearing.

[Quantitative Assessment of Human Health Risks Based on Soil Heavy Metals and PAHs Sources:Take a Polluted Industrial Site of Beijing As an Example].

In this study, 130 surface soil samples were collected at an industrial pollution site in Beijing and the contents of As, Be, Cd, Cu, Cr, Hg, Ni, Pb, Sb, Ti, Zn, and 16 PAHs were determined. The positive matrix factorization (PMF) model was used to analyze the sources of heavy metals and PAHs, and the contributions of these sources to carcinogenic risk and hazard index in the study area were calculated. The results showed that the contents of Cd, Cu, Pb, Hg, As, Zn, and Cr in the soil exceeded the background values in different degrees; Cd, Hg, Pb, Zn, and Cu exceeded the background values by>50%. Low molecular weight PAHs (two and three rings) and high molecular weight PAHs (four to six rings) accounted for 39.6% and 60.4% of the total content of 16 PAHs. The PAH content at 77% of the sampling points at the target site was more than 1000 µg ·kg-1, which suggests severe PAH pollution at the site. Heavy metals Be, Ti, As, and Ni mainly originated from natural sources. There are three major sources of 7 heavy metals and 16 PAHs at the site: coal combustion (Hg and ∑16PAHs), smelting (Cu, Cr, Pb, and Zn), and traffic (Sb and Cd). The contribution rates of these sources to the total average contents of seven heavy metals and sixteen PAHs at 130 sampling sites were 8.46% (coal combustion), 90.61% (smelting), and 0.94% (traffic). Human health risk assessment results showed that the carcinogenic risk of seven heavy metals and ∑16PAHs ranged from 4.17×10-6 to 39.38×10-4, and the hazard index ranged from 0 to 32.23. The maximum carcinogenic risk and hazard index values were calculated near the coking plant. Benzo[α]pyrene was the PAH that posed the highest carcinogenic risk and Zn was the heavy metal that had the highest hazard index value. The average carcinogenic risk of coal combustion was 2.16×10-4, accounting for 50.26% of the total average carcinogenic risk. The average hazard index of smelting was 0.834, accounting for 56.43% of the total average non-carcinogenic risk. These two pollution sources are responsible for the high levels of heavy metals and PAHs in the soil of the steel smelting sites that pose the most severe health risks. The results of this study can provide reference for soil remediation and process optimization at other heavily polluted industrial sites.

Association of Computer-Assisted Virtual Preoperative Planning With Postoperative Mortality and Complications in Older Patients With Intertrochanteric Hip Fracture.

Importance: The outcomes of surgical treatment in patients with intertrochanteric hip fractures are unsatisfactory. Computer-assisted virtual preoperative planning may provide an opportunity to solve this treatment dilemma. Virtual preoperative planning is a technique based on dynamic 3-dimensional computed tomographic imaging, which allows precise evaluation of fracture details and simulation of reduction of fracture and internal fixation procedures before surgery is performed. Objective: To evaluate the association of computer-assisted virtual preoperative planning with the risk of 90-day all-cause mortality and postoperative complications. Design, Setting, and Participants: This retrospective cohort study was conducted from using patient data from a level 1 trauma center database. A total of 1445 patients 65 years and older with intertrochanteric hip fractures between January 1, 2009, and March 31, 2018, were identified and divided into 2 cohorts: 558 patients received computer-assisted virtual preoperative planning (virtual planning group), and 887 patients received conventional preoperative planning (conventional planning group). Of the initial 1445 patients, 224 patients (93 patients in the virtual planning group and 131 patients in the conventional planning group) were excluded, resulting in 1221 patients in the final cohort. Data were analyzed from April 5 to October 5, 2019. Exposures: Computer-assisted virtual vs conventional surgical preoperative planning. Main Outcomes and Measures: Primary outcomes were 90-day all-cause mortality and postoperative complications (including myocardial infarction, heart failure, stroke, kidney failure, and sepsis). Secondary outcomes were 90-day outpatient visits, hospital readmissions, and reoperations. Results: Among 1221 patients who underwent hip surgery, the mean (SD) age was 73.2 (12.3) years, and 927 patients (75.9%) were women. A total of 465 patients (38.1%) were in the virtual planning group and 756 patients (61.9%) were in the conventional planning group. Among the 814 patients (407 patients in each group) who were matched by propensity score, the virtual planning group had a lower incidence of mortality (37 patients [9.1%] vs 55 patients [13.5%]; hazard ratio [HR], 0.64; 95% CI, 0.41-0.99; P = .04) and postoperative complications (25 patients [6.1%] vs 44 patients [10.8%]; HR, 0.54; 95% CI, 0.32-0.90; P = .02) compared with the conventional planning group. The incidence of outpatient visits was not substantially different in the virtual planning group (1.51 incidents per 30 person-days) compared with the conventional planning group (1.48 incidents per 30 person-days; incidence rate ratio [IRR], 0.90; 95% CI, 0.49-1.68; P = .75). Similar results were observed for the rate of hospital readmissions (0.99 incidents per 30 person-days in the virtual planning group and 1.01 incidents per 30 person-days in the conventional planning group; IRR, 0.91; 95% CI, 0.49-1.67; P = .76). However, the rate of reoperations was lower in the virtual planning group (0.76 incidents per 30 person-days) than in the conventional planning group (0.97 incidents per 30 person-days; IRR, 0.41; 95% CI, 0.22-0.76; P = .01). Conclusions and Relevance: Among older patients with intertrochanteric hip fractures, computer-assisted virtual preoperative planning was associated with decreases in the risks of all-cause 90-day mortality, postoperative complications, and reoperations compared with conventional preoperative planning.

The accuracy of intra-operative fluoroscopy in evaluating the reduction quality of intertrochanteric hip fractures.

PURPOSE: To investigate the capability of intra-operative fluoroscopy to determine the reduction quality of intertrochanteric fractures and to determine which view (anteroposterior [AP] or lateral) can better predict the reduction quality. METHODS: A retrospective analysis of 128 patients with intertrochanteric fractures. Two observers were asked to independently evaluate the quality of reduction (positive or non-positive support) based on intra-operative fluoroscopy (AP and lateral view). Results based on CT scans were considered as the gold standard. Sensitivity, specificity, percentage of correct interpretations, and agreement were calculated. RESULTS: At the first reading, sensitivity, false-negative rate, specificity, false-positive rate, and percentage of correct interpretations were 86.1%, 13.9%, 69.4%, 30.6%, and 79.7% for junior resident and 81.0%, 19.0%, 67.3%, 32.7%, and 75.8% for senior resident (all p > 0.05). It was highly predictive of a reliable cortical support when cortical position in AP view was consistent with that in lateral view (85/85, 100% for junior, and 86/86, 100% for senior). Lateral view was generally predictive of a final cortical support when the position between AP and lateral view was inconsistent (90.7% [39/43] vs 9.3% [4/43] for junior, p < 0.001; 92.9% [39/42] vs 7.1% [3/42] for senior). Comparable results were reported at the second reading. The average inter-observer and intra-observer agreement was 0.670 and 0.654, respectively. CONCLUSIONS: We should ensure the cortical support for both AP and lateral view are positive intra-operatively as far as possible. Even if this is not possible, we need to make sure the lateral position is positive support.

Computational Biomechanical Analysis of Postoperative Calcaneal Fractures with Different Placement of the Sustentaculum Screw.

OBJECTIVE: To evaluate the computational biomechanical analysis of intra-articular calcaneal fractures with different fixation status of the sustentaculum plate screw, when the finite element modeling of calcaneal fractures were fixed by the lateral locking plate. METHODS: The normal right foot of a male (age: 36 years; height: 174 cm; body weight: 65 kg) was scanned by the CT scanner. As the computational biomechanical study, the three-dimensional finite element model of the simplified Sanders type-II calcaneal fracture was built. Fixation with the lateral calcaneal locking plate and screws was simulated using a finite element software package according to clinical operation. According to the different placement of the sustentaculum plate screw, the models were categorized as the accurate fixation group, marginal fixation group, and non-fixation group. The loading of 650 N with the vertical axial compression was applied to simulate the standing phase with single foot. The Von Mises stress distribution, maximal displacement, and contact area of the subtalar joint were analyzed among three groups. RESULTS: The pressure distribution of the subtalar joint facet was inhomogeneous. The stress concentration of the calcaneus was located at the medial zone of the posterior subtalar joint facet. The peak Von Mises stress distribution in three groups was similar at the subtalar joint facet of 4.9 MPa, 5.1 MPa, and 5.4 MPa. In the accurate fixation group, the contact area on the posterior articular facet was 277.1 mm2 ; the maximal displacement was 0.18 mm. The contact area of the marginal fixation group was 265.3 mm2 on the posterior facet, where the maximal displacement was 0.23 mm. In the non-fixation group, the contact area was 253.8 mm2 ; the maximal displacement was 0.25 mm. There was a slight change in the contact area of the subtalar joint and no prominent displacement of the calcaneus could be detected among the three groups. CONCLUSIONS: The biomechanical results, including the peak stress distribution, contact area, and maximal displacement of subtalar joint, were similar whether the screw is placed exactly within the sustentaculum tali or not, when the calcaneal fractures were fixed by the lateral locking plate. The sustentaculum plate screw had less effect on the biomechanical performance of the calcaneus.

Quantitative Evaluation of Articular Involvement of Posterior Malleolus Associated with Operative Indication: A Comparative Study of Six Methods Based on Radiography and CT.

The aim of this study was to compare the values of six methods in measuring the involvement of posterior malleolus and to demonstrate the reliability and reproducibility of each method. Three independent orthopaedic surgeons, retrospectively, measured 106 cases. The difference between the six methods was analyzed using Bonferroni-corrected paired t-tests after one-way ANOVA. The agreement between the six methods was analyzed using Bland-Altman analysis. The intraclass correlation coefficient (ICC) was used to assess intraobserver reproducibility and interobserver reliability. Significant differences were observed between values of any two of the six measurement methods (P < 0.0033), except between any two of the plane radiograph linear, axial CT linear, sagittal CT linear, and 3D CT linear. The Bland-Altman plots demonstrated poor agreement between values of any two of the six methods. The lowest intraobserver reproducibility was 0.46 (moderate) for resident surgeon using plain radiographs. The intraobserver reproducibility for three surgeons using two-dimensional (2D) and 3D images was almost perfect (ICC, 0.82-0.96). The lowest interobserver reliability was 0.41 (moderate) between chief and attending surgeon using plain radiographs, and it improved to almost perfect (ICC, 0.81-0.95) with the use of 3D CT images. The standard error of measurement showed almost the same results as ICC values. The existing operative indications which were determined based on plain radiography are neither reliable nor suitable for other measurement methods. Both 3D linear and 3D surface measurement methods are reliable and reproducible in measuring posterior fragment involvement, and experience is not so crucial. Operative indications for posterior malleolar fractures need to be redefined based on the 3D measurement method.

Computer-assisted preoperative planning improves the learning curve of PFNA-II in the treatment of intertrochanteric femoral fractures.

BACKGROUND: Intertrochanteric femoral fractures are prevalent among the elderly, and usually demands surgical treatments. Proximal femoral nail antirotation Asian version (PFNA-II) is widely used for intertrochanteric fracture treatment. The computer-assisted preoperative planning (CAPP) system has the potential to reduce the difficulty of PFNA-II in the treatment of intertrochanteric fractures. The aim of the study was to investigate and compare the learning curves of PFNA-II treatment with CAPP and conventional preoperational planning methods for intertrochanteric femoral fractures. METHODS: A total of 125 patients with intertrochanteric fracture who were treated with PFNA-II between March 2012 and June 2015 were retrospectively analyzed. Patients who underwent surgery with CAPP procedure by a junior surgeon were regarded as group A (n = 53); patients who underwent the conventional surgery by another junior surgeon were regarded as group B (n = 72). Each group was divided into three subgroups (case 1-20, case 21-40, case 41-53 or case 41-72). RESULTS: The average operation time of group A was 45.00(42.00, 50.00) minutes, and in group B was 55.00 (50.00, 60.00) minutes (P < 0.01). Average radiation frequency and blood loss were 13.02 ± 2.32, 160.00 (140.00, 170.00) ml and 20.92 ± 3.27, 250.00 (195.00, 279.50) ml, respectively, with significant differences (P < 0.01). The learning curve of the surgical procedure in group A was steeper than that in group B. There were no significant differences in patient reported outcomes, hospital stay and complication rate between the two groups. Significant differences were observed between group A and B in Harris score at last follow-up in the AO/OTA type 31-A2 intertrochanteric fracture (P < 0.05). CONCLUSION: Compared with conventional preoperative planning methods, CAPP system significantly reduced operation time, radiation frequency and blood loss, thus reshaped the learning curve of PFNA-II treatment with lower learning difficulty. TRIAL REGISTRATION: researchregistry4770. Registered 25 March 2019.

Heavy metal pollution and human health risk assessment at mercury smelting sites in Wanshan district of Guizhou Province, China.

The Wanshan district of Guizhou Province has a long history of mercury mining and smelting. Previous studies have been carried out on heavy metal (HM) pollution in the soil around Wanshan (such as in urban and farmland areas), but these studies have not been conducted at mercury smelting sites. In this study, the distribution characteristics of As, Be, Cd, Cr, Cu, Hg, Ni, Sb, Pb and Zn and their sources in the shallow stratum (<10 m) of the mercury smelting site in the Wanshan district were analyzed. Human health risks were evaluated using deterministic risk assessment (DRA) and probabilistic risk assessment (PRA) models. The contribution rates of different HM sources to human health risks were also calculated. The maximum HM concentration in mercury smelting site soil occured in the shallow soil (0-1 m), and the concentration sequences were as follows: 358.51 mg kg-1 (Hg) > 248.6 mg kg-1 (Zn) > 67.42 mg kg-1 (As) > 59.04 mg kg-1 (Ni) > 57.56 mg kg-1 (Pb) > 49.59 mg kg-1 (Cr) > 46.65 mg kg-1 (Sb) > 15.65 mg kg-1 (Cu) > 2.02 mg kg-1 (Be) > 0.78 mg kg-1 (Cd). The variable coefficients (CVs) were 1.64 (As), 0.67 (Be), 3.15 (Cd), 1.89 (Cr), 0.95 (Cu), 3.08 (Hg), 0.79 (Ni), 1.41 (Sb), 0.68 (Pb) and 1.13 (Zn), respectively. The HM concentrations in deep soils (9 m) still exceed the local background values, suggesting that heavy metals in shallow soil have migrated downward in the site. Three pollution sources identified with the shallow soil (0-1 m) HMs using the positive matrix factorization (PMF) model, were mercury smelting and coal combustion mixed sources (As, Hg and Zn), parent material sources (Ni, Cu, Cr, Cd and Sb) and wastewater discharge sources (Cu and Pb), respectively. DRA indicated that oral ingestion was the main pathway affecting the carcinogenic risk (CR) and hazard quotient (HQ) of heavy metals. The total-CR of twenty-five sampling points is between 1.219 × 10-6 and 3.446 × 10-4, and the total-HQ is between 0.37 and 43.56. PRA results indicated that DRA will underestimate the health risk of all populations in Guizhou Province, especially female, and BWa is the most influential variable for the PRA results. Smelting and coal combustion mixed sources contributed the most CR (99.29%) and with an HQ of 89.38% were the major sources of pollution affecting human health.

Evaluation of the computer-assisted virtual surgical technology in preoperative planning for distal femoral fracture.

BACKGROUND: The application of computer-assisted virtual surgical technology in preoperative planning for distal femoral fractures has been rarely presented. This study aimed to evaluate the intra-operative realization of this technology and the clinical outcomes based on it for distal femoral fractures. METHODS: Between February 2014 and May 2017, 32 patients with distal femoral fractures treated by open reduction and internal fixation were included and divided into 2 groups on the basis of preoperative planning methods: conventional (N = 17) and virtual surgical (N = 15). The time required for virtual segmentation, reduction, and fixation of the fracture fragments in virtual surgical group were analyzed. Operation time, intra-operative blood loss, times of fluoroscopy during operation and days of hospital stay in two groups were compared. Postoperative functional outcomes were assessed using the Knee Society Score (KSS), Short Form-36 (SF-36) scoring systems, and visual analogue scale (VAS) for pain. RESULTS: Mean total planning time for 33-A, 33-B, and 33-C fractures in virtual surgical group were 43.0 ±â€¯1.7, 23.0 ±â€¯1.3, and 51.4 ±â€¯3.7 min, respectively. Compared with the conventional group, Patients in virtual surgical group had lower blood loss, fewer fluoroscopic images, less operative time, and shorter days of hospital stay (P < 0.05). No significant difference could detected in the KSS, SF-36, or VAS scores between the two groups at the final follow-up (P > 0.05). CONCLUSIONS: Computer-assisted virtual surgical technology could rapidly complete surgical treatment protocol, improve operative efficiency, and provide satisfying clinical and radiographic outcomes for distal femoral fractures.

The influence of selective arthrodesis on three-dimensional range of motion of hindfoot joint: A cadaveric study.

BACKGROUND: The purpose of this study was to measure the three-dimensional range of motion of adjacent, unfused joint or joints after different arthrodesis of hindfoot. METHODS: Sixteen fresh frozen cadaver feet were immobilized in the non-weight bearing position. The three-dimensional coordinates of markers in tarsal were measured in six directions (involving dorsiflexion-plantarflexion, eversion-inversion, and adduction-abduction) before and after single (involving subtalar joint, talonavicular joint, and calcaneocuboid joint) and double (talonavicular and calcaneocuboid joints) arthrodesis with a three-dimensional coordinate instrument. The range of motion of the joint was calculated with the least square method and matrix transformation. FINDINGS: We found that the range of motion of joints in all direction was reduced significantly after any combination of selective arthrodesis (all p < 0.001). After arthrodesis of the subtalar joint, the motion of talonavicular joint was reduced by 72%, and that of calcaneocuboid joint by 36%. After arthrodesis of talonavicular joint, the motion of subtalar joint was diminished by 36%, and that of calcaneocuboid joint by 51%. After arthrodesis of calcaneocuboid joint, the motion of subtalar joint was decreased by 21%, and that of talonavicular joint by 42%. After double arthrodesis, the motion of subtalar joint was reduced by 62%. INTERPRETATION: In single arthrodesis, subtalar arthrodesis had the greatest effect on the motion of unfused joints, and the least was the calcaneocuboid arthrodesis. The motion of the subtalar joint was eliminated more than half after double arthrodesis. The data provide a biomechanical rationale to ascertain the clinical implication of the arthrodesis.

Computer-assisted virtual surgical technology in pre-operative design for the reconstruction of calcaneal fracture malunion.

PURPOSE: No computer-assisted pre-operative design for calcaneal fracture malunions has been presented. The aim of the study is to evaluate the intra-operative realization of computer-assisted pre-operative planning (CAPP) and the clinical outcomes based on computer-assisted virtual surgical technology for calcaneal malunions. METHODS: Between 2010 and 2016, 20 patients with 21 calcaneal fracture malunions were retrospectively reviewed with the average follow-up time of 22.3 months (range, 12 to 43 months), which were operatively treated with the help of CAPP. The CAPP steps included the image segmentation, exostectomy of lateral wall, simulated reconstruction of calcaneal thalamus, morphological evaluation, and the implantation of internal fixation devices. Post-operative outcomes were assessed with the American Orthopaedic Foot and Ankle Society (AOFAS) score, SF-36 physical component summary (PCS), VAS for pain, range of motion of ankle, and the morphological parameters of the calcaneus including the axial length of the calcaneus, the height of the posterior facet, the talocalcaneal angle, Böhler's angle, and Gissane's angle. RESULTS: The mean time required for CAPP was 41.8 minutes. All the surgical processes were carried out according to CAPP. Six patients (6 feet) were treated with the joint-preserving osteotomy. Fourteen patients (15 feet) underwent the subtalar distraction bone block arthrodesis, among which the medial displacement calcaneal osteotomy was additionally performed in six patients (6 feet). At the final follow-up, the average AOFAS, SF-36 PCS, and VAS scores were significantly improved to 77.4, 64.3, and 1.4, respectively (P < 0.001). The postoperative calcaneal morphological parameters and the range of motion of ankle were significantly restored (P < 0.05). CONCLUSION: CAPP can assist surgeons in understanding calcaneal malunions, thereby improving intraoperative correction and reconstruction. The satisfying clinical and radiographic outcomes could be provided after treating calcaneal malunions aided by the computer-assisted virtual surgical technology.