Validation of the in vivo volumetric wear measurement for total knee prostheses in model-based RSA.

Implant failure related to polyethylene wear remains an important issue in total knee arthroplasty. Polyethylene wear is usually assessed in vivo by measuring the remaining insert thickness on X-ray images of the knee. To reflect the amount of wear debris more accurately, a 3-dimensional overlap measurement has been suggested, which is based on implant component models which are matched on calibrated stereo X-ray images using model-based roentgen stereophotogrammatic analysis. The goal of this study was to determine the influence of pose estimation, insert thickness deviation and variation in the femoral-tibial contact location on the accuracy and precision of the measurement using simulations and a phantom experiment. We found that the pose estimation was the largest source of variation. The 95% prediction interval varied between 111 and 283 mm(3), which is approximately 100-200% of the detected volumetric wear. Insert thickness variation resulted in prediction intervals of 74-174 mm(3). Variation of the femoral-tibial contact location in the phantom experiment gave a prediction interval of 40 mm(3). Large differences in the detected wear volume were found for different flexion angles. At most 56% of the true wear volume was detected (129 of 230 mm(3), 30° of flexion). In summary, both the accuracy and precision of the volumetric wear measurement were low. The prediction interval of the volumetric wear measurement is at least as large as the measurement outcome itself. This is an important limitation to the applicability of the volumetric wear measurement in clinical practice and further clinical validation is required.

Clinical and technical factors influencing outcomes of unicompartmental knee arthroplasty: Retrospective multicentre study of 944 knees.

INTRODUCTION: Unicompartmental knee arthroplasty (UKA) is reserved for osteoarthritis confined to a single femoro-tibial compartment with an intact anterior cruciate ligament. UKA remains controversial. The objective of this retrospective multicentre study in a large sample was to assess the influence of age, sex, body mass index (BMI), patellofemoral involvement, and implant design on functional outcomes and prosthesis survival rates. MATERIAL AND METHODS: Nine hundred and forty-four patients who underwent UKA at centres located in western France between 1988 and 2008 were re-evaluated. The IKS scores and KOOS were determined. Prosthesis survival according to various factors was assessed using the Kaplan-Meier method. RESULTS: A clinical evaluation was performed in 720 cases after a mean follow-up of 62 months. The IKS function score improved by 23.6 points in men and 17.3 points in women (P=0.007). Ten-year prosthesis survival was 83.7% overall; 79% in women versus 87% in men (P<0.01); and 76.7% in patients younger than 70 years versus 88.3% in those 70 years or over (P<0.01). BMI had no significant influence on prosthesis survival. No significant differences between clinical outcomes or prosthesis survival were found across implant design categories. DISCUSSION: The retrospective design and large number of centres and surgeons mandate caution when interpreting our results. Subgroup sizes were too small for an analysis of factors such as anterior cruciate ligament deficiency, BMI>40 kg/m(2), or cementless implant. LEVEL OF EVIDENCE: Level IV, retrospective study.

Oral thromboprophylaxis following total hip replacement: the issue of compliance.

INTRODUCTION: Thirty-five to 40 days' thromboprophylaxis is recommended following total hip replacement (THR). Low molecular weight heparin (LMWH) injected by a health professional ensures good compliance. Compliance with recent oral anticoagulants has not been precisely assessed. Oral self-administration, without coagulation monitoring tests, may be a worrying issue in the management of what is a potentially catastrophic adverse event, without prodromal symptoms alerting the patient to the need for regular intake throughout the prescription period. HYPOTHESIS: It was hypothesized that compliance with these new oral anticoagulants is good over the entire treatment period. PATIENTS AND METHOD: The present cohort study prospectively assessed compliance with oral medication (two capsules of dabigatran etexilate [Pradaxa(®)] per day in a single dose at a set time) following THR. An electronic device continuously monitored the day and time of extraction of capsules from the package. All included patients underwent clinical and echo-Doppler examination at day 30±5 after the start of the study. RESULTS: Fifty-six patients were included at their discharge home. Overall compliance was 98.1% (3,188/3246 capsules correctly taken), falling off slightly over time but never below 97.1%. One patient was diagnosed with symptomatic thrombophlebitis 34 days postoperatively, associated with non-compliance at day 11. End of follow-up echo-Doppler found four cases of asymptomatic distal venous thrombosis. There were no hemorrhagic complications. DISCUSSION: The risk of thromboembolic complications diminishes over time, while oral anticoagulants have a wide therapeutic window and relatively long half-life (15-17 hrs). Efficacy was demonstrated, with improved patient comfort and cost-saving. Compliance in the present series was satisfactory. This, however, should not mean that patients not be appropriately informed, as in the present study, so as to improve compliance. LEVEL OF EVIDENCE: Level III, prospective diagnostic.

Posterior tibial slope changes after opening- and closing-wedge high tibial osteotomy: a comparative prospective multicenter study.

INTRODUCTION: Valgus high tibial osteotomy is considered to be an effective treatment for unicompartmental medial osteoarthritis. It is generally admitted that tibial slope increases after open-wedge high tibial osteotomy and decreases after closing-wedge high tibial osteotomy. However, the effects on posterior tibial slope of closing- or opening-wedge osteotomies remain controversial. HYPOTHESIS: We analyzed the modifications of tibial slope after opening- and closing-wedge high tibial osteotomies and compared the results of these two procedures. We hypothesized that there was no difference in postoperative tibial slope between opening and closing-wedge osteotomies. PATIENTS AND METHODS: This prospective consecutive nonrandomized multicenter study was conducted between January 2008 and March 2009 and included 321 patients: 205 men and 116 women. A total of 224 patients underwent an opening-wedge high tibial osteotomy and 97 a closing-wedge osteotomy. The mean age was 52 years ± 9 and the mean body mass index was 28kg/m(2) ± 5. The main etiology was primary arthritis. Posterior tibial slope was measured preoperatively and at the last follow-up on a lateral radiograph in relation to the posterior tibial cortex. RESULTS: In the opening-wedge group, a definite 0.6° increase in tibial slope (P=0.016) was observed. In the closing-wedge group, a definite 0.7° decrease in tibial slope (P=0.02) was found. Fourteen percent of the opening-wedge osteotomies increased tibial slope by 5° or more versus only 2% of the closed-wedge osteotomies (P<0.001). Twelve percent of the closing-wedge high tibial osteotomies led to a decrease of 5° or more of the tibial slope versus 7% of the opening-wedge osteotomies (P<0.02). DISCUSSION AND CONCLUSION: These results confirm what is generally reported in the literature, i.e., an increase in tibial slope in opening-wedge high tibial osteotomy and a decrease in the slope in closing-wedge osteotomies. These tibial slope changes appear to be very limited in this series, less than 1° on average. However, there was a bias since the open-wedge technique was preferred in cases with substantial varus deformity. We emphasize the importance of surgical technique to avoid alteration of the tibial slope, particularly in opening-wedge high tibial osteotomy for which we recommend a release of posterior soft tissue and a complete osteotomy of the posterior cortex of the tibia. LEVEL OF EVIDENCE: III. Prospective consecutive nonrandomized multicenter study.

Mosaic osteochondral transplantations in the knee joint, midterm results of the SFA multicenter study.

INTRODUCTION: There are several possible options to treat focal articular cartilage defects of the knee. The aim of this study was to evaluate the results and prognostic factors cartilage defects of the knee treated by autologous osteochondral mosaicplasty after more than five years of follow-up. PATIENTS AND METHODS: One hundred forty-two cases were included in this retrospective multicenter study. Etiologies included osteochondral fractures (n=79), and osteochondritis dissecans (n=61). Mean age of patients was 31. There was a majority of men (76%). Mean BMI was 25 (range: 21-41). Fifty-three percent of the knees had a history of surgery. Mean delay between the accident and surgery was 2.5 years. Mean area of the defect was 2.29 cm(2) (range: 0.3-12.25 cm(2)). The depth of the defect was 3 or 4 on the ICRS score in 97% of cases. An additional surgical procedure was associated with mosaicplasty in 14% of the cases. The follow-up evaluation was based on the Hughston score, the ICRS score, the IKDC subjective score, and the IKDC radiological score. Evaluation of control MRI was based on a modified MOCART score. RESULTS: The mean follow-up was 96 ± 28 months. There were complications in 19 patients. Patients were able to begin athletic activities again after a mean 35 weeks. Most patients (81.8%) were satisfied or very satisfied. There was a significant improvement (p<0.001) in the ICRS, IKDC function and Hughston scores at follow-up. The factors for a good prognosis were: male gender, medial femoral condyle defects, osteochondritis dissecans, deep, small defects, and the shortest possible delay to surgery. Obesity, smoking, work-related accidents, the level of sports practiced, the percentage of coverage of the defect, the number of plugs, and associated lesions did not have a statistically significant effect on the functional results in the final follow-up. DISCUSSION: Autologous osteochondral mosaicplasty seems to be a reliable technique in the short and intermediate term. It has the advantage of being less expensive than reconstructive techniques, is a one-step surgical procedure and results in immediate restoration of cartilage surface. Nevertheless, this is a difficult technique, which may result in complications and requires articular harvesting. This technique is limited by the size of the defect to be treated. The primary indication is deep, small defects on the medial femoral condyle.

Total knee arthroplasty three-dimensional kinematic estimation prevision. From a two-dimensional fluoroscopy acquired dynamic model.

INTRODUCTION: To determine six-degree of freedom of total knee arthroplasty kinematics (TKA), optimized matching algorithms for single fluoroscopic image system may be used. Theoretical accuracy of these systems was reported. Nevertheless, all reports were done under idealized laboratory experimental conditions. The aim of this study was to evaluate the "true" accuracy of a flat panel single plane video-fluoroscopy system based on computed-assisted design (CAD) model matching and compare it to TKA kinematics obtained from optoelectronic measurements as gold standard. HYPOTHESIS: The estimation of the error produced by 2D/3D fluoroscopic registration in daily practice is misjudged in most available laboratory reports. MATERIAL AND METHODS: The experimental set-up used a TKA implanted into femoral and tibial cadaver bones. Thirty flexions were simultaneously registered using single plane fluoroscopy and an active optical tracking system. Kinematics registered were compared using the root mean square error (RMS), the concordance correlation coefficient and Bland & Altman plot analysis. RESULTS: The mean range of motion of flexion during the experiment was 106°. The respective RMS for flexion, varus-valgus and internal-external rotation were 0.68, 0.67 and 1.02°. The respective RMS for antero-posterior, medio-lateral and proximo-distal displacement were 1.3, 2.4 and 1.06 mm. Extreme values of the measured error concerning medio-lateral displacement were -5.4 and 22,1mm. DISCUSSIONS: Analysis found some outliners in all degree of freedom with a systematic error and larger standard deviation than already published data. One should make sure that during the experiment the motion of interest is in the in-plane direction. Moreover, this study brings out the true threshold detection of this type of analysis.

Dual mobility hip arthroplasty wear measurement: Experimental accuracy assessment using radiostereometric analysis (RSA).

INTRODUCTION: The use of dual mobility cups is an effective method to prevent dislocations. However, the specific design of these implants can raise the suspicion of increased wear and subsequent periprosthetic osteolysis. HYPOTHESIS: Using radiostereometric analysis (RSA), migration of the femoral head inside the cup of a dual mobility implant can be defined to apprehend polyethylene wear rate. STUDY OBJECTIVES: The study aimed to establish the precision of RSA measurement of femoral head migration in the cup of a dual mobility implant, and its intra- and interobserver variability. MATERIAL AND METHODS: A total hip prosthesis phantom was implanted and placed under weight loading conditions in a simulator. Model-based RSA measurement of implant penetration involved specially machined polyethylene liners with increasing concentric wear (no wear, then 0.25, 0.5 and 0.75mm). Three examiners, blinded to the level of wear, analyzed (10 times) the radiostereometric films of the four liners. There was one experienced, one trained, and one inexperienced examiner. Statistical analysis measured the accuracy, precision, and intra- and interobserver variability by calculating Root Mean Square Error (RMSE), Concordance Correlation Coefficient (CCC), Intra Class correlation Coefficient (ICC), and Bland-Altman plots. RESULTS: Our protocol, that used a simple geometric model rather than the manufacturer's CAD files, showed precision of 0.072mm and accuracy of 0.034mm, comparable with machining tolerances with low variability. Correlation between wear measurement and true value was excellent with a CCC of 0.9772. Intraobserver reproducibility was very good with an ICC of 0.9856, 0.9883 and 0.9842, respectively for examiners 1, 2 and 3. Interobserver reproducibility was excellent with a CCC of 0.9818 between examiners 2 and 1, and 0.9713 between examiners 3 and 1. DISCUSSION: Quantification of wear is indispensable for the surveillance of dual mobility implants. This in vitro study validates our measurement method. Our results, and comparison with other studies using different measurement technologies (RSA, standard radiographs, Martell method) make model-based RSA the reference method for measuring the wear of total hip prostheses in vivo. LEVEL OF EVIDENCE: Level 3. Prospective diagnostic study.

Cemented total hip stem design influence on adaptative cortical thickness and femoral morphology.

INTRODUCTION: Five-year following total hip implantation femur adaptive morphology was compared between two groups differing only in their femoral stem design. MATERIAL AND METHODS: Group 1, recruited prospectively, included 51 Dédicace stems(Stryker-Howmedica) and group 2, retrospectively matched to group 1, comprised 51 Kerboull MK3 stems (Stryker-Howmedica). While MK3 prosthetic system increases in size homogeneously (widening along the whole length as the implant dimension increases), the Dédicace prosthetic system provides various metaphyseal widths for a given diaphyseal size. We opted for primary fixation (press fit according to the "French paradox") prior to cementing in both cases, despite the risk of discontinuity in the cement mantle. The homogeneous dimensioning of the MK3 stem enables distal primary fixation, whereas the Dédicace range allows differentiated adaptation to diaphyseal length and metaphyseal caliber. The following parameters were measured and calculated: Noble index, femoral cortical thickness score of Barnett and Nordindiaphyseal filling and stress-shielding at three levels around the stem. RESULTS: Bone-remodeling, assessed on X-ray, was without clinical impact, whether it took the form of spongialization or stress-shielding. The sole factor tending to induce stress-shielding was a high degree of canal filling by the distal third of the stem, more frequently encountered with the MK3 model. Metaphyseal filling was equivalent with all stems. In the matched series on the contralateral healthy side, femoral spongialization was comparable. LEVEL OF PROOF: Level III; case/control study.

[Antithrombotic prophylaxis after THA and TKA: the surgeon's point of view]. / Prophylaxie antithrombotique après PTH et PTG : le point de vue du chirurgien.

Total hip arthroplasty (THA) and total knee arthroplasty (PTG) are surgical interventions aiming at functional improvement. They therefore cannot accommodate any "collateral damage" produced, notably by symptomatic thromboembolic events (STE). Use of the necessary thromboprophylaxis has made STEs rare (<3% after THA and 2% after TKA). Pulmonary embolism (PE) is exceptional (0.3%) and only accounts for 15% of the deaths occurring in the 1st postoperative month. However, atherothrombotic disease is significantly associated with thromboembolic venous disease. The causes of STEs are mechanical, directly related to surgical maneuvers, but also biological (familial or acquired thrombophilia, hypercoagulability, particularly associated with hip surgery). Delayed resumption of walking, which promotes venous stasis, has been improved by modern pain management techniques. There is consensus on the need to prolong thromboprophylaxis after THA, but it is more controversial after TKA and depends on the added risk factors. In France, prolonged prevention is widespread. The relatively low STE rate should be put into perspective with the risk of hemorrhage. The surgeon should be particularly attentive to the risk of bleeding at the operative site because it generates a risk of sepsis, and a risk of stiffness for TKA. The risk of hemorrhage essentially results from the misuse of all the anticoagulants, particularly observed with the anti-vitamin K medications because their use is more restricted. The risk of hemorrhage has become quite comparable to the risk of thromboembolism with prophylaxis. To prevent this event, the prescriber must know the characteristics of each drug : Tmax, half-life, mode of elimination, as well as the risk of accumulation in the patient receiving such treatment (creatinine clearance). Currently, the thrombohemorrhagic risk for each patient must be assessed. Per os treatment with Dabigatran etexilate is highly advantageous because it is easy to use, there is no thrombopenia induced by heparin, and there is no need for complementary monitoring exams, thus reducing costs. Efficacy in terms of prevention and hemorrhagic risk, demonstrated in phase II studies, must be confirmed by widespread used in real-life conditions.

[Survival of the cementless Bousquet dual mobility cup: Minimum 15-year follow-up of 437 total hip arthroplasties]. / Survie à 16,5 ans de recul moyen de la cupule, double mobilité, non scellée de Bousquet dans l'arthroplastie totale de hanche. Série historique de 437 hanches.

PURPOSE OF THE STUDY: The purpose of this study was to evaluate the long-term results of a retrospective series of primary arthroplasty with a cementless dual mobility socket and a cemented Charnley type femoral component. MATERIAL AND METHODS: This study included 437 hip replacements performed between 1984 and 1990, in 388 patients. The Bousquet's acetabular component, an original concept of cementless dual mobility socket has been used, associated with a cemented Charnley type femoral component. A clinical and radiologic analysis was done. RESULTS: The outcome is known for 345 hips (79%): 164 alive without revision at a mean of 16,5 years follow-up, 137 died without revision and 44 failures. Ninety-two (21%) were lost at follow-up. According to Kaplan-Meier analysis, the 5-year survival rate, was 84,4%+/-4,5 with revision for any reason (infection, dislocation, osteolysis...) for end point. Revision, for aseptic loosening of femoral or acetabular component, was performed in 30 hips (6,8%). Five dislocations occurred and were revised: two early related to technical errors and three after 10 years or more of follow-up. The young age of the patients at the time of the index surgery was correlated with higher rate of aseptic loosening. DISCUSSION: The prevalence of revision for dislocation is very low in our series. This concept does not avoid wear, osteolysis and aseptic loosening, especially in young active patients but the long-term stability is confirmed. We recommend this type of prosthesis for patients over 70 years and for younger patients with high risk of dislocation Q.

Allergen-induced mediator release tests.

The diagnosis of allergic reactions in clinical practice is based on both clinical history and the determination of specific immunoglobulin E (IgE), either in the serum or on skin mast cells. However, for various reasons, identification of the causative factors is not possible in all the cases. Moreover, not all allergies are IgE-dependent. In an attempt to find sensitive, specific and cost-effective methods to investigate hypersensitivity reactions, in vitro tests were developed at a very early stage. Allergen-induced mediator release assays analyze the mediator released from effector cells, mainly peripheral blood cells, when stimulated in vitro with serial dilutions of the putative allergens. Described initially as research tools, they could well become diagnostic tests. However, relatively few high quality reports have been published so far. In this review, we will detail allergen-dependent histamine, tryptase, arachidonic acid metabolite, e.g. cysteinyl leukotrienes and 15-hydroxyeicosatetraenoic mediator release tests.

Inhibition of mediator and cytokine release from dispersed nasal polyp cells by mizolastine.

BACKGROUND: Mizolastine is a potent and selective H1-receptor antagonist with antiallergic properties; in in-vitro animal models, mizolastine was shown to inhibit 5-lipoxygenase activity and to decrease the release of leukotrienes (LT) and tumor necrosis factor-alpha (TNF-alpha). This study investigated the effects of three concentrations of mizolastine (0.1, 1.0, 10 microM) on the release of LT (LTB4 and LTC4/D4) and prostaglandin D2 (PGD2) after stimulation by anti-IgE, and on the spontaneous release of cytokines (TNF-alpha and granulocyte/macrophage-colony-stimulating factor [GM-CSF]), from dispersed cells obtained from surgically resected nasal polyps of patients with nasal polyposis. METHODS: Cells from nasal polyps were obtained using enzymatic dispersion. For experiments involving the measurement of LT and PGD2, the cells were preincubated with mizolastine or its dissolution vehicle for 20 min prior to challenge with 10 microg/ml epsilon-chain specific anti-IgE for 45 min at 37 degrees C; for the cytokine release, cells were incubated with mizolastine or its dissolution vehicle for 24 h. LT and PGD2 were measured by enzyme immunoassay (EIA) and cytokines by enzyme-linked immunosorbent assay (ELISA) using commercially available kits. RESULTS: Mizolastine inhibited significantly and in a dose-dependent manner the release of LTB4 and TNF-alpha at all concentrations, LTC4/D4 at 10 microM, and GM-CSF from 1 microM; no effect was observed on the release of PGD2. CONCLUSION: Mizolastine inhibits the release of LT, TNF-alpha and GM-CSF in this in vitro model, which mimics closely the inflammatory cells of allergic rhinitis.

Cysteinyl-leukotriene release test (CAST) in the diagnosis of immediate drug reactions.

BACKGROUND: The diagnosis of allergic reactions to drugs is difficult. Most skin tests are not standardized, and in vitro tests are needed to avoid provocation tests. Cross-linking of IgE on basophils is known to cause the release of both cysteinyl leukotriene (Cys-LT) and histamine. We aimed to evaluate the diagnostic utility (sensitivity, specificity, and efficiency) of measurement of sulfidoleukotrienes in drug allergy. METHODS: We performed a prospective study in 55 patients with proven immediate adverse reactions to drugs (30 to beta-lactams, six to acetaminophen, and 19 to aspirin) and 64 drug-exposed nonallergic controls. Positive diagnosis was established by history, skin tests, and, if needed, oral provocation tests. Cys-LT release was determined after drug-allergen stimulation by the cellular antigen stimulation test (CAST(R)) technique. Histamine release was also assessed on the same samples by enzyme immunoassay. Spontaneous and anti-FcepsilonRIalpha-induced mediator release was also studied in all subjects. Sensitivity, specificity, and efficiency were calculated. RESULTS: Net Cys-LT release was over the maximal threshold given by the manufacturer in 19/55 patients and in 9/64 controls. Net histamine release was over 5% of total histamine content in 28/55 patients and 34/64 controls. The efficiency of both tests was low. CONCLUSION: Thus, in most cases, the in vitro Cys-LT test has little or no diagnostic utility and is not superior to histamine release.

Basophils and exercise-induced hypoxemia in extreme athletes.

This study examined whether the increase in histamine release (%H, i.e., plasma histamine expressed as a percentage of whole blood histamine) associated with exercise-induced hypoxemia (EIH) is related to high training-induced changes in basophil and osmolarity factors in arterial blood. All parameters were measured in 20 endurance athletes, 11 of whom presented an EIH (HT(hyp)) and 9 of whom were nonhypoxemic (HT(nor)), and in 10 untrained control subjects (UT). Measurements were made at rest, at the maximal workload of an incremental exhaustive exercise test, and at the fifth minute of recovery. %H increased during exercise in HT(hyp) (P < 0.01) but did not increase significantly in HT(nor) and UT controls. The results indicated that 1) osmolarity and Na(+) and K(+) concentrations did not differ between the two trained groups and 2) the basophil count and basophil histamine content did not differ among groups. We concluded that the %H increase associated with EIH was not due to a training effect on these parameters. The relatively low increase in histamine content during exercise in HT(hyp) in comparison to HT(nor) (P < 0.05) and UT (P < 0.01) and the low recovery vs. resting basophil count only in HT(hyp) (P < 0.01) suggested an accentuated exercise-induced basophil degranulation in the hypoxemic athletes.

Interleukins 1-beta, -8, and histamine increases in highly trained, exercising athletes.

PURPOSE: Exercise-induced hypoxemia (EIH) in highly trained athletes is associated with an increase in histamine release (%H) during exercise. Certain cytokines, known as histamine-releasing factors, are capable of interacting with basophils and/or mast cells to cause the release of histamine. The aim of this study was to determine whether the increased histamine release in highly trained athletes is related to a high plasma level in interleukin-1 beta (IL-1beta), IL-3, or IL-8 in arterial blood. METHODS: These parameters were measured in 11 endurance athletes (23.2 +/- 1.2 yr (mean +/- SEM)) known to develop exercise-induced hypoxemia and 11 control subjects (25.0 +/- 1.1 yr) at rest, during an incremental exhaustive exercise test, and at the fifth minute of recovery. RESULTS: Histamine release increased between rest and maximal exercise in the athletes (P < 0.01), showing a strong correlation with EIH (r = 0.76, P < 0.01) and was unchanged in the controls. IL-3 plasma concentration was not altered with training and/or with exercise. Circulating IL-8 levels were not different between trained and untrained subjects at any testing level and increased at maximal exercise in both groups (P < 0.01). IL-1beta plasma levels were higher in athletes than in controls (P < 0.05) at each testing level and increased during exercise only in the athletes (P < 0.05). CONCLUSION: An elevated concentration of IL-1beta in plasma and its association with increased IL-8 levels during exercise may partly explain the increase in %H associated with EIH in highly trained athletes. Histamine, IL-8, and IL-1beta releases during exercise reflect an inflammatory reaction, which is probably involved in EIH.

In vitro diagnosis of cypress pollen allergy by using cytofluorimetric analysis of basophils (Basotest).

BACKGROUND: Cupressaceae pollen allergy is a worldwide pollinosis, but its in vitro diagnosis is notoriously difficult. The Basotest is a newly available in vitro test for the detection of allergen-specific IgE based on the level of cellular activation of basophils by using flow cytometry. OBJECTIVES: The Basotest was compared with the measurement of cypress pollen-specific IgE in highly selected patients. METHODS: We analyzed 34 patients allergic to cypress pollen selected on the basis of a suggestive clinical history and positive skin test and nasal challenge responses to cypress pollen extract. We also analyzed 8 patients with positive skin test responses to cypress pollen extract who did not present symptoms during the pollen season (intermediate group) and 33 control subjects. Sensitivity, specificity, and efficiency of the Basotest and serum-specific IgE levels measured by using the CAP System were determined in patients allergic to cypress pollen. Histamine release was studied in a selected group of patients. RESULTS: The Basotest was more sensitive (91.2%) than the CAP System (76%) for the in vitro diagnosis of cypress pollen allergy. A dose-response curve was observed in basophils obtained from patients allergic to cypress pollen. There were no false-positive results with either test (specificity 100%). The results of the Basotest or those of the CAP System did not correlate with the patients' in vivo threshold sensitivity assessed by skin tests and nasal challenge. CONCLUSIONS: The Basotest was found to be an effective diagnostic test in patients allergic to cypress pollen.

Experimental models in rhinitis.

Nasal challenge with allergen or mediators is a useful model to understand the pathophysiology of allergic rhinitis. Some mechanisms have thereby been clearly clarified. Different methods have been proposed to mimic the natural allergen exposure and to measure the clinical and biological responses. Nasal challenges can also be used in clinical practice, mainly when there is a discrepancy between results of skin tests and in vitro or when occupational allergens are involved. Nasal challenges are also valuable to assess the efficacy of specific immunotherapy or some drugs.