Modified Low-Flow Arthroscopic Sandwich Technique for Complex Osteochondral Lesions of the Talus.

Treatment of osteochondral lesions of the talus proves to be challenging given the unique anatomy of the intra-articular surface and associated complexity of larger lesions. Simple bone marrow-stimulating procedures for large complex lesions often lead to poor results with increased risk of lesion progression, refractory pain, and associated functional limitations. Other methods of osteochondral autografts or allografts often require osteotomies, bone windows, or fibrin glue, which are associated with donor pain and nonunion. Thus, for larger and cystic lesions, we report our experience using a modified low-flow arthroscopic sandwich technique consisting of autologous cancellous bone graft, followed by a viable cryopreserved cartilage fiber, cartilage allograft matrix putty.

Influence of Staphylococcus epidermidis biofilm on the mechanical strength of soft tissue allograft.

We sought to determine the impact of bacterial inoculation and length of exposure on the mechanical integrity of soft tissue tendon grafts. Cultures of Staphylococcus epidermidis were inoculated on human tibialis posterior cadaveric tendon to grow biofilms. A low inoculum in 10% growth medium was incubated for 30 min to replicate conditions of clinical infection. Growth conditions assessed included inoculum concentrations of 100, 1000, 10,000 colony-forming units (CFUs). Tests using the MTS Bionix system were performed to assess the influence of bacterial biofilms on tendon strength. Load-to-failure testing was performed on the tendons, and the ultimate tensile strength was obtained from the maximal force and the cross-sectional area. Displacements of tendon origin to maximal displacement were normalized to tendon length to obtain strain values. Tendon force-displacement and stress-strain relationships were calculated, and Young's modulus was determined. Elastic modulus and ultimate tensile strength decreased with increasing bioburden. Young's modulus was greater in uninoculated controls compared to tendons inoculated at 10,000 CFU (p = 0.0011) but unaffected by bacterial concentrations of 100 and 1000 CFU (p = 0.054, p = 0.078). Increasing bioburden was associated with decreased peak load to failure (p = 0.043) but was most significant compared to the control under the 10,000 and 1000 CFU growth conditions (p = 0.0005, p = 0.049). The presence of S. epidermidis increased elasticity and decreased ultimate tensile stress of human cadaveric tendons, with increasing effect noted with increasing bioburden.

Ratiometric SERS detection of polycyclic aromatic hydrocarbons assisted by ß-cyclodextrin-modified gold nanoparticles.

A surface-enhanced Raman scattering (SERS) method is described for the determination of trace polycyclic aromatic hydrocarbons (PAHs) in the environment efficiently and economically. Detection sensitivity is improved by modifying gold nanoparticles (AuNPs) with 4-mercaptophenylboronic acid (4-MPBA) conjugated to ß-cyclodextrin (ß-CD) as a new method for ratiometric determination of PAHs in solution. Pyrene (with a Raman band at 580 cm-1) and anthracene (750 cm-1) were used as the model analytes, while 4-MPBA (1570 cm-1) was used as the internal reference to normalize the SERS signals. The intensity ratios of pyrene/4-MPBA increase linearly in the 2 to 10 nM pyrene concentration range, and the intensity ratios of anthracene/4-MPBA increase linearly in the 10 to 100 nM anthracene concentration range. The detection limits are 0.4 nM for pyrene and 4.4 nM for anthracene. This method was applied to the determination of the two analytes in soil sample extracts and the recoveries of pyrene (at levels of 236 ng∙g-1 and 170 ng∙g-1) and anthracene (334 ng∙g-1 and 510 ng∙g-1) agreed well with the results from GC-MS analyses. The good recovery rates (101.8% and 102.5% for pyrene and 106.4% and 101.7% for anthracene) confirmed the reliability of the method. Graphical abstract Schematic illustration of SERS signal enhancement of pyrene, as an example of polycyclic aromatic hydrocarbons, by ß-cyclodextrin modified gold nanoparticles.