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At least 865 records · Page 48Linked to original sources
PubMed2002

Oxygen consumption during ambulation: comparison of using a prosthesis fitted with and without a tele-torsion device.

OBJECTIVE: To determine the energy expenditure and subjective comfort rating of walking in transtibial amputee patients using their prosthesis fitted either with or without a tele-torsion device (TT Pylon). DESIGN: Randomized, before-after trial. SETTING: Gait laboratory. PARTICIPANTS: Six men, moderately active, with unilateral transtibial amputation (mean age, 39.5 +/- 9.9y). INTERVENTION: Subjects walked on a motorized treadmill using their prosthesis fitted either with (ProsWith) or without (ProsWithout) a TT Pylon. Trials were repeated with subjects walking at speeds 100%, 130%, and 160% of their "normal" pace. MAIN OUTCOME MEASURES: The energy expended (VO(2)) and subjective comfort rating during each walking trial. RESULTS: VO(2) during walking with the prosthesis fitted with the TT Pylon was 5.4% and 9.1% lower than when using the prosthesis without the TT Pylon, at the speeds 130% and 160% of normal, respectively. Findings at the speed 160% greater than normal were significant (P <.05). Two of the subjects perceived no difference in prosthetic comfort between ProsWith and ProsWithout. The other 4 subjects preferred the TT Pylon at all speeds. CONCLUSION: Use of a TT Pylon can significantly reduce the energy expenditure of walking at speeds above normal.

Adult↗
PubMed2001

The effect of femoral prosthesis design on cement strain in cemented total hip arthroplasty.

Finite element studies show that the highest cement stresses are located at the most proximal and distal ends of the prosthesis. In vitro biomechanical and histologic analyses of autopsy-retrieved cemented femoral components show these areas to be associated with cement-prosthesis debonding. In this study, cement strains were measured in 2 geometrically different femoral stems in paired cadaver femora: A straight, collared, moderately tapered stem (Centralign) was compared with an anatomically curved, collarless, dramatically tapered stem (Scientific Hip Prosthesis [SHP]). Results showed that the maximum strain and the overall strain profile differed between the 2 stems. The Centralign had peak strains located at the most proximal gauge positions, whereas the peak strains of the SHP were located around the middle of the femoral stem. Minimization of cement strain, especially at the crucial proximal and distal areas of the stem, by altering component design may be able to reduce cement-prosthesis debonding and improve clinical results.

Arthroplasty, Replacement, Hip↗
PubMed2003

TMJ Concepts/Techmedica custom-made TMJ total joint prosthesis: 5-year follow-up study.

This prospective study evaluated the 5 to 8 year subjective and objective results of 42 consecutive patients who had TMJ reconstruction using the TMJ Concepts/Techmedica custom made total joint prosthesis. Criteria for use of the prosthesis included the following TMJ conditions: (1) multiply operated, (2) previous alloplastic implants, (3) osteoarthritis, (4) inflammatory or resorptive arthritis, (5) connective tissue or autoimmune disease, (6) ankylosis, and (7) absent or deformed structures. Thirty-eight of 42 patients (90%) with 69 TMJs reconstructed using the TMJ Concepts/Techmedica total joint prosthesis had appropriate data for inclusion in the study. The average age at surgery was 36 years and average follow-up was 73.5 months. The entire group and three subgroups were objectively evaluated for incisal opening, lateral excursions, and occlusal stability, while subjectively assessed for pain and jaw function. Paired t-test and comparison analyses were used to assess outcomes. For the group of 38 patients, there was statistically significant improvement in incisal opening (P=0.001), jaw function (P=0.001), and pain level (P=0.0001). Lateral excursion movements significantly decreased (P=0.04). The occlusion remained stable in all cases. Complications occurred in six patients. Comparison analysis of the three groups demonstrated significantly better outcomes for patients with fewer previous TMJ surgeries and without exposure to Proplast-Teflon or Silastic TMJ implants. This study demonstrated that the TMJ Concepts/Techmedica total joint prosthesis is a viable technique for TMJ reconstruction as a primary procedure and for patients with previous multiple TMJ surgeries and mutilated anatomy of the TMJ.

Adolescent↗
PubMedDate not supplied

[Midterm results and revisions of the thrust plate prosthesis (TPP)].

AIM: Although already in use for 20 years, the concept of the metaphyseal anchored thrust plate prosthesis has not yet gained general acceptance. Clinical and radiological follow-up examinations were carried out 5 to 8 years after implantation of a TPP. We tried to answer the question if the metaphyseal anchorage of the cement-less TPP is equal to a diaphyseal anchorage of a cement-less stem prosthesis and to define the advantages of the TPP. METHODS: We included 170 of the patients from our clinic with an implanted TPP in this study. Furthermore we reviewed the results of 30 revision hip arthroplasties of the TPP. The clinical examination were carried out using the Harris hip score while the radiological examinations were performed on the basis of predefined criteria. RESULTS: We found good clinical results. The preoperative Harris score of 48.7 increased to 93.7 at 24 months postoperatively. Radiolucencies were detected and were of varying relevance in dependence on their localization. The Kaplan-Meier survival analysis at 8 years was 90.5 %. The clinical results after changing the TPP were also good to excellent. The mean Harris hip score was 87.3. CONCLUSION: Our study suggests that in spite of a slightly higher aseptic loosening rate in comparison to the cement-less stem prosthesis, the thrust plate prosthesis proved to be worthwhile. On the basis of previous experience we assume that the TPP is a good alternative implant especially for young patients.

Adolescent↗
PubMed2002

A maxillary lip prosthesis retained by an obturator with attachments: A clinical report.

This article describes the prosthetic rehabilitation of small maxillary lip and maxilla defects with a lip prosthesis attached to an obturator. The definitive obturator prosthesis was designed with 3 plastic ball attachments on the labial surface that provided adequate retention for the lip prosthesis. The thin margin of the lip prosthesis ensured that it adapted well to functional movements.

Carcinoma, Adenoid Cystic↗
PubMed1992

Motion of the bipolar hip prosthesis components. Friction studied in cadavers.

It has been postulated that most hip motion occurs at the inner bearing in bipolar hip prosthesis. However, radiography and cineradiography analyses have shown that the inner bearing is not always the primary articulation. We studied the frictional behavior of bipolar prosthesis and Austin-Moore prostheses and the motion of the bipolar prosthesis using a pendulum apparatus. The primary articulation was altered according to the amount of loading. When a load of 10 kg was applied to the joint, motion occurred at both bearings with friction coefficients 0.061 at the inner bearing and 0.026 at the outer bearing. With loads of over 20 kg, the outer bearing was the primary articulation. The inner bearing was the dominant articulation only when the acetabular cartilage had been removed. Our results suggest that the motion of bipolar prostheses occurs mainly at the outer bearing during normal walking, and that this prosthesis cannot be expected to reduce wear of articular cartilage.

Biomechanical Phenomena↗
PubMed1999

A large maxillofacial prosthesis for total mandibular defect: a case report.

We successfully fabricated a large maxillofacial prosthesis for replacement of a total mandibular defect resulting from surgical failure to reconstruct the mandible. Although a number of reports have described procedures for fabricating midfacial prostheses, there is little information on prostheses to compensate for total loss of the mandible. A 54-year-old woman was referred to the Dentistry and Oral Surgery Division of the National Cancer Center Hospital with total loss of the mandible and the surrounding facial soft tissue. The facial prosthesis we used to treat this patient is unique in that it is adequately retained without the use of extraoral implants and conventional adhesives. This prosthesis is retained by the bilateral auricles and the remaining upper front teeth. We present details of the design of this large silicone maxillofacial prosthesis, with which we successfully rehabilitated the patient.

Female↗
PubMed2001

The kinematic rotating hinge prosthesis for complex knee arthroplasty.

Fifty-eight patients (69 knees) treated with the Kinematic Rotating Hinged knee prosthesis for complex primary and salvage revision total knee arthroplasty were followed up for an average of 75.2 months (range, 24-199 months). The indications for use of the Kinematic Rotating Hinged knee prosthesis included severe bone loss combined with ligamentous instability (30 knees), nonunion of a periprosthetic fracture (10 knees), an acute periprosthetic fracture (nine knees), severe collateral ligamentous instability (five knees), reimplantation for infection (six knees), nonunion of a supracondylar femoral fracture (four knees), congenital dislocation of the knee (three knees), and treatment of a severely comminuted distal femur (two knees). At the time of surgery, the average patient age was 72 years (range, 46-92 years). Preoperatively, knee extension averaged 4.94 degrees (range, 0 degrees-40 degrees) and flexion averaged 81 degrees (range, 15 degrees-125 degrees). At final followup, knee extension averaged 1.25 degrees (range, -5 degrees-25 degrees) and flexion averaged 94.2 degrees (range, 5 degrees-125 degrees). The preoperative Knee Society Knee score averaged 40.3 points (range, 2-93 points) and improved to 77 points (range, 33-99 points) at final followup. Complications were numerous: 23 (32%) patients experienced at least one complication and 12 (17%) patients had two or more complications. Deep periprosthetic infection was the most common complication (14.5%), followed by patellar complications (13%), and prosthetic component breakage (10%). During the period of this study, there were 15,798 primary and 2673 revision total knee arthroplasties done at the authors' institution. The patients receiving a Kinematic Rotating Hinged knee prosthesis represent a highly complex and small subset (0.37%) of the overall population having knee arthroplasty. Although the use of the Kinematic Rotating Hinged knee prosthesis for these limited indications has been useful for the authors, the incidence of complications and the poor outcome of these complications is disconcerting. Hinged total knee arthroplasty should be reserved for the final salvage option of the treatment options available when doing complex primary and salvage revision knee arthroplasties.

Aged↗
PubMedDate not supplied

Fracture of the radial head with associated elbow dislocation: results of treatment using a floating radial head prosthesis.

OBJECTIVES: To assess elbow function, complications, and problems of radial head fractures associated with elbow dislocation receiving surgical treatment with a floating prosthesis. DESIGN: Prospective clinical study. SETTING: University Hospital, Orthopaedic Department, Sart Tilman, Liège, Belgium. PATIENTS: Eleven consecutive adult patients were treated with a floating prosthesis for acute radial head fractures associated with elbow dislocation from January 1994 to September 1996. INTERVENTION: The floating radial head prosthesis (Tornier SA, Saint-Ismier, France) was used in all our patients. The implant is in two parts: a radial head made of high-density polyethylene enclosed in a cobalt-chrome cup, which articulates in a semiconstrained manner with the spherical end of a cemented intramedullary stem. The implants were inserted within the first week following the injury (range 2 to 7 days). Three cases also required internal fixation of the coronoid process of the ulna; in one case plate fixation of an olecranon fracture was also performed. MAIN OUTCOME MEASUREMENTS: Patients were assessed by physical examination, a functional rating index (Morrey et al.), and radiographs. The parameters evaluated were motion, stability, pain, and grip strength. Potential complications such as infection, prosthetic failure, or dislocation were investigated. RESULTS: The minimum follow-up time was two years (mean 32 months, range 24 to 56 months). Four patients were considered to have excellent results, four patients were considered to have good results, two patients had fair results, and one patient had a poor result. There were no cases of infection, prosthetic failure, or dislocation. No patient required prosthetic revision. CONCLUSION: The basic principle of maintaining anatomic and physiologic relationships applies when deciding on treatment for radial head fractures with associated elbow dislocation. The loss of lateral osseous support will render the elbow grossly unstable. We believe that a floating prosthesis may be indicated in Mason Type III radial head fractures associated with elbow dislocation, especially in the presence of associated destabilizing fractures. Well-controlled comparative randomized studies will be needed to delineate the optimal treatment for a given situation.

Adult↗
PubMed2002

Hearing results with a hydroxylapatite/titanium bell partial ossicular replacement prosthesis.

OBJECTIVES/HYPOTHESIS: To study the preliminary hearing results in patients receiving a hybrid hydroxylapatite/titanium bell partial ossicular replacement prosthesis (PORP) and compare these with a cohort of patients receiving a HAPEX PORP. We hypothesized that the design of the hybrid PORP would enhance its acoustic properties. In particular, the titanium bell, which allows the prosthesis to be freestanding, would obviate the need for Gelfoam, preventing fibrosis. STUDY DESIGN: A retrospective study was made of two cohorts of patients. METHODS: A computerized otologic database was used to identify all patients implanted with either PORP. The four-frequency (500, 1000, 2000, and 3000 Hz) pure-tone average air-bone gap (PTA-ABG) and ABG values for individual frequencies were compared using the Student test. RESULTS: The PTA-ABG for the titanium bell prosthesis was 9.8 +/- 5.7 dB, compared with 13.2 +/- 8.3 dB for the HAPEX PORP, which was statistically significant ( P<.05). The average ABG values at 500 and 1000 Hz were also statistically significantly improved with the titanium bell PORP ( P<.05). CONCLUSIONS: The titanium bell PORP showed improved postoperative results for the PTA-ABG and at 500 Hz and 1000 Hz. The prosthesis is freestanding and may provide better coupling with the capitulum, factors which may lead to improved hearing results in the lower frequencies.

Adolescent↗
PubMed2003

The effect of prosthesis design on vibration of the reconstructed ossicular chain: a comparative finite element analysis of four prostheses.

HYPOTHESIS: It was hypothesized that the differences in the bioacoustic performance of ossicular replacement prosthesis designs, and insertion positions, could be quantified using finite element analysis. BACKGROUND: Many designs of prosthesis are available for middle ear surgery. The materials used, and the shape of the implants, differ widely. Advances in computer simulation technologies offer the possibility of replicating the in vivo behavior of the different prostheses. If this can be achieved, insight into the design attributes required for improved biofunctionality may be gained. METHODS: Micro-computed tomography and nuclear magnetic resonance imaging were used to obtain geometric information that was translated into a finite element model of the outer and middle ear. The forced frequency response across the hearing range of the normal middle ear was compared with the middle ear reconstructed with partial and total ossicular replacement prostheses. RESULTS: The amplitude of vibration of the footplate was more similar to that of the normal ear when a Kurz total ossicular replacement prosthesis was implanted than when a Xomed total ossicular replacement prosthesis was implanted. This may be attributed to the latter's titanium link. Partial ossicular replacement prostheses were stiffest and had lower umbo vibrations and higher stapedial footplate vibrations. In all cases but one, the vibration of the prostheses had resonances that caused the vibration of the stapes footplate to be noticeably different from normal. CONCLUSION: The authors confirmed the hypothesis that finite element modeling can be used to predict the differences in the response of ossicular replacement prostheses. This study shows that computer simulation can potentially be used to test or optimize the vibroacoustic characteristics of middle ear implants.

Acoustic Impedance Tests↗
PubMed2003

Early multicenter experience with a noninvasive expandable prosthesis.

A noninvasive expandable prosthesis for skeletally immature children after limb salvage surgery has been developed. Between 1998 and 2001, 18 Phenix prostheses were implanted in 15 pediatric patients who had been diagnosed and treated for osteosarcoma about the knee. Of the 15 original prostheses, 10 were implanted at the time of primary tumor resection and five were revisions from an endoprosthetic modular knee system. Sixty expansions of the 18 prostheses were done, with all but two done as outpatient procedures. An average 8.5 mm was obtained per lengthening (range, 1-30 mm). The average followup was 21.5 months (range, 12-33 months) and the latest Musculoskeletal Tumor Society functional scores averaged 90%. Eight revisions were required for stem fracture or loosening. There was one amputation because of a postoperative arterial thrombosis. The principle of the Phenix prosthesis involves storage of energy in a spring compressed by a locking system. Lengthening is achieved via exposure to an electromagnetic field that allows controlled release of the spring. This is a unique expandable custom prosthesis that offers many benefits in maintaining limb length equality in growing patients. Although the early experience is promising, additional data are required regarding the long-term structural integrity of the prosthesis. We are optimistic that this technology will prove beneficial, not only for patients with malignant bone tumors but in applications requiring serial limb length equalizations or for spinal deformities.

Activities of Daily Living↗
PubMed1995

A 3-D finite element analysis of the natural frequencies of vibration of a stapes prosthesis replacement reconstruction of the middle ear.

In this work, the natural frequencies of vibration of two different stapes prosthesis replacement reconstructions have been analysed using the finite element method. Prosthesis 1 was constructed of fine stainless steel wire and a Teflon base, while prosthesis 2 was made entirely of Teflon. The results have indicated that generally, the first natural frequency of vibration falls as the prostheses become larger and more bulky. However, the fall in the first natural for prosthesis 1 was modest when compared with that of the isolated tympanic membrane. An important variable influencing frequencies and mode of vibration of the reconstruction was the tightness of fit of the prostheses within the remaining ossicular chain. The tightness of fit in this work was modelled as a range of spring constants applied at the stapes pseudo footplate, together with a series of joint elements at the incus tip/prosthesis head for the Teflon implant. When these spring constraints were below approximately 10 N/mm, the reconstruction exhibited normal mode 1 vibration behaviour, but at larger spring values, an abnormal mode 1 became established resembling the normal mode 2 vibration characteristics. The formation of new geometries and surfaces following reconstruction, introduces new constraints between umbo and stapes footplate particularly at the natural/artificial interfaces. These unnatural constraints may inhibit and modify the natural movements normally occurring at the stapes footplate leading to abnormal modes of vibration.

Ear Ossicles↗
PubMed1982

Echocardiographic assessment of the Hall Kaster mitral prosthesis.

To study the effect of the Hall Kaster prosthesis on left ventricular filling characteristics after mitral valve replacement, postoperative M-mode echocardiograms of the left ventricle from sixteen patients were digitized to determine the peak rate of dimension (D) increase of the left ventricle during diastole (peak dD/dt) and the rapid filling period (RFP). These were compared with fourteen normal controls, thirty patients with Starr Edwards and thirty patients with Bjork Shiley mitral prosthesis. Results suggest that the Hall Kaster mitral prosthesis is less obstructive than either the Starr Edwards or the Bjork Shiley prosthesis, and tends to approximate the normal mitral valve.

Adolescent↗
PubMed2005

Rare complication of multiple revision surgeries of penile prosthesis.

INTRODUCTION: Migration of the penile prosthesis reservoir into the bladder is rare. METHODS: A 67-year-old male was found with painful gross hematuria after two revision surgeries of the penile prosthesis. RESULTS: The inflatable penile prosthesis reservoir migrated into the bladder. A new reservoir was repositioned on the contralateral side to the erosion site with salvage surgery. CONCLUSIONS: Erosion of penile prosthesis reservoir into the bladder due to shortened tubing by multiple revision surgeries is rare. In selected cases, reposition of a new reservoir on the contralateral side to the erosion site can be used as salvage surgery.

Aged↗
PubMed2002

A literature review of "failures" of the Swanson finger prosthesis in the metacarpophalangeal joint.

This paper reviews the use of the Swanson finger prosthesis, concentrating on clinical results from the metacarpophalangeal (MCP) joint and modes of prosthetic "failure". While "failure" is generally associated with fracture, it is recognised that fracture does not always necessitate replacement of the Swanson prosthesis. Fracture tends to occur at the junction of the distal stem and hinge of the prosthesis. Initial improvements in ulnar deviation and range of motion (ROM) tend to be gradually reduced over the duration of implantation, and there is little evidence to suggest any long-term improvement in hand strength. Bone erosion and silicone synovitis have been seen but at a much lesser incidence than in other joints implanted with silicone spacers. An evaluation of retrieved Swanson prostheses, tied in with patient history and hand measurements might provide additional information to improve the design of the Swanson prosthesis itself and of other finger prostheses.

Arthritis↗
PubMedDate not supplied

A new stapedotomy prosthesis: preliminary report.

Our study describes a newly designed stapedotomy prosthesis which consists of two components: (1) a platinum ribbon, and (2) a Teflon shaft. The first innovation is a flattened 'tab' on the posterior aspect of the platinum ribbon. The second innovation concerns the dual diameter cylinder-like shaft. Our prosthesis was implanted into 25 individuals, who underwent stapedotomy for stapes fixation, and the results are shown and discussed. Our innovations offer a proper and safe insertion of the prosthesis into the oval window associated with excellent manipulation and handling. At the same time, maximum visualization of the surgical field is achieved, while the stepped-down design of the shaft prevents the prosthesis protruding into the vestibule.

Adult↗
PubMedDate not supplied

Long-term results of a new stapedotomy prosthesis.

The long-term results of a new, home-made stapedotomy prosthesis are presented. The innovations of this prosthesis concern both portions, design for attachment to the incus and shaft. Our series include a total number of 42 individuals with stapes fixation, operated using the new prosthesis, with a medical follow-up period between eighteen months and five years. Our innovations offer a proper and safe insertion of the prosthesis into the oval window associated with excellent manipulation and handling. These advantages could be of major importance for younger surgeons and trainees. Postoperative hearing results are similar to those achieved with other commercially available pistons.

Adult↗