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PubMed2005

Primary Souter-Strathclyde total elbow prosthesis in rheumatoid arthritis. Surgical technique.

BACKGROUND: Total elbow arthroplasty is a well-established treatment for the painful elbow joint in patients with rheumatoid arthritis. We present the results of what we believe to be the first prospective study of the Souter-Strathclyde total elbow prosthesis. METHODS: Between June 1982 and December 2000, 204 primary total elbow prostheses were inserted in 166 patients who had rheumatoid arthritis. No patient was lost to follow-up. The mean duration of follow-up was 6.4 years. All patients were examined preoperatively, at one and two years postoperatively, and at regular intervals thereafter. RESULTS: Six of the 204 elbows had pain at rest at the time of the latest follow-up. Ten patients (ten elbows) without previous neurological symptoms had development of paresthesias in the distribution of the ulnar nerve postoperatively. Patients who had pain at rest or at night and those who had ulnar nerve symptoms preoperatively were found to have a significant chance of having the same complaints postoperatively. Pain at rest or at night and a decrease in function during the follow-up period were associated with humeral loosening. Twenty-four elbows had revision of the total elbow prosthesis because of loosening of the humeral component (ten), loosening after fracture (six), dislocation (four), infection (two), restricted range of motion (one), or fracture of the middle part of the humeral shaft, proximal to the prosthesis (one). One prosthesis was removed because of humeral loosening, and eight were removed because of deep infection. Another five prostheses were radiographically loose at the time of the latest follow-up. The rate of implant survival, according to the method of Kaplan-Meier, was 77.4% after ten years and 65.2% after eighteen years. CONCLUSIONS: Total elbow replacement is associated with a high complication rate and therefore may be warranted only for seriously disabled patients. Currently, the results associated with the Souter-Strathclyde total elbow prosthesis are comparable with the results associated with other prostheses, but loosening of the humeral component remains a concern.

Arthritis, Rheumatoid↗

PubMed2003

A patient with MRSA infection to prosthesis of femoral head diagnosed non-invasively using bi-digital O-ring test: a clinical case report.

Prosthesis of femoral head is a common surgical procedure, but the diagnosis of infection associated with the prosthesis remains difficult. We diagnosed non-invasively methicillin resistant Staphylococcus aureus (MRSA) infection of prosthesis of femoral head with Bi-Digital O-Ring Test (BDORT). BDORT uses the resonance phenomenon between 2 identical substances, and electromagnetic field principle. The method can non-invasively detect viral & bacterial infection. Accuracy of the BDORT findings was confirmed through bacterial culture & sensitivity test to antibiotics. Patient was successfully treated with operation of evulsion of the prosthesis of femoral head and administration of antibiotics and Cilantro. The drug compatibility was tested with BDORT. BDORT was an effective technique for non-invasively detecting infection of prosthesis and selecting the most effective antibiotics.

Aged↗

PubMed1998

[Is a maxillary prosthesis difficult for patients with trismus?].

Of patients with a postoperative maxillary defect, around 30% are though to have trismus to some extent. In these patients, some difficulty in fabricating a maxillary prosthesis is expected. In this study, 54 patients with trismus were compared with a control group to find some proof of difficulty in making a maxillary prosthetics. Fifty-four of trismus less than 20 mm of a mandibular stroke were experienced out of 185 patients with maxillary prosthetics between October 1984 and October 1992. The trismus was divided into 4 groups of less than 5 mm (1 case), 5 mm-10 mm (10 cases), 11 mm-15 mm (19 cases), and 16 mm-20 mm (24 cases). These case were analyzed by in taking an impression failure, average weight of the prosthesis, time needed to complete the prosthesis and some special form of prosthesis. No apparent differences among the 4 groups or with the control group were found. The cause of the difficulty in making a prosthesis for such patients with trismus are suggested not to be simply due to the range of mouth opening but also to the complexed space formed by the dental defect, alveolar bone defect, spreadability of the lip and the cheek, the mandibular stroke and the so-called scar bundle of the cheek next to the defect.

Adult↗

PubMed2000

10 years of experience with penile prosthesis implantation in Taiwanese patients.

PURPOSE: We evaluated the long-term results of penile prosthesis implantation during the last 10 years. Special considerations were examined concerning Asian corporeal diameter, device survival and sociocultural factors influencing patient-partner satisfaction. MATERIALS AND METHODS: We followed 331 patients who underwent penile prosthesis implantation from December 1985 to May 1996. Surgical data, postoperative complications and information from a survey on satisfaction are reported. RESULTS: The most prevalent corporeal diameter in our patients was 11.0 to 11.5 cm. Postoperatively wound infection was the most serious surgical complication. The 5-year device survival was similar in the malleable and inflatable types except for a poorer outcome with the self-contained inflatable Hydroflex penile prosthesis. Overall patient satisfaction with surgery was 86.6%. CONCLUSIONS: Penile prosthesis implantation still has its place as definitive therapy in some patients with uncorrectable erectile dysfunction. In Taiwanese society more consideration of prosthesis selection, surgical preparation and patient-partner counseling is the basis for further success in the future.

Actuarial Analysis↗

PubMed2000

The CarboMedics 'Top-Hat' aortic valve prosthesis: short-term results.

BACKGROUND AND AIM OF THE STUDY: The CarboMedics 'Top-Hat' aortic valve prosthesis has been specifically designed for supra-annular implantation. The aim of this study was to assess the safety of implantation of this prosthesis by reporting the short-term results of follow up. METHODS: Between May 1993 and May 1998, 128 patients (mean age 62.5 +/- 9.8 years; range: 22-76 years) received a CarboMedics 'Top-Hat' prosthesis at our institution. Among patients, 55% were in NYHA functional classes III or IV, and 54.7% had an isolated aortic valve replacement. Associated procedures were: coronary artery bypass grafting (25.7%), double valve replacement (17.1%), treatment of ascending aortic aneurysm (4.7%) and miscellaneous (5.5%). Follow up was 100% complete; total cumulative follow up was 265 patient-years (pt-yr) (range: 2-60 months). RESULTS: The overall mortality rate was 1.5% (two deaths). The operative mortality rate was 0.8% (one death); this patient died from neurological complications after operation for aortic dissection. The other patient died on postoperative day 40 from a massive cerebral hemorrhage. Four patients presented thromboembolic events; in all cases these were reversible ischemic neurologic deficits. One patient had a nonstructural deterioration (endocarditis) and required reoperation. Freedom from mortality was 98.3% at five years (linearized rate of 0.75%/pt-yr). Freedom from thromboembolism was 63.1% at five years (linearized rate 1.5%/pt-yr). CONCLUSION: Short-term results with the CarboMedics 'Top-Hat' prosthesis were satisfactory, with low rates of morbidity and mortality. As this prosthesis has demonstrated a good reliability to date, we have continued its implantation in our institution, and long-term follow up will be necessary to confirm these good early results.

Adult↗

PubMedDate not supplied

Shoulder prosthesis in reconstruction of the scapulohumeral girdle after wide resection to treat malignant neoformation of the proximal humerus.

Progress in preoperative chemotherapy and radiation therapy, both intra- and postoperative, has in time allowed for an increase in indications for shoulder implant surgery in malignant tumors, thus drastically reducing the number of amputations. The use of prostheses, particularly those of the more recent generation, respond to the needs to overcome the limits of loss of movement, as long as good anatomical reconstruction of the soft tissues, the premise for good functional and cosmetic recovery, is also possible. The current tendency is that of using modular shoulder prostheses that provide a wide variety of sizes. This type of prosthesis has surpassed custom made prostheses in terms of simplicity, adaptability and economy. The use of cementation in stabilization of the intramedullary stem has made them more stable even in the long term, allowing for early rehabilitation. The main problem in reconstruction with a prosthesis is the quantity of residual muscular tissue (deltoideus, extrarotators) and the stabilization system of the same to the prosthesis in order to avoid dislocation, which constitutes the main complication. It is the purpose of this study to present the clinical and functional results obtained in 23 implants carried out for primary malignant neoformation of the upper limb. The implants studied were of three types (custom made, modular in Cr-Co-Mb and Ti-Al-Va). The results reported show how a shoulder prosthesis can obtain good functional results, particularly when a part of the activator muscles of the shoulder such as the deltoideus and the extrarotators is preserved. When the contrary is true, the results obtained are modest because the prosthesis acts as a simple spacer.

Arthrodesis↗

PubMed2003

Results of lumbar disk prosthesis after a follow-up period of 48 months.

BACKGROUND: Damage to the intervertebral disk is usually corrected by means of a prosthesis. OBJECTIVES: To report the outcome of the artificial lumbar disk replacement with the Charité SB III disk prosthesis in 20 patients after a 48 month follow-up. METHODS: The 20 patients were evaluated clinically and radiographically during this period. Preoperative diagnosis included degenerative diskopathy in 17 patients and failed posterior conventional diskectomy in 3. The prosthesis was implanted at one level in 17 patients and bi-level implantation was performed in the other 3 patients. RESULTS: Eighty percent of patients reported satisfactory to very good results. Poor results were reported by four patients, one of whom underwent posterolateral fusion and another is waiting for the same operation. There were two dislocations of the prosthesis followed by immediate revision surgery. CONCLUSIONS: Contraindications for surgery appear to be the principal cause of failure rather than the prosthesis itself.

Adult↗

PubMedDate not supplied

Finite element analysis of effect of prosthesis height, angle of force application, and implant offset on supporting bone.

PURPOSE: This finite element analysis was conducted to determine the magnitude of stress in the supporting bone when implants were arranged in either a straight-line or an offset configuration. In addition, the effects of axial and nonaxial loading and changes in prosthesis height were assessed. MATERIALS AND METHODS: An 8-node hexahedral solid-element 3-dimensional finite element analysis model of the mandible was created using PATRAN software. Three titanium endosseous implants were placed in the model 7 mm apart. The center implant was placed on the line from the centers of the terminal implants (no offset), 1.5 mm lateral to this line (1.5-mm offset), or 3.0 mm lateral to this line (3.0-mm offset). Forces of 200 N were applied to a point corresponding to the center of the middle implant when the implants were in a straight-line configuration. Forces were applied in a straight vertical direction or in 15-degree increments to the vertical to a maximum of 60 degrees. Simulated type IV gold prostheses were made to simulate heights of 6 and 12 mm. RESULTS: The least stress in the supporting bone was found with vertical loading of the no-offset implants with the 6-mm prosthesis (3.12 MPa) followed by the same alignment with the 12-mm prosthesis (3.86 MPa). Changing the angle of force application by 15 degrees resulted in increased stress to the underlying bone, and the creation of an offset did not fully compensate for this increased stress. DISCUSSION: In contrast to previous studies, this study examined 3 elements not previously studied together in a single finite element analysis, using the maximum offset defined by normal anatomic contours of mandibular premolar and molar teeth, thereby describing the relative importance of clinically relevant methods for stress reduction. CONCLUSIONS: Vertical loading of an implant-supported prosthesis produced the lowest stress to the supporting bone. Changes in the angle of force application resulted in greater stress to supporting bone. Reduction in prosthesis height or use of an offset implant location for the middle implant reduced stress, but the reduction did not compensate for the increase found with off-axis loading.

Alveolar Process↗

PubMed2006

Surgical planning and prosthesis construction using computer technology and medical imaging for immediate loading of implants in the pterygomaxillary region.

This report describes a protocol that uses computerized tomography (CT), computer-aided design/computer-assisted manufacture (CAD/CAM) technology, and the Internet to plan placement of anterior and posterior dental implants and construct a precise surgical template and definitive prosthesis, which is connected at the time of implant placement. This procedure drastically reduces surgical treatment time and the recovery period. Patients with an edentulous arch had a denture with radiopaque markers constructed for CT scans of the appropriate jaw. The CT images, with acquisition slices of 0.5 mm, were transferred into a three-dimensional image-based program for planning and strategic placement of dental implants. After implants were virtually placed on the computer, the surgical treatment plan was sent to a manufacturing facility for construction of a surgical template and the prosthesis, Special surgical guide components were also manufactured for placement of implants in the pterygomaxillary region. The manufactured surgical components, surgical template, and definitive prosthesis were then delivered to the clinical site. Implant placement surgery was performed using the surgical template, without a flap, and the prosthesis was delivered, achieving immediate functional loading. Minor occlusal adjustments were made. The total surgical treatment time required was less than 60 minutes. Postoperative symptoms, such as pain, swelling, and inflammation, were minimal. Identification of the bone in relationship to the tooth position via three-dimensional CT prior to surgery allows precise placement of implants. CAD/CAM technology using the three-dimensional images allows for fabrication of the surgical guide and final prosthesis. This is a significant advancement in implant dentistry and prosthodontics.

Computer-Aided Design↗

PubMed2006

Early wear development in a novel mechanical heart valve prosthesis made from polymeric materials.

BACKGROUND AND AIM OF THE STUDY: Currently, 95% of all implanted mechanical heart valve prostheses are constructed completely, or at least partially, from pyrolytic carbon. In order to develop a mechanical heart valve prosthesis made from alternative materials, a special hinge design was tested which enabled the integration of wear-resistant tribomaterials into the highly loaded hinges of leaflets. METHODS: The wear behavior of different material couples was investigated in vitro. Wear testing was performed using a specially designed durability tester that controlled the pressure difference across the closed heart valve prosthesis in a water-glycerol mixture with blood analog viscosity. Conditions were set according to FDA and ISO standards for heart valve testing. Qualitative assessment of wear behavior was performed using light microscopy and scanning electron microscopy at intervals of 10, 40, and each subsequent 50 million cycles. RESULTS: None of the investigated heart valve prostheses failed during the durability tests. Compared to the reference valve made from polymeric materials, wear especially in the hinges could be reduced to an acceptable level by integrating wear-resistant tribomaterials into the leaflets. CONCLUSION: A leaflet design which enables the integration of tribomaterials into the highly loaded hinges of leaflets leads to an optimization of wear behavior of a mechanical heart valve prosthesis made from polymeric materials. Abrasive wear in the hinges may be reduced to an acceptable level for the functionality of the heart valve prosthesis. Durability tests will be continued in order to confirm the promising wear behavior of this novel heart valve prosthesis.

Alloys↗

PubMed2006

Early wear development in a novel mechanical heart valve prosthesis made from polymeric materials.

Biocompatible Materials↗

PubMed1991

[Hinge endoprosthesis of the knee joint. Long-term results based on the Blauth prosthesis].

Knee prostheses of the condylar or hinge type have constructional features that have both advantages and disadvantages. Both types are compromises as a result of different demands. Here we report long-term results with the Blauth prosthesis as an example of the efficiency of the hinge concept. The Blauth prosthesis is constructed according to the low-friction principle without a weight-bearing axis. Load transmission to the bone is accomplished by large interface areas. The sliding bearing of the patella is oriented perpendicular to the transverse axis of rotation. A prospective multicentric study reports on 511 prosthesis with a follow-up between 1 and 15 years. Aseptic loosenings were confirmed in 1.2% of the patients, deep infections in 3.3%. The survival analysis showed a probability of 89% that a prosthesis would not have a deep infection or loosen. A hinged knee prosthesis shows positive long-term results even compared with the condylar types if the relevant principles of construction are adequately considered.

Aged↗

PubMed1990

Design and development of a contoured ossicular replacement prosthesis: clinical trials of 125 cases.

A columellar ossicular replacement prosthesis has been developed to simplify ossiculoplasties. The hydroxylapatite head has flattened egg-shaped contours set on a teflon shaft. One hundred and twenty-five prostheses have been implanted and the results of eighty-two cases between five and eighteen months' maturity are presented. Sixty-six percent of good risk partial ossicular replacement prosthesis (PORP) cases achieved air-bone closure within ten decibels and eighty-five percent within twenty decibels. Of all total ossicular replacement prosthesis (TORP) and PORP cases, 51.5 percent closed to within ten decibels and 69.5 percent to within twenty decibels. The design has simplified the preparation and implantation techniques and the prosthesis can be used in most ossiculoplasty situations. A malleus handle is not required and interposition of cartilage is unnecessary. The simplicity of the prosthesis should provide particular benefits for the occasional or trainee otologist.

Clinical Trials as Topic↗

PubMed1990

[Resection of the knee reconstructed with a massive prosthesis. Results after a 5 to 9 years follow-up].

Since ten years, with the progress of the adjuvant chemotherapy we treated conservatively 170 osteosarcomas. We try to review the functional and mechanical results of the knee prosthesis with 5 years of follow-up or more. There were 64 resections, 51 of the lower femur and 13 of the upper tibia. The early postoperative complications are few (less than 2%). The functional results are satisfying with 90% of excellent and good results. We observed 3 local recurrences (2 femur, 1 tibia). The survey is really increased by the adjuvant chemotherapy with a rate of 70% at 5 years. However for us the problem is the evolution of our reconstitution prosthesis. 3 kinds of mechanical failures occurred: a wear of the hinge, a fracture of the stem and a loosening of the massive component. The Guepar hinge was finally a good solution when it was metallic, but all the hinges with metal plastic. Articulation needed reinterventions because of quick wearing. For the tibial reconstitution prosthesis we did not observed any problem but for the femoral massive prosthesis, the failures were more frequent, perhaps because the mechanical situation is different. We observed 4 fractures of the stem, 5 loosening of femoral stem (bipolar loosening in one case). In all except one, the reintervention gave a good result. Finally, the result seems to be encouraging, the progress of the implant (Titanium stem, modular prosthesis, semi-constrained knee) may again decrease the rate of mechanical failures.

Adolescent↗

PubMed1989

[Hancock pericardial prosthesis. Intrinsic dysfunctions].

The frequency of primary dysfunction of 432 Hancock pericardial bioprosthesis was evaluated during a mean follow-up period of 53.1 months per patient. This frequency was 3.20% valve-year in mitral valve prosthesis and 0.92% valve-year in aortic valve prosthesis. Only one case of calcification was noted. Dysfunction was usually due to tearing of one or several pericardial cusps (25 cases), occasionally to tissue retraction (4 cases). Pathological examination of the explanted valves showed fibrin formation followed by organization into fibrous tissue in the host, retracting or fragilizing the pericardial valvular tissue. A preliminary study of the same group had led to discontinuation of Hancock prosthesis. The long follow-up period makes it possible to compare the results obtained with those of pericardial prosthesis of the same generation, to stress the need for echocardiographic monitoring of the implanted valves and to hope that new techniques of pericardial valve fitting will improve the mechanical reliability of prosthesis which, from the point of view of thrombogenesis and haemodynamics, have unquestionable advantages.

Adolescent↗

PubMed1989

The anthropometric total hip femoral prosthesis. Preliminary clinical and roentgenographic findings of exact-fit cementless application.

Total hip arthroplasty in the young patient remains a considerable challenge. Cemented arthroplasty has an unacceptably high failure rate. Porous ingrowth designs are one alternative, but bone ingrowth is unpredictable, thigh pain is a frequent clinical finding, stress shielding is often observed, revision is more complicated, and microporous components are mechanically weaker. A new anthropometric femoral component has been designed with a goal of long-term stability through osseointegration. The prosthesis is optimized for canal fill in the distal metaphysis and proximal diaphysis. The components are manufactured in 16 sizes, with cutting broaches precisely machined to the same dimensions to provide an exact fit to the femur. The high-strength TiAl6V4 alloy stem is combined with heads of either CoCr alloy or alumina (Al2O3) for reduced polyethylene wear. The 135 degrees neck-shaft angle and modular design allow for restoration of the abductor lever arm. Because the prosthesis is not porous coated, it is also suitable for use with cement. In cemented application, the prosthesis shape provides an optimal cement mantle. Seventy-one total hip arthroplasties have been performed using the Anthropometric Total Hip (ATH) prosthesis: 31 with exact-fit cementless fixation and 40 with cement. Of those using cementless fixation, 21 have been followed for more than one year (mean, 20 months; range, 12-48 months). The early clinical findings are as good as, or superior to, other cementless designs used at the authors' institution. Stress remodeling of the proximal femur occurs early and stabilizes by one year. The observed changes appear to improve the stability of the prosthesis. Clinical and roentgenographic findings suggest the osseointegration of the ATH femoral component.

Adult↗

PubMed1989

[Experimental study on the mechanism of serum leakage from expanded polytetrafluoroethylene (EPTFE) vascular prosthesis].

Even in recent years, the Blalock-Taussig (B-T) shunt operation has been carried out in order to increase pulmonary blood flow in patients of low pulmonary flow congenital heart disease. In such a case, a modified B-T shunt using an EPTFE vascular prosthesis would be employed in order to prevent blood flow obstruction in the upper extremity, and occasionally serum leakage from EPTFE vascular prosthesis is a complication. This has often troubled cardiovascular surgeons the world over, and we attempted to elucidate the mechanism of serum leakage and to discover how to prevent the situation from occurring. Using scanning electron microscopy, the structure of EPTFE vascular prosthesis was found to consist of an average of 0.5 micro meter polytetrafluoroethylene (PTFE) fibers arranged in parallel 5.0 micro meters from each other. The reason why serum does not usually leak from these widely spaced fibers is due to the presence of a repellent force derived from the surface tension and the contact angle between the solid surface of PTFE and the liquid. When the contact angle is over 90 degrees, the repellent force is in effect, while when it is below 90 degrees, this force is decreased. The surface tension and contact angle of physiological saline on the surface of PTFE showed values of 71.6 dyn/cm and 114.0 degrees, respectively, while demonstrating a strong repellent force. On the other hand, the surface tension of heparinized blood on the surface of the PTFE was 56.5 dyn/cm and the contact angle was 90.6 degrees. Thus, heparinized blood was assumed to act on the surface of the PTFE with a weak repellent force and for that reason had a tendency to easily leak from the EPTFE vascular prosthesis. When the surface of the PTFE was in contact with blood, blood protein was fixed to the surface of the PTFE and the contact angle of blood was thereby decreased. When the inner pressure of the vascular prosthesis was increased, the wall was stretched easily in a circumferential direction but with great difficulty in a longitudinal direction. With the PTFE stretched and released repeatedly, the expanded circumference was enlarged progressively due to the plastic character of the PTFE and because the spaces between the PTFE fibers were widened. In order to examine the relationship between the space between fibers and the critical pressure leading to serum leakage, computer simulation was carried out and the results showed a reversed linear correlation between the density of the fibers and the minimal pressures responsible for serum leakage.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1988

Patellar prosthesis positioning in total knee arthroplasty. A roentgenographic study.

Patellar prosthesis positioning in 40 primary total knee replacements was evaluated with regard to (1) patellar tilt, (2) angle between the patellar component and patellar bony remnant, (3) lateral versus medial placement, (4) patellar height, and (5) size of the patellar component versus patellar length. Two different designs were evaluated. Twenty knees that were resurfaced with a patellar button prosthesis and implanted with conventional surgical technique constituted Group A. Twenty knees that were resurfaced with a new biconvex prosthesis and implanted with specially designed instrumentation constituted Group B. For Group A, the patellar tilt averaged 4.25 degrees preoperative and 8.35 degrees postoperative. For Group B the patellar tilt averaged 4.60 degrees preoperative and 1.83 degrees postoperative. In Group B, there was significant improvement in patellar position, with only two patients showing values exceeding the neutral range (p = 0.0409). The angle between the patellar component and the bony remnant in Group A averaged 5.975 degrees, and in Group B, 1.447 degrees. Two patients in Group A and 18 patients in Group B had values in the normal range for patellar tilt and the angle between the prosthesis and the bone. The prosthesis was inserted medial to the patellar center in six patients in Group A and one patient in Group B. A significant decrease in patellar height was noted for both groups, but values were still within the normal range. Both groups showed significant increase in the postoperative articular length, indicating that oversized prostheses were inserted and excess bone removed.

Follow-Up Studies↗