German C. Steiner

The Reliability of Analysis of Intraoperative Frozen Sections for Identifying Active Infection during Revision Hip or Knee Arthroplasty

A prospective study was performed to determine the reliability of analysis of intraoperative frozen sections for the identification of infection during 175 consecutive revision total joint arthroplasties (142 hip and thirty-three knee). The mean interval between the primary and the revision arthroplasty was 7.3 years (range, three months to twenty-three years). To reduce selections bias, tissue was obtained for frozen sections during all revisions in patients who did not have active drainage from the wound or a sinus tract. Of the 175 patients, twenty-three had at least five polymorphonuclear leukocytes per high-power field on analysis of the frozen sections and were considered to have an infection. Of these twenty-three, five had five to nine polymorphonuclear leukocytes per high-power field and eighteen had at least ten polymorphonuclear leukocytes per high-power field. The frozen sections for the remaining 152 patients were considered negative. On the basis of cultures of specimens obtained at the time of the revision operation, nineteen of the 175 patients were considered to have an infection. Of the 152 patients who had negative frozen sections, three were considered to have an infection on the basis of the results of the final cultures. Of the twenty-three patients who had positive frozen sections, sixteen were considered to have an infection on the basis of the results of the final cultures; all sixteen had frozen sections that had demonstrated at least ten polymorphonuclear leukocytes per high-power field. The sensitivity and specificity of the frozen sections were similar regardless of whether an index of five or ten polymorphonuclear leukocytes per high-power field was used. Analysis of the frozen sections had a sensitivity of 84 per cent for both indices, whereas the specificity was 96 per cent when the index was five polymorphonuclear leukocytes and 99 per cent when it was ten polymorphonuclear leukocytes. However, the positive predictive value of the frozen sections increased significantly (p < 0.05), from 70 to 89 per cent, when the index increased from five to ten polymorphonuclear leukocytes per high-power field. The negative predictive value of the frozen sections was 98 per cent for both indices. The current study suggests that it is valuable to obtain tissue for intraoperative frozen sections during revision hip and knee arthroplasty. At least ten polymorphonuclear leukocytes per high-power field was predictive of infection, while five to nine polymorphonuclear leukocytes per high-power field was not necessarily consistent with infection. Less than five polymorphonuclear leukocytes per high-power field reliably indicated the absence of infection.

Vascular tumors of bone.

Abstract Primary tumors of bone of vascular origin are rare. Consequently, knowledge of their clinical and pathologic features is still scanty. A morass of misleading terminology, particularly in connection with the malignant vascular tumors, has added to the difficulties. This paper is a review of our current knowledge of these lesions based on a series of 42 personally studied cases. It presents a classification of the vascular tumors of bone and its converings and attempts to sort out in an orderly way the confusing array of terms applied to the malignant bone tumors of blood vessel origin.

Bone morphogenetic protein promotes vascularization and osteoinduction in preformed hydroxyapatite in the rabbit

Early reconstruction of large osseous defects in children is often delayed due to limited availability of autogenous bone graft donor sites. With the advent of growth factors, osteoinductive proteins, and delivery matrices, it is possible to fabricate new bone at extraskeletal sites. Due to their own blood supply, adequate bony volume, and decreased resorption, vascularized bone flaps have demonstrated greater success in restoring large bony defects compared with nonvascularized bone grafts. The purpose of this study is to prefabricate a vascularized bone flap in the immatureage rabbit using the auricularis anterior muscle as a muscle pedicle. Sixteen female New Zealand White rabbits, 2.0 to 2.5 kg, were divided into two groups. Group 1 contained 8 animals that had T-shaped, 10 ×6 × 4-mm hydroxyapatite (HA) implants combined with 100-µg bovine-derived bone morphogenetic protein (BMP) placed supraperiosteally and fixed deep to the auricularis anterior muscle. Implants with HA alone were placed in the same animal and secured to the contralateral auricularis anterior muscle. Group 2 contained 8 animals that had HA/BMP placed subperiosteally and fixed deep to the auricularis anterior muscle, while implants with HA alone were secured in the same animal to the contralateral auricularis anterior muscle. In each group, 4 animals were sacrificed at 4 and 8 weeks. The animals underwent randomized bilateral carotid artery Injection with micropaque barium suspension just prior to sacrifice to help maintain vascularity. At harvest the implants and surrounding muscle and cranium were removed en bloc. New bone formation in the HA implants was examined by using routine histology and scanning electron microscopic backscattering image (quantitative) analysis. Microradiographs were performed on representative specimens. At 4 weeks postimplantation, backscattering analysis in the subperiosteal HA/BMP showed a mean 17.1% bone ingrowth vs. 11.3% of HA alone (p < 0.05). Supraperiosteal HA/BMP showed a mean 12.9% bone ingrowth vs. 0% of HA alone (p < 0.05). At 8 weeks, backscatter analysis of supraperiosteal HA/BMP showed a mean 19.33% bone ingrowth vs. 0% of HA alone (p < 0.05). Subperiosteal HA/BMP showed a mean 22% bone ingrowth vs. 20.85% of HA alone. This was the only group that did not have statistically significant results. Implant histology demonstrated woven bone within the interstices of HA/BMP placed either supra- or subperiosteally. In the HA-alone implants placed supraperiosteally, fibrovascular ingrowth was seen without any evidence of bone formation. In the HA-alone implant placed subperiosteally, woven bone was seen at the calvarium-implant junction. Microradiographs also demonstrated vascularization and bone formation similar to that seen on scanning electron microscopy. BMP-treated specimens appeared to have slightly greater vascularity than the nontreated specimens. The greatest bone formation occurred with the HA/BMP implant placed subperiosteally in the immature rabbit. Furthermore, these results demonstrate the potential prefabrication of vascularized bone flaps as early as 4 to 8 weeks. The clinical advantage of HA permits the surgeon to design osseous flaps that are customized in shape, fill all contour defects, and have little resorptive properties. Such prefabricated bone with an axial blood supply may allow for ultimate transfer as a pedicle or free flap to reconstruct osseous defects in children.

Eosinophilic granuloma: MRI manifestations

The appearance on magnetic resonance imaging (MRI) of 16 cases of pathologically proven eosinophilic granuloma were reviewed retrospectively and correlated with the radiographic appearance of the lesion. The most common MR appearance (ten cases) was a focal lesion, surrounded by an extensive, ill-defined bone marrow and soft tissue reaction with low signal intensity on T1-weighted images and high signal intensity on T2-weighted images, considered to represent bone marrow and soft tissue edema (the flare phenomenon). The MRI manifestations of eosinophilic granuloma, especially during the early stages, are nonspecific, and may simulate an aggressive lesion such as osteomyelitis or Ewings sarcoma, or other benign bone tumors such as osteoid osteoma or chrondroblastoma.

Osteopontin : An intrinsic inhibitor of inflammation in cartilage

OBJECTIVE To identify extracellular and intraarticular matrix components that are differentially expressed in normal and osteoarthritis (OA)-affected cartilage and to investigate their functions with respect to regulation of mediators of inflammation. METHODS Differential-display reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of a pool of messenger RNA (mRNA) from 10 human OA cartilage samples and 5 normal cartilage samples was performed using arbitrary primers. Confirmatory analysis of the up-regulated transcripts of fibronectin (FN) and osteopontin (OPN) was performed by RT-PCR of individual RNA samples from a separate set of donors. The effect of recombinant OPN (or anti-OPN antiserum) on chondrocyte function was examined by analyzing the spontaneous or interleukin-1 (IL-1)-induced release of nitric oxide (NO) and prostaglandin E2 (PGE2) from human OA-affected cartilage under ex vivo conditions. RESULTS Up-regulation (300-700%) of FN and OPN mRNA was observed in human OA-affected cartilage as compared with normal cartilage. Functional analysis of the role of OPN in OA cartilage showed that 1) Addition of 1 microg/ml (20 nM) of recombinant OPN to human OA-affected cartilage under ex vivo conditions inhibited spontaneous and IL-1beta-induced NO and PGE2 production, and 2) neutralization of intraarticular OPN with anti-OPN antiserum augmented NO production. CONCLUSION The data indicate that one of the functions of intraarticular OPN, which is overexpressed in OA cartilage, is to act as an innate inhibitor of IL-1, NO, and PGE2 production. These findings suggest that the production of pleiotropic mediators of inflammation that influence cartilage homeostasis, such as NO and PGE2, is regulated by the interaction of chondrocytes with differentially expressed proteins within the extracellular matrix.

Bone island (enostosis): clinical significance and radiologic and pathologic correlations.

This study was undertaken to explain the increased scintigraphic activity of some bone islands by correlating the clinical, radiographic, scintigraphic, and histopathologic findings. The material for the study consisted of six patients with bone islands who had undergone histopathologic examinations of the lesions. Based on histopathologic-radiologic correlations, we postulate that the osteoblastic activity of a bone island makes it appear “hot” on scintigraphy, although other factors such as the size of the lesion may play some role in this phenomenon. In addition, we tried to find a logical algorithm for the radiologic evaluation and management of sclerotic lesions that look like bone islands but exhibit increased uptake of radiopharmaceuticals on bone scan examination. We emphasize that the morphology of the lesion, as demonstrated on the radiologic examination, rather than its degree of activity on the bone scan is a guide to the correct diagnosis.

Chondrocalcinosis of the hyaline cartilage of the knee: MRI manifestations

Abstract Purpose. To determine the ability of MRI to detect the presence of crystals of calcium pyrophosphate in the articular cartilage of the knee. Design and patients. The MR studies of 12 knees (11 cases) were reviewed retrospectively and correlated with radiographs (12 cases) and the findings at arthroscopy (2 cases) and surgery (1 case). A total of 72 articular surfaces were evaluated. Radiographic, surgical or arthroscopic demonstration of chondrocalcinosis was used as the gold standard. Additionally, two fragments of the knee of a patient who underwent total knee replacement and demonstrated extensive chondrocalcinosis were studied with radiography and MRI using spin-echo T1-, T2- and proton-density-weighted images as well as two- and three-dimensional fat saturation (2D and 3D Fat Sat) gradient recalled echo (GRE) and STIR sequences. Results. MRI revealed multiple hypointense foci within the articular cartilage in 34 articular surfaces, better shown on 2D and 3D GRE sequences. Radiographs showed 12 articular surfaces with chondrocalcinosis. In three cases with arthroscopic or surgical correlation, MRI demonstrated more diffuse involvement of the articular cartilage than did the radiographs. The 3D Fat Sat GRE sequences were the best for demonstrating articular calcification in vitro. In no case was meniscal calcification identified with MRI. Hyperintense halos around some of the calcifications were seen on the MR images. Conclusion. MRI can depict articular cartilage calcification as hypointense foci using GRE techniques. Differential diagnosis includes loose bodies, post-surgical changes, marginal osteophytes and hemosiderin deposition.

In situ analysis of Paget's disease of bone for measles-specific PCR-amplified cDNA.

Pagets disease of bone is a disease of unknown etiology. The demonstration of viral-like particles on ultrastructural examination and the putative detection of viral antibodies and nucleic acids in the tissues suggest a possible viral association. The purpose of this study was to search for nucleic acid sequences homologous to measles virus using the recently described reverse transcriptase (RT) polymerase chain reaction (PCR) in situ hybridization (ISH) technique. After performing RT PCR ISH utilizing primers specific for the nucleocapsid region of the measles virus, an intense signal was evident in most measles-infected HeLa cells compared with a weak signal in few of these cells using standard cDNA-RNA ISH analysis. Amplified measles nucleic acid was detected in tissue from a patient who died of measles infection and was not detected in any of the 11 cases of Pagets disease of bone studied or in a giant cell tumor of bone that had tubuloreticular inclusions on electron microscopy. Therefore, these data suggest that infection by the measles virus is not associated with Pagets disease of bone.

Ultrastructure of hemangioendothelial sarcoma of bone

The ultrastructural findings in a case of well‐differentiated hemangioendothelial sarcoma of bone are described. The tumor vessels are lined by plump endothelial cells, with a larger number of organelles than their normal counterparts. Discontinuities of the vessel wall with endothelial gaps are observed. Pericytes are present in the wall of the vessels, and some are loosely attached. A few fibroblasts and smooth muscle cells are seen. Transitional stages between fibroblasts and pericytes and between pericytes and smooth muscle cells are observed. The intervascular cellular infiltration is most likely the result of extravasation through gaps in the fragile neoplastic vessels. It is proposed that the pericytes are the main source of reticulum fibers in the tumor.

MULTIDIMENSIONAL DISTRACTION OSTEOGENESIS : THE CANINE ZYGOMA

The principle of distraction osteogenesis, well-established in the enchondral bones of the axial skeleton, has recently been applied to the membranous bones (mandible, cranium) of the craniofacial skeleton in the experimental animal and in the human. In the craniofacial skeleton, however, the technique has been used only to lengthen bone in a direction along its major axis, i.e., unidimensional distraction. A canine model is presented to demonstrate the feasibility of distracting membranous bone away from its dominant axis, i.e., multidimensional distraction. Four mongrel dogs, 5 months of age, were the subjects of this study. Two osteotomies were made in the zygomatic arch, and the bone-lengthening device was fixed to the zygoma. After 7 days of external fixation, the osteotomized segment was lengthened 1 mm/day away from the long axis of the bone for 15 days. External fixation was then maintained for a minimum of 4 weeks, after which the dogs were sacrificed. Craniofacial CT with three-dimensional reconstruction documented multidimensional bone lengthening, and histologic analysis of the specimen confirmed the presence of new cortical bone in the expanded areas. Refinement in technique and miniaturization and internalization of the bone-lengthening device may allow for more precise changes in the amount and direction of lengthening, thus making distraction osteogenesis more widely applicable for use in the human craniofacial skeleton.