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At least 883 records · Page 49Linked to original sources
PubMed2001

[Investigation of explanted hip and acetabulum hip prostheses].

Retrieved ceramic femoral heads and acetabular cups were investigated. On the basis of the case studies, the reasons for revision are discussed. Wear patterns and wear rates were found to differ from those observed in hip simulating testing. Monolithic ceramic cups showed a high wear rate. Owing to their limited range of motion, ceramic "mushroom heads" are associated with impingement that leads to a high risk of cup loosening, high wear rates and in vivo fractures. The combination of ceramic "mushroom heads" and cups is not recommended. An evaluation of complications shows that some can be explained by patient behaviour--e.g. Japanese sitting position, horse riding. Designers need to develop new concepts offering a larger range of motion, for example, with head diameters of 32 and 36 mm that reduce the risk of impingement, subluxation and dislocation, while increasing the range of motion. The potential of ceramic/ceramic coupling has been known since the 70s, and ceramic concepts for total hip replacement are currently experiencing a renaissance, although further developments are still possible.

Acetabulum↗
PubMed2003

Clinical biomechanics of wear in total hip arthroplasty.

Complementary clinical and laboratory studies were performed to identify variables associated with polyethylene wear following total hip replacement, and to elucidate the mechanisms responsible for accelerated wear in the total hip arthroplasty construct. Observational cohort studies were performed using a prospective clinical database of more than 4000 consecutive primary total hip arthroplasties performed by a single surgeon, to identify wear-related variables. These variables included head size, acetabular/femoral component impingement, and third body debris. Novel digital edge detection techniques were developed and employed to accurately measure wear, and to determine the relationships of head size and third body debris to acceleration of wear. A novel sliding-distance-coupled finite element model was formulated and employed to examine the mechanisms responsible for wear. The long-term cohort studies demonstrated smaller head sizes to be associated with less wear. Third body debris generated from cable fretting was associated with an increase in wear, osteolysis, and acetabular loosening, especially with larger head sizes. The sliding-distance-coupled finite element model replicated the wear rates occurring in vitro and in vivo, demonstrating the importance of sliding distance on polyethylene wear following total hip arthroplasty. It also demonstrated substantial increases in wear associated with femoral head scratching from third body debris. Further extension of the finite element formulation demonstrated the potential for acetabular component rim damage from impingement wear, and the enhanced potential for third body ingress to the bearing surface with larger head sizes. Edge detection wear measurement techniques demonstrated that early wear rates were predictive of long-term wear rates. These complementary clinical and laboratory investigations have provided insight into 1) the significance of sliding distance and physiologic loci of motion as contributing factors in minimizing wear, 2) the deleterious effects of third body particulates in accelerating wear, 3) the potential for, and factors related to, impingement wear, and 4) the potential advantages and compromises related to the use of larger head sizes in the bearing surface construct.

Arthroplasty, Replacement, Hip↗
PubMed2004

The troubles of zirconia.

A new ceramic material was introduced into clinical practice five years ago with the expectation that it would improve performance and give better fracture toughness and wear resistance. In reality, the reverse happened and far more failures have occurred. This article asks whether there are any lessons to be learnt.

Biocompatible Materials↗
PubMed2004

[Plethysmographic assessment of pulse wave may be helpful in the detection of prosthetic valve dysfunction--a case report].

A case of a 63-year-old female with prosthetic mitral and aortic valves is described. The long-term post-operative period was complicated by infective endocarditis, persistent atrial fibrillation requiring pacemaker implantation and total a-v node ablation as well as ischaemic stroke which occurred one year before present hospitalisation. This time the patient was admitted to the hospital due to progressive heart failure. Transesophageal echocardiography showed a cyclic intermittent opening of both prosthetic valves full opening was present during every second cardiac cycle. The same phenomenon was documented using plethysmographic recording of a pulse wave from a finger. The patient underwent prosthetic valve replacement. Intraoperatively, a fibrous tissue ingrowth was detected.

Aortic Valve↗
PubMed1992

[A case report of thrombosed St. Jude Medical valve in a patient with macroglobulinemia].

A 66-year-old man who had undergone MVR using a ST. Jude Medical valve entered the hospital with acute heart failure and cardiogenic shock 3 months after surgery. He had had a symptom of petechiae due to macrogloburinemia after initial MVR and had been in the poor control of anticoagulation therapy because of presence of petechiae. He was diagnosed as prosthetic valve thrombosis using echocardiography and underwent emergency re-MVR using a Central Open Bioprosthesis (COB) which was developed by our department. He was doing well 8 month after re-MVR. Selection of prosthetic valve should be performed carefully in the patient with hemorrhagic disease, and careful observation and proper anticoagulant therapy should be carried out after valve replacement.

Aged↗
PubMed1992

[Asymptomatic aortic dissection associated with a mitral prosthetic leak: a clinical case report].

A case of aortic dissection ("DeBakey type III") in an asymptomatic 78-year-old woman is described. The patient underwent a mitral valve replacement (bioprosthesis Sorin) in June 1990 for severe mitral stenosis; in October 1990 she was admitted to our hospital for severe dyspnea and cardiac failure with good response to medical treatment. The routine echo color Doppler examination showed only a hint of paraprosthetic leak, which required further investigation by transesophageal echocardiography. This approach revealed the presence of a regurgitant jet extending from the prosthetic mitral valve toward the atrial septum. The examination of the thoracic aorta revealed the presence of a dissection flap; the color Doppler technique showed a bidirectional flow through the site of communication between the two lumina. The extension of the dissection from the aortic arch to the origin of the renal branches was confirmed by computerized axial tomography. We emphasize the importance of the transesophageal approach in elderly patients with aortic dissection, often asymptomatic.

Aged↗
PubMed1987

[Dysfunctions of heart valve prostheses and their surgical treatment].

Today the dysfunctions and complications relating to prosthetic cardiac valves are less frequent than 15-20 years ago. The materials used to manufacture mechanical cardiac valves, e.g. carbon pyrolyte, are much more resistant than Teflon or Derlin, and wear is therefore an exceptional event. In regard to bioprostheses, research is now aimed at preventing calcifications, tears and deterioration. Complications such as thrombosis and thromboembolic accidents are seen with all prosthetic cardiac valves and affect mechanical valves rather than bioprostheses. Hemorrhage, a complication of anticoagulant therapy, can be seen in any patient with a prosthetic cardiac valve undergoing such treatment. This complication is far less frequent in patients with a bioprosthesis since most of these (75%) are not on long-term anticoagulation. Paravalvular leakage is another rare complication related to valvular surgery and is often associated with prosthetic valve endocarditis. Prosthetic cardiac valve endocarditis is a very severe complication with a high mortality rate, and is more lethal when endocarditis occurs soon after surgery (up to 2 months). Elimination of infectious foci before surgery, observation of strict rules of asepsis, a high level of surgical technique, and prescribing of prophylactic antibiotic therapy during surgery, or later if necessary, will reduce the risk of prosthetic valve endocarditis. Where reoperation is decided for the above complications it is almost always necessary to replace the failing prosthetic valve.

Endocarditis↗
PubMed1988

Patellar component dissociation in total knee arthroplasty. A report of two cases.

Dissociation of the polyethylene from the metal baseplate of the patellar component in total knee arthroplasty (TKA) occurred in two patients. Analysis of intraoperative and postoperative photographs of the specimens indicates that "cold flow" of the polyethylene precedes dissociation from the metal baseplate. The diagnosis can be made on the basis of a pathogonomic metallic crepitus.

Aged↗
PubMed1988

Fractures of the polyethylene bearing insert in Bateman bipolar hip prostheses.

Six cases of fractures of the polyethylene bearing insert of Bateman bipolar hip prostheses were observed in three patients at four to eight years after implantation. Three fractured prostheses were salvaged by replacement with new bearing inserts. In three patients, excessive acetabular cartilage wear was the indication for revision to total hip arthroplasty. Although dislocation and component disassembly have been reported as complications of the Bateman and other bipolar prostheses, fractures of the polyethylene bearing insert seems not to have been previously reported. The presumed mechanism of failure is cyclic loading of a femoral cup that is tipped into varus alignment. This concentrates stress on the weakest part of the polyethylene insert--the deep circumferential groove that joins the leaflets to the main body of the insert. Obesity and overuse were associated factors in this rare complication.

Adult↗
PubMed1988

The rationale of cementless revision of cemented arthroplasty failures.

Patients with failed cemented total hip replacements develop minor to massive bone loss. In nearly all cases, the quality of the endosteal surface has been converted to a sclerotic tube. Because of the bone loss and the change in character of the remaining bone stock with which to form an interface with polymethylmethacrylate (PMMA), the microinterlock necessary for long-term interface stability cannot be achieved. Moreover, the first failure leads to the production of cement particles that incite a histiocytic osteolytic response. The difficulty in achieving interfacial stability in the revision setting is borne out in the published clinical results of cemented revision total hip arthroplasties showing failure rates ranging from 17% to 60.3%. Porous-surfaced prostheses have been introduced to permit biologic fixation as an alternative to cement fixation of each implant component. The good midterm clinical results and the lack of catastrophic bone loss when failure does occur have given impetus to the application of this technology to the revision situation. The preliminary clinical experience with cementless revision arthroplasty has yielded favorable results. The authors have fully developed the rationale against the use of PMMA in revision total hip replacements and for the cementless approach with porous-surfaced metal prostheses and bone grafts. The latter appear as a viable approach to a growing clinical problem.

Adult↗
PubMed1993

Prosthetic valve dysfunction in a Nigerian.

A case is presented of a mechanical cardiac valve dysfunction occurring in a 19-year-old Nigerian 7 years after valve surgery and presenting with cardiac failure, supraventricular tachycardia and later, cardiogenic shock but initially masquerading as generalised bleeding probably from Warfarin-drug interaction. The problem of management of an artificial heart valve in our setting is discussed.

Adult↗
PubMed1993

[A case report of redo Fontan operation].

A 21-year-old man, who had undergone Fontan operation for tricuspid atresia type 1b using 21 mm Hancock valved conduit 15 years ago, had right sided heart failure when his heart rhythm turned to atrial fibrillation. On cardiac catheterization, pressure data revealed that trans valved conduit pressure gradient reached to 5.2 mmHg. Chest CT and right atrial angiography showed right atrial wall thrombus. Right upper lobe perfusion defect was detected by lung perfusion scintigraphy. Then he was recommended redo Fontan operation. He underwent resection of stenosed valved conduit, right atrial thrombectomy and reconstruction of new route between right atrium and pulmonary artery with bovine pericardium. He tolerated well that operation and now 3 months passed, he resumed fairly vigorous physical activity.

Adult↗