Identification of the vascular and avascular zones of the human meniscus using magnetic resonance imaging: correlation with histology.

Since the initial employment of magnetic resonance imaging (MRI) to diagnose meniscal tears, a characteristic low-signal intensity, triangular-shaped structure has been interpreted as representing the entire meniscus. The difficulty in diagnosing meniscocapsular separations with MRI has brought attention to our lack of understanding of the appearance on MRI of the outer third of the meniscus and the meniscocapsular junction. We correlated MRIs of the meniscus in cadaver knees with histological sections and found that the low-signal, wedge-shaped structure corresponds only to the avascular (white) zone of the meniscus, whereas the high-signal zone peripheral to it corresponds to the vascularized (red) zone.

Drain entrapment and titanium to ceramic head deposition: two unique complications following closed reduction of a dislocated total hip arthroplasty.

Postoperative dislocation remains one of the most frequent complications following total hip replacement. In this report, a case is presented that illustrates two potential concerns with postoperative dislocation and subsequent closed reduction. The first complication presented in this report is entrapment of a closed drainage system tube in the joint space following closed reduction.

The effects of cobalt chromium upon macrophages.

The purpose of this study was to elucidate the mechanisms by which cobalt chromium particulate wear debris contribute to the aseptic loosening of total joint prostheses. Incubation of macrophages with cobalt chromium led to release of tumor necrosis factor-alpha (TNF-alpha) and prostaglandin E2 (PGE2), but did not lead to release of interleukin-1 beta (IL-1 beta) or interleukin 6 (IL-6). Exposure of macrophages cocultured with osteoblasts to cobalt chromium also led to significant release of TNF-alpha and PGE2, but did not lead to significant IL-6 or IL-1 beta production.

Similarities in the phenotypic expression of pericytes and bone cells.

Bovine brain microvessel pericytes, bone cells, and fibroblasts were grown in tissue culture in 3%, 21%, or 60% oxygen for 7 weeks. Alkaline phosphatase activity was highest in bone cells and pericytes grown in 3% oxygen, with the activity higher in the former than the latter. Alkaline phosphatase activity was very low in fibroblasts at every oxygen concentration.

Impact of CT scan on treatment plan and fracture classification of tibial plateau fractures.

Objective: To evaluate the interobserver and intraobserver agreement for both treatment plan and fracture classification of tibial plateau fractures using plain films alone and with computed tomography (CT) scans.

Design: Prospective study to assess the impact of an advanced radiologic study on the agreement of treatment plan and fracture classification of tibial plateau fractures.

Setting/participants: Two orthopaedic traumatologists, two orthopaedic residents, and two skeletal radiologists were presented with twenty-one cases of tibial plateau fractures imaged with plain films and with CT scans.