Implant‐associated infections (IAIs) are a common cause of orthopedic surgery failure due to microbial biofilm‐induced antibiotic‐resistance and innate immune inactivation. Thus, the destruction of microbial biofilm plays a key role in reducing IAIs. Herein, first, a magneto‐based synergetic therapy (MST) is proposed and demonstrated against IAIs based on biofilm destruction. Under an alternating magnetic field (AMF), CoFe2O4@MnFe2O4 nanoparticles (MNPs), with a rather strong magnetic hyperthermal capacity, can generate sufficient thermal effect to cause dense biofilm dispersal. Loosened biofilms provide channels through which nitrosothiol‐coated MNPs (MNP‐SNOs) can penetrate. Subsequently, thermosensitive nitrosothiols rapidly release nitric oxide (NO) inside biofilms, thus efficiently killing sessile bacteria under the magnetothermal effect of MNPs. More importantly, MNP‐SNOs can trigger macrophage‐related immunity to prevent the relapse of IAIs by exposing the infected foci to a consistent innate immunomodulatory effect. The notable anti‐infection effect of this nanoplatform is also confirmed in a rat IAI model. This work presents the promising potential of combining magnetothermal therapy with immunotherapy, for the effective and durable control and elimination of IAIs.

Vertical femoral neck fractures in patients younger than 65 years of age often require hip‐conserving surgeries. However, traditional fixation strategies using three parallel cannulated screws often fail in such patients due to an unfavorable biomechanical environment. This study compared different cannulated screw fixation techniques in patients via patient‐specific finite element analysis with linear tetrahedral (C3D4) elements. Forty vertical femoral neck fracture models were created based on computed tomography images obtained from eight healthy participants. Five different fixation strategies: alpha, buttress, rhomboid, inverted triangle, and triangle were assessed in walking status. Biomechanical parameters including stiffness, interfragmentary motion in two directions (detachment and shearing), compression force, and maximal implant stress were evaluated. The mean relative coefficient of strain distribution between the finite element analysis and experiment was from 0.78 to 0.94. Stiffness was highest (p < .05) in the buttress group (923.1 N/mm), while interfragmentary motion was lowest (p < .05) in the alpha group. Maximal stress was highest (p < .05) in the buttress group and lowest in the alpha group. Shearing values were significantly lower in the alpha group than in the rhomboid group (p = .004). Moreover, Shearing values were significantly higher (p = .027), while detachment values were significantly lower (p = .027), in the inverted triangle than in the triangle group. Clinical significance: Our results suggest that alpha fixation is the most reliable and biomechanically efficient strategy for young patients with vertical femoral neck fractures. Regular and inverted triangular fixation strategies may be suitable for fractures of different skeletal constructions due to antidetachment/shearing abilities.

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BackgroundThe position of Kirschner wires (K-wires) has an influence on the outcome of modified tension-band wiring (MTBW) in fixing patella fractures. However, the instruction for K-wires positioning is not clear enough. This study tried to clarify the effect of K-wires positioning and provide evidence for a more definite instruction.MethodsThe sagittal position (SP) suitable for placing K-wires was evenly divided into SP 1–5 from anterior to posterior, and the finite element models of midpatella transverse fractures fixed by the figure-of-eight or figure-of-zero MTBW were built up at each SP. Separating displacement of the fracture, stress of the fracture, and stress of the internal fixations were measured at 45° knee flexion by using finite element analysis.ResultsThe separating displacement of the fracture was smaller at SP 3–5 (23% smaller than SP 1–2). From SP 1 to 5, the compression of the fracture surfaces increased (R = 0.99, P = 0.001); the improper stress area of the fracture surfaces decreased (R = − 0.96, P = 0.01), and so was the stress of K-wires (R = − 0.93, P = 0.02). However, the stress of stainless steel wires showed a stable trend.ConclusionsThe SP of K-wires plays a role in the function of MTBW in the surgical management of transverse patella fracture. At 45° knee flexion, posteriorly placed (close to the articular surface) K-wires enable optimal stability and stress for the fracture, which provides basis for the positioning of K-wires in clinical practice.