[Pollution Characteristics and Health Risk Assessment of Heavy Metals in PM2.5 of Different Air Masses During Heating Season in Tianjin].

In order to explore the pollution characteristics and health risks of heavy metals in PM2.5 in Tianjin, heavy metal samples (Pb, Cd, Cr, As, Zn, Mn, Co, Ni, Cu, and V) in PM2.5 were analyzed from November 2020 to March 2021 using the Xact-625 heavy metal online analyzer. The spatial and temporal distribution characteristics were analyzed using the HYSPLIT model, and the health risks of heavy metals were analyzed using the US EPA risk assessment model. The results indicated that the average total concentration of the 10 heavy metal elements was (261.56±241.74) ng·m-3, among which the concentrations of Cr ï¼»converted Cr(Ⅵ)ï¼½ and As were higher than the annual average limit of the National Ambient Air Quality Standard (GB 3095-2012). According to the back trajectory results, the medium-distance transmissions from northwest areas (NO.1), the long-distance transmissions from northwest areas (NO.2), the transmissions from southwest areas (NO.3), and the transmissions from northeast areas (NO.4) were the major sources in Tianjin City. The heavy metals of different air masses presented different pollution characteristics and health risks; the concentration of PM2.5, the total concentration of the 10 heavy metal elements, and the total carcinogenic risk of the five heavy metal elements of the NO.3 air mass were the highest, whereas the total non-carcinogenic risk of the 10 heavy metal elements of the NO.2 air mass was higher than that of the other two air mass. The health risk assessment showed that Mn posed non-carcinogenic risks to children, and Cr and As presented carcinogenic risk. Meanwhile, Cd of the NO.3 air masses also presented carcinogenic risk.

[Arthroscopic treatment of tibial intercondylar eminence fractures in children with single Kirschner wire and suture avoiding epiphyseal line fixation technique].

OBJECTIVE: To discuss arthroscopic technique of single Kirschner wire and suture avoiding epiphyseal line fixation for tibial intercondylar eminence fracture and its clinical results. METHODS: From May 2008 to December 2012, 21 patients (13 males, 8 females, ranging in age from 6 to 14 years old) with tibial intercondylar eminence fracture were treated arthroscopically with single Kirschner wire and suture avoiding epiphyseal line fixation technique. According to Meyers and McKeever classification, 7 patients were type II, 10 patients were type III, and 4 patients were type IV. Active rehabilitation began at one week after operation. The patients were followed up for 10 to 30 months. X-ray films were taken to evaluate fracture healing at 1, 3, 6 months after operation; range of motion, the anterior drawer test, the lachman test and the Lysholm knee score were used to evaluate clinical effects. RESULTS: All fractures were healed without displacement at 6 weeks after operation. Anterior drawer test and the lachman test were both negative in all patients at 3 months after operation. Lysholm knee score was 95.5 ±2.5 at 6 months after operation, and postoperative X-ray film did not find epiphyseal line broadening or narrowing. CONCLUSION: Arthroscopic treatment for tibial eminence intercondylar fracture with single Kirschner wire and 8-shaped suture avoiding epiphyseal line fixation technique has many advantages, such as firm fixation,early mobilization, less invasive, less injury of physis and satisfactory effect.

[Characteristics of treating dislocation and fracture of sacroiliac joint through anterior and posterior approches].

OBJECTIVE: To investigate characteristics of treating dislocation and fracture of sacroiliac joint through anterior and posterior approaches. METHODS: Between January 2006 and September 2012, 39 patients with dislocations and fractures of sacroiliac joint were treated with operation. There were 28 males and 11 females, aged 12 to 64 (mean, 41.3) years old. Seventeen cases were chosen through anterior approach, 13 cases through posterior and 9 cases were combined with anterior and posterior approaches. The anterior approach were made with supine position, performed open reduction, and two plates with 4 holes were used as internal fixation for arthrodesis of sacroiliac joint after reduction; while posterior approach prone position, close or open reduction was performed, and one or two partial thread lag screws, which with 7.3 mm in diameter and 60 to 75 mm in length, were penetrated via sacroiliac joint for fixation under X-ray. Postoperative complications were observed, Matta and Majeed scoring were used to evaluated currative effects. RESULTS: All patients were followed up from 6 to 36 months. The patient could sit on the bed 2 to 4 weeks after surgery and walk with a crane 6 weeks' later. No breakage or loosening of screw occurred during follow-up. In all but one case with old sacral iliac fractures reducted poor, others obtained good opposition. According to Matta's criteria, 30 cases got excellent results, 8 good and 1 fair. According to Majeed's funtional standard, 14 patients got excellent results, 20 good 4 fair and 1 poor. CONCLUSION: Treating dislocation and fracture of sacroiliac joint through anterior and posterior approaches can obtain good effects. However, anatomic location, fracture types, degree of displacement, the rate of preoperational reduction, vulnerability assessment of operation and fixation strength should be considered.