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PubMed1977

Implantation of the total artificial heart by lateral thoracotomy.

Progress in the techniques for surgical implantation of the artificial heart has progressed in parallel with the technology and design of the prosthesis. In the author's first experience with total artificial heart (TAH) implantation (1968) a trans-sternal split was used opening the sixth intercostal space on the right side across the sternum to the left space. This obviously was not the optimum approach but the complexity, design and size of the prosthesis required maximum exposure of the atria and great vessels. Subsequently the mid-sternal split incision was used. The Dacron fibril coated silicone rubber 8 cm Kwan-Gett ventricles implanted by the mid-sternal split sustained a calf for 14 days in 1972. A calf with the improved Jarvik 3 ventricles fabricated with the same material and implanted via mid-sternal split survived 19 days in early 1973. The surgical techniques for lateral (right) thoracotomy were adopted in this laboratory in 1973. These techniques were applicable only when the prosthesis fit better in the chest. This procedure has been adopted by other laboratories replacing the natural heart of the calf with a TAH. This report describes in detail the stepwise procedure for implantation of the total artificial heart by a lateral thoracotomy in the calf.

Animals↗
PubMed2005

Implant-supported facial prostheses provided by a maxillofacial unit in a U.K. regional hospital: longevity and patient opinions.

PURPOSE: The aim of this study was to acquire information on the types and longevity of implant-retained facial prostheses and the opinions of patients on several factors related to their prostheses. MATERIALS AND METHODS: A survey of 75 maxillofacial prosthetic patients currently under treatment and review at the Maxillofacial Unit, Morriston Regional Hospital was conducted through a 23-question postal questionnaire. These patients were selected as representative of a group of individuals receiving treatment or under review for the fabrication of maxillofacial prostheses. RESULTS: Of the prosthetic replacements, 83% were ear prostheses, 8% nose, 6% eye, and 2% combination prostheses. Of the 47 respondents, 8 (17%) reported that they were currently wearing their original prostheses. The remaining 39 (83%) respondents had all been provided with at least 1 replacement prosthesis. The mean lifetime of the prostheses was found to be 14 months (range: 4-36 months). The majority of replacement prostheses in this study were provided as a result of color fade or wear of the silicone material of the previous prosthesis. Individuals with no previous experience wearing a prosthesis had an unrealistic expectation of their prosthesis longevity, with a mean value of 17.8 months. In comparison, individuals with previous experience had reduced expectations, with a mean of 14.4 months. In terms of the patients' opinions of the overall quality of their prostheses, the results demonstrated that a large number of patients were satisfied. Thirty-five patients rated their prostheses as excellent and 9 as good. At 7-12 months, 4 patients rated their prostheses as excellent and 8 as good. At 13 months, 4 patients rated their prostheses as excellent and 5 as good. CONCLUSIONS: It is important that advice be given to patients on the expected average longevity of their prostheses, together with information on factors affecting the longevity (i.e., environmental staining, cosmetics, and cleaning regimes). In this study, 26% of the replacement prostheses were provided due to color fading of the original prosthesis. This highlights the need for continuing research in the development of materials used for the construction of facial prostheses with improved properties, and in particular, improved color stability.

Adolescent↗
PubMed2003

The effect of clamping a tensioned wire: implications for the Ilizarov external fixation system.

This study demonstrates that clamping a tensioned wire can cause a reduction in wire tension. Tension (about 1275 N) was applied to a wire that was subsequently clamped, using cannulated bolts, to the steel half-ring of an Ilizarov external fixator. The tension in the wire was monitored before, during and after clamping. The apparatus was disassembled and the deformations in the wire caused by the clamps were measured. This experiment was repeated 15 times. When the wire was clamped to the frame, the wire tension was reduced by 22 +/- 7 per cent (mean +/- standard deviation, SD). The drop in wire tension was linearly correlated (r = 0.96; p < 0.001) with the deformation caused by the bolts. A finite element (FE) model of the wire was also constructed. The model was pre-stressed (tensioned), and the clamping effect replicated. This analysis showed that clamping the wire could be considered to squeeze the wire outwards (like toothpaste from a tube) and so reduce its tension during fixator assembly. To assess the magnitude of this effect in the clinical situation, the FE model analysis was repeated to replicate clamping a 1.8-mm-diameter wire to a 180-mm-diameter steel Ilizarov ring component. The analysis showed that for these conditions the tension reduced by 8-29 per cent. The results of this study highlight a general engineering problem: how can a tensioned wire be secured to a structure without an appreciable loss of tension? If the performance of the structure depends on the wire tension, this performance will change when the wire is secured.

Bone Wires↗
PubMed2003

Yielding of the clamped-wire system in the Ilizarov external fixator.

This study demonstrates that the clamped-wire system used to suspend bones within an Ilizarov external fixator yields when the perpendicular load exceeds 50 N per wire. Cyclic loading was applied to tensioned wires clamped within an Ilizarov ring component, with steadily increasing load amplitude. Wires were tested at four initial tension settings. The amount of energy lost within the clamped-wire system per load cycle was calculated for every test. The results showed that there was a consistent trend to increasing non-recoverable energy loss per load cycle when peak loads exceed 50 N for all initial tension settings. A finite element (FE) model replicating the experimental conditions was performed to investigate the levels of stress within the loaded wires. The FE model analyses showed that high stresses were generated in the wires close to the clamping sites, and that the stress levels could reasonably be expected to exceed the material yield stress when loaded to about 55 N, for all initial tension settings. The results show that material yield, accompanied by some wire slippage through the clamps, is responsible for system yield, in agreement with previous studies. Although the initial wire tension has an appreciable effect on the wire stiffness, it did not affect the elastic load range of the clamped-wire system. To prevent yield of the clamped-wire system in practice, the fixator should be assembled with sufficient wires to ensure that the load transmitted to each wire by the patient does not exceed 50 N.

Bone Wires↗
PubMed2005

An in-vitro investigation into the cement pressurization achieved during insertion of four different femoral stems.

Adequate cement pressurization during stem insertion improves the interdigitation of cement into bone. This increases the strength of the cement-bone interface, thus contributing to the reduction of the incidence of aseptic loosening, the commonest cause of revision surgery. This in-vitro study compared the cement pressurization achieved during insertion of four different stems of equivalent sizes: the Elite Plus (DePuy, UK), C-Stem (DePuy, UK), Exeter (Stryker, USA), and CPS-Plus (Plus Orthopedics, Switzerland). The maximum pressures attained at the time of stem insertion were recorded at proximal, mid and distal stem levels. The Elite Plus generated significantly higher distal pressures than the other stems. The CPS-Plus generated significantly greater proximal cement pressures than the Elite Plus, C-Stem, and Exeter prostheses. The triple taper of the C-Stem increased the cement pressurization medial to the stem. The stem shape and the presence or absence of a proximal stem centralizer affect cement pressurization. The presence of a proximal stem centralizer, a large stem volume, and a lateral-medial taper are all factors associated with increased cement pressurization during stem insertion.

Adhesiveness↗
PubMed1988

Revision of total hip replacement for primary osteoarthritis.

During the 11-year-period from 1970 to 1980, 799 total hip arthroplasties with metal-on-plastic prostheses were performed for primary osteoarthritis. In all cases high viscosity cement was used, but not under pressure; acetabular cartilage was removed, but the femoral canal was not plugged. The rate of revision and risk factors were evaluated by survivorship analysis. The overall cumulative revision rates were 11%, 14% and 19% after 8, 10, and 14 years respectively. When prophylactic antibiotics were not used, there was a significant risk of revision for infection. The risk of revision for mechanical loosening of both the acetabular and femoral components was significantly increased for men, younger patients, and if a snap-fit prosthesis with a 35 mm head and short wedged stem was used. The survivorship findings were validated by multivariate statistical analysis.

Adult↗
PubMed1992

The morphology of the proximal femur. A three-dimensional radiographic analysis.

Biological fixation of cementless femoral implants requires primary stability by optimal fit in the proximal femur. The anatomy of the bone must then be known precisely. We analysed in vitro the accuracy of bone measurements of 32 femurs and compared the dimensions obtained from radiographs and CT scans with the true anatomical dimensions. Standard radiographs gave only a rough approximation of femoral geometry (mean difference: 2.4 +/- 1.4 mm) insufficiently accurate to allow selection of the best fitting prosthesis from a range of sizes and altogether inadequate to design a custom-made prosthesis. CT scans give greater accuracy (mean difference: 0.8 +/- 0.7 mm) in our experimental conditions, but in clinical practice additional sources of error exist.

Aged↗
PubMed2002

[Cadaver study: robot-assisted cranial resection and implantation of titanium plates].

A processing chain for the prefabrication of individual titanium implants for cranioplasty was developed at the Ruhr-University Bochum. In patients with tumours a simultaneous resection of cranial bone and insertion of the individual implant is desirable. At first resection templates were used for this. New developments aim at a preoperative definition of resection trajectories for surgical robots corresponding to both the planning of the resection and the implant. This study used ovine cadaver skulls for robot resection experiments. The results demonstrate possible applications, limitations and necessary prerequisites in robot assisted cranial surgery.

Animals↗
PubMed1991

Factors influencing rehabilitation of arteriosclerotic lower limb amputees.

This survey considered 598 arteriosclerotic amputees over a period of 9 years: 267 below-knee; 81 Gritti-Stokes; 195 above-knee; and 55 double amputees. A walking ability index (WAI) ranging from 1 for a normal gait to 6 for inability to walk was determined for these amputees by clinical grading at 3, 6, 9, and 12 months after prosthesis fitting. Amputees with the below-knee operation had better WAI at 3 and more months than those with either Gritti-Stokes or above-knee operations. There was no statistical evidence for a difference between Gritti-Stokes and above-knee operations at any time of assessment of WAI. The 50-59 year-old age group had significantly better WAI at 6, 9, and 12 months than did the 60-69 or 70+ age group, but the 60-69 year-old group was not significantly different from the 70+ age group. On an average, the 78 amputees (14 percent) with ischemic heart disease had a poorer WAI at 6 and more months than did those without it; the 46 amputees (8 percent) with hemiplegia were worse at 12 months than those without hemiplegia; and the 15 amputees (11 percent) with bronchitis were worse at 12 months than those without bronchitis. Double amputees had poorer WAIs at 12 months than those of single amputees.

Age Factors↗
PubMed1996

Clinical rehabilitation of the amputee: a retrospective study.

The aim of this study was to determine the rehabilitation outcome of lower limb amputee patients after clinical rehabilitation. Altogether 183 amputee patients admitted for clinical rehabilitation in the years 1987-1991 were reviewed by retrospective analysis of medical record data. Three groups of amputee patients were identified by reason for amputation. The vascular group: (N = 132), mean age 67 years, mean admission time 119 days, 85% prosthetic fitting. The oncology group (N = 15), mean age 55 years, mean admission time 77 days, 60% prosthetic fitting. The traumatic amputee group: (N = 14), mean age 41 years, mean stay 134 days and 100% prosthetic fitting. Some 22 patients were bilateral amputees and were assessed separately. The most important reasons for not fitting a prosthesis were oncological metastases, stump and wound healing problems. After rehabilitation 86% of all patients could be discharged home. These results are more favourable than those seen in previous studies.

Adolescent↗
PubMed1999

Creating a model for fabricating a partial hand glove prosthesis using the realigned casts of the contralateral digits.

A method for creating a model for fabricating a partial hand glove prosthesis is described. The realigned casts of the corresponding digits of the contralateral uninjured hand were used to substitute for the lost digits on a cast of the stump. The technique allows an exact reproduction of the anatomical and fine surface details of the digits. It has the advantage of customisation, allowing a close match in the size, shape and surface characteristics of the prosthesis to that of the remaining digits of the hand.

Adult↗
PubMedDate not supplied

Botulinum A toxin treatment of a deviated orbital implant.

We report a case of progressive deviation of an implant that resulted in conjunctival thinning and an inadequately fit prosthesis. Such a case may have been treated with conjunctival grafting or replacement of the implant with an hydroxyapatite sphere. In this case, injection of botulinum A toxin (Botox) into the contracted medial rectus muscle contributed to the successful refitting of a new and stable prosthesis and improvement of the conjunctival integrity. Possible explanations of the progressive shift in the position of the implant and its postinjection stability are discussed.

Adult↗
PubMedDate not supplied

[Cosmetic results of posttraumatic eyeball subatrophy surgical treatment using "alloplant" biomaterials with subsequent use of prostheses].

A complex of surgical operations making use of Alloplant biomaterials, performed in 47 patients with initial posttraumatic subatrophy and 79 patients with well-developed and far advanced stages of this condition, helped preserve the eye as anatomical organ in 97.5% patients, with enlargement of the eyeball in two-thirds of patients and stabilization in one-third. Optic reconstructive operations were later performed and visual acuity improved in patients with the initial stage of subatrophy. Use of allotransplant for eyeball bandage in order to create a carcass for the sclera helped conceal the cicatricial deformation of the sclera and repair the shape and volume of the eyeball in patients with initial subatrophy, due to which a good cosmetic result was attained. In well-developed and far advanced subatrophy use of biomaterial for bandage created optimal conditions for thin-wall cosmetic prostheses, ruled out the irritating effect of the prosthesis in cases when corneal sensitivity was retained and/or there were coarse corneaoscleral cicatrices, and thus extended the indications for cosmetic prostheses of subatrophic eyes.

Adolescent↗
PubMed2001

Intraoperative fabrication of palatal prosthesis for maxillary resection.

BACKGROUND: Immediate placement of a palatal prosthesis has become the standard of care after maxillectomy or palatectomy, except when free-flap reconstruction is used. Palatal prostheses are usually fabricated preoperatively. Infrequently, the surgeon may face a situation where upper jaw resection has been performed and a prefabricated prosthesis is not available. OBJECTIVE: To describe a method of rapid intraoperative fabrication of a palatal prosthesis, which allows immediate oral intake and excellent speech. PROCEDURE: Two sheets of thermoplastic dressing (Aquaplast; WFR/Aquaplast Corporation, Wyckoff, NJ) were immersed in hot water. As they became soft and pliable, they were applied to the remaining hard palate and alveolar ridge. As the material cooled, it hardened, with its shape conforming to the remaining hard palate, alveolar ridge, and teeth. The rigid stent was then removed, trimmed, and fashioned to cover the palatal and maxillary defect. The stent was then wired to the remaining alveolar ridge and to the ipsilateral zygomatic buttress or lateral orbital rim. Removal of the stent was easily accomplished in an office setting. PATIENTS: Twelve patients required partial upper jaw resection without available prefabricated prostheses. Of these, 3 patients underwent emergency surgery for mucormycosis and 2 for bleeding malignant tumors; 3 underwent bone resection more extensive than that anticipated preoperatively; and 4 did not have prefabricated prostheses for other reasons. RESULTS: The thermoplastic prosthesis achieved its goals in all 12 patients. Eleven patients achieved oral food intake within 24 hours. One patient remained in a coma after extensive maxillary, orbital, and skull base resection for mucormycosis. The prosthesis was removed after 4 to 12 weeks and replaced with a permanent implant in 11 of the 12 patients. CONCLUSIONS: This simple, quick, and inexpensive intraoperative fabrication of palatal prosthesis requires no special expertise and equipment. It allows immediate oral intake and excellent speech.

Carboxymethylcellulose Sodium↗
PubMed1975

Common problems in ophthalmic plastic surgery.

Many ophthalmic plastic surgical problems are ignored because the patient seems to be ""getting along." Frequently physicians are only vaguely aware of the constant daily discomfort their patients experience from seemingly minor problems such as endocrine exophthalmos, an ill-fitting prosthesis or baggy eyelids. As a result, too often the patient is unaware of the treatment possibilities that are available to relieve and often eliminate his problem. These conditions are often first seen by the family physician.

Adult↗
PubMed2001

[Extra-oral implants: surgical procedures].

The different extra-oral implant systems (screw and plate fixation) are not compatible. Rigorous surgical procedure (detailed and illustrated here) is mandatory to obtain the best implant osseointegration and epithesis loading 3 months later. Besides surgical procedure, careful bone and peri-abutment suture are required for success.

Bone Plates↗
PubMed2001

Amputation and phantom limb pain: a pain-prevention model.

Within the figure of more than 200,000 surgical amputations performed in the United States each year lies another--70% of patients experience phantom limb pain after the procedure, and 50% still experience phantom pain 5 years after surgery. Patients describe burning, stabbing, twisting, cramping, or throbbing pains in the missing part. Adding to the patient's and the anesthesia professional's conundrum has been the lack of a simple model that tissue injury produces pain. The patient with a surgical amputation who experiences phantom limb pain can have several sources for discomfort including problems from the original tissue injury or from pathology, e.g., scarring or continued cellular dysfunction resulting from diabetes, ischemia, or infection. Suboptimal prosthesis fit and tissues and joints connected to the affected part can continue to generate pain long after surgical wound healing. In addition, nonaffected tissues and joints now made to carry extra loads as a result of altered gait and balance can sustain collateral stress and damage and produce nociception. In addition to this series of problems, amputee patients remain susceptible to the pain problems experienced by the general population. There is a positive correlation between a painful limb before amputation and experiencing chronic phantom limb pain. Authors have described patients with preamputation pain who benefited from effective preemptive analgesia and experienced less phantom limb pain. CRNAs can have a significant role in providing anesthesia and analgesia services to these patients and can begin to think in terms of preventing lifelong pain.

Algorithms↗