An antibacterial coated polymer prevents biofilm formation and implant-associated infection.

To prevent infections associated with medical implants, various antimicrobial silver-coated implant materials have been developed. However, these materials do not always provide consistent antibacterial effects in vivo despite having dramatic antibacterial effects in vitro, probably because the antibacterial effects involve silver-ion-mediated reactive oxygen species generation. Additionally, the silver application process often requires extremely high temperatures, which damage non-metal implant materials. We recently developed a bacteria-resistant coating consisting of hydroxyapatite film on which ionic silver is immobilized via inositol hexaphosphate chelation, using a series of immersion and drying steps performed at low heat. Here we applied this coating to a polymer, polyetheretherketone (PEEK), and analyzed the properties and antibacterial activity of the coated polymer in vitro and in vivo. The ionic silver coating demonstrated significant bactericidal activity and prevented bacterial biofilm formation in vitro. Bio-imaging of a soft tissue infection mouse model in which a silver-coated PEEK plate was implanted revealed a dramatic absence of bacterial signals 10 days after inoculation. These animals also showed a strong reduction in histological features of infection, compared to the control animals. This innovative coating can be applied to complex structures for clinical use, and could prevent infections associated with a variety of plastic implants.

Surgical Results of Microscopic Cervical Foraminotomy for Cervical Radiculopathy Presenting Drop Finger and Proposal of Classification Based on Drop Finger Patterns.

INTRODUCTION: In drop finger, the extension of the finger is limited, although the wrist can be flexed dorsally. There have been no well-organized reports on drop finger pattern caused by cervical nerve root disorder. Moreover, diagnosis and treatment are delayed because of the inability to distinguish cervical radiculopathy from peripheral nerve disease. This study aimed to clarify the operative outcome of microscopic cervical foraminotomy (MCF) for cervical radiculopathy presenting drop finger and to investigate whether our classification based on drop finger patterns is useful retrospectively. METHODS: Overall, 22 patients with drop finger who underwent MCF were included. Grip power (GP) and longitudinal manual muscle test (MMT) score of each finger were examined. Drop finger patterns were classified as types I, II, and III. In type I, the extension disorders of the middle and ring fingers are severe and those of index and little fingers are mild. In type II, the extension disorders are severe from the little finger and slightly to index finger. In type III, the extension disorder is consistently severe in all fingers. Perioperative nerve root disorder and paralysis degree were investigated for all types. RESULTS: The mean GP was significantly postoperatively improved in all 22 patients. The mean MMT score would benefit from exact data for almost all muscles, except the abductor pollicis brevis at the last follow-up. However, pre- and postoperative paralyses were severe in type III patients. C7 nerve root disorder was confirmed in 5/6 type I patients and C8 nerve root disorder in 12/13 type II and 3/3 type III patients. CONCLUSIONS: The operative results of MCF were relatively good, except in type III patients. As a certain tendency was confirmed between the drop finger types and injured nerve roots, our classification may be useful in reducing misdiagnosis and improving the operative results to some extent.

Potential osteomyelitis biomarkers identified by plasma metabolome analysis in mice.

Osteomyelitis, which often arises from a surgical-site infection, is a serious problem in orthopaedic surgery. However, there are no specific biomarkers for osteomyelitis. Here, to identify specific plasma biomarkers for osteomyelitis, we conducted metabolome analyses using a mouse osteomyelitis model and bioluminescence imaging. We divided adult male pathogen-free BALB/C mice into control, sham-control, and infected groups. In the infected group, a bioluminescent Staphylococcus aureus strain was inoculated into the femur, and osteomyelitis was detected by bioluminescence imaging. We next analysed the metabolome, by comprehensively measuring all of the small molecules. This analysis identified 279 metabolites, 12 of which were significantly higher and 45 were significantly lower in the infected group than in the sham-control and control groups. Principal component analysis identified sphingosine as the highest loading factor. Several acyl carnitines and fatty acids, particularly ω-3 and ω-6 polyunsaturated fatty acids, were significantly lower in the infected group. Several metabolites in the tricarboxylic acid cycle were lower in the infected group than in the other groups. Thus, we identified two sphingolipids, sphinganine and sphingosine, as positive biomarkers for mouse osteomyelitis, and two components in the tricarboxylic acid cycle, two-oxoglutarate and succinic acid, as negative biomarkers.

Plate Fixation of Expansive Open-Door Laminoplasty Decreases the Incidence of Postoperative C5 Palsy.

STUDY DESIGN: Retrospective study. OBJECTIVE: To compare outcomes for plate fixation versus suture suspension in expansive open-door laminoplasty (ELAP) for cervical spondylotic myelopathy (CSM). SUMMARY OF BACKGROUND DATA: C5 palsy and laminar closure have been reported to occur after ELAP when suture suspension is used to anchor the opened lamina. MATERIALS AND METHODS: We assessed 174 patients with CSM who were treated by ELAP using either suture suspension (114 patients, mean age 63.3 y, 83 men and 31 women, mean follow-up 12.0 mo) or laminoplasty plate (60 patients, mean age 65.6 y, 45 men and 15 women, mean follow-up 12.6 mo) to maintain the position of the opened laminae. We compared clinical outcomes, radiographic findings, and complications between the 2 groups. RESULTS: Mean Japanese Orthopaedic Association scores had improved significantly for both groups at the final follow-up (P<0.001), with similar recovery rates: scores improved from 10.8±2.8 to 13.4±2.8 points in the suture-suspension (SS) group and from 11.3±2.7 to 13.6±2.2 points in the laminoplasty plate (LP) group. The incidence of C5 palsy was significantly higher in the SS group (7.9%) than in the LP group (1.7%; P<0.05). Computed tomography (CT) showed larger mean angles of the opened laminae in the SS group compared with the LP group (P<0.01). Magnetic resonance imaging (MRI) showed that the mean anterior spinal-cord space at the C5 level was larger in the SS group than in the LP group (P<0.01). CONCLUSIONS: Plate fixation in ELAP produced comparable clinical outcomes and significantly lowered the incidence of C5 palsy compared with suture suspension. CT and MRI findings indicated that laminoplasty plate fixation prevented excessive opening of the lamina and decreased dorsal spinal-cord shift, which might explain the lower incidence of C5 palsy.

Delayed Propionibacterium acnes surgical site infections occur only in the presence of an implant.

Whether Propionibacterium acnes (P. acnes) causes surgical-site infections (SSI) after orthopedic surgery is controversial. We previously reported that we frequently find P. acnes in intraoperative specimens, yet none of the patients have clinically apparent infections. Here, we tracked P. acnes for 6 months in a mouse osteomyelitis model. We inoculated P. acnes with an implant into the mouse femur in the implant group; the control group was treated with the bacteria but no implant. We then observed over a 6-month period using optical imaging system. During the first 2 weeks, bacterial signals were detected in the femur in the both groups. The bacterial signal completely disappeared in the control group within 28 days. Interestingly, in the implant group, bacterial signals were still present 6 months after inoculation. Histological and scanning electron-microscope analyses confirmed that P. acnes was absent from the control group 6 months after inoculation, but in the implant group, the bacteria had survived in a biofilm around the implant. PCR analysis also identified P. acnes in the purulent effusion from the infected femurs in the implant group. To our knowledge, this is the first report showing that P. acnes causes SSI only in the presence of an implant.

A novel mouse model of soft-tissue infection using bioluminescence imaging allows noninvasive, real-time monitoring of bacterial growth.

Musculoskeletal infections, including surgical-site and implant-associated infections, often cause progressive inflammation and destroy areas of the soft tissue. Treating infections, especially those caused by multi-antibiotic resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) remains a challenge. Although there are a few animal models that enable the quantitative evaluation of infection in soft tissues, these models are not always reproducible or sustainable. Here, we successfully established a real-time, in vivo, quantitative mouse model of soft-tissue infection in the superficial gluteus muscle (SGM) using bioluminescence imaging. A bioluminescent strain of MRSA was inoculated into the SGM of BALB/c adult male mice, followed by sequential measurement of bacterial photon intensity and serological and histological analyses of the mice. The mean photon intensity in the mice peaked immediately after inoculation and remained stable until day 28. The serum levels of interleukin-6, interleukin-1 and C-reactive protein at 12 hours after inoculation were significantly higher than those prior to inoculation, and the C-reactive protein remained significantly elevated until day 21. Histological analyses showed marked neutrophil infiltration and abscesses containing necrotic and fibrous tissues in the SGM. With this SGM mouse model, we successfully visualized and quantified stable bacterial growth over an extended period of time with bioluminescence imaging, which allowed us to monitor the process of infection without euthanizing the experimental animals. This model is applicable to in vivo evaluations of the long-term efficacy of novel antibiotics or antibacterial implants.