Stress and strain changes of the anterior cruciate ligament at different knee flexion angles: A three-dimensional finite element study.

OBJECTIVE: This study aimed to analyze the stress and strain changes of the anterior cruciate ligament (ACL) at different knee flexion angles using a three-dimensional finite element model. METHODS: Computed tomography and magnetic resonance imaging scans were performed on the right knee of 30 healthy adult volunteers. The imaging data were used to construct a three-dimensional finite element model of the knee joint. The magnitude and concentration area of stress and strain of ACL at knee flexion angles 0°, 30°, 60° and 90° were assessed. RESULTS: The magnitude of stress remained consistent at 0-30° (P > 0.999) and decreased at 30-90° (P < 0.001, P = 0.005, respectively), while the magnitude of strain increased between 0° and 30° (P = 0.004) and decreased between 30° and 90° (P < 0.001, P = 0.004, respectively). The stress concentration area remained consistent at the proximal end, midsubstance, and distal end between 0° and 60° (P > 0.05). The concentration area of strain increased at the proximal end, decreased at the midsubstance between 0° and 30°, and remained consistent between 30° and 90° (P < 0.001). CONCLUSION: At the low knee flexion angle, ACL's magnitude of stress and strain reached the peak, and the concentration area of ACL strain gradually shifted from midsubstance to the proximal end.

[Effect of electroacupuncture on transforming growth factor-ß1 and renal tubular epithelial mesenchymal transformation in renal tissue of spontaneously hypertensive rats].

OBJECTIVE: To observe the effects of electroacupuncture (EA) on renal fibrosis, the expression of transforming growth factor-ß1 (TGF-ß1) and epithelial mesenchymal transition (EMT) marker proteins in renal tissue of spontaneously hypertensive rats (SHR), so as to explore the underlying mechanism on EA alleviating hypertensive renal impairment. METHODS: Twenty-four male SHR were randomly divided into model group, losartan group and EA group, with 8 rats in each group, and eight male Wistar-Kyoto rats were taken as the normal group. Rats in the losartan group received gavage of losartan potassium solution (3 mg/mL, 30 mg·kg-1·d-1),once every other day for 12 weeks. Rats in the EA group received EA stimulation at bilateral "Shenshu" (BL23) and "Geshu" (BL17) (2 Hz/15 Hz, 1.0 mA), 15 min each time, once every other day for 12 weeks. The systolic blood pressure of caudal artery was measured before, and 4, 8 and 12 weeks after the intervention. The 24-hour urinary protein was measured before, and 6 and 12 weeks after the intervention. Histopathological changes of the left renal tissue were observed under light mircoscope after H.E. stain. Extracellular matrix (ECM) in renal tissues was observed after periodate Schiff staining. Basement membrane and collagen fibers were observed after Masson staining with collagen volume fraction (CVF) evaluated. The expression of TGF-ß1 mRNA in the right renal was detected by real-time fluorescence quantitative PCR. The expression of TGF-ß1 and EMT marker E-cadherin, α-SMA and fibronectin (FN) proteins in the left renal tissue was measured by immunohistochemistry. RESULTS: In the model group, irregular arrangement of nephrocytes, renal tubule atrophy, lumen stenosis, ECM hyperplasia and deposition, scar and sclerosis were observed, which were relatively milder in the EA and losartan groups. Compared with the normal group, tubulointerstitium CVF, systolic blood pressure of caudal artery before, and at 4, 8 and 12 weeks after the intervention, 24-hour urinary protein before, and at 6 and 12 weeks after the intervention, the expression of TGF-ß1 mRNA, area of TGF-ß1, α-SMA and FN positive staining in renal tissues were significantly increased (P<0.01), while the area of E-cadherin positive staining was significantly decreased (P<0.01) in the model group. Compared with the model group, tubulointerstitium CVF, systolic blood pressure of caudal artery at 4, 8 and 12 weeks after the intervention, 24-hour urinary protein at 6 and 12 weeks after the intervention, the expression of TGF-ß1 mRNA, area of TGF-ß1, α-SMA and FN positive staining in renal tissues were significantly decreased (P<0.01，P<0.05), while area of E-cadherin positive staining was significantly increased (P<0.01) in the losartan and EA groups. Compared with the losartan group, the area of E-cadherin was conside-rately increased (P<0.01), while the area of α-SMA protein decreased (P<0.01) in the EA group. CONCLUSION: EA could effectively alleviate hypertension and renal interstitial fibrosis in SHR, the mechanism of which may be related to its function in reducing the expression of TGF-ß1 and inhibiting EMT in renal tissue.

A clinical and biomechanical comparison of INFIX plus single versus double sacroiliac screw fixation for unstable pelvic ring injury.

BACKGROUND: The aim of this study is to compare the clinical and biomechanical outcome of INFIX plus single with two sacroiliac screw fixation for unstable pelvic fractures of Type C. METHODS: Sixteen cadavers were randomly subjected to INFIX plus single or double sacroiliac screw fixations and then mounted onto the ElectroForce loading machine under different vertical loads. To investigate the clinical outcomes of the two techniques, nineteen patients were retrospectively analyzed. The main outcome measures were postoperative radiographic reduction grading (using the Tornetta and Matta grading system), functional outcome (using the Majeed scoring system), and incidence of complications. RESULTS: In the biomechanical study, INFIX plus double sacroiliac screw fixation showed better biomechanical stability than fixation with a single sacroiliac screw (p < 0.05). In our clinical case series, all 19 patients had bony union 6 months after the operation. INFIX plus double sacroiliac screw fixation also demonstrated a better functional outcome and a higher radiographic satisfactory rate than INFIX plus single sacroiliac screw fixation (79.25 ± 5.47; 91.33 ± 4.97; p < 0.05), (77.78% vs. 60%; p = 0.05). One patient in INFIX plus single-screw fixation group had screw loosening at 6-month follow-up postoperatively. One case in each group suffered heterotopic ossification and the lateral femoral cutaneous nerve paralysis, and one patient suffered from infection. CONCLUSION: INFIX plus double sacroiliac screw fixation demonstrated more stability in cadaveric biomechanical analysis and better clinical outcomes than INFIX plus single sacroiliac screw fixation.

An Improved Device Clears Blockages in the Tube of Irrigation and Drainage Systems.

The outflow tube may be blocked during continuous irrigation for the treatment of septic joints. Although multiple solutions have been applied to clear the blockage, there are still many disadvantages. The success rate is difficult to guarantee, and bacteria may enter the joint cavity and cause secondary infection. We designed an improved irrigation and drainage system that avoids these disadvantages and is particularly convenient to use. In addition, the improved system provides more thorough lavage and drainage and prevents joint adhesion.

[Effect of electroacupuncture on renal fibrosis in spontaneously hypertension rats and its related mechanisms].

OBJECTIVE: To observe the effect of electroacupuncture (EA) on blood pressure, renal fibrosis and expression of tissue inhibitors of metalloproteinase-1 (TIMP-1), plasminogen activator inhibitor 1 (PAI-1), and alpha smooth muscle actin (α-SMA) in spontaneous hypertension rats (SHR), so as to explore its mechanisms underlying improving hypertensive renal damage. METHODS: Forty male SHR (15 weeks in age) were randomly divided into 5 groups: model, medication (Losartan), Shenshu, Geshu, and Shenshu＋Geshu groups(n=8 rats in each group), and the same age-old male 8 Wistar-Kyoto (WKY) rats were used as the normal control group. Rats of the medication group were treated by gavage of Losartan potassium solution (3 mg/mL, 30 mg·kg-1·d-1, once a day for 12 weeks), and those of the 3 EA groups treated by EA stimulation of bilateral "Shenshu" (BL23), "Geshu"(BL17) or both BL23 and BL17 (2 Hz/100 Hz, 1 mA, 15 min each time, once every other day for 12 weeks). The systolic blood pressure of the tail artery was measured before, and 4, 8 and 12 weeks after the intervention. The expression of TIMP-1, PAI-1 and α-SMA proteins of the right kidney tissue was measured by immunohistochemistry. Histopathological changes of the right renal tissue were observed under light microscope after H.E. stain. RESULTS: The blood pressure was significantly higher in the mo-del group than those in the normal control group (P<0.01), and considerably decreased at the 4th , 8th, and 12th week of the interventions in the medication and 3 EA groups (P<0.01). The expression levels of renal TIMP-1, PAI-1 and α-SMA proteins were notably higher in the model group than those in the normal control group and considerably decreased at the 12th week of the interventions in the medication and 3 EA groups than in the model group (P<0.01). H.E. staining of the renal tissue showed disordered arrangement of the renal cells, congestion and dilation of capillaries with thickened vascular wall, renal tubule atrophy and lumen stenosis with some necrosis of renal tubules, protein tubule and cell tubules, increase of some glomerular mesangial matrix and hyperplasia of fibrous tissue in the model group, which was re-latively milder in the medication and 3 EA groups. CONCLUSION: EA of BL23 and BL17 can reduce the blood pressure in SHR, which may be related to its function in down-regulating expression of TIMP-1, PAI-1 and α-SMA proteins.