Orthopedics Research Today is a free monthly online journal that collates and summarizes the latest research about Orthopedics, including details on chronic injuries, muscoskeletal disorders, surgery, reconstruction.

The in vitro effect of ultrasound on bacteria and a suggested protocol for sonication and diagnosis of prosthetic infections.

Monsen T, Lövgren E, Widerström M, Wallinder L

Department of Clinical Bacteriology and Department of Orthopedics, University Hospital of Umeå, SE-90185 Umeå, Sweden; Department of Infectious Diseases, Hospital of Ostersund, SE-83183 Ostersund, Sweden; Department of Medical Microbiology, St. Olavs University Hospital and Institute of Laboratory Medicine, Children's and Women's Health, Norwegian University of Science and Technology, Trondheim, Norway.

Sonication of implants has been shown to be a promising method for diagnosis of prosthetic infections due to its improved sensitivity, simplicity and low cost. The aim of the present study was to evaluate the effect of ultrasound performed during different conditions regarding temperature, duration and composition of sonication tubes on bacterial species often associated with prosthetic infections. We found that ultrasound had an inhibitory effect on bacteria of which Gram-negative bacteria and in particular E. coli were almost eradicated after 5 minutes of sonication at 35 degrees C. Gram-positive bacteria were found to be resistant to the effect of ultrasound. Four factors were important for the inhibitory effect of sonication; the type of microorganism, temperature of the sonication buffer, time of exposure to ultrasound (minutes) and the material and composition of sonication tube in which sonication is performed. Based on the results from the present study we propose a protocol for sonication and recovery of bacteria associated with biofilm on infected implants prior to conventional culture. From the present protocol we recommend sonication for 7 minutes at 22 degrees C at maximum effect which permit survival of Gram-negative bacteria.

Published 18 June 2009 in J Clin Microbiol.
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Articles on Orthopedics published 17 June 2009:

Investigation of the histology and interfacial bonding between carbonated hydroxyapatite cement and bone.   Biomed Mater, 4(4): 45003.

An ideal bone implant should facilitate the formation of a new bone layer as an osteo-integrated interface between bone and the implanted biomaterials. In the present work, the interface between carbonated hydroxyapatite (CHA) cement and bone was evaluated by interfacial bonding strength measurements and histological characterizations. CHA cement was implanted into a mongrel dog's femoral supracondylar and below the tibial plateau area, and was then tested ex vivo by, respectively, detaching ... [Abstract] [Full-text]

Articles on Orthopedics published 15 June 2009:

Prediction of bone density around orthopedic implants delivering bisphosphonate.   J Biomech, 42(9): 1206-11.

The fixation of an orthopedic implant depends strongly upon its initial stability. Peri-implant bone may resorb shortly after the surgery. This resorption is directly followed by new bone formation and implants fixation strengthening, the so-called secondary fixation. If the initial stability is not reached, the resorption continues and the implant fixation weakens, which leads to implant loosening. Studies with rats and dogs have shown that a solution to prevent peri-implant resorption is to ... [Abstract] [Full-text]

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Few studies have investigated the factors related to the disability and physical function in degenerative lumbar spondylolisthesis using axially loaded magnetic resonance imaging (MRI). Therefore, we aimed to investigate the effect of axial loading on the morphology of the spine and the spinal canal in patients with degenerative spondylolisthesis of L4-5 and to correlate morphologic changes to their disability and physical functions. From March 2003 to January 2004, 32 consecutive cases (26 ... [Abstract] [Full-text]

Case Report: Primary Squamous Cell Carcinoma of a Tarsal Bone.   Clin Orthop Relat Res.

We describe a rare case of primary squamous cell carcinoma of the cuneiform bone of the foot in a 57-year-old man. In the appendicular skeleton, epithelial carcinomas of bone are usually metastatic deposits, primary squamous cell carcinomas of bone being found more frequently in the skull. A review of the English literature revealed only two other reported cases of primary squamous cell carcinoma outside the skull-one in the ilium and one in the tibia. In our patient, extensive metastatic ... [Abstract] [Full-text]

Cervical chordoma in childhood without typical vertebral bony destruction: case report and review of the literature.   Spine, 34(14): E493-7.

STUDY DESIGN: Case report. OBJECTIVE: We present a giant cervical chordoma without typical vertebral bony destruction in an 11-year-old girl. SUMMARY OF BACKGROUND DATA: Chordomas are rare malignant bone tumors that arise at both the cranial and the caudal ends of the axial skeleton, characteristically destroying the bone. Cervical chordomas comprise only 3% to 7% of all chordomas. To our knowledge, there is no case of cervical chordoma in a child, presenting without vertebral body involvement, ... [Abstract] [Full-text]

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Results of recent imaging studies and theoretical models suggest that the superior femoral neck is a location of local weakness due to an age-related thinning of the cortex, and thus the site of hip fracture initiation. The purpose of this study was to experimentally determine the spatial and temporal characteristics of the macroscopic failure process during a simulated hip fracture that would occur as a result of a sideways fall. Twelve fresh frozen human cadaveric femora were used in this ... [Abstract] [Full-text]

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Capturing patient photographs on digital flash cards rather than film has several advantages, but also a few disadvantages. Among the latter, the primary disadvantage is the possibility of accidentally deleting or corruping the files before they are downloaded from the memory card. In this article, we describe utilities that enable image recovery from deleted, reformatted, or physically damaged flash memory cards. [Abstract] [Full-text]

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