Quantitative analysis of technetium-99m-sestamibi uptake and washout in parathyroid scintigraphy supports dual mechanisms of lesion conspicuity.

PURPOSE: Proposed mechanisms of parathyroid localization in 'dual-phase' technetium-99m-sestamibi imaging include increased presence of mitochondria leading to greater uptake and slower washout compared with thyroid tissues owing to reduced expression of P-glycoprotein. Using new techniques of quantitative single-photon emission computed tomography (SPECT)/computed tomography (CT), we have measured MIBI uptake and washout to better understand factors related to conspicuity. PATIENTS AND METHODS: We retrospectively reviewed 125 consecutive patients. Early and delayed SPECT/CT images were reconstructed using a previously validated technique. Maximum standardized uptake values of parathyroid adenomas and thyroid tissue were measured, and corresponding washout rates were calculated. RESULTS: Of 53 patients with localization of parathyroid adenoma (42%), median maximum standardized uptake values were higher for parathyroid adenomas than for thyroid tissue on both early (6.43±3.78 vs. 4.43±1.93, P<0.001) and delayed (3.40±3.09 vs. 1.84±1.05, P<0.001) images, being true on a per-patient basis in 41 (77%) and 48 (91%) patients, respectively. Median washout rates were slower from parathyroid adenomas than from thyroid lobes (0.26±0.16 vs. 0.42±0.18 h, P<0.001), being true on a per-patient basis in 43 (81%) patients. Similar findings were observed in a subgroup of 37 patients with surgically-confirmed adenomas. Of the patients where initial parathyroid uptake did not exceed thyroid uptake, all 12 exhibited slower MIBI washout from the parathyroid adenomas than from the thyroid gland. The characteristics of the thyroid gland did not differ in 67 patients without parathyroid localization. CONCLUSION: Quantitative analysis of 53 patients with localization of parathyroid adenoma revealed both a generally higher initial absolute uptake and slower rate of washout of MIBI in parathyroid adenomas than in thyroid tissue. The findings may support the hypothesis that both mechanisms proposed for parathyroid conspicuity in the dual-phase examination increased mitochondrial binding and slower washout owing to reduced P-glycoprotein expression. The technique of quantitative SPECT/CT represents a powerful tool for measuring tissue uptake to elucidate the contribution of these factors to lesion conspicuity.

Can this prosthesis be saved?: implant salvage attempts in infected primary TKA.

BACKGROUND: Open débridement with polyethylene liner exchange (ODPE) remains a relatively low morbidity option in acute infection of total knee arthroplasty (TKA), but concerns regarding control of infection exist. We sought to identify factors that would predict control of infection after ODPE. METHODS: We identified 44 patients (44 knees) with culture-positive periprosthetic infection who underwent ODPE. Failure was defined as any reoperation performed for control of infection or the need for lifetime antibiotic suppression. Patients had been followed prospectively for a minimum of 1 year (mean, 5 years; range, 1-9 years). RESULTS: Twenty-five of the 44 patients (57%) failed ODPE. Of these 25 patients, two had one additional procedure, 21 had more than one additional procedure, and two required lifetime antibiotic suppression. Failure rates tended to differ based on primary organism: 71% of Staphylococcus aureus periprosthetic infection failed versus 29% of Staphylococcus epidermidis, although with the limited numbers theses differences were not significant. Age, gender, or measures of comorbidity did not influence the risk of failure. There was no difference in failure rate (58% versus 50%) when the ODPE was performed greater than 4 weeks after index TKA. After a failed ODPE, 19 of the 25 failures went on to an attempted two-stage revision procedure. In only 11 of these 19 cases was the two-stage revision ultimately successful. CONCLUSIONS: Eradication of infection with ODPE in acute TKA infections is unpredictable; certain factors trend toward increased success but no firm algorithm can be offered. The success of two-stage revision for infection may be diminished after a failed ODPE. LEVEL OF EVIDENCE: Level III, retrospective comparative study. See Guidelines for Authors for a complete description of levels of evidence.

The John Insall Award: unicompartmental knee replacement: a minimum twenty-one-year followup, end-result study.

UNLABELLED: We report the results of a minimum 21-year followup of a consecutive series of 103 patients who had 136 Marmor cemented unicompartmental knee replacements done between 1975 and 1982. Patients were evaluated clinically and radiographically. At minimum 21-year followup 14 patients (19 knees) were alive, 87 patients (115 knees) had died, and only two patients (two knees) were lost to followup. The average age at surgery was 70.9 years. The average followup Hospital for Special Surgery knee score was 58. The average Knee Society final followup clinical and functional scores averaged 72 and 53 points, respectively. Nineteen knees (14%) were revised during the 21-year followup period: nine for progression of disease, eight for loosening, and two for pain, at an average of 10.6 years (range, 1-22 years). Of the 19 knees in the 14 patients who were still alive at final followup, seven (37%) were revised: two for tibial loosening, four for disease progression, and one for pain. Unicompartmental knee replacements in this relatively older age group of patients performed well at minimum 21-year followup. Although we are encouraged by these results, only 22% were done in patients who were younger than 65 years at the time of surgery and the results in this group were significantly less durable. LEVEL OF EVIDENCE: Therapeutic study, Level IV-1 (case series). See the Guidelines for Authors for a complete description of levels of evidence.

Thromboembolic disease in surgery for malignancy-rationale for prolonged thromboprophylaxis.

Patients undergoing surgery for malignancy are at increased risk of initial and recurrent venous thromboembolism (VTE). Several factors have been found to increase the risk of deep vein thrombosis (DVT) in cancer patients both during the first days after the operation and after discharge from hospital. Although, in general, thromboprophylaxis is provided to cancer patients after surgery, the length of time these patients require prophylaxis has not yet been established. Autopsy series, clinical series, and clinical trials indicate that up to about 40% of VTE occurs post discharge. General surgical patients undergoing major abdominal surgery require VTE prophylaxis, and prolonged thromboprophylaxis should be considered in the post-discharge period in high-risk patients, particularly those with cancer. Evidence from studies in general and orthopedic surgery show that prolonged prophylaxis reduces the number of thromboembolic events after discharge from hospital. Prophylaxis should be simple, safe, and effective and should be administered easily to allow continuation of therapy after discharge. Low-molecular-weight heparins are potentially the most suitable agents for long-term thromboprophylaxis in cancer patients.

Vaccinia virus semaphorin A39R is a 50-55 kDa secreted glycoprotein that affects the outcome of infection in a murine intradermal model.

Vaccinia virus (VV) protein A39R has amino acid similarity to the extracellular domain of a glycosylphosphatidylinositol-linked cell surface semaphorin (SEMA7A/CDw108) that has an immunological expression profile and binding properties, thereby implicating A39R as an immunomodulator. Previously, a closely related A39R protein expressed by ectromelia virus was shown to induce cytokine production and up-regulate ICAM-1 expression in mouse monocytes in vitro. In this study, we show that the A39R gene of VV strain Copenhagen (COP) encodes a 50-55 kDa secreted glycoprotein and is expressed late during infection. The A39R protein was secreted by eight of 15 strains of VV, but not by strain Western Reserve (WR). To analyse the VV A39R function, several recombinant viruses were made, including an A39R deletion mutant of VV COP and a WR mutant containing the A39R sequence from COP. Loss of the gene from COP did not affect virus growth in vitro, or VV virulence in a mouse intranasal model, and had only a slight effect on lesion size in an intradermal model. In contrast, expression of COP A39R by VV WR was associated with an increase in the severity and persistence of skin lesions after intradermal infection of mice. Finally, a histological examination of mouse skin infected with recombinant viruses suggested that A39R has direct or indirect pro-inflammatory properties.