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PubMed2005

[Knee arthroplasties performed at Akureyri University Hospital in the years 1983-2003. Results with emphasis on revision and complication rates].

OBJECTIVE: Osteoarthrosis (OA) is a growing medical problem in western societies and the cost of the treatment has grown accordingly in the last years. Patients with OA often need to be operated on with arthroplasties and one important outcome measure for this type of surgery is the revision rate. The purpose of this study was to assess the results of knee arthroplasties performed at Akureyri University Hospital during 1983-2003, with special emphasis on revision rates, infections and other complications. MATERIAL AND METHODS: Information was gathered from journals of the 457 patients who underwent knee arthroplasties during 1983-2003. Information about the operation and hospital stay was recorded as well as if patients later became the subject of revision. CRR (cumulative revision rate) uses survival statistics to estimate the risk of revision after primary operation and was calculated for patients with OA operated on with knee arthroplasty. Statistical informations were calculated in Microsoft Excel. Kaplan Mayer analysis was used to calculate the CRR and that was done in SPSS 11.5. RESULTS: 560 primary operations were performed during the period, 515 total knee arthroplasties and 45 unicompartmental. 200 operations were performed on males and 360 on females. Mean ages for males was 70.8 years and for females 69.4 years. Revision rates varied depending on the type of implant. Twelve unicompartmental and 28 total knee arthroplasties became subject of revision. The PCA unicompartmental prosthesis most frequently needed revision, or in over 50% of cases. The CRR for the AGC total knee prosthesis was the lowest or around 3% at seven years, including revisions due to infections. Revisions due to infections were three in the period or 0.6% of all the total knee arthroplasties. Complications that substantially increase the risk of revision and/or are life-threatening were recorded in 1.8% of the operations at the time of discharge. Only one patient had pulmonary embolism (0.2%) and two patients (0.4%) had deep venous thrombosis. CONCLUSION: Our high revision rate for the PCA implant is consistent with what has been seen in other studies. This prosthesis was found to have mechanical problems and was withdrawn from the market. Our revision rate for the AGC implant as well as the rate of infections are low and the results are quite comparable to what has been found in Sweden by the Swedish Knee Arthroplasty Registry. The results of knee arthroplasties performed at Akureyri University Hospital, regarding revision rates, infections and complications, are fully comparable to other known results internationally.

Aged↗
PubMed2005

[Septic loosing of hip and knee prosthesis].

Loosening of an artificial joint is a common complication in orthopedic surgery. It is estimated that bacteriological implant contamination is responsible for its loosening in 2-5 percent of cases, and in most cases aseptic loosening takes place. Despite low percentage of positive microbiological studies, histopathological examinations and modern laboratory techniques, including PCR (Polymerase Chain Reaction) allow to diagnose the bacterial contamination of the loose implant to ca 70 percent. Those observations point out to the high coincidence of bacterial contamination with implant loosening strongly suggesting its influence on activation of the inflammatory process destabilizing an implant. But the question, why in those cases bacterial contamination does not lead to clinically obvious suppuration, remains unknown. The possibility to activate the immune system by the subcellular elements of the bacterial cells leading to persistent inflammation with granulation tissue formation is likely. Presented paper discusses the process of orthopedic prosthesis loosening, the role of bacterial contamination in it. and the newest techniques for their examination.

Arthroplasty, Replacement, Hip↗
PubMedDate not supplied

[Emergencies in total hip replacement].

Over the last three decades total hip replacement became one of the most common surgical procedures in orthopaedic surgery. According to the number of large joint endoprosthesis, hip replacement is on the first place. Lately, the number of revisional and special tumoral endoprosthesis is increasing, with more severe complications. Dislocation is a leading early complication of total hip arthroplasty. Dislocations after primary total hip arthroplasties occur at an overall incidence of 1-3%, and at 15-20% in revision and tumoral procedures. Closed reduction and eventually immobilization is the method of treatment. If closed reposition in not possible, revision surgery must be performed. Periprosthetic fractures are, as every other fracture, indication for a surgical treatment. Depending on the type of fracture the method of treatment is either open reduction and internal fixation or removal of the primary and implantation of revision endoprosthesis. Deep infection following total joint replacement remains one of the most serious complications, often needing surgical treatment. Treatment consists of incision and debridement. If there is a fever, increased erythrocyte sedimentation and CRP with signs of sepsis, endoprosthesis must be removed. A haematoma appearance after surgical procedure is an emergency which needs a surgical treatment--haematoma evacuation in order to prevent further complication, on the first place infection. Fractured endoprosthesis is one of the most severe complication in the total hip replacement, and need to be surgically treated as soon as possible with endoprosthesis replacement. Aseptic loosening can also be considered as a relative emergency in surgical treatment of total hip replacement. Longer waiting for reoperation can cause losing valuable bone mass needed for revisional endoprosthesis implantation and fixation. Although emergencies in hip replacement are not very common, they must be recognized and eventually surgically treated as soon as possible.

Arthroplasty, Replacement, Hip↗
PubMed2005

[Septic complication in hip and knee arthroplasty].

The authors present the management of acute infections affecting joint alloarthroplasty. Study consist 23 patients (10 male 13 female. Age between 48-84 years). Consisting of surgical elimination of inflammated soft tissue, and granulation surrounding the joint endoprothesis, local antibiotic application and suction drenage instalation. In cases of chronic infection associated with loosening of the implant and bone-matrix destruction, dealloplasty is indicated with precise removal of bone - cement followed by, local antibiotic administration, and changes affecting the bone-matrix should be approached as posttraumatic osteitis with all consequences, related to it.

Aged↗
PubMed1992

Durability of porcine valves at fifteen years in a representative North American patient population.

Isolated aortic (n = 857) or mitral (n = 793) valve replacement with a porcine bioprosthesis was performed in 1650 patients between 1971 and 1980. Follow-up (total = 12,012 patient-years) extended to more than 15 years and was 96% complete. Patient age ranged from 16 to 87 years; mean age was 59 +/- 11 years (+/- 1 standard deviation) for the aortic valve replacement cohort and 56 +/- 12 years for the mitral valve replacement cohort. The operative mortality rates were 5% +/- 1% (+/- 70% confidence limits) and 8% +/- 1%, respectively, for the aortic and mitral subgroups. Estimated freedom from structural valve deterioration (+/- 1 standard error of the mean) after 10 and 15 years was significantly higher for the aortic than for the mitral valve replacement subgroup (85% +/- 0.4% and 63% +/- 3% versus 78% +/- 2% and 45% +/- 3%, respectively, p = 0.001). Reoperation-free actuarial estimates were also significantly greater for the aortic valve replacement cohort: 83% +/- 2% and 57% +/- 3% versus 78% +/- 2% and 43% +/- 3% for mitral valve replacement at 10 and 15 years, respectively. The mortality rate for reoperative aortic valve replacement was 11% +/- 1%; it was 8% +/- 1% for reoperative mitral valve replacement. Importantly, the estimates of freedom from valve-related death (including sudden, unexplained deaths) were relatively high at 10 and 15 years: 78% +/- 2% and 69% +/- 3% in the aortic cohort and 74% +/- 2% and 63% +/- 3% in the mitral cohort (p = not significant). Excluding sudden, unexplained deaths, these estimates were 81% +/- 3% (aortic) and 73% +/- 4% (mitral) at 15 years. Thromboembolism-free rates were 84% +/- 3% (aortic) and 78% +/- 6% (mitral) at 15 years, and freedom from anticoagulant-related hemorrhage was 96% +/- 1% and 89% +/- 2%, respectively. At the time of current follow-up, 13% of patients having aortic valve replacement and 50% of patients having mitral valve replacement were receiving warfarin sodium. The hazard functions for thromboembolism and prosthetic valve endocarditis were constant and remained less than 1%/pt-yr over the entire follow-up period.(ABSTRACT TRUNCATED AT 400 WORDS)

Actuarial Analysis↗
PubMed1992

Clinical evaluation of the Omniscience cardiac valve prosthesis. Follow-up of up to 6 years.

From January 1984 to June 1989, 259 Omniscience valve prostheses were implanted in 225 patients. Of the 225 patients; 143 (63.6%) received mitral, 48 (21.3%) aortic, and 34 (15.1%) double valve replacements. The early mortality rate was 8.9%; 97.6% of the patients were included in this study. These patients represent a cumulative follow-up of 407.9 patient-years, with a mean follow-up of 2.03 +/- 0.1 (standard error) years. The late mortality rate was 4.03% overall, which corresponds to 2.0% +/- 0.7%/pt-yr (SE). The annual rate of valve endocarditis was 1.0% +/- 0.5%/pt-yr (SE). The linearized rate of thromboembolism was 1.2% +/- 0.5%/pt-yr (SE). Anticoagulant-related hemorrhage occurred in 15 patients with an annual rate of 3.7% +/- 0.9%/pt-yr (SE). The linearized rate of valve thrombosis was 0.2% +/- 0.2%/pt-yr (SE). By echocardiography the mean mitral valve opening was 75.9 +/- 3.1 degrees (standard deviation) for 27 patients. During follow-up study, 136 (70.8%) patients were in New York Heart Association class I, 44 (22.9%) were in class II, and 12 (6.3%) were in class III; there were 25 (11.1%) patients in class II, 166 (73.8%) in class III, and 34 (15.1%) in class IV preoperatively. Actuarial freedom from thromboembolism was 94.5% +/- 3.6% (SE); freedom from endocarditis, 97.8% +/- 1.0% (SE); freedom from anticoagulant-related hemorrhage, 91.5% +/- 2.0% (SE); freedom from valve thrombosis 99.1% +/- 0.8% (SE); and freedom from hemolysis 98.5% +/- 1.2% (SE). Actuarial survival at 6 years is 94.0% + 2.3% (SE) overall. In conclusion, the overall rate of valve-related complications with this valve is low.

Actuarial Analysis↗
PubMed1992

Heart valve replacement with the Sorin tilting-disc prosthesis. A 10-year experience.

From 1978 to 1988, 697 patients with a mean age of 48 +/- 11 years (range 5 to 75 years) received a Sorin tilting-disc prosthesis; 358 had had aortic valve replacement, 247 mitral valve replacement, and 92 mitral and aortic valve replacement. Operative mortality rates were 7.8%, 11.3%, and 10.8%, respectively, in the three groups. Cumulative duration of follow-up is 1650 patient-years for aortic valve replacement (maximum follow-up 11.4 years), 963 patient-years for mitral valve replacement (maximum follow-up 9.9 years) and 328 patient-years for mitral and aortic valve replacement (maximum follow-up 9.4 years). Actuarial survival at 9 years is 72% +/- 4% after mitral valve replacement, 70% +/- 3% after aortic valve replacement, and 50% +/- 12% after mitral and aortic valve replacement, and actuarial freedom from valve-related deaths is 97% +/- 2% after mitral valve replacement, 92% +/- 2% after aortic valve replacement, and 62% +/- 15% after mitral and aortic valve replacement. Thromboembolic events occurred in 21 patients with aortic valve replacement (1.3% +/- 0.2%/pt-yr), in 12 with mitral valve replacement (1.2% +/- 0.3% pt-yr), and in seven with mitral and aortic valve replacement (2.1% +/- 0.8%), with one case of prosthetic thrombosis in each group; actuarial freedom from thromboembolism at 9 years is 92% +/- 3% after mitral valve replacement, 91% +/- 3% after aortic valve replacement, and 74% +/- 16% after mitral and aortic valve replacement. Anticoagulant-related hemorrhage was observed in 15 patients after aortic valve replacement (0.9% +/- 0.2%/pt-yr), in 9 after mitral valve replacement (0.9% +/- 0.3%/pt-yr), and in 6 with mitral and aortic valve replacement (0.9% +/- 0.5%/pt-yr); actuarial freedom from this complication at 9 years is 94% +/- 2% after aortic valve replacement, 91% +/- 4% after mitral valve replacement, and 68% +/- 16% after mitral and aortic valve replacement. Actuarial freedom from reoperation at 9 years is 97% +/- 2% after mitral and aortic valve replacement, 92% +/- 4% after mitral valve replacement, and 89% +/- 3% after aortic valve replacement, with no cases of mechanical fracture. The Sorin valve has shown a satisfactory long-term overall performance, comparable with other mechanical prostheses, and an excellent durability that renders it a reliable heart valve substitute for the mitral and aortic positions.

Actuarial Analysis↗
PubMed1991

[Alloarthroplasty of the hip joint. Radiologic diagnosis of loosening and infection in cemented total endoprostheses].

Patients with problems following implantation of cemented total hip prostheses must be clinically examined. This examination is followed by a series of diagnostic imaging procedures. These include X-ray diagnosis, 3-phase 99mTc-MDP bone scans, scintigraphy for inflammation, and arthrography, performed singly or as sequential studies. X-ray findings and scintigraphic patterns arousing or confirming a suspicion of aseptic (mechanical) or septic (infectious) loosening of the prosthesis are evaluated and discussed.

Hip Prosthesis↗
PubMed1990

The failed restoration: causes of failure and how to prevent them.

Ceramic restorations lack tensile strength and suffer from static fatigue. The margins of safety required to prevent fracture are much greater than for metal. Composite restorations, even laboratory cured, have yet to be fully tested over long periods. The hydrolytic stability of these materials still requires improvement. Glass-ionomer cements lack fracture toughness and will not accept a high polish due to their porous surfaces. Failure in restorations can only be avoided by recognizing the deficiencies in physical properties of all our restorative materials and using them in areas where the hostile oral environment causes minimal damage. The cast-gold restoration will probably remain supreme for crown and inlay work. The unique properties of the metallic bond are ideally suited to withstand maximum occlusal stress under most clinical conditions.

Crowns↗
PubMed1988

The effect of the extracorporeal shock wave lithotriptor on the bone-cement interface in dogs.

The extracorporeal shock wave lithotriptor (ECSWL) is a machine that generates shock waves that transfer energy through biologic materials. This study focused the wave at a composite bone-cement (polymethylmethacrylate) interface and evaluated the effects both quantitatively and qualitatively. Six matched sets of dog femora were selected. The intramedullary canals were packed uniformly with cement. One of the set was randomly selected for treatment with impulses while the other served as the control. The bone was then sectioned transversely into discs, and scanning electron microscopy and mechanical push-out studies were performed. The results indicated that the ECSWL does have a loosening effect on the bone-cement interface. Using a paired Student's t-test, the shear strength was significantly less in the treated group than in the control (p less than 0.003). Microscopically, the treated specimens revealed relative sparing of the surrounding bone. At the bone-cement interface, however, microfractures, loose bodies, and widening were seen. Revision total arthroplasty has a significant morbidity, which can be partially attributed to cement extraction. The results of this study indicate that the ECSWL may be a useful adjunct in revision surgery by facilitating the extraction of polymethylmethacrylate and thereby reducing the morbidity.

Animals↗