ABSTRACT
Objective: To compare the biomechanical properties of two ultra-strong sutures and suturing methods in panda rope bridge technique (PRBT) application, and provide guidance for clinical selection of suture threads and suture methods. Methods: Forty Achilles tendons from bulls were randomly divided into 4 groups ( n=10) and transected at the 4 cm proximal to the tendon insertion. Groups A and B used Ethibond sutures (USP 5), the proximal end was fixed at the myotendious junction with Krackow sutures and the distal end was fixed through a calcaneus canal. Groups A and B had 4 and 8 threads through the stump plane, respectively. Groups C and D used Ultrabraid sutures (USP 2), the proximal end was fixed at the myotendious junction with Krackow sutures and the distal end was fixed in the calcaneus with two anchors. Groups C and D had 4 and 8 threads through the stump plane, respectively. The dynamic tensile forces of 20-100, 20-200, 20-300, and 20-400 N were tested respectively by using a dynamic tensile testing machine at 0.5 Hz for 250 cycles. After each stage of testing, the gap between stumps was measured with a caliper and the type of suture failure was recorded. Results: After dynamic tensile forces of 20-100 N and 20-200 N, the gaps of the four groups arranged from small to large were groups D, B, C, and A. The differences between groups A and B and groups C and D were significant ( P0.05). After dynamic tensile forces of 20-400 N, the suture retention rates of groups A, B, C, and D were 0, 50%, 0, and 70%, respectively. There were significant differences between groups A and B and groups C and D ( P<0.05). Conclusion: Repairing Achilles tendon rupture via PRBT with 8 ultra-strong sutures through the stump plane can meet the mechanical requirements for walking by using ankle boots and heel pads in the early accelerated rehabilitation after operation.
ABSTRACT
Objective To explore the effect of Notch1 signal pathway on the osteogenic differentiation in human periodontal ligament stem cells(PDLSCs) under dynamic strain.Methods PDLSCs were separated from freshly extracted teeth then identified and prolifed.Notch1 signal pathway was regulated by chemicals.Dynamic strains were applied to PDLSCs with the tension plus system.Then Notch1 signal pathway key factor Notch intracellular domain(NICD),osteoblastic related indexes alkaline phosphatase(ALP) and bone morphogenetic proteins 2 (BMP2) were detected by western blot expression.The deformation rate of stress parameters was 0 to 12%,and the frequency was 0.1 Hz.The loading time was 0 h,6 h,12 h and 24 h.Results As Notch1 signal pathway was activated,the expression of osteogenic markers ALP and BMP2 both reduced (P<0.05).On the contrary, the expression of osteogenic markers ALP and BMP2 both increased obviously (P<0.05) as Notch1 signal pathway was inhibited.Conclusion The activated Notch1 signal pathway will inhibit osteogenic differentiation of PDLSCs under dynamic tensile.