[Three-dimensional printing combined with distal humeral osteotomy for cubital varus deformity in children].

OBJECTIVE: To explore clinical effect of three-dimensional(3D) printing combined with distal humerus osteotomy for children with cubital varus deformity. METHODS: From January 2017 to January 2020, 17 cubital varus deformity children treated with distal humerus osteotomy were retrospective analysis, included 11 boys and 6 girls, aged from 5 to 11 years old with an average of (7.8±1.7) years old. A model of affected side elbow joint was made by 3D printing technique before operation, pre-operation was performed on the model. Three-dimensional model was successfully used for distal humeral osteotomy during operation. Carrying angle, flexion and extension angle of elbow joint were compared before and six months after operation, and Flynn scoring criteria was used to evaluate clinical effect. RESULTS: All children were followed up for 6 to 12 months with an avergae of (9.6±1.7) months. One child occurred wound infection and healed completely after dressing change. No complications such as nonunion, internal fixation and nerve injury occurred. Carrying angle of affected limb was improved from (-20.8±2.4)°before operation to (7.2±2.3)°at 6 months after operation (P<0.01). Angle of affected elbow joint extension improved from (-5.6±3.9)° before opeation to(-2.6±2.1)°at 6 months after operation (P<0.01). There was no significant difference in extension angle of elbow joint between preopertaion and postopertaion at 6 months (P>0.05). While there was no difference in elbow joint function on the healthy side and affected side at 6 months after opertaion (P>0.05). According to Flynn scoring criteria, 13 patients got excllent results and 4 moderate. CONCLUSION: Three-dimensional printing combined with distal humerus osteotomy in treating elbow varus deformity could receive satisfactory clinical effect, which could accurately assist correction of cubital varus deformity, restore physiological structure and function of elbow joint.

Effect of 3D Printing Technology in Proximal Femoral Osteotomy in Children with Developmental Dysplasia of the Hip.

OBJECTIVE: To investigate the effect and safety of 3D printing technology in proximal femoral osteotomy in children with developmental dysplasia of the hip. METHODS: 40 cases of children with developmental dysplasia of the hip treated by pelvic osteotomy combined with proximal femoral osteotomy at Ningbo No. 6 Hospital from January 2017 to December 2019 were retrieved and retrospectively analyzed. Among them, 20 cases received preoperative measurement and design assisted by 3D printing technology (the 3D printing group), and 20 cases received conventional preoperative measurement and design (the conventional group). RESULTS: All patients were followed up for an average of 25 (12~36) months. During the follow-up, there were no complications such as infection, fracture of internal fixation, or malunion of osteotomy. Compared with the conventional group, the 3D printing group had a shorter operation time, less intraoperative blood loss, and fewer intraoperative X-ray fluoroscopies (all p < 0.05). In the last follow-up, the clinical efficacy was evaluated by the McKay standard: in the 3D printing group, 14 cases were excellent, 5 cases were good, and 1 case was fair. In the conventional group, 10 cases were excellent, 9 cases were good, and 1 case was fair (Z = -0.382, p > 0.05). CONCLUSION: Preoperative 3D printing of bilateral femur and other large physical models is accurate, which is ideal for the development of individual preoperative planning. Proximal femoral osteotomy using preoperative measurements and simulated surgical data improves the safety of the operation.

[Nomograma prediction of the surgical treatment in triad of elbow].

OBJECTIVE: To establish an individualized Nomogram prediction model for predicting the postoperative recovery of patients with triad of elbow (TE) by analyzing risk factors of triad of elbow joint. METHODS: From January 2012 to December 2018, 116 patients with TE who met the criteria were collected. The independent risk factors were screened by univariate Logistic regression analysis. The statistically significant risk factors were included in the multivariate Logistic regression model. The R software was used to establish the Nomogram diagram model to predict the postoperative recovery of TE patients. C index was used to verify the discrimination, Calibration plot of the model, and the decision curve (decision curve analysis, DCA) to verify the net clinical benefit rate of the model. RESULTS: Forty-four of the 116 patients with TE developed symptoms after operation, with an incidence of 37.93%. Age (OR=1.930, 95% CI 1.418 to 2.764), work (OR=6.153, 95%CI 1.466 to 31.362), smoking(OR=4.463, 95%CI 1.041 to 2.291), the Mason of radial head(OR=1.348, 95%CI 2.309 to 9.348), the Regan-Morrey of coronal process (OR=4.424, 95%CI 1.751 to 2.426) and postoperative elbow immobilization time(OR=7.665, 95%CI 1.056 to 5.100) were independent risk factors for postoperative recovery of TE (P<0.05). The C-index of Nomogram plot was 0.716. Calibration plot showed that the predictive model was consistent, and the DCA curve showed satisfactory clinical net benefit. CONCLUSION: The Nomogram for predicting postoperative results of TE patients based on six independent risk factors:age, work, smoking, Mason classification of radial head, Regan-Morrey classification of coronal process and immobilization time of elbow joint after operation, has good distinguishing capacity and consistency. Thepredictive model could help clinicians to identify high risk population and establish appropriate intervention strategies.

[Measurement of femoral neck anteversion of developmental dislocation of hip in children by 3D printing technique].

OBJECTIVE: To explore the method and accuracy of measuring the femoral neck anteversion in children with developmental dislocation of the hip by using 3D printing technology, so as to find out the method of measuring the femoral neck anteversion accurately and guide the formulation of the operation plan. METHODS: From June 2016 to September 2018, 17 patients with unilateral developmental dislocation of the hip were enrolled in the study, including 2 males and 15 females, aged 2 to 13 (5.47±0.81) years old, 11 on the left and 6 on the right. The methods of CT, 3D printing and intraoperative anteversion of femoral neck were used to measure the anteversion of femoral neck respectively. The intraoperative measurement was used as the standard reference value forstatistical analysis, and the accuracy of the first two methods was compared. RESULTS: The average value of CT was (36.00±1.66)°, the average value of model method was(43.91±1.62)°, and the average value of intraoperative method was(44.21±1.62)°. There were significant differences in CT measurement, model measurement and intraoperative measurement(P<0.05). There was no significant difference between model method and intraoperative method (P>0.05). CONCLUSION: Compared with the traditional CT method, the 3D printing model method is simpler, more accurate and more repeatable, and can simulate the operation before operation. It is an ideal method to measure the femoral neck anteversion.

[Experimental study on internal fixation with screws through femoral epiphyseal plate].

OBJECTIVE: To explore the effect of internal fixation with screw through femoral epiphyseal plate on growth in- hibition via an experimental study. METHODS: Forty New Zealand rabbits were randomly divided into 4 groups and 10 rabbits in each group. Epiphyseal plate was injured by penetrating of screws, and the size of damage area was controlled by changing the number of threads. Group A: blank group; group B: injury area accounted for 4% of the epiphyseal plate; group C: injury area accounted for 6%; group D: injury area accounted for 8%. The internal fixation was removed after 2 weeks, and the results were observed with X-ray film for 4 groups to judge the complications such as early closure of epiphyseal. RESULTS: In each group, there were no statistical differences in the length of the femoral neck, the diameter of femoral neck, the diameter of the femoral head, and the epiphyseal plate closure time. The growth speed of the length and diameter of the femoral neck, as well as the diameter of femoral head, were quicker on the early phase, and the speed was slowest when the epiphyseal plate was being closed. CONCLUSION: The injury area of epiphyseal plate under 8% is safe for its growth. Because no evidences demonstrate the growth inhibition of epiphyseal plate, the screws can be used for rabbit epiphyseal plates.

[Treatment of radial neck fracture in children with elastic stable intramedullary nails].

OBJECTIVE: To investigate effects of elastic stable intramedullary nails for the treatment of radial neck fracture in children. METHODS: From July 2006 to December 2011, 25 children with radical neck fractures, which included 16 males and 9 females aged from 7 to 15 years old (means 10.7), were treated with elastic stable intramedullary nails. According to Judet classification, 6 cases were type II, 17 cases were type III and 2 cases were type IV (including 1 case with type IVa and 1 case with type IVb). The fracture healing, pain, deformity and range of motion of elbow were recorded. RESULTS: All patients were followed up for 6 to 24 months with an average of 14 months. Twenty-five patients were obtained bone healing. According to Tibone and Stoltz evaluation standard, 18 cases got excellet results, 4 cases in good and 3 cases in moderate. CONCLUSION: Elastic stable intramedullary nails for the treatment of radial neck fracture in children has advantages of simple operation,less trauma and good results.

[Anatomic study of the posterior laminar screw fixation on C7].

OBJECTIVE: To measure anatomic data of laminar of C7 and evaluate the possibility of the placement of C7 laminar screw. METHODS: Twenty-two specimens of C7 were measured with an vernier caliper and a goniomete and finded out the anatomic data for prominent vertebra laminar screw placement. The indicators included the thickness of the superior, median and inferior part of C7 laminar (T1, T2, T3), the height of the laminar(H), the distance of the anchor point to the medial wall of C7 pedicle and the lateral wall of the lateral mass (L1, L2) and the angle between the axis of C7 lamina and sagittal plane(alpha). RESULTS: The mean thickness of superior part of C7 lamina (T1) was (4.30 +/- 0.27) mm, (5.32 +/- 0.27) mm in median part (T2) with 27% (6 cases) of specimens thickness less than 4.50 mm and (4.78 +/- 0.26) mm in inferior part (T3). Both median part and inferior part were thicker than 4.50 mm. The mean height of C7 laminar (H) was (14.83 +/- 0.26) mm. The distance from the laminar anchor point to the medial wall of C7 pedicle (L1) and the lateral wall of the lateral mass (L2) was (26.99 +/- 0.48) mm and (41.60 +/- 1.10) mm respectively. The mean angle between the axis of C7 laminar and sagittal plane(alpha) was (49.3 +/- 1.1) degrees. CONCLUSION: It is feasible to place screw in C7 laminar and this technique can be applied in 73% of Chinese. Compared with C7 pedicle screw technique, this technique is simple with little risk to the nerve and vascular structures.

[Comparison of two approaches for the treatment of supracondylar fractures in children by K-wires].

OBJECTIVE: To explore the clinical effect between two approaches for the treatment of supracondylar fractures of humerus by K-wires in children. METHODS: From Jan. 2004 to Dec. 2006,117 children with supracondylar fractures of humerus were divided into two groups according to different methods of the K-wires fixation involving two K-wires group and three K-wires group. In two K-wires groups,there were 45 children including 31 boys and 14 girls with an average age of 5.6 years ranging from 1 to 11 years; according to Garland classification, 19 cases were type II, 26 cases were type III. In three K-wires groups, there were 72 children including 47 boys and 25 girls with an average age of 6.8 years ranging from 2 to 12 years; according to Garland classification, 22 cases were type II, 50 cases were type II. The movement and carrying angle of elbow joint were measured for all these patients. According to Flynn criteria for supracondylar fracture the results of two approaches with K-wires were compared. RESULTS: All patients were followed-up from 2 to 24 months (means 15.4 months). In two K-wires group, the results of Flynn were excellent in 27 cases, good in 12 cases, fair in 4 cases and poor in 2 cases, 41 cases gained bony healing, however, fail of fixation arosed in 4 cases and cubitus varus arosed in 2 cases. In three K-wires group, the results of Flynn were excellent in 60 cases, good in 11 cases and poor in 1 case, all cases of three K-wires group achieved bony healing after 6 weeks of operation, the function of joints recovered through exercise and cubitus varus arosed in one case after operation. CONCLUSION: The technique of fixation with K-wires is a stable and reliable methods for unstable supracondylar fracture but medial-lateral three-pin fixation is better than one with two pins.

[Analysis on complications of elastic nail treating children's long bone fractures].

OBJECTIVE: To analyze the reasons on complications of treatment with elastic nail in children's long bone fracture. METHODS: Sixty-six cases (75 parts of long bone fratures) were treated by elastic nail including 49 male and 17 female. The age ranged from 3 to 17 years, mean 7.8 years. There were 35 femur fractures (2 cases were hibateral), 20 tibia and fibula fractures (12 cases were tibia fractures), 8 radial fractures (1 case was ulna fracture) and 3 humerus fractures. The cases included 4 open fractures and 62 closed fractures. All cases were fresh fractures, no multi-segmental fractures. Three cases associated with brain and chest injuries. These cases were treated by open or closed reduction and internal fixaion with elastic nail. A cast or brace had been used after operation for a month. Following-up included the function of the joint,the bottom of the nail and the callus. Complications were timely recorded. RESULTS: All the patients were followed-up for 12 to 29 months, averaged 17 months. The cases occurrenced compilications including 2 cases of nonunion, 2 of new fracture, 1 of displacment, 4 of joint dysfunction, 3 of irritation of the bottom of the nail and 1 malunion. CONCLUSION: Strict indication, well design,canonical operation is a good way to avoid compliacations. At the same time,early treatment can reduce the sequela.

[The therapeutic strategy of humeral supracondylar fracture with never injury in children].

OBJECTIVE: To determine the clinical features and therapeutic strategy of humeral supracondylar fractures with nerve injuries in children. METHODS: From June 2000 to December 2006,28 patients of humeral supracondylar fracture (Gartlang III) with never injuries were analyzed. Twenty-four patients were close injuries and the others were open. Sixteen cases (group A)were treated with close reduction and K-wires fixation. Twelve cases (group B)were treated with open reduction and nerve exploration, among them, contusive nerve injuries in 8 cases, incarceration in 3, complete neurotmesis in 1. RESULTS: The symptoms of nerve injuries of 28 cases recovered completely within 4 to 6 weeks in 13 cases, 8 to 10 weeks in 2 cases and 12 weeks in 1 case in group A, meanwhile, within 4 to 6 weeks in 6 cases, 8 to 10 weeks in 3 cases and 12 to 16 weeks in 3 cases in group B. CONCLUSION: Most nerve injuries in humeral supracondylar fractures in children can be cured after close reduction of the fracture. Sometimes, open reduction and nerve exploration are necessary, which has important practical significance.

Gasification characteristics of MSW and an ANN prediction model.

Gasification characteristics make up the important parts of municipal solid waste (MSW) gasification and melting technology. These characteristics are closely related to the composition of MSW, which alters with climates and seasons. It is important to find a practical way to predict gasification characteristics. In this paper, five typical kinds of organic components (wood, paper, kitchen garbage, plastic, and textile) and three representative types of simulated MSW are gasified in a fluidized-bed at 400-800 degrees C with the equivalence ratio (ER) in the range of 0.2-0.6. The lower heating value (LHV) of gas, gasification products, and gas yield are reported. The results indicate that gasification characteristics are different from sample to sample. Based on the experimental data, an artificial neural networks (ANN) model is developed to predict gasification characteristics. The training and validating relative errors are within +/-15% and +/-20%, respectively, and predicting relative errors of an industrial sample are below +/-25%. This indicates that it is acceptable to predict gasification characteristics via ANN model.

[Prevention of ulnar nerve injury during fixation of supracondylar fractures in children by a medial-lateral three-pin fixation technique].

OBJECTIVE: To expore the prevention of ulnar nerve injury during fixation of supracondylar fracture in children by a medial-lateral three-pin fixation technique. METHODS: Eighty-one patients including 54 boys and 27 girls with average age of 6 years old (2.5 to 11 years)were treated by a three-pin fixation technique with insertion of two Kirscher wires from the lateral side and the third wire through the medial side. They were followed-up without any complications related to the ulnar nerve. According to Garland system, there were 25 cases of type II supracondylar fracture and 56 of type III. All patients were treated by a medial-lateral three-pin fixation technique, and external fixation with plaster for 3 weeks. RESULTS: All cases achieved immediate stability and long-term bony fusion postoperatively and no iatrogenic ulnar nerve injury happen. CONCLUSION: The technique is a stable and reliable methods for unstable supracondylar fracture and the iatrogenic injury ulnar nerve can be avoided completely.

Experimental study on MSW gasification and melting technology.

In order to develop municipal solid waste (MSW) gasification and melting technology, two preliminary experiments and a principle integrated experiment were fulfilled respectively. The gasification characteristics of MSW were studied at 500-750 degrees C when equivalence ratio (ER) was 0.2-0.5 using a fluidized-bed gasifier. When temperature was 550-700 degrees C and ER was 0.2-0.4, low heat value (LHV) of syngas reaches 4000-12000 kJ/Nm3. The melting characteristics of fly ash were investigated at 1100-1460 degrees C using a fixed-bed furnace. It was proved that over 99.9% of dioxins could be decomposed and most heavy-metals could be solidified when temperature was 1100-1300 degrees C. The principle integrated experiment was carried out in a fluidized-bed gasification and swirl-melting system. MSW was gasified efficiently at 550-650 degrees C, swirl-melting furnace maintains at 1200-1300 degrees C stably and over 95% of fly ash could be caught by the swirl-melting furnace. The results provided much practical experience and basic data to develop MSW gasification and melting technology.

Investigation of polycyclic aromatic hydrocarbons from coal gasification.

The hazardous organic pollutants generated from coal gasification, such as polycyclic aromatic hydrocarbons(PAHs), are highly mutagenic and carcinogenic. More researchers have paid particular attention to them. Using air and steam as gasification medium, the experiments of three kinds of coals were carried out in a bench-scale atmospheric fluidized bed gasifier. The contents of the 16 PAHs specified by US EPA in raw coal, slag, bag house coke, cyclone coke and gas were measured by HPLC to study the contents of PAHs in raw coal and the effects of the inherent characters of coals on the formation and release of PAHs in coal gasification. The experimental results showed that the distributions of PAHs in the gasified products are similar to raw coals and the total-PAHs content in coal gasification is higher than in raw coal(except Coal C). The total-PAHs contents increase and then decrease with the rise of fixed carbon and sulfur of coal while there has an opposite variation when volatile matters content increase. The quantities of PAHs reduce with the increase of ash content or the drop of heating value during coal gasification.

Experimental study on the removal of PAHs using in-duct activated carbon injection.

This paper presents the incineration tests of municipal solid waste (MSW) in a fluidized bed and the adsorption of activated carbon (AC) on polycyclic aromatic hydrocarbons (PAHs). An extraction and high performance liquid chromatography (HPLC) technique was used to analyze the concentrations of the 16 US EPA specified PAHs contained in raw MSW, flue gas, fly ash, and bottom ash. The aim of this work was to decide the influence of AC on the distribution of PAHs during the incineration of MSW. Experimental researches show that there were a few PAHs in MSW and bottom ash. With the increase of AC feeding rate, the concentrations of three- to six-ring PAHs in fly ash increased, and the concentration of two-ring PAH decreased. The total-PAHs in flue gas were dominated by three-, and four-ring PAHs, but a few two-, five-ring PAHs and no six-ring PAHs were found. PAHs could be removed effectively from flue gas by using in-duct AC injection and the removal efficiencies of PAHs were about 76-91%. In addition, the total toxic equivalent (TEQ) concentrations of PAH in raw MSW, bottom ash, fly ash, and flue gas were 1.24 mg TEQ kg-1, 0.25 mg TEQ kg-1, 6.89-9.67 mg TEQ kg-1, and 0.36-1.50 microg TEQ Nm-3, respectively.

Occurrence and volatility of several trace elements in pulverized coal boiler.

The contents of eight trace elements(Mn, Cr, Pb, As, Se, Zn, Cd, Hg) in raw coal, bottom ash and fly ash were measured in a 220 t/h pulverized coal boiler. Factors affecting distribution of trace elements were investigated, including fly ash diameter, furnace temperature, oxygen content and trace elements' characters. One coefficient of Meij was also improved to more directly show element enrichment in combustion products. These elements may be classified into three groups according to their distribution: Group 1: Hg, which is very volatile. Group 2: Pb, Zn, Cd, which are partially volatile. Group 3: Mn, which is hardly volatile. Se may be located between groups 1 and 2. Cr has properties of both group 1 and 3. In addition, the smaller diameter of fly ash, the more relative enrichment of trace elements (except Mn). The fly ash showed different adsorption mechanisms of trace elements and the volatilization of trace elements rises with furnace temperature. Relative enrichments of trace elements(except Mn and Cr) in fly ash are larger than that in bottom ash. Low oxygen content can not always improve the volatilization of trace elements. Pb is easier to form chloride than Cd during coal combustion. Trace elements should be classified in accordance with factors.