No abstract

III.

Despite the tremendous efforts devoted to the structural analysis of hydrogel microspheres (microgels), many details of their structures remain unclear. Reported in this study is that thermoresponsive poly(N‐isopropyl acrylamide) (pNIPAm)‐based microgels exhibit not only the widely accepted core–shell structures, but also inhomogeneous decanano‐sized non‐thermoresponsive spherical domains within their dense cores, which was revealed by temperature‐controlled high‐speed atomic force microscopy (TC‐HS‐AFM). Based on a series of experiments, it is concluded that the non‐thermoresponsive domains are characteristic for pNIPAm microgels synthesized by precipitation polymerization, and plausible structures for microgels prepared by other polymerization techniques are proposed.

Purpose Concomitant meniscus injuries in the anterior cruciate ligament (ACL) injuries have been suggested to exacerbate rotational laxity. However, the effect is supposed to be so small, if any, that some quantitative pivot-shift measurement is needed. The purpose of this prospective study was to determine the effect of meniscus tear on rotational laxity in ACL-deficient knees by an quantitative measurement. We hypothesized that a concomitant meniscus tear, especially a lateral one, would induce greater pivot-shift. Methods Fifty-seven unilateral ACL-injured patients (26 men and 31 women, mean age: 24±10 years) were included. The pivot-shift test was performed prior to ACL reconstruction while a quantitative evaluation using an electromagnetic system to determine tibial acceleration and a clinical grading according to the IKDC were performed. Meniscus injuries were diagnosed arthroscopically, and concomitant meniscus tear was confirmed in 32 knees. Chi-squared and Mann-Whitney U tests were used to assess the difference between knees with and without meniscus tear. A subgroup analysis was subsequently performed for the medial, bilateral, and lateral meniscus-torn groups compared with the meniscus-intact group, using the chi-squared test and analysis of variance. Statistical significance was defined at p<0.05.

Compared with 3 weeks postoperatively, the articular side outlets of the femoral and tibial bone tunnels at 1 year postoperatively had enlarged slightly but statistically maintained their volume, and they had moved a little in the direction that the grafts were pulled.

No abstract

Anterior cruciate ligament (ACL) reconstruction with the hamstring tendon graft takes a long time, as the tendon graft needs to heal at the site of the bone-tendon integration in the created bone tunnels. Several reports have shown the therapeutic effects of simvastatin on bone formation with neovascularization. The aim of this study was to test the hypothesis that enhanced angiogenesis and osteogenesis by locally applied simvastatin promotes tendon-bone healing after ACL reconstruction. Rabbits received ACL reconstruction with hamstring tendon graft and were implanted with either simvastatin-conjugated gelatin hydrogel or gelatin hydrogel alone in their bone tunnels, and then bone regeneration and neovascularization at tendon-bone interface and biomechanical properties were assessed. Histological analysis at week 2 demonstrated that tendon-bone healing was significantly greater with angiogenesis and osteogenesis in the simvastatin-treated group than in the control group. Computed tomography at weeks 2 and 4 showed a significantly smaller tibial bone tunnel in the simvastatin-treated group. Biomechanical testing at week 2 demonstrated a significant increase in ultimate failure load in the simvastatin-treated group. This study suggested that local administration of low-dose simvastatin-conjugated gelatin hydrogel promotes the tendon-bone healing via its effect on both angiogenesis and osteogenesis at an early phase in a rabbit model, but does not affect biomechanical property in long-term after ACL reconstruction.

III.