ObjectiveTo explore the feasibility of Lisfranc ligament reconstruction with autogenous tendon through biomechanical testing. MethodsTwelve fresh-frozen cadaveric lower limbs were prepared three sequential testing conditions:intact Lisfranc ligament (intact group), disrupted Lisfranc ligament (disrupted group), and Lisfranc ligament reconstruction (reconstruction group). Under fixing on the Bose mechanical test machine, three models were given 0-600 N axial loading in the neutral position and the plantar flexion of 30° according to the speed of 10 N/s, every 100 N load with a 1-minute interval. The medial cuneiform (C1) and the second metatarsal (M2) base displacement and the foot transverse arch height were recorded under different loads. ResultsIn the neutral position and the plantar flexion of 30°, C1-M2 displacement and foot transverse arch height showed an increasing trend with increased load under 0-600 N axial loading. There were significant differences in C1-M2 displacement variation in 2 positions among groups (P＜0.05). In disrupted group, the C1-M2 displacement variation in neutral position was significantly lower than that in plantar flexion of 30° (t=7.392,P=0.000). In the neutral position, the foot transverse arch height variation in the disrupted group and the reconstruction group was significantly higher than that in the intact group (P＜0.05), but there was no significant difference between the disrupted group and reconstruction group (P>0.05). ConclusionLisfranc ligament reconstruction with autogenous tendon can reduce the C1-M2 displacement variation and stabilize Lisfranc joint to a certain degree. Reconstruction of both dorsal ligament and Lisfranc ligament will not improve the buffering capacity. The C1-M2 displacement variation in the plantar flexion of 30° is more obvious than that in neutral position, so it is helpful to improve clinical diagnosis of occult Lisfranc damage.
ObjectiveTo explore whether FTY-720P could enhance the effect of allograft bone for bone defect repair by suppressing osteoclast formation and function. MethodAnimal experiment:Forty-eight New Zealand white rabbits were selected to establish the tibia defect model (1.5 cm in length) and were divided into 4 groups (n=12) . Defect was not repaired in group A, defect was repaired with allograft bone in group B, with autogenous fibula in group C, and with allograft bone and FTY-720P in group D. Lane-Sandhu scoring system and bone density examination were used to evaluate the effect at 2, 4, 8, and 12 weeks after operation. Cell experiment:Bone marrow-derived mononuclear phagocytes (BMMs) were harvested from 1-month-old Sprague Dawley rats and induced into osteoclasts with macrophage colony stimulating factor (M-CSF) and receptor activator of nuclear factor-κB ligand (RANKL), then were identified with tartrate-resistant acid phosphatas (TRAP). According to different concentrations of FTY-720P before induction, experiment was divided into 0, 500, 600, 700, 800, 900, 1 000, and 1 500 ng/mL groups. The effect of FTY-720P was studied by counting the number of osteoclasts and the number of bone resorption lacunae made by osteoclasts. ResultsAnimal experiment:Lane-Sandhu score showed no significant difference between groups at 2 weeks after operation (P>0.05) , but the score was significantly better in groups C and D than groups A and B, and in group B than group A (P<0.05) . The bone density of group C was significantly greater than that of groups A, B, and D at 2 weeks after operation (P<0.05) , but no significant difference was found among groups A, B, and D (P>0.05) ; the bone density of groups B, C, and D was significantly greater than that of group A at 4, 8, and 12 weeks (P<0.05) , but no significant difference was shown among groups B, C, and D (P>0.05) . Cell experiment:BMMs could be induced into osteoclasts by the addition of M-CSF and RANKL, which could be proved by counting the number of the nuclear and TRAP staining. The osteoclasts were significantly more in 0, 500, 600, 700, 800, 900 ng/mL groups than 1 000 and 1 500 ng/mL groups (P<0.05) , in 0, 500, 600, and 700 ng/mL groups than 800 and 900 ng/mL groups (P<0.05) , in 0, 500, 600 ng/mL groups than 700 ng/mL group (P<0.05) ; and there was no significant difference between the other groups (P>0.05) . The number of bone resorption lacunae in 0, 500, 600, and 700 ng/mL groups was significantly higher than that in 800, 900, 1 000, and 1 500 ng/mL groups (P<0.05) , and it was significantly higher in 0, 500 and 600 ng/mL groups than 700 ng/mL group (P<0.05) , but difference was not significant between the other groups (P>0.05) . ConclusionsFTY-720P combined with allograft bone for bone defect repair can have the same effect to autogenous bone by means of inhibiting osteoclast formation and function, which reduces bone loss.