Healing of aortic prosthetic grafts: a study by magnetic resonance imaging

Thirty-six patients with aortoiliac reconstruction were studied by magnetic resonance imaging (MRI) to determine the diameter, baseline signal, and subsequent magnetic signal characteristics of postoperative periprosthetic collection (PPC). Our study confirmed the presence of PCC in most cases (32/36). The diameter was significantly (p < 0.05) correlated with the type of disease being treated, the type of proximal anastomosis created, and whether or not drainage and postoperative transfusion were used. PPC usually disappeared within 3 to 6 months postoperatively. Modifications of magnetic signals T1 and T2 require approximately the same amount of time to diminish. During follow-up investigations in this series, there was one case of prosthetic infection characterized by the persistence of PPC and a strong T2 signal 6 months after surgery, the latter corresponding to incomplete or delayed healing. The MRI aspects of normal healing of aortic grafts were analyzed to correctly interpret the MRI aspects of complications in surgery of the aorta.

Complications of shoulder arthroplasty

Early and mid-range followup studies of shoulder arthroplasty have been encouraging, showing good and excellent results in > 90% of shoulders. Despite this success, complications in shoulder replacement surgery are inevitable, with an incidence of approximately 14%. Numerous complications have been identified and include the following factors in order of decreasing frequency: instability, rotator cuff tear, ectopic ossification, glenoid component loosening, intraoperative fracture, nerve injury, infection, and humeral component loosening. Successful treatment of these difficulties requires careful identification and subsequent analysis of all factors contributing to the complication, knowing that the etiology is often multifactorial. Failed shoulder arthroplasty can be successfully managed with revision surgery, but the technically challenging surgery and the overall results are inferior compared with other diagnostic categories.

Diagnostic protocol in prosthetic loosening

The authors report the results they obtained in 35 cases studied based on a protocol to identify prosthetic loosening and to preoperatively establish its possible septic etiology. After clinical and radiographic assessment, the protocol called for a total body bone scan with Tc 99 m which, in positive cases, were associated laboratory tests and further instrumental testing (CT, bone scan and needle aspiration). Thanks above all to bone scan with labelled granulocytes the protocol provided high accuracy (91.4%) in preoperatively identifying the causes of infection.

Evaluation and management of infected total knee arthroplasty

Infection after total knee arthroplasty is an infrequent but devastating complication. An understanding of the cause of infection, its diagnosis, and potential treatment options is essential to achieve a satisfactory result. The most successful treatment option is reimplantation with an 89% success rate of elimination of infection. However, some individuals require alternative salvage techniques.

[Risk analysis of primary endoprosthetic management of proximal femur fractures]

From 1984 to 1991 439 patients with fractures of the coxal femur (303 femoral neck fractures, 136 pertrochanteric fractures) were treated by primary arthroplasty. The average age of the 370 female and 69 male patients was 80.9 (+/- 9.9) years. In 368 patients (83.8%) concomitant diseases were diagnosed and 212 patients (48.3%) showed more than 1 risk factor. There were 205 alloarthroplasties and 234 hemiarthroplasties performed. The percentage of patients treated by total hip endoprosthesis was 31.2% in 1984 and increased to 63.1% in 1991. In 49.2% of all cases general complications occurred, pre-dominantly nosocomial infections and pressure sores. Local (surgical) complications were diagnosed after 10.5% of all operations. The 30-day-mortality was 5.2%, the in-hospital-mortality 5.9%. Statistical analysis by multivariate logistic regression showed an independent negative influence of pre-operative immobility, pertrochanteric fractures, diabetes mellitus and multiple concomitant diseases on mortality. Age, sex or other single risk factors were not independently associated with an increased mortality. Patients with the above mentioned risk factors are easy to identify pre-operatively and do perform better after intensive preparation, short operation time and early mobilisation after surgery.

[C-reactive protein as a postoperative parameter of infection in hip joint replacement and knee joint operations]

Prospectively 70 male patients with elective arthroplasty of the hip (n = 34) and with operation of the anterior cruciate ligament (n = 36) were studied in respect of the postoperative screening of C-reactive protein (CRP), the erythrocyte sedimentation rate (ESR), the white blood cell count and the clinical signs of infection. There were 9 infectious postoperative complications, all with an increase of CRP. But also 6 other patients with no clear infection showed a rise or a plateau of CRP, which could only be explained by the presence of a hematoma, an effusion or a subclinical infection. The close postoperative screening of CRP appeared to be quite costly and laborious, especially in a population with a low infection rate. We therefore suggest a CRP-screening only on patients or operative procedures with wellknown high risk. In addition we studied the determination of two CRP-levels with a short interval following the clinical suspect of a postoperative infection (described in part II of this paper).

Infection following total elbow arthroplasty

Total elbow arthroplasty can be a safe, effective means of relieving the pain and loss of motion owing to arthritis of the elbow; however, infection is a frequent and devastating complication that occurs in 1 of every 20 total elbows. Through careful patient selection, meticulous operative technique, and vigilant postoperative care, this risk can be decreased. If infection does develop, early, aggressive operative management provides the best hope for salvage of the joint.

[Endocarditis due to Mycobacterium chelonei in a valvular prosthesis]

Male aged 40 year, with infective endocarditis in valvular prosthesis caused by Mycobacterium chelonei. This agent is unusual in this situation and rarely identified by the blood cultures.

Clostridial aortic graft infection

Aortic graft infection represents one of the most formidable challenges encountered by the vascular surgeon. Current principles of treatment are based on experience primarily derived from infection with Staphylococcus and enteric bacteria. Anaerobic prosthetic infection is a case event. Infection with Clostridium has heretofore been reported only twice. An additional case of clostridial infection of an aortic prosthesis is presented with review of the literature. Its clinical significance and management are discussed.

[Aortic and mitral valve endocarditis after infection of the pacemaker pocket]

The case of a 76-year-old diabetic patient with known aortic valve sclerosis is reported. One week after implantation of a permanent pacemaker system (indication: 2nd degree AV-block type Mobitz) he developed fever. Large endocarditic vegetations were found on the aortic and mitral valve (blood cultures: were positive for Staphylococcus aureus). Also from the pacemaker bed Staphylococcus aureus was isolated and an antibiotic treatment including vancomycin was started. Nevertheless the patient developed insufficiencies of both the aortic and mitral valves and became hemodynamically unstable. Due to cerebral embolisms and further deterioration of the patient's overall clinical state the already planned operative replacement of the aortic and mitral valve could not be performed. The patient died because of left ventricular failure after pacemaker infection which was complicated by endocarditis.

Prosthetic graft infection

This article outlines the tenets and basic data critical for the management of prosthetic graft infections. Diagnostic algorithms and treatment options appropriate for patients with symptoms and signs suggestive of graft infection are presented.

Legionella micdadei prosthetic valve endocarditis

Legionella usually causes pneumonia, but occasionally is in the differential diagnosis of "culture negative endocarditis" which sometimes involves prosthetic heart valves. Legionella prosthetic valve endocarditis is nearly always due to Legionella pneumophila and its clinical presentation is indistinguishable from other causes of prosthetic valve endocarditis. Diagnosis of Legionella prosthetic valve endocarditis is by recovery of the organism from the blood, demonstration or isolation of the organism from the prosthetic heart valve, or by persistently high Legionella titers which are extremely elevated in prosthetic valve endocarditis compared to Legionella pneumonia. We believe this is the first case reported of prosthetic valve endocarditis caused by Legionella micdadei, and the first case of Legionella prosthetic valve endocarditis with microscopic hematuria.

Use of Sentinel blood culture system for analysis of specimens from potentially infected prosthetic joints

The Sentinel blood culture system was used for the analysis of 657 specimens from infected prosthetic joints and blood cultures (83 from prosthetic joints and 574 from standard blood cultures). The positivity rate was similar for specimens from prosthetic joints and blood cultures (18% compared with 14%). However, there was an unacceptable rate of false positive results with specimens from prosthetic joints (58% compared with 8%). This high false positivity rate was due to (i) prolonged incubation and (ii) the lack of blood in these specimens. It is therefore recommended that the Sentinel system should only be used for the initial seven days of incubation of specimens taken from prosthetic joints. Further incubation should take place in a standard incubator and a terminal subculture performed after 21 days.

A case of Trichosporon beigelii endocarditis 8 years after aortic valve replacement

We report a case of Trichosporon beigelii endocarditis in a 77-year-old diabetic man who presented with an embolic stroke 8 years ago after a porcine aortic valve replacement. He was treated successfully with amphotericin, rifampin, and replacement of the original porcine valve; however, he died suddenly 8 months later from unknown causes. Blood cultures 2 months prior to death were negative. The first manifestation of the endocarditis was a left hemiparesis followed some days later by a splenic infarction. Transthoracic echocardiography failed to demonstrate the aortic vegetation, which was clearly visualized subsequently by transesophageal echocardiography. The literature on Trichosporon beigelii endocarditis is reviewed.

Immunoscintigraphy using technetium-99m-labeled anti-NCA-95 antigranulocyte antibodies as an adjunct to echocardiography in subacute infective endocarditis

OBJECTIVES

This study was performed to assess the clinical value of immunoscintigraphy in subacute infective endocarditis.

BACKGROUND

Radiolabeled granulocytes can reveal inflammatory lesions.

METHODS

Using technetium-99m-labeled anti-NCA-95 anti-granulocyte antibodies, planar scintigraphy and single-photon emission computed tomography of the thorax were performed in 72 consecutive patients with suspected endocarditis. Each patient also underwent transthoracic and, if findings were negative, transesophageal echocardiography.

RESULTS

Thirty-three patients were found to have endocarditis on the basis of clinical criteria (surgical confirmation in 17 patients), and the remaining 39 served as control subjects. Initial scintigraphy was true positive in 26 patients (sensitivity 79%) and false positive in 7 (specificity 82%). Echocardiography was true positive in 29 patients (sensitivity 88%) and false positive in 1 (specificity 97%). Scintigraphy was positive in the four patients with false negative echocardiography, and echocardiography was positive in the seven patients with false negative scintigraphy. Thus, the combination of scintigraphy and echocardiography yielded a sensitivity of 100% and a specificity of 82%. In 10 of the 11 patients with two to three follow-up studies, scintigraphy became negative parallel to clinical improvement, indicating decreasing floridity of the inflammatory process.

CONCLUSIONS

Immunoscintigraphy in patients with subacute infective endocarditis provides valuable diagnostic information in equivocal echocardiographic findings and may be used to monitor antibiotic therapy.

[Surgical treatment of pseudoaneurysms of the proximal anastomosis after aortofemoral reconstructions]

The authors discuss surgical treatment of pseudoaneurysms of proximal anastomoses of prostheses with the aorta after reconstructive operations in the aortofemoral zone in 9 patients, whose ages ranged from 32 to 65 years. The time between the formation of the aneurysms and the operation before their diagnosis ranged from 15 days to 6 years. The pseudoaneurysms developed due to infection in 3 patients, poor-quality suture material (silk) in one patient, endarterectomy from the aorta at the proximal anastomosis in one patient, and further development of the principal disease in 2 patients; the cause of the disease in 2 patients could not be identified. Six patients were subjected earlier to bifurcation aortofemoral shunting, one patient to bifurcation aortofemoral prosthetics, and 2 patients to linear prosthetics of the infrarenal part of the aorta. The primary reconstructive operation was conducted for occlusive lesions of the aortofemoral zone in 7 patients (of atherosclerotic genesis in 6 of them and one patient had unspecific aortoarteritis), and for aneurysm of the abdominal aorta in 2 patients (of posttraumatic origin on one). The authors claim resection with repeated replacement of the aorta by a linear or bifurcation prosthesis to be the optimal method for reconstruction in pseudoaneurysms of proximal anastomoses. One patient died in the immediate postoperative period. The immediate and late-term results of repeated operations were good in 8 of 9 patients in follow-up periods of 8 months to 5 years. Recurrences of the disease were not encountered.

In situ replacement of arterial prosthesis infected by bacterial biofilms: long-term follow-up

PURPOSE

Bacterial biofilm infections of vascular prostheses are characterized by an absence of systemic sepsis, a fluid-filled cavity surrounding the graft, a draining sinus tract, and microorganisms that must be removed from the fabric prosthesis for bacterial culture.

METHODS

Since 1987 we have treated 20 infected grafts with prosthetic excision and in situ replacement in 14 men and 6 women. The time from initial graft implantation to diagnosis of graft infection ranged from 3 months to 14 years (mean 4.5 years). The original graft (Dacron-17, polytetrafluoroethylene-3) was an aortobifemoral in 14, axillofemoral femorofemoral in 3, iliofemoral in 2, and femoropopliteal in 1 patient. Presenting symptoms were groin false aneurysm with perigraft fluid in 10, inflammatory mass in 6, and sinus tract in 4. At surgery all unincorporated graft material and the perigraft capsule were excised from a point where the proximal graft was incorporated, including debridement of vessels at the distal anastomosis. Of the 14 aortobifemoral grafts, only the femoral limbs were excised at the initial presentation of biofilm infection. The conduit was replaced with an in situ polytetrafluoroethylene interposition graft, which was covered with a gracilis or sartorius muscle flap when possible.

RESULTS

All surgical sites healed, all grafts remained patent, and there was no limb loss. After ultrasonic oscillation of the explanted graft, bacterial cultures recovered coagulase-negative Staphylococcus species in 14, coagulase-positive Staphylococcus species in one, both species in three, with no growth from two specimens. During follow-up, two patients have had clinical involvement in the proximal intraabdominal portion of the graft that had not been previously resected. In all grafts, the in situ replacement graft remained well incorporated.

CONCLUSION

In situ graft replacement is effective treatment for biofilm infections of vascular prostheses. Because of the indolent nature of these infections, subsequent infection of previously uninvolved graft segments may be expected.

Diagnosis and treatment of peri-implant disease

With the increased use of osseointegrated implants and with many implants functioning for long periods of time, various complications have been reported. This paper reviews progressive loss of peri-implant bone--one of the major concerns during the function period of implants. The recognition and treatment of peri-implant bone loss around functioning implants is a major challenge for the clinician. Diagnostic techniques, such as probing pocket depth, radiographic tools, and microbial sampling have been modified from the periodontal arena and used during the maintenance phase of the dental implant. The long-term goals in the treatment of peri-implant disease are to arrest the progression of the disease and to achieve a maintainable site for the patient's implant. Recent reports indicate that peri-implant bony defects can be treated with either nonsurgical or surgical techniques. Bone regeneration is possible in selected peri-implant bony defects when appropriate surgical techniques are used, implant surface preparation is achieved, and the cause is eradicated.

Rothia dentocariosa endocarditis

Despite its presence normally in the mouth, R dentocariosa appears rarely to cause infection outside the oral cavity. There is no doubt, however, as additional reports accumulate, that this organism should be recognized as having the ability to cause a serious illness in humans. In addition, in vivo experience seems to suggest that a penicillin regimen should remain first-line therapy for this infection, with the efficacy of other agents remaining unproved.

[Cardiac and extracardiac abscesses in bacterial endocarditis]

Cardiac abscesses are observed in 20 to 30% of cases of infective endocarditis and in at least 60% of prosthetic valve endocarditis. The aortic valve ring is more frequently affected than the mitral valve ring. A cavity contiguous with a cardiac chamber forming a pseudo-aneurysm or a closed purulent collection, the abscess may extend to the neighbouring cardiac structures or to the ascending aorta. This extension may cause conduction defects, abnormal communications between the cardiac chambers, pericardial disease and, exceptionally, myocardial ischaemia, complications which are clinical signs of abscess formation in patients with infective endocarditis. The presence of a cardiac abscess is a poor prognostic factor in infective endocarditis. The diagnosis must be made at an early stage when surgical treatment is optimal. The most valuable investigation is transoesophageal echocardiography with a sensitivity of over 80% and a specificity of about 95%. This investigation has become practically routine in all patients with endocarditis in order to diagnose abscesses at an early stage, especially in cases of aortic or prosthetic valve endocarditis. Information about the site, size and extension of the abscess may be obtained and existing or potential complications may be envisaged with a view to surgery. Other imaging diagnostic techniques, such as angiography, CT scanning and nuclear magnetic resonance imaging have a number of disadvantages and are not more sensitive than transoesophageal echocardiography. Surgical techniques depend on the site and extension of the abscess. They are sutured or closed with dacron or pericardial patches after having been cleaned and filled with formulated resorcin glue. The valvular prosthesis is inserted either in anatomical position or in a sub or supracoronary dacron tube necessitated by the perivalvular extension of the infectious lesions. These complex procedures may require associated coronary reimplantation or revascularisation when the coronary ostia are affected. The highest operative mortality is observed in prosthetic valve endocarditis with abscess and extra-annular prosthetic implants. The risk of secondary valvular dehiscence, often recurrent, is much higher when there is an abscess at operation. Extracardiac abscesses in cases of infective endocarditis are mainly observed in the cerebral and/or splenic territories. They may become the main problem, especially cerebral abscesses, but they rarely require surgery.

[Bacterial endocarditis occurring on native valves: identification of risk patients]

Analysis of the large series of infective endocarditis reported in the medical literature allows identification of the principal poor prognostic factors. Of the clinical factors, the worst prognosis is observed in the most elderly patients, in those with persistence of the infections syndrome despite antibiotic therapy, those with cardiac failure or complications, principally arterial embolism (cerebral or peripheral). From the anatomical viewpoint, aortic valve endocarditis seems to carry a slightly worse prognosis than mitral valve endocarditis, but the extension of infection to the paravalvular region is the complication most likely to aggravate the condition. The infecting organism is also an important factor: non-streptococci, especially staphylococcal endocarditis, have a much worse prognosis. Finally, echocardiographic analysis of the vegetations allows identification of the cases with the highest risk of embolism: those with vegetations over 10 mm in size which appear very mobile. The appearance of signs of poor haemodynamic tolerance, the persistence of an infectious syndrome despite appropriate medical therapy and the detection of large, mobile vegetations by echocardiography should lead to early surgical referral: this attitude now provides good immediate and long-term results.

Bone scan, gallium scan, and hip aspiration in the diagnosis of infected total hip arthroplasty

The difficulty in differentiating aseptic loosening from infection in painful total hip arthroplasty is well recognized. This prompted a review of the efficacy of the preoperative investigations used at the authors' institution. One hundred forty-four patients who underwent revision hip arthroplasty were reviewed. Seventy-two had sequential bone-gallium scan, and/or hip aspiration, and intraoperative Gram stain. These were compared to intraoperative culture as the gold standard. Twenty infected hips were detected on culture. For prediction of infection, the bone-gallium scan had a sensitivity of 38% and a specificity of 100%. Hip aspiration had a sensitivity of 57% and a specificity of 97%. The investigations combined gave a sensitivity of 64% and a specificity of 95%. Intraoperative Gram stain compared with subsequent culture yielded a sensitivity of 23% and a specificity of 100%. Uncemented hips were infected more frequently (47%) than cemented hips (9%), significant at P < .0001. It was concluded that bone-gallium imaging is not an effective method for investigating painful hip prostheses for sepsis and offers no additional advantage over hip aspiration. Intraoperative Gram stain also missed a large number of infections. Other modalities, such as indium-labeled-leukocyte imaging and capsular histologic examination, may be more efficacious. A significant difference in the number of infections found in cemented versus uncemented hips was shown, hence greater vigilance for infection is required when patients present with painful uncemented hip arthroplasties.

Hip aspiration: a cost-effective and accurate method of evaluating the potentially infected hip prosthesis

PURPOSE

The accuracy of fluoroscopy-guided hip aspiration in the diagnosis of infection in hip prostheses was evaluated.

MATERIALS AND METHODS

Results from 147 preoperative aspiration cultures were compared with results of operative cultures. The relative costs of aspiration and nuclear medicine studies were also compared.

RESULTS

With the operative culture results as the standard, sensitivity of hip aspiration was 92.8% and specificity was 91.7%. The negative and positive predictive values were 99.2% and 54.2%, respectively. Aspiration arthrography costs approximately 20% as much as complementary technetium sulfur colloid-indium-111 granulocyte scans, the most accurate nuclear medicine study used to evaluate potentially infected hip prostheses.

CONCLUSION

Hip aspiration is an accurate and cost-effective method of evaluating the potentially infected hip prosthesis.

Diagnosis of infection and the role of permanent excision arthroplasty

The symptoms, signs, and investigation of the infected hip replacement are reviewed. Aspiration, combined with needle biopsy of the interface tissue, gives the best opportunity for establishing a bacteriologic diagnosis. The surgical technique for excision arthroplasty is described, and the complications of this procedure reviewed. The functional results of permanent excision arthroplasty are described in relation to the altered biomechanics of the hip pseudarthrosis.

Diagnoses and staging. Osteomyelitis and prosthetic joint infections

The diagnoses of osteomyelitis and prosthetic joint infections are usually made on the basis of clinical, laboratory, and radiographic examination. The diagnostic studies presently employed to diagnosis and assess osteomyelitis and prosthetic joint infections are described. A universally applied classification system for stratifying osteomyelitis and prosthetic joint infection would provide a framework for the evaluation of medical and surgical treatment efficacy. Such a system would enable treatment results to be compared among institutions. Staging systems currently being used are described.

Exchange arthroplasty for infection. Perspectives from the United Kingdom

A number of factors are considered with a bearing on outcome assessment and survivorship analysis. The results achieved in more than 440 exchange arthroplasties are discussed. Despite the apparent threefold increased risk of recurred infection associated with a one-stage approach, this statistic is an oversimplification of the many complex factors involved in the analysis of these results and in the decision between a one- and a two-stage approach to treatment, when presented with an infected hip replacement. The authors think that a one-stage approach remains a reasonable alternative, given certain prerequisites.

Management of infected knee and hip prostheses

Infection following total hip or total knee arthroplasty can be devastating. It can result in instability of the hip or knee, diminished function, amputation, or death. Fulminant infection is unusual. Chronic low-grade infection is more commonly seen clinically. Differentiation of pain in a total hip or total knee replacement from loosening or infection may be difficult. Aspiration of the hip or knee for three aerobic and anaerobic cultures and sensitivities is the most reliable method of diagnosing infection. In the hip joint, aspiration should be performed under radiographic control. Treatment of the infected total hip or total knee by antibiotics alone is ineffective. Debridement of the hip or knee joint with retention of the prosthesis and intravenous antibiotics is successful in 18% to 40% of cases. Resection arthroplasty of the hip or knee usually results in eradication of the infection but leaves a painful, unstable, and shortened extremity and diminished ability to ambulate. Arthrodesis of the knee usually clears the infection but imposes the disability of a stiff knee. Two-stage reimplantation of the hip or knee is the most successful means of treating the infected total hip or knee replacement. In the knee, the success rate with two-stage reimplantation is 80% to 97%. In the hip joint, the success rate of two-stage reimplantation is 83% to 87%. Recently, debridement of the hip or knee with retention of the prosthesis and the local installation of antibiotics for a prolonged period has been used in cases of acute infection of less than 3 months' duration without evidence of implant loosening.(ABSTRACT TRUNCATED AT 250 WORDS)

[Q fever-induced endocarditis. An analysis of 6 cases]

Endocarditis by Q fever is a diagnostic and therapeutic challenge given the diagnostic delay and elevated morbidity and mortality it carries. Six cases of endocarditis by Q fever attended over the last 7 years were retrospectively studied. Five patients had been previously diagnosed of valvular involvement and three had prosthesis. Five patients presented a febrile syndrome of prolonged duration with negative hemocultures and progressive valvular changes. One patient presented acute valvular failure requiring emergency surgery. The most significant laboratory data were anemia, thrombocytopenia, high ESR and hypergammaglobulinemia. In the echocardiograms valvular vegetations were observed in 4 cases. All the patients received medical treatment with doxicylin, one associated with rifampicin and another cotrimoxazol. In 4 patients valvular reposition was required due to a severe hemodynamic alteration. After a minimum follow up of 2 years all the patients remain asymptomatic. The serologic evolution is described.

Knee effusion after total knee replacement

The various causes of effusions in artificial knees can be divided into four groups: implant related, technique related, interface problems, and infection. Diagnosis can be made from the patient's history and a clinical examination. Treatment is usually surgical revision.

Late infection in healed fractures after open reduction and internal fixation

Nine patients with normal fracture healing after open reduction and internal fixation presented with late infection 15 months to 19 years after injury. Eight of the nine patients had a history of pain at the fracture site for 3 weeks or longer. Elevated temperature and white blood cell count were unreliable indicators of infection. Six patients had an elevated erythrocyte sedimentation rate that correlated with osteomyelitis. Roentgenograms showed resorption around the implant in seven patients and a small nidus in two patients. There was a change in position of fixation screws in four patients. Cigarette smoking and alcoholism were the most common systemic risk factors. Local risk factors were open fracture, lower-extremity site, distal femur site, and chronic edema of the lower extremities. Late infection should be included in the differential diagnosis of patients presenting with new-onset pain and a retained orthopaedic implant. Patients who fall into this group may be at increased risk for development of late hematogenous infection of orthopaedic implants.

[Infection of the vascular prosthesis. The diagnostic, preventive and treatment protocols: preliminary results]

A number of strategies for the management of vascular graft infections are described in literature. Nevertheless, this serious compliance is still burdened with high rates of morbidity and mortality. At the present the principal efforts are therefore directed towards prevention and early diagnosis. In this view, the authors propose their protocol of study, on the basis of the encouraging results till now obtained.

[Prosthetic valve endocarditis after double valve replacement]

This is a report of a patient who underwent re-AVR due to prosthetic valve endocarditis after double valve replacement (MVR, AVR). A 54-year-old female was admitted to other hospital on April 14, 1990, because of high fever, progressive anemia, and cardiomegaly. The patient was hospitalized to our department urgently with the diagnosis of prosthetic valve endocarditis. Arterial blood culture grew methicillin-resistant Staphylococcus epidermidis. Echocardiography showed a vegetation at the disc of the mechanical valve in the mitral position, but we could not find any vegetation or thrombus there at the reoperation, and the aortic mechanical valve seemed to be intact. Signs of inflammation continued to be positive after reoperation. On the 33rd hospital day, a diastolic murmur was heard, and emergency cardiac catheterization was done. Detachment of the prosthetic aortic valve and rupture of the sinus of Valsalva due to mycotic aneurysm, and the dissection of the aorta had occurred. We performed re-AVR and replacement of the ascending aorta. The patient died of multiple organ failure following drug-induced hepatic failure. It is suggestive that we missed the prosthetic aortic valve endocarditis during the reoperation. Our thoughts and introspections on the echocardiographic diagnosis of the prosthetic valve endocarditis after double valve replacement were discussed.

STIR imaging of synthetic vascular graft infection

Nine patients with suspected prosthetic vascular graft infection were studied with axial spin echo (SE) and short TI inversion recovery (STIR) magnetic resonance imaging. Images were assessed for presence and extent of abnormality. All patients had either surgical (8/9) or bacteriologic (6/9) confirmation of infection. STIR images better defined the extent of infection and had greater fat-fluid contrast than SE images in 6/9 studies. In 3 cases with peri-graft fluid alone, T2-weighted images had slightly greater contrast, although the STIR images were still diagnostic. STIR imaging can offer improved accuracy in evaluation of suspected prosthetic graft infection when used in conjunction with SE techniques.

Managing infection in the revision total hip replacement patient

Deep infection is one of the most devastating complications in total hip replacement. This dreaded complication is presented in considerable detail with special emphasis on prevention, diagnosis, and various methods of surgical and antibiotic treatment. Basic fundamentals of antibiotic therapy are reviewed. In addition, guidelines are given for the indications of surgical intervention, the type and staging of operative procedures, with detailed techniques of the various operative procedures used to treat the infected total hip implant patient.

[Infection involving arterial prosthesis: clinical picture, etiology, and predisposing factors]

Thirty patients were operated for arterial reconstruction with synthetic grafts. They presented one of the following complications: 1) prosthesis exposed by a cutaneous fistula; 2) prosthesis in communication with a hollow viscus; 3) prosthesis involved by pus; 4) positive culture of a fragment of the prosthesis or of the surrounding secretion. The clinical manifestations were cutaneous fistula in 21 patients (70%), external bleeding in 14 (47%), exposition of the prosthesis in five (17%), anastomotic aneurysm in five (17%), and enteric fistula in four (13%). The infection became evident during the first postoperative year in half of the patients. The most important agents of infection were staphyilococci and Gram negative bacteria.

The value of aspiration of the hip joint before revision total hip arthroplasty

The role of aspiration of the hip joint before revision of a total hip arthroplasty remains controversial. To address this issue, we reviewed the results of 270 consecutive hips in which aspiration had been attempted before revision procedures that were performed between 1980 and 1988. All hips had intraoperative findings and clinical follow-up of at least two years to confirm the presence or absence of infection. Only six (2 per cent) of the 270 hips were determined to be infected. Aspiration had been attempted in all six hips, but fluid could be obtained from only four. All six hips also had clinical or radiographic signs, or both, of infection, including increasing pain within three years after the arthroplasty (four hips), inability of the patient to attain pain-free status after the original procedure (four hips), radiographic findings compatible with infection (six hips), and a positive finding on culture of a specimen obtained from a previous aspiration (two hips). Because of these factors, aspiration was attempted a second time in four of the six hips and a third time in three of the four. The four hips from which fluid could be obtained had a total of ten successful aspirations; the cultures of specimens obtained from six of these procedures were positive and those from four were negative. The appearance of the capsular tissue at the time of the operation suggested infection in five of the six infected hips. Histological sections were positive for inflammation in all six: there was acute inflammation only in one, chronic inflammation only in two, and acute and chronic inflammation in three. No organisms were seen on gram stains of specimens from any of the six infected hips. Of the 254 hips that did not have an infection and had been aspirated successfully, thirty-two (13 per cent) had a false-positive result on culture of a specimen of the aspiration fluid. Only two (6 per cent) of the thirty-four hips that had a positive result on culture of fluid from the initial aspiration had a true-positive result. No hip had a true-positive result on culture of fluid that had been aspirated preoperatively without also having clinical and radiographic evidence of infection. On the basis of these findings, we recommend that aspiration be performed in selected patients rather than routinely. It also should be performed only if a detailed clinical history suggests infection or if radiographs demonstrate focal lysis, aggressive non-focal lysis, or periostitis.

Prosthetic vascular graft infection

The aetiology, diagnosis and management of prosthetic vascular graft infection are reviewed. The importance of contamination at the time of surgery as the crucial aetiological factor is highlighted. Staphylococcus epidermidis is the causative organism in over 50 per cent of cases and the reasons for this are explored. Sound surgical technique, use of prophylactic antibiotics and the avoidance of a groin incision are emphasized as the most important factors in prevention of graft infection. Difficulties of diagnosis are highlighted and the diagnostic role of various imaging methods is assessed. Graft excision with extra-anatomic revascularization is presented as the conventional surgical solution, while the roles of less radical surgical solutions and non-operative management are discussed.

Pulmonary artery catheterization: the right heart should not be left out--a case report

Tricuspid valve stenosis in the setting of endocarditis is associated with a high morbidity. Diagnostic approaches incorporate a high clinical index of suspicion, echocardiographic evidence, and inferences about hemodynamic data derived from pulmonary artery catheterization. As demonstrated by the case presented herein, inadequate initial evaluation of right-sided pressures delayed the diagnosis and treatment of prosthetic tricuspid valve stenosis.

Pasteurella multocida infection of a total hip arthroplasty. A case report

The authors report a case history of a diabetic woman requiring revision hip arthroplasty of a Charnley total hip prosthesis that was infected with Pasteurella multocida. The infection of the loose prosthesis followed a cat bite to the same leg. Advice is given on the management of patients with infection following animal inoculations, and the subject of increased risk with a loose prosthesis is discussed.

Inflammatory aortic aneurysm: a case report and review of literatures

A case of an uncommon variant of aortic aneurysm, inflammatory type, is reported. A 51-year-old Thai male presented with a pulsatile abdominal mass associated with pain. Ultrasonography demonstrated infrarenal abdominal aortic aneurysm preoperatively and operative findings revealed dense fibrous tissue around the lesion. Serological tests for syphilis and bacteriological studies of aneurysm contents were all negative. Aneurysmorrhaphy was done, using Dacron straight graft, and two serious complications developed at six and two months interval: aortocolonic and aortoduodenal fistulae. However, the patient survived the three operations. Definite diagnosis of inflammatory aortic aneurysm was confirmed by typical pathological findings. Clinical presentations, operative and pathological findings were compared to previous literature.

Aspergillus infection of total knee arthroplasty presenting as a popliteal cyst. Case report and review of the literature

Fungal infections have only rarely been reported to occur in patients having undergone total knee arthroplasty. This case report documents the first known case of Aspergillus fumigatus as the offending organism. Its initial presentation as a popliteal cyst further reinforces the known association of popliteal cysts and intra-articular knee pathology.

Diagnosis and treatment of biomaterial-associated vascular infections

Management of biomaterial-associated vascular infections requires an understanding of pathogenetic mechanisms, risk factors, and microbiologic characteristics. Staphylococci sp., especially slime-producing strains of S. epidermidis are the prevalent pathogens. Experimental and clinical studies have indicated in situ replacement, particularly with an antibiotic-bonded prosthesis, as effective treatment for infections caused by coagulase-negative staphylococci. When sepsis is a presenting sign, prompt intervention, total excision of the prosthesis, and antibiotic administration are required.

Thrombus with infection in total artificial heart animals

From January 1980 to December 1990, several types of total artificial hearts were implanted into 378 animals. In a retrospective study of these animals, 147 (39%) were found to have thrombus with infection (T&I). The criteria for diagnosis was thrombus formation in the artificial heart and a positive blood culture. The most common pathogen isolated from T&I animals was Pseudomonas species. Concurrent skin lesions and contamination from the pressure lines may be the primary sources of infection, but bacterial translocation from the intestine is another possible route. The main pathological findings at necropsies of artificial heart animals with T&I were associated with sepsis, congestive heart failure, infected thrombus, thromboembolism, and multiple organ infarctions. Most thrombi appeared to have originated from valve junctions and connectors. On the basis of these observations, a possible mechanism for pathogenesis of T&I has been proposed. The results suggest that design improvements and surface modifications to reduce thrombosis are important factors that should be carefully considered. Similarly, it is important to eliminate the route of entry of pathogenic microorganisms. These findings imply that bacterial interaction with thrombus, device related bacterial colonization, and host immunomodulation and gut barrier function following artificial heart implantation need further investigation.

Prosthetic knee infection due to Achromobacter xylosoxidans

Achromobacter xylosoxidans is an aerobic gram negative organism that has been infrequently implicated in clinical infections in a variety of anatomical sites. We describe a case of a prosthetic knee infection due to Achromobacter xylosoxidans in a patient with rheumatoid arthritis receiving high dose prednisone.

Total hip arthroplasty sepsis. Prevention and diagnosis

Postoperative deep wound infection following total hip arthroplasty remains a serious and all too frequent complication. Although diagnostic capabilities have improved with the evolution of new imaging and immunologic techniques, the devastating consequences for patients with an early diagnosis cannot yet be aborted. Thus, further emphasis must be placed on prevention of this complication. Although major referral centers have managed to achieve exceptionally low incidences of postoperative sepsis with the prophylactic administration of antimicrobial agents and discipline within the operating room, these advances have not translated into a similar reduction of the national experience. Thus, further investigation and the development of additional techniques must be sought.