Rocco P. Pitto

The clinical relevance of embolic events detected by transesophageal echocardiography during cemented total hip arthroplasty: a randomized clinical trial.

The first aim of this prospective clinical study was to characterize the relationship between embolic events observed during cemented total hip arthroplasty using transesophageal echocardiography (TEE), and changes in cardiopulmonary function. The second aim was to assess the efficiency of a modified cementing technique that was developed to reduce the risk of embolism. The modification consists in a vacuum drainage placed in the proximal femur to reduce the increase of intramedullary pressure during insertion of the prosthesis. One hundred twenty patients were randomized into two groups. Group 1 received a total hip arthroplasty cemented conventionally, whereas Group 2 was cemented with the modified technique. Continuous TEE, hemodynamic monitoring, and blood gas analysis were done during the perioperative period. Severe embolic events were imaged during the insertion of the femoral component and the reduction of the hip joint. Embolism occurred in 93.3% of patients operated on with the conventional cementing technique, compared with 13.3% of patients operated on with the modified technique (P < 0.05). Intraoperative shunt values during insertion of the femoral component increased from 8.2% to 10.3% (P < 0.05) in Group 1 patients, whereas there was no significant change in Group 2 patients. We observed no clinical signs of fat embolism syndrome in any study patient. The results of the study indicate that embolic events observed using TEE can cause increased pulmonary shunt values during hip arthroplasty, especially in patients with systemic disease (ASA physical status III). The modified surgical technique effectively reduced the incidence of embolization during cemented hip arthroplasty. IMPLICATIONS Use of conventional cementing techniques is associated with echocardiographic evidence of embolism in 93% of patients and with a significant increase in pulmonary shunting. The incidence of embolism and change in shunting are reduced with a modified cementing technique that limits increases in intramedullary pressure.

Differential Gene Expression in Cultured Osteoblasts and Bone Marrow Stromal Cells From Patients With Paget's Disease of Bone†

Pagets disease is a focal condition of bone. To study changes in cells within pagetic lesions, we cultured osteoblasts and stromal cells from 22 patients and compared gene expression in these cells to cells from healthy bone. We identified several differentially regulated genes, and we suggest that these changes could lead to the formation of the lesions.

Pre-formed articulating knee spacer in two-stage revision for the infected total knee arthroplasty

We performed a prospective study to assess safety and effectiveness of a pre-formed articulating spacer made of gentamicin-impregnated acrylic cement in the management of infected total knee arthroplasty. Twenty-one consecutive patients with unilateral deep infection were treated by two-stage revision in two centres. Two patients were excluded, and 19 patients remained available for assessment. The mean implantation time of the spacer was 12 weeks. The rehabilitation programme between stages consisted in early range of motion exercises and partial weight bearing. Mean follow-up after removal of the spacer and insertion of the final prosthesis was 24 (range, 12–43) months. No patient had recurrence of infection at the latest follow-up. The mean Knee Society functional score during spacer management was rated 75 points and was rated 84 points at the latest follow-up. No device-related complication was observed.RésuméNous avons étudié prospectivement la sécurité et l’efficacité d’un espaceur articulé pré-formé fait en ciment acrylique imprégné de gentamicine dans la gestion de l’arthroplastie totale infectée du genou. Vingt et un malades consécutifs avec une infection profonde monolatérale ont été traités dans deux centres, avec une révision en deux temps. Deux malades ont été exclus, et 19 malades sont restés disponibles pour l’estimation. Le temps d’implantation moyen de l’espaceur était de 12 semaines. La rééducation entre les deux étapes a consisté en un travail précoce de la mobilité et un appui partiel. Le suivi moyen après réimplantation prothétique était de 24 mois (12 à 43 mois). Aucun malade n’avait de récidive de l’infection au dernier recul. Le score fonctionnel moyen (Knee Society) pendant le port de l’espaceur a été estimé à 75 points et à 84 points au dernier recul. Aucune complication liée à l’espaceur n’a été observée.

Prophylaxis of fat and bone marrow embolism in cemented total hip arthroplasty

The efficiency of a new cementing technique developed to prevent the risk of intraoperative pulmonary embolism was assessed. Seventy patients with coxarthrosis entered into a prospective, randomized clinical trial. In the control group of 35 cases the total hip replacement was cemented conventionally. In the second group a proximal drainage placed along the Linea aspera, and a distal drainage placed in the diaphysis, created a vacuum in the medullary cavity of the femur during the insertion of the stem. The operation was performed with the patient under blood gas analysis and hemodynamic and transesophageal echocardiography monitoring. Severe transatrial embolic events were observed during the insertion of the femoral component in 94% of the cases of the control group and in 14% of the cases of the vacuum group; the difference is statistically significant. A significant decrease of arterial partial pressure of O2 (-40.8 mm Hg) and increase of the pulmonary shunt values (+28.3%) occurred 5 minutes after the observation of embolic events in the cases operated on conventionally, but these parameters showed minimal changes in the vacuum group. The rise of intramedullary pressure in the femur is the most decisive pathogenic factor of pulmonary embolism during total hip arthroplasty. The logical prophylactic measure to prevent intravasation of fat and bone marrow is to create sufficient drainage. The cohorted investigation showed the value of the vacuum cementing technique for a substantial reduction of intraoperative embolism and pulmonary impairment.

Antibiotic-loaded bone cement spacers in two-stage management of infected total knee arthroplasty

We reviewed the current use of spacers in the management of the infected knee prosthesis. There are two types of temporary spacers: block or non-articulating spacers and articulating or mobile spacers. Generally, spacers improve mobilisation and hasten recovery with shorter hospital stay between stages. Furthermore, spacers facilitate the second-stage procedure by maintaining joint space, and articulating spacers may also maintain range of motion. Last but not the least, the cost of spacers represents only a small fraction of the total expenses for management of infected knee arthroplasties.RésuméNous avons examiné l’usage courant d’espaceurs dans la gestion de la prothèse du genou infectée. Il y a deux types d’espaceurs temporaires: articulants ou non. Généralement les espaceurs améliorent la mobilisation et hâtent la récupération des malades, avec un plus court séjour d’hospitalisation entre les deux étapes. En outre, ils les facilitent le deuxième temps chirurgical en maintenant l’espace articulaire et les espaceurs articulants peuvent aussi maintenir une gamme de mouvement. Dernier avantage, et non le moindre, le coût des espaceurs représente seulement une petite fraction des dépenses totales pour la gestion des arthroplasties du genou infectées.

Prophylaxis against fat and bone-marrow embolism during total hip arthroplasty reduces the incidence of postoperative deep-vein thrombosis A controlled, randomized clinical trial

Background: Clinical and experimental studies have suggested that the maximum risk of thrombogenesis occurs during, rather than after, total hip arthroplasty. With use of conventional cementing techniques, insertion of a femoral component results in marrow embolization of tissue thromboplastin into the veins of the proximal part of the femur, leading to activation of the clotting cascade and thrombogenesis. We hypothesized that an operative technique designed for the prevention of fat and bone-marrow embolism can also reduce the incidence of postoperative deep-vein thrombosis and pulmonary embolism. Methods: A total of 130 consecutive patients with osteoarthritis who were to have a primary total hip arthroplasty were randomly assigned to one of two groups. One group consisted of sixty-five patients (sixty-five hips) who had the femoral component inserted with our standard cementing technique without use of a bone vacuum, and the other group included sixty-five patients (sixty-five hips) who had the femoral component cemented with use of a bone-vacuum technique. In the hips managed with the bone vacuum, suction (–800 mbar) was applied to a drainage cannula placed along the linea aspera of the femur in order to prevent an increase in intramedullary pressure during the insertion of the stem. We measured the incidence of intraoperative fat and bone-marrow embolism with use of echocardiography and a transesophageal probe and the incidence of deep-vein thrombosis with use of serial duplex ultrasonography on the day before the operation and on postoperative days 4, 14, and 45. All patients were managed with prolonged pharmacological prophylaxis (low-molecular-weight heparin) against deep-vein thrombosis. Results: The control group had significantly more severe and prolonged echocardiographic embolic events than did the group managed with the bone-vacuum technique (p < 0.05). A cascade of fine echogenic particles or embolic masses with a diameter of £5 mm was observed during the insertion of the stem in fifty-nine hips (91%) in which our standard cementing technique was used and in ten hips (15%) in which the bone-vacuum cementing technique was used. Deep-vein thrombosis was detected on postoperative day 4 in twelve patients (18%) in the control group and in two patients (3%) in the group managed with the bone-vacuum technique; the difference was significant (p < 0.05). Conclusions: Intraoperative prophylaxis against fat and bone-marrow embolism during total hip arthroplasty with cement can reduce the incidence of postoperative deep-vein thrombosis. We now use the bone-vacuum technique routinely in all total hip arthroplasties performed with cement.

Failure to Detect Measles Virus Ribonucleic Acid in Bone Cells from Patients with Paget’s Disease

BACKGROUND Pagets disease is a condition of focal accelerated bone turnover. Electron-microscopy investigations of osteoclasts from pagetic lesions have identified nuclear inclusion bodies that have a similar appearance to viral nucleocapsid particles. Subsequently, RNA from several paramyxoviruses has been detected in pagetic tissue, and it was suggested that these viruses, in particular measles, might play a role in the etiology of Pagets disease. We have tested for measles virus sequences in osteoblasts and bone marrow cells collected from pagetic lesions and healthy bone. METHODS Bone and bone marrow samples were taken from Pagets patients and control subjects, and cells were cultured from each of these tissues. RNA was extracted from 13 osteoblast cultures and 13 cultures of bone marrow cells derived from pagetic lesions, and from 26 and 23 control osteoblast and bone marrow cultures, respectively. These samples were sourced from 22 patients with Pagets disease and 31 controls. RT-PCR-nested PCR amplification was used for the detection of the genes for the measles nucleocapsid and matrix proteins. RESULTS Measles virus sequences were not detected in any of the pagetic or control samples. However, measles virus sequences were identified in samples of a measles virus culture isolate included as a positive control, and in a brain sample from a patient with subacute sclerosing panencephalitis, a condition associated with chronic measles infection. CONCLUSION The results of the study do not support the hypothesis that measles virus plays a role in the pathogenesis of Pagets disease.

Treatment of the dysplastic acetabulum with Wagner spherical osteotomy. A study of patients followed for a minimum of twenty years.

Background: The purpose of this study was to evaluate the long-term clinical and radiographic results of spherical acetabular osteotomy, performed with the surgical technique described by Wagner, in patients with hip dysplasia. Methods: The results of the first twenty-two spherical osteotomies performed by one surgeon at one institution were reviewed at a minimum of twenty years (median, 23.9 years; maximum, 29.3 years) postoperatively. Preoperative and follow-up radiographic measurements included the lateral and anterior center-edge angles, acetabular index angle, and acetabulum-head index of Heyman and Herndon. Anteroposterior radiographs of the pelvis were evaluated for the presence of joint congruency, joint-space narrowing, increased sclerosis of the subchondral bone, and bone cysts. Clinical evaluation was performed with use of the Harris hip score. Results: Osteotomy improved the mean lateral center-edge angle from -2° to +13° and the mean acetabulum-head index from 52% to 72%. The mean postoperative anterior center-edge angle was 23° (range, -1° to 62°). Seven (32%) of the twenty-two hips were converted to a total hip replacement. At the latest follow-up examination, the average Harris hip score of the remaining fifteen patients was 86 points (range, 50 to 100 points). The clinical result was rated good or excellent for eleven of the fifteen patients. At the latest follow-up examination, the severity grade of the osteoarthritis was unchanged in thirteen hips. Only three of the nine hips that subsequently required a total hip replacement or that showed progressive osteoarthritis had been congruent after the index operation, whereas ten of the thirteen hips that did not require total hip replacement or show progressive osteoarthritis had been congruent after the index operation. The twenty-year Kaplan-Meier survival estimate, with conversion to total hip replacement as the end point, was 86.4% (95% confidence interval, 63.4% to 95.4%). The twenty-five-year survival estimate was 65.1% (95% confidence interval, 35.6% to 83.7%). Conclusions: The Wagner spherical osteotomy prevented progression of osteoarthritis both clinically and radiographically in a high proportion of patients with residual hip dysplasia who were followed for a minimum of twenty years. Operative restoration of joint congruency is associated with a satisfactory long-term outcome in a very high proportion of cases. Level of Evidence: Therapeutic study, Level IV (case series [no, or historical, control group]). See Instructions to Authors for a complete description of levels of evidence.

Development and Validation of Patient-Specific Finite Element Models of the Hemipelvis Generated From a Sparse CT Data Set

To produce a patient-specific finite element (FE) model of a bone such as the pelvis, a complete computer tomographic (CT) or magnetic resonance imaging (MRI) geometric data set is desirable. However, most patient data are limited to a specific region of interest such as the acetabulum. We have overcome this problem by providing a hybrid method that is capable of generating accurate FE models from sparse patient data sets. In this paper, we have validated our technique with mechanical experiments. Three cadaveric embalmed pelves were strain gauged and used in mechanical experiments. FE models were generated from the CT scans of the pelves. Material properties for cancellous bone were obtained from the CT scans and assigned to the FE mesh using a spatially varying field embedded inside the mesh while other materials used in the model were obtained from the literature. Although our FE meshes have large elements, the spatially varying field allowed them to have location dependent inhomogeneous material properties. For each pelvis, five different FE meshes with a varying number of patient CT slices (8-12) were generated to determine how many patient CT slices are needed for good accuracy. All five mesh types showed good agreement between the model and experimental strains. Meshes generated with incomplete data sets showed very similar stress distributions to those obtained from the FE mesh generated with complete data sets. Our modeling approach provides an important step in advancing the application of FE models from the research environment to the clinical setting.

Periacetabular bone changes after uncemented total hip arthroplasty evaluated by quantitative computed tomography

Background There are few dual X-ray absorptiometry (DXA) studies on periacetabular bone density changes after cup implantation. This study was designed to analyze the load-transfer mechanism and stress pattern of periacetabular cortical and cancellous bone after implantation of a ihemispherical titanium alloy press-fit cup with alumina-alumina pairing in vivo. We introduced a novel method of computed tomography (CT)-assisted osteodensitometry. Method We investigated 26 hips (26 patients) with osteoarthritis using conventional sequential CT examinations performed within the first 10 days after implantation, and after a mean period of 1.1 years postoperatively. Bone density of full, cancellous and cortical bone (mgCaHA/mL) was measured. Results At the time of follow-up, the mean bone density values of the cortical bone cranial to the cup increased by 3.6% (p = 0.03) while the cancellous bone density decreased by 18%. Cancellous bone loss was greater in the region ventral to the cup (–35%) than in the dorsal region (–30%). Cortical bone density decreased ventral to the cup (–6.4%). All these changes were statistically significant. The bone density changes in the dorsal cortical region were not significant. Interpretation The method presented is an excellent tool for detailed measurement of bone density changes around the cup after total hip arthroplasty, and allows a thorough assessment of stress shielding phenomena in vivo. The hemispherical titanium alloy press-fit cup is a rigid implant which stress shields cancellous bone and enhances load transfer to the cranial cortical bone. Further investigations will demonstrate the impact these factors have on the long-term results of the implant, and may allow a type-related predictable prognosis of the longevity of the prosthesis.