Faculty Bibliography

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

Aneurysmal bone cyst of the long bones in a purely intracortical or subperiosteal location is unusual. Three such cases are reported, and the radiographic and pathologic differential diagnoses are discussed. Those subperiosteal or intracortical aneurysmal bone cysts with radiographic features similar to the intramedullary variety should suggest the same diagnosis. However, the radiographic features may be less specific, so that a diagnosis of aneurysmal bone cyst must be entertained when considering a subperiosteal or intracortical lytic lesion.

Sarcoma associated with bone infarct is rare, and only 41 well-documented cases have been published. We describe five additional patients, three women and two men, aged 39 to 57 years. The tumors involved the femur (three patients), tibia (one patient), and humerus (one patient). In three patients, the infarcts were idiopathic. Radiologic evidence of malignancy was found in all patients, and bone infarcts were suspected in four. Four of the patients had malignant fibrous histiocytoma and one an osteosarcoma. Histologically, bone infarcts were seen in all patients, but in three they were mostly replaced by tumor. Portions of intact infarcts were seen adjacent to the tumor, indicating that they had preceded the development of the sarcoma. No hypercellular or atypical reparative tissue was found in the infarcted bones or in three additional uncomplicated infarcts studied from the same patients. The pathogenesis of sarcoma arising in bone infarct is unknown. The prognosis is poor; four of our five patients died within 2 years.

We performed a retrospective analysis of thirty-three consecutive total hip and knee (twenty-three hip and ten knee) revision arthroplasties during which intraoperative frozen sections were analyzed. Data for the study were collected by means of a review of the charts, radiographic analysis, and evaluation of both frozen and permanent histological sections. The frozen sections, of periprosthetic tissue at the bone-cement interface or the pseudocapsule, were considered positive for active infection if there were more than five polymorphonuclear leukocytes per high-power field in at least five distinct microscopic fields. All patients were available for follow-up, at an average of thirty-six months (range, seventeen to seventy-nine months) after the initial revision operation. The frozen sections from ten patients were positive for infection, and those from twenty-three patients were negative. Comparison of the results of the analyses of the frozen sections (both positive and negative) with those of the analyses of the permanent histological sections of similar tissue showed a correlation of 100 per cent (sensitivity, 1.00; specificity, 1.00; and accuracy, 1.00). Nine patients had positive intraoperative cultures, and all of them had positive frozen sections (sensitivity, 1.00). Of the twenty-four patients who had negative intraoperative cultures, twenty-three had negative frozen sections (specificity, 0.96). Of the nine patients who had positive intraoperative cultures, only two were found to have infection on intraoperative gram-staining. The surgeon's operative assessment regarding the presence of infection, compared with the final pathological diagnosis, demonstrated a sensitivity of 0.70, a specificity of 0.87, and an accuracy of 0.82. All ten patients who had positive frozen sections were managed with excision arthroplasty; six of them subsequently had reimplantation, and the excision was the definitive procedure in the remaining four. One patient who had had a delayed reimplantation had a secondary skin slough and eventually was managed with an arthrodesis of the knee. In the group that had negative frozen sections, eighteen patients had a primary exchange revision arthroplasty and five had a delayed reimplantation. At the time of follow-up, one patient who had had a delayed reimplantation had radiographic loosening of the femoral component and was asymptomatic. One patient who had had a primary exchange arthroplasty was managed with a second revision because of aseptic loosening. There was no clinical recurrence of infection in any patient. The data indicate that analysis of frozen sections of periprosthetic tissue is a reliable predictor of the presence of active infection during revision joint arthroplasty. We recommend its use to differentiate aseptic from septic loosening

A biomechanical study was performed to examine a proposed mechanism of fracture blister formation. Sixty cadaver ankle skin specimens were subjected to several levels of uniaxial strain and examined histologically. Dermal-epidermal separation patterns similar to those found histologically in previous studies of biopsied fracture blisters were seen in specimens strained 152% and greater. These findings support the hypothesis that fracture blisters can result from strain developed in the skin during initial fracture deformation

Light and electron microscopy was used for a histologic examination of normal heel fat pads and atrophic heel fat pads from patients with peripheral neuropathies. Histomorphometric analysis revealed an average 30% smaller mean cell area and 16% smaller mean cell diameters in the atrophic pads compared with the normal heel fat pads. Septal walls in the atrophic fat pads were often fragmented and approximately 75% wider than normal. Perineural fibrosis was also found in the atrophic heel fat pads. The Verhoeff elastic staining technique was used to determine the relative percentage of collagen to elastic tissue within the septae. No significant differences were noted between the normal and atrophic heels. The ultrastructure of the adipocytes from the normal and atrophic heel pads was similar to those found in abdominal subcutaneous fat. Lipid droplets of variable size and density thin the center of the adipocyte were surrounded by a thin border of cytoplasm. The interphase between adipocytes contained fine collagen and elastic fibers

This article describes a patient with a 10-year history of persistent ankle pain. Differential diagnosis included osteoid osteoma and anterior ankle impingement. This patient subsequently underwent arthroscopic excision of a lesion on the talar neck following a complete radiographic work-up, which was nondiagnostic. The diagnosis of osteoid osteoma was finalized upon pathologic study of the arthroscopic shavings. The use of a motorized instrument for excision did not preclude pathologic evaluation of the specimen. Therefore, in an accessible location on the talar neck, arthroscopic excision of an osteoid osteoma can be performed

A clinical and histological study was performed on fracture blisters found in association with 13 surgically treated ankle fractures. The timing of surgery was dependent upon soft tissue swelling; the status of the blister did not affect this aspect of the decision making process. The average time from injury to surgery was 2.1 days (range, 1-3 days). At the time of surgery all blisters were intact. Skin biopsies were obtained from the edge of the incision in proximity to the blister, and from the bed of the blister when the incision was made through the blister. Clinically, 2 blister types were identified: (1) clear fluid filled, and (2) blood filled. Histologically, both blister types demonstrated a cleavage injury at the dermoepidermal junction. However, the dermis of the clear fluid filled blister retained occasional epithelial cells, while the dermis of blood filled blisters was completely devoid of epidermis. Minimal to no evidence of dermal injury was found in histologic sections from the blister beds or from the skin in close proximity to blisters. All incisions made through and around skin blisters went on to heal without evidence of infection or wound breakdown. Delayed wound healing occurred in 1 patient in whom an incision was placed through a blood filled blister. The blood filled blister appears to represent a slightly deeper injury than the clear fluid blister and had a higher risk of poor healing of surgical incisions

Capillary gas-liquid chromatography was used to analyze the fatty acid composition of normal heel fat pads from subjects without systemic disease (N = 8) and atrophied heels from patients with diabetic peripheral neuropathy (N = 4), rheumatoid arthritis (N = 1), peripheral vascular disease (N = 1), and hereditary sensory neuropathy (N = 1). In the normal subjects, the fatty acid composition of subcutaneous abdominal fat was also obtained for comparison. Three saturated fatty acids (myristate, palmitate, and stearate) and four unsaturated fatty acids (palmitoleate, oleate, vaccenate, and linoleate) comprised over 90% of the total fatty acid composition. Higher percentages of unsaturated fatty acids and lower percentages of saturated fatty acids were found in the normal heel fat pads when compared to subcutaneous abdominal fat. The increase in the ratio of unsaturated fatty acids to saturated fatty acids (4.4 versus 2.5, P < .01) may decrease triglyceride viscosity and enhance the biomechanical efficiency of the heel fat pad. Though the number of patients is small, no statistically significant compositional differences were noted between the heel fat from normal subjects and from subjects with peripheral neuropathies, rheumatoid arthritis, or peripheral vascular disease. However, the heel fatty acid composition of the one subject with a hereditary sensory neuropathy was less unsaturated and more saturated than normal with a ratio of unsaturates to saturates similar to that of the abdomen (2.8)