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Comparison of myoelectric and conventional prostheses for adolescent amputees.

We questioned whether myoelectric prostheses were a reasonable alternative to conventional prostheses for adolescents with unilateral, congenital, below-elbow amputations in respect to fit, function, cosmesis, and cost. Ten patients were studied. Each received a physical, functional, and psychosocial evaluation prior to prosthetic fitting. The physical evaluation included myopotential, residual limb length and circumference, active range of motion, terminal device grasp force, and mechanical range. The functional evaluation consisted of a questionnaire of 38 bimanual activities. The psychosocial evaluation included an assessment of both the patient and the family. Following prosthesis fabrication, each patient received 10 days of training, a 3-month checkup, and a 6-month reevaluation. Wearing patterns, perception of cosmesis, change in physical attributes of the residual limb, and functional performance were documented. Results indicate that for these subjects myoelectric prostheses with a hand were an acceptable alternative to conventional prostheses with a hook.

Activities of Daily Living↗

An algorithm to identify knee prostheses from their radiographic appearances.

Modularity in total knee system design makes it important for the surgeon to know the model of prostheses being revised since components of different designs are not interchangeable. Preoperative information on the manufacturer and model of prostheses implanted may not always be available. This article describes an algorithm that allows surgeons to identify the prosthesis from standard radiographs. Ninety-nine percent of the knee prostheses implanted between 1985 and 1992 can be identified using this algorithm. The algorithm uses the shape of the tibial keel, the type of baseplate, and the shape of the femoral component as branch points to identify the model and manufacturer of 15 primary total knee prostheses. In addition, certain models were found to have radiographic "fingerprints" such as the presence of a spiked tibial keel. This algorithm should be an aid to surgeons performing total knee revisions.

Algorithms↗

Life table analysis and clinical evaluation of oral implants supporting prostheses after resection of malignant tumors.

Seventeen mostly elderly patients, 13 men and 4 women, were consecutively admitted for implant-prosthodontic treatment after they had undergone resection of malignant tumors in the oral cavity. A total of 53 dental implants (ITI-Straumann) was placed, 12 in the maxilla, 41 in the mandible. The prosthetic rehabilitation consisted of overdenture therapy in 15 patients, and 2 patients were treated with fixed partial prostheses. Thirty-three implants were prescribed for patients who received radiotherapy either before or after implant placement. The average dose varied between 50 and 74 Gy. Eighteen implants were located in grafted bone from the fibula, scapula, or hip. For 2 patients, hyperbaric oxygen therapy was also prescribed after osteoradionecrosis had developed. One implant was lost before prosthetic loading. During an observation period of up to 7 years after loading, 3 more implants were removed. All implant losses occurred in the mandibles of patients who had received radiotherapy. A life table analysis was performed, and the cumulative survival rates, calculated for 2, 3, and 5 years, were 93%, 90%, and 90% respectively. No failures or complications were observed with technical components of the implants or prostheses. All prostheses could be maintained during the entire observation time. Although in the present investigation the survival rate of implants was slightly lower than under standard conditions, the treatment with implant-supported prostheses seemed to be advantageous for patients who had undergone intraoral resections.

Adult↗

Fixation of proximal humeral prostheses and rotational micromotion.

Twenty pairs of cadaveric humeri were used to compare the rotational stability of proximal humeral prostheses fixed by proximal cementation with the stability offered by press fit or full cementation. For each proximally cemented specimen, only the upper portion of the prosthesis was coated with cement. For the fully cemented specimens, a cement restrictor was used just distal to the prosthesis, and a finger-packing technique was used to fill the proximal humeral medullary canal. Torque was applied to the Morse taper of the prostheses, and rotational micromotion was measured at the level of the osteotomy. In each of 11 pairs of cadaveric humeri, one side was press fit and the contralateral side was proximally cemented; in each of 9 pairs, proximal cementation was compared with full cementation. Proximally cemented prostheses' micromotion was significantly less than that of press-fit prostheses (P = .0016). There was no difference in micromotion between proximal cementation and full cementation (P = .82). Proximal cementation increased initial fixation over press fit. Full cementation did not increase rotational stability.

Arthroplasty↗

"Stiction-friction" of total hip prostheses and its relationship to loosening.

The static friction, or "stiction-friction", in McKee-Farrar and Charnley-Müller prostheses in a hip joint simulator was compared with dynamic friction determined while the prostheses were oscillated. Under physiological conditions stiction-friction differed little from dynamic friction in both metal-on-metal and metal-on-plastic prostheses, and was affected very little by the lubricant as long as some fluid was present. Stiction-friction increased significantly only after relatively long stationary periods and high loads. However, the frictional forces generated in total hip-replacement prostheses were at least forty times higher than those generated in normal joints and may well be enough to cause late loosening of acetabular components by fatigue failure.

Acetabulum↗

[Development of small-diameter vascular prostheses covered with human endothelial cells: Possibilities and limits of in vitro-tests]

There is an increasing demand for small-diameter vascular prostheses for the replacement of arteriosclerotic coronary arteries. They may be replaced by autologous blood vessels, usually parts of the saphenous vein. Prostheses of synthetic materials and an inner diameter of less than 4 to 6 mm are unsatisfactory and, therefore, not implanted for coronary arteries. A substantial improvement is, however, expected for prostheses covered with human autologous endothelial cells. It has to be proved that this new type of vascular prostheses is an adequate replacement for small arteries. Tests of the new prosthesis should comprise cell and tissue compatibility of the synthetic materials as well as normal function of the endothelial cells. The aim of the present paper was to reduce the number of animal experiments in this development by establishing new in vitro tests for endothelial cell compatibility of synthetic materials and for the adherence of endothelial cell on the prosthesis. Physiologically haemodynamic streaming conditions are in vitro produced by self-constructed circulatory systems. First results demonstrate that physiologic shear stress is achieved. Limits and relevance of the in vitro tests are discussed in relation to animal experiments and clinical studies.

Journal Article↗

Condylar prostheses in head and neck cancer reconstruction.

OBJECTIVE: To discuss the use of condylar prostheses after mandibular resection for tumor. DESIGN: Case series and literature review. SETTING: Tertiary referral center. PATIENTS: Four patients underwent condylar reconstruction with metallic condylar prostheses after hemimandibulectomy for either squamous cell cancer or Ewing sarcoma. MAIN OUTCOME MEASURE: Complications related to the condylar prostheses. RESULTS: Clinical and radiological follow-up in these patients revealed several complications, including exposure or extrusion of the prosthesis and migration of the prosthesis into the epitympanum, resulting in profound sensorineural hearing loss owing to bony destruction of the cochlea. Two of our patients required removal of the mandibular hardware because of the seriousness of the complications, and 1 of the 2 underwent reconstruction of the condyle with a fibular free flap. CONCLUSIONS: Metallic condylar prostheses in the setting of tumor resection and reconstruction involve significant risks. Autogenous materials, such as vascularized bone grafts, should be used whenever possible.

Carcinoma, Squamous Cell↗

Implant-supported mandibular telescopic prostheses in oral cancer patients: an up to 9-year retrospective study.

PURPOSE: The aim of this retrospective study was to present the results of implant-supported telescopic prostheses in the mandible after removal of malignant tumors. MATERIALS AND METHODS: Between 1991 and 2000, 24 patients with squamous cell carcinoma (16 irradiated, eight nonirradiated) underwent mandibular rehabilitation with implant-supported telescopic prostheses. A total of 111 dental implants were placed. Treatment complications were observed. The cumulative survival rates of the implants and prostheses were evaluated by lifetable analysis. RESULTS: Within a mean follow-up period of 30 months (1 to 108 months), only three implants failed. All other implants are still in function. Of 24 patients, 23 were satisfied with their implant-supported telescopic restorations. Soft tissue, implant, or prosthetic complications occurred very rarely. The cumulative implant survival rate was about 97% and the cumulative prosthesis survival rate was about 95% at 9 years. CONCLUSION: Implants and implant-supported telescopic maxillofacial prostheses can successfully remain in function over a long period. Increased implant and prosthetic complications should not be expected. Therefore, telescopic implant attachments seem to be very useful as a treatment option for prosthetic restoration of the mandible in tumor patients.

Adult↗

The effect of body weight and age on frequency of repairs in lower-limb prostheses.

INTRODUCTION: Overweight patients sometimes present a practical problem for provision of lower-limb prostheses. Most information about the effect of body weight on the endurance of prostheses is based on laboratory tests. This is a retrospective study based on an audit to study the effect of body weight and age on the frequency of repairs. SUBJECTS: One hundred and sixteen patients were involved (98 male), age 16-96 years, mean=58.7 years; weight 47-140 kg, mean=88 kg; 68 were transtibial amputees and 48 were transfemoral amputees. Causes of amputation were trauma (49), peripheral vascular disease (29), and others (38). Amputation was done 1-66 years prior to assessment, mean=13.66 years. Period of use of current prostheses was 0.5-28 years, mean=3.5 years. RESULTS: One hundred and one repairs were done in a period of 6 months. The number of repairs was found to correlate significantly with weight (P value<0.001) and inversely with age (P value=0.003). No significant correlation was found between repairs and gender, cause of amputation, or level of amputation. CONCLUSION: Body weight and age of amputee are determining factors in the frequency of repairs of lower-limb prostheses. However, a larger study for a longer period will be needed to confirm our finding.

Adolescent↗

A prospective 5-year study of two cast framework alloys for fixed implant-supported mandibular prostheses.

PURPOSE: A longitudinal 5-year clinical investigation was carried out to compare screw-retained frameworks constructed from two alloys with different mechanical properties, either gold or silver-palladium, supported in the mandible by the Astra Tech implant system. MATERIALS AND METHODS: Twenty-six edentulous patients with mandibular implants were divided into two groups: group A was provided with Chicago IV gold alloy superstructures, and group B was provided with Palliag M silver-palladium alloy superstructures. The surgical procedures for placing the mandibular bone implants and the prosthodontic and laboratory techniques for constructing the prostheses were carried out according to standard, well-documented practices. All patients wore conventional maxillary complete dentures. The integrity of prostheses and health of supporting tissues were compared over a 5-year period. RESULTS: Both materials had similar accuracy of fit and resistance to functional stress, although silver-palladium was technique sensitive and necessitated meticulous laboratory practice to achieve accuracy of casting. Clinical performance of both prostheses was similar, and radiographic assessment showed no statistically significant differences in periimplant bone changes. CONCLUSION: There were no differences in clinical performance and radiographic changes between the two materials. Therefore, silver-palladium alloy may be considered a suitable low-cost substitute for gold alloy for fixed implant-supported prostheses.

Dental Alloys↗

Comparison of the resistance to infection of rifampin-bonded gelatin-sealed and silver/collagen-coated polyester prostheses.

PURPOSE: The purpose of this study was to compare the efficacy of rifampin-bonded gelatin-sealed and silver acetate/collagen-coated knitted polyester prostheses for the prevention of bacteremic graft infection in an animal model. METHODS: Eighteen 6.0-mm polyester grafts (length, 5.0 cm) were implanted in dogs end-to-end into the infrarenal aorta. The dogs were divided into four groups as a function of type of prosthesis implanted. The dogs in groups I (n = 3) and II (n = 3) received control gelatin-sealed or collagen-coated polyester prostheses, respectively. In group III (n = 6), the dogs received rifampin-bonded gelatin-sealed polyester prostheses. In group IV (n = 6), the dogs received silver/collagen-coated polyester prostheses. Two days after implantation, the grafts were challenged with 6 x 10(9) Staphylococcus aureus intravenously. One week after implantation, the grafts were harvested with sterile technique. Quantitative cultures were obtained from all the harvested grafts. The results were expressed as colony-forming units per cm(2) of graft material. Bacteriologic study was also performed on various tissue samples. The chi(2) test was used to compare the culture proven infection of control and antimicrobial grafts. RESULTS: All the control grafts were infected with S aureus at the time of removal. Five of the six silver/collagen-coated grafts were infected, whereas none of the six rifampin-bonded gelatin-sealed grafts grew S aureus (P <.01). There was no significant difference in the number of positive culture results of organ samples between the different groups of dogs. CONCLUSION: These results indicate that rifampin-bonded gelatin-sealed polyester grafts are significantly more resistant to bacteremic infection than are silver/collagen-coated polyester grafts in a highly challenging model.

Acetates↗

Observations on dental prostheses and restorations subjected to high temperatures: experimental studies to aid identification processes.

In large scale disasters associated with fire the damage caused by heat can make medico-legal identification of human remains difficult. Teeth, restorations and prostheses, all of which are resistant to even quite high temperatures can be used as aids in the identification process. In this project the behaviour and morphology of teeth and dental prostheses exposed to a range of high temperatures was studied. Healthy teeth, dental restorations and prostheses were placed in a furnace and heated at a rate of 30 degrees C/min and the effects of the predetermined temperatures 200, 400, 600, 800, 1000 and 1100 degrees C were examined by stereomicroscopy and scanning electron microscopy (SEM). Our observations show that some prostheses and restorative materials resist higher temperatures than theoretically predictable and that even when a restoration is lost because of detachment or change of state its ante-mortem presence can be confirmed and detected by both stereomicroscopic examination and SEM of the residual cavity. We further conclude that a reasonably reliable estimation of the temperature of exposure can be made from an analysis of the teeth and restorative materials.

Composite Resins↗

Complications after treatment with implant-supported fixed prostheses: a retrospective study.

PURPOSE: The aim was to retrospectively evaluate the frequencies of different complications, as well as the number of visits to dentists because of such complications, after treatment with implant-supported fixed prostheses. MATERIALS AND METHODS: The study group comprised 75 patients who had been treated with implant-supported fixed prostheses 3 years earlier. All case records were scrutinized, and notes of complications in association with implants and superstructures were registered. RESULTS: The most common intervention made was occlusal adjustment/selective grinding of the prostheses. Complications in association with both implants and superstructures were fairly common. The most frequent complication was fractures of the acrylic resin matrix, including artificial acrylic resin teeth. Consultations because of periimplant mucosal inflammation were much more common among women compared to men, while complications that could be attributed to heavy loading tended to be more common in men. CONCLUSION: Complications with both implants and superstructures are fairly common after treatment with implant-supported fixed prostheses. Regular follow-ups to maintain optimal function in these patients are thus mandatory.

Acrylic Resins↗

[Comparison of healing characteristics of DALLON-standard and DALLON-double velour vascular prostheses].

By means of histological method and the scanning and transmission electron microscope healing processes of two types of Polish prostheses: DALLON-standard and DALLON-double velour were compared. The experiments were carried out on 36 dogs. The two types of prostheses mentioned were implanted in abdominal aorta. The grafts were removed 1, 4 and 12 months after implantation. The performed studies showed that although the sequence and nature of morphological changes leading to the reconstruction of the vascular wall in both types of grafts were similar, the development of the neointima as well as the formation of the neo-adventitia firmly accreted with surrounding tissues were considerably faster in double velour DALLON prostheses. Unlike in standard DALLON prostheses, the neointima of double velour DALLON grafts was rich in cells, had elastic fibres. Already after 12 months double velour DALLON grafts were completely covered by endothelial cells, which proves better reconstruction of the vascular wall. Rapid endothelial cells coverage of the lumen surface prevents thrombosis. Morphological differences observed in endothelial cells covering the neointima of standard grafts and double velour graft suggest the existance of various sources of endothelialization in both types of grafts.

Animals↗

Clinical evaluation of resin-bonded prostheses.

Resin-bonded prostheses were clinically evaluated following a mean period of 41 months. The abutment teeth were minimally prepared, and one groove was placed on the surface approximating the edentulous space. Retainers were treated using the Silicoater technique. Thirty-four prostheses were made for 32 patients. Four patients were lost from the study and 30 units were re-examined. Two prostheses had debonded. The results suggest that resin-bonded prostheses can be successful if meticulous attention is given to the procedures outlined.

Adult↗

Peri-implant mucosal level in patients treated with implant-supported fixed prostheses: a 1-year follow-up study.

PURPOSE: The purpose of this follow-up study was to quantify the change in the peri-implant mucosal level after treatment of edentulous patients with fixed prostheses on osseointegrated endosseous implants. MATERIALS AND METHODS: Twenty patients were included in the study: 10 were treated in the maxilla, and 10 were treated in the mandible. Both groups had fixed prostheses on osseointegrated Brånemark implants. Peri-implant mucosal level was measured with a calibrated probe after removal of the prostheses at the 1-year follow-up. These measurements were compared to those made on the original master casts. RESULTS: A larger mean retraction (-) was observed in the mandible (-1.6 mm) compared to the maxilla (-0.8 mm), but there was great variation. The individual values varied from -4.5 to +1.0 mm in the mandible and from -6.0 to +6.0 mm in the maxilla. CONCLUSION: Peri-implant soft tissue recession occurs during the first year in edentulous jaws after treatment with implant-supported fixed prostheses and more so in the maxilla than the mandible.

Aged↗

[Microflora of the voice prostheses].

The study was made of the condition of voice prostheses Provox and Blom-Singer in 27 patients wearing them. The prostheses were to be replaced by new ones as they lost impermeability for water. The prostheses were used for 6 months to 2 years. At the prosthesis removal from the tracheoesophageal bypass it was found that the esophageal flange and protective valve were contaminated with fungi and pathogenic bacteria. The valve was deformed, had limited motility and did not close tightly the esophageal opening of the prosthesis as the result of which liquid leaked into the airways. Bacteriological examination identified C.albicans, C.krusei, C.glabralis in 11 patients. Nistatin, flucostat, fluconasol, amphotericin were used in antifungal therapy. Prophylactic use of these drugs against fungi prolonged use of the prostheses 2-fold.

Bacterial Infections↗

Conventional and implant oral prostheses.

Despite advances in preventive dentistry, many elderly persons present with several missing teeth replaced by oral prostheses of various kinds. An increasing number of prostheses are retained and supported by oral implants. Maintaining a complete dentition with fixed, removable, or implant-retained prostheses improves function and patient self-esteem. Irrespective of the prosthesis type, periodic functional and health reassessments are necessary. Strict oral hygiene protocols must be reinforced continually and appropriate modifications (relines) and repairs should be performed to prevent possible degeneration of supporting structures. Although implants promise enhanced function and greater patient satisfaction, they too require careful maintenance. Thus, all oral prostheses require close monitoring and maintenance care. A physician can make an important contribution to a patient's health and quality of life by ensuring that he or she receives routine oral health care.

Aged↗