SEARCH · PubMed Health

Results for “Prosthesis Design”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 253 records · Page 14Linked to original sources

PubMedDate not supplied

The evolution of the Buck-32 total hip prosthesis.

The total hip prosthesis designed by Buchholz has had an excellent clinical record. Despite its unique features, popularity in the United States has been lacking because of the large head size and the single-size neck length. The Buck-32 modification offers a 32 mm head with varying neck lengths, but retains the salient features of a longer stem and a ventral recess in the acetabular component. Laboratory studies demonstrate that the modified Buchholz prosthesis (Buck-32) does demonstrate an excellent range of motion, superior strength qualities, and excellent flexibility which allows its use in clinical conditions requiring maximum prosthetic strength.

Biomechanical Phenomena↗

PubMed2007

Engineering long term clinical success of advanced ceramic prostheses.

Biocompatability and, in some applications, esthetics make all-ceramic prostheses compelling choices but despite significant improvements in materials properties and toughening mechanisms, these still have significant failure rates. Factors that contribute to the degradation in strength and survival include material selection and prosthesis design which set the upper limit for performance. However, fabrication operations introduce damage that can be exacerbated by environmental conditions and clinical function. Using all-ceramic dental crowns as an example, experimentally derived models provide insight into the relationships between materials properties and initial critical loads to failure. Analysis of fabrication operations suggests strategies to minimize damage. Environmental conditions can create viscoplastic flow of supporting components which can contribute additional stress within the prosthesis. Fatigue is a particularly challenging problem, not only providing the energy to propagate existing damage but, when combined with the wet environment, can create new damage modes. While much is known, the influence of these new damage modes has not been completely elucidated. The role of complex prosthesis geometry and its interaction with other factors on damage initiation and propagation has yet to be well characterized.

Biomedical Engineering↗

PubMed1995

Cemented collarless (Exeter-CPT) versus cementless collarless (PCA) femoral components. A 2- to 14-year follow-up evaluation.

The purpose of this study was to compare the intermediate results of total hp arthroplasty with a cemented, collarless, femoral prosthesis design (Exeter, Howmedica, Middlesex, UK and CPT, Zimmer, Warsaw, IN) with those of a cementless, collarless, porous-coated femoral component (PCA, Howmedica). A total of 151 hips in 128 patients were reviewed. In the cemented group, 85 Exeter-CPT prostheses were used in 71 patients with an average follow-up period of 6.5 years. In the uncemented group, 66 PCA prostheses were placed in 57 patients with an average follow-up period of 7 years. Harrington hip scores improved from 50.1 to 80.7 for the PCA group and from 49.5 to 87.3 for the Exeter-CPT group. The patient satisfaction rates were 89 and 96%, respectively. Sixty-eight patients with Exeter or CPT prostheses had excellent function and no significant thigh pain after 2 years. One Exeter stem was revised 10 years after the primary surgery because of aseptic osteolysis due to cement defect. Two Exeter sockets were revised because of aseptic loosening. In the PCA group, the incidence of thigh pain that persisted beyond 2 years was 39.4%, and there were high incidences of distal cortical hypertrophy (66.6%) and bead loosening (45.5%). Sixteen hips were revised for aseptic stem loosening of the socket. The cementless ingrowth stems failed earlier (around 5 years), whereas the cemented stems continued to perform well past 14 years. In this study, the cemented, collarless, tapered, femoral prosthesis gave results superior to those of the uncemented collarless, porous-coated anatomic design at an average follow-up period of 7 years (range, 2-14 years).

Aged↗

PubMed1990

Computer applications in orthopaedics.

With the rapid developments in microprocessors, the widespread availability of computers has brought about broad applications in the field of orthopaedics. The present technology enables large quantities of data to be logically processed in a very short span of time. This has led to the development of information management database systems where relevant medical information may be retrieved very quickly and effectively. The analytical power of the computer has also been utilised in expert systems to assist in clinical-decision making process. Computer graphics have revolutionised the visualisation of physical features of internal and external body parts, providing new and improved modalities of diagnosis. In some centres, surgical planning and rehearsals are already being carried out at the computer terminal with the use of animation and computer graphics. Computer technology has also played an active role in the field of prosthetics and rehabilitation. Intelligent robotic systems and microprocessor with functional neuromuscular stimulation have been applied to benefit, and in some cases restore some motor functions to the physically disabled. With more collaboration between engineers, scientists and the medical community, several prototypes of computer-controlled prostheses and prosthesis designed and manufactured by Computer-Aided Design/Computer-Aided Manufacturing (CAD/CAM) technology are available today to assist the amputees in their daily living and ambulatory activities.

Computer Graphics↗

PubMed1986

Analogue femurs for laboratory investigations of prosthesis stress distributions and fixation failures.

A polymeric analogue femur in combination with a brittle-coating stress-analysis technique was used to compare the relative femoral surface-strain distributions for various hip prostheses. The influence of prosthesis design factors, such as the geometry and material, the effect of a collar, and surface texturing, were readily ascertained and in agreement with previous investigations using other techniques. The fixation failures observed with this laboratory test model were similar to those of published clinical findings.

Bone Cements↗

PubMed2005

Prosthetic valve hemodynamics assessed by the left ventricular outflow tract area utilization index: a randomized study of the carbomedics reduced versus the Medtronic Hall valve.

BACKGROUND AND AIM OF THE STUDY: Continuous changes are made in valve prosthesis design in order to improve hemodynamic performance. In this prospective, randomized study, hemodynamic properties of the bileaflet CarboMedics Reduced (CM-R) valve with a thinner sewing ring was compared to the Medtronic Hall (MH) disc valve. Special emphasis was placed on the ability of the two valve types to make the most effective use of the available left ventricular outflow tract (LVOT) area as defined by preoperative echocardiographic measurements. METHODS: Twenty patients scheduled for a mechanical aortic valve prosthesis were randomized to receive either a CM-R or MH valve. Only patients receiving a prosthesis < or = 25 mm were included. A complete Doppler echocardiographic study was performed preoperatively and at six months postoperatively. Transprosthetic gradients, effective orifice area (EOA), effective orifice area index (EOAI) and LVOT-utilization index (LVOT-UI; defined as EOA/preoperative LVOT area) were compared. RESULTS: The CM-R valve was superior to the MH valve for all hemodynamic parameters studied: EOA 2.03 +/- 0.50 versus 1.56 +/- 0.20 cm2 (p < 0.01); EOAI 1.07 +/- 0.22 versus 0.83 +/- 0.13 cm2/m2 (p = 0.01); and LVOT-UI 0.47 +/- 0.09 versus 0.38 +/- 0.05 (p = 0.001). Although cardiac output was significantly higher in the CM-R group, transprosthetic gradients were lower (peak 21 +/- 5 versus 27 +/- 5 mmHg (p = 0.02); mean 11 +/- 4 versus 13 +/- 2 mmHg (p = 0.07)). CONCLUSION: The results of this study showed that the CM-R aortic valve offers favorable hemodynamics compared to the MH valve. The inclusion of preoperative LVOT area measurements (as LVOT-UI) showed that the CM-R offers a more effective use of the available LVOT area.

Aortic Valve↗

PubMed2001

The Harris-Galante Porous acetabular component at intermediate follow-up.

Outcome of the acetabular component in 90 consecutive primary noncemented total hip arthroplasties (THAs) was prospectively studied. The acetabular cup consisted of a hemispherical titanium alloy shell with a titanium fiber-mesh porous coating and a modular polyethylene liner (Harris-Galante Porous-1, Zimmer, Warsaw, Ind). The cup was implanted using line-to-line reaming with adjunctive dome screw fixation. The femoral component consisted of a titanium alloy stem with titanium fiber-mesh porous coating and a 28-mm cobalt-chrome modular head. Mean patient age was 53 years (range: 27-75 years); male:female ratio was 48:42; and mean follow-up was 6 years (range: 4.5-8 years). One acetabular component was revised for aseptic loosening. Of 81 unrevised hips available for follow-up, mean Harris hip score was 57 preoperatively and 96 at final follow-up (72% excellent, 15% good, 1 3% fair, and none poor). Of 61 unrevised hips with adequate radiographic follow-up, radiographic failure (complete periprosthetic radiolucency) was evident in 3 (4.9%) and periacetabular osteolysis in none. Radiographic failure did not correlate with poor clinical outcome. Linear polyethylene wear rate (mean: 0.13 mm/year) did not correlate with age, gender, weight, outcome, or cup abduction angle, but did correlate with the presence of femoral periprosthetic osteolysis (0.18 mm/year with femoral osteolysis versus 0.11 mm/year without; P= .01). This series of porous-coated hemispherical cups demonstrated excellent intermediate-term clinical and radiographic outcome, comparable with similarly favorable results reported by the prosthesis designers. A potentially adverse effect of polyethylene wear on the longevity of a THA was supported by a positive correlation between polyethylene wear rate and femoral osteolysis.

Adult↗

PubMed2005

Preliminary results after total knee arthroplasty without femoral trochlea: evaluation of clinical results, quality of life and gait function.

Evaluation of the clinical and functional results of a new prosthetic knee design with conservation of the physiologic properties of the patellofemoral joint. After total knee arthroplasty there are often patella problems. Some of them may be a result of excessive retropatellar pressure caused by the prosthetic design. Twelve patients with an average age of 68.6 years were evaluated after a follow-up of 16.4 months after implantation of a new prosthetic design. The clinical results were evaluated with the Hospital for Special Surgery Scores (HSS) and the Knee Society Clinical Rating Systems (KSS). Pain was rated on a Visual Analog Scale (VAS). Quality of life was determined with the SF-36 questionnaire. Furthermore, clinical gait analysis was performed with a 3D motion analysis system and force plates as well as surface electromyography of seven lower extremity muscles. The HSS-Score reached a mean value of 79.3 points. The KSS reached 82.3 points for the knee score and 75 points for the functional score. The VAS for pain revealed an average value of 1.7. For the gait analysis only three parameters indicated significant differences between the affected and the contralateral leg. The mean EMG amplitude revealed a significant difference only for the biceps femoris. The clinical and functional outcome of a new prosthesis design show satisfactory results. Even if the presented results appear promising, a further application and long term results are needed.

Aged↗

PubMed2000

The hydroxyapatite-ABG hip system: 5- to 7-year results from an international multicentre study. The International ABG Study Group.

A proximally hydroxyapatite (HA)-coated hip prosthesis designed for proximal stem bonding and stress transfer was studied in a consecutive series of 398 patients in an ongoing, prospective multicenter study. Follow-up was 5 to 7 years. The clinical results were excellent with a mean preoperative Merle d'Aubigné score of 8.5 and 17.3 at 5 years. Only mild thigh pain not necessitating analgesics or a walking stick was reported in 3.6% at 5 years. Three cups and 3 stems had to be revised, all before the 2-year assessment and mainly for technical reasons. No components needed revision after 2 years. The 5-year HA-coated component survival was 99.2%. Serial radiographs showed excellent osseointegration, which was independent of pre-existing bone stock. The rate of radiographic bone remodeling was highest during the first 3 years, and positive bone remodeling (bone formation) preceded negative bone remodeling (bone resorption). The concept of transitional load transfer from proximal to distal could be acknowledged, with proximal load transfer highest in 77%. The combination of anatomic stem design with distal overreaming and proximal HA coating was thought to be the reason for these excellent results. Proximal circumferential osseointegration seems to be real because no linear or distal osteolysis was observed.

Adult↗

PubMed1999

Knee and hip joint replacements. Longer lasting prostheses.

BACKGROUND: Conventional hip replacement prostheses consist of a metal femoral stem and head articulating with a polyethylene acetabular component fixed to the skeleton by polymethylmethacrylate 'cement'. In these prostheses the main problems are breakdown of cement and wear of the polyethylene acetabular articulation. Particles produced by this wearing process contribute to osteolysis (bone stock loss). These problems affect the long term results of joint replacements particularly in the younger, active patients. OBJECTIVE: This article discusses new advances in prosthesis design, which reduce these problems, and techniques to overcome bone loss in revision procedures. DISCUSSION: Improved fixation to the skeleton using cementless prostheses may improve long term results for younger, active patients. The problems of wear and osteolysis may be reduced by the utilisation of metal on metal or ceramic on ceramic articular surfaces.

Arthroplasty, Replacement, Hip↗

PubMed2006

Sagittal curvature of total knee replacements predicts in vivo kinematics.

BACKGROUND: It is known that in vivo kinematics after total knee replacement is influenced by the design of the implant. The goal of this study was to show that the sagittal curvature of two different knee prostheses differing in geometric design predicts their in vivo motion behavior. METHODS: Three-dimensional tibio-femoral displacements of two prosthesis designs (single radius vs. dual radius) were measured during knee extension under weight bearing conditions by in vivo video fluoroscopy. Finite helical axes were computed to represent the tibio-femoral motions. Angular deviation alpha and the spatial localization deviation delta were used to characterize the motions. Angular deviation is the angle between each incremental finite helical axis and the medio-lateral axis of the femoral component of the prosthesis. The spatial localization deviation is the distance between each finite helical axis and the center of the femoral component of the prosthesis. Statistical comparisons were performed using the median and the interquartile range of the angular deviation and the spatial localization deviation. FINDINGS: The single-radius design showed finite helical axes concentrated at a single axis near to the medio-lateral axis of the femoral component. The angular and spatial localization deviation of the dual radius design were larger compared to the single radius design, exhibiting finite helical axes varying between two axes. INTERPRETATION: Video fluoroscopy in combination with finite helical axis analysis proved to be suitable methods to evaluate the in vivo kinematical behavior of total knee arthroplasty, which can be useful for implant designers. Knowledge of in vivo kinematics can also provide surgeons with more background information about the total knee arthroplasty models they implant.

Arthroplasty, Replacement, Knee↗

PubMed1984

Endoscopic palliative treatment of esophageal and cardial cancer: a new antireflux prosthesis. A study of 40 cases.

Forty patients with malignant cardioesophageal obstruction were treated by fiberoptic intubation. Their ages ranged from 38 to 84 years. Eight patients had bronchoesophageal fistula, 9 had tumor relapse after radiation therapy, and 5 had hiatal hernia. In 7 with severe or total stenosis, diathermic resection was used with no morbidity or mortality. Complications were hemorrhage, 2; regurgitation, 2; atelectasis, 1; tube migration, 1; and bronchoesophageal fistula, 1, for a total of 17.5%. The procedure mortality was 2.5%. Actual survival time after intubation was 37.5% at 12 months. It was demonstrated that a new antireflux prosthesis, designed for endoscopic insertion, diminished morbidity and avoids mortality due to regurgitation; we would therefore recommend to be used in patients not otherwise amenable to surgery or radiotherapy, with cancer of the cardia, lower esophagus or lesions beyond 24 mm from the incisors associated with hiatal hernia.

Adult↗

PubMed2000

[Long-term results following cemented total hip alloplasty in primary hip arthrosis. What to expect?].

The aim was to investigate the age-, gender- and implant related survival up to 14 years postsurgery in patients with primary hiparthrosis in one or both hips and operated in county hospitals with cemented prosthesis designs. The subjects consisted of 1,199 patients operated in the years 1981-1990, and the cohort was followed till 31.12.1994. The 1,199 patients had a total of 1,477 cemented total hipalloplastics (THA's) inserted. Two hundred and fourty-eight patients died during follow-up. Until 1990, 278 patients had had both hips operated, and a further 58 patients had the contralateral hip operated during follow-up to 31.12.1994. Fourty-nine hips were revised between four and 14 years (median: nine years) postsurgery. The cumulative survival for all THA's was 92.5%. Respective figures for the Richard Series 2 and the Charnley-prosthesis were 91.5% and 92%, now more than 14 years from the first operations. In conclusion, cemented total hip arthroplasty is a good treatment option for patients with primary hip arthrosis. Younger patients have an increased risk of revision, and alternative fixation may be considered. With an overall prosthesis-survival more than 14 years postsurgery of 92.5%, the treatment can take place at local orthopaedic departments. Our results are comparable to figures from the Swedish national register.

Aged↗

PubMed1991

[Joint prostheses components of warm-forged and surface treated Ti-6Al-7Nb alloy].

In 1978 development of a TiAl alloy with the inert alloying element niobium was initiated. In 1984, the optimal composition was found to be Ti-6Al-7Nb (Protasul-100). This custom-made alloy for implants has the same alpha/beta micro-structure and equally good mechanical properties as Ti-6Al-4V. The corrosion resistance of Ti-6Al-7Nb is better than that of pure titanium and Ti-6Al-4V, due to the very dense and stable passive layer. Since 1985, highly stressed anchoring stems of various hip prosthesis designs have been manufactured from hot-forged Ti-6Al-7Nb/Protasul-100. Polished surfaces of hip, knee or wrist joints made of Ti-6Al-7Nb intended to articulate with polyethylene are surface-treated by the application of a very hard, 3-5 microns thick titanium nitride coating (Tribosul-TiN), or by oxygen diffusion hardening (Tribosul-ODH) to a depth of 30 microns.

Alloys↗

PubMed2003

Mobile and fixed bearing total knee prosthesis functional comparison during stair climbing.

OBJECTIVE: The purpose of this investigation is to determine the functional performance of the mobile bearing total knee replacement prosthesis as compared to the fixed bearing type total knee replacement prosthesis. DESIGN: Kinematics, kinetics, and electromyography data were gained from 10 patients with mobile bearing and 10 patients with a fixed bearing posterior stabilized Insall Burstein II total knee replacement during ascending and descending stairs. A control group of 10 normal subjects, matched by sex and age, was also analysed. BACKGROUND: No significant biomechanical differences in patients with different total knee replacement designs have been reported from level-walking studies. Slightly better performance of posterior retaining with respect to cruciate sacrificing total knee replacement designs have been claimed from stair climbing studies. Only one study has been conducted regarding mobile versus fixed bearing total knee replacement assessed by gait analysis. This study did not show any biomechanical differences between the two groups. METHODS: Motion analysis was used to quantify the knee kinematics, kinetics, and electromyography (right and left longissimus dorsi, gluteus medius, rectus femoris, biceps femoris, semitendinosus, gastrocnemius and tibialis anterior muscles) during stair ascent and descent. RESULTS: The mobile bearing group demonstrated a reduced knee extensor moment during stair climbing and descending, and a reduced knee adductor moment during stair climbing. When ascending stairs, most of the mobile bearing patients show a peak knee flexion and a peak knee flexion moment at the late stance phase during the double support period. This kinematic and kinetic pattern is absent in normal subject. Both mobile bearing and fixed bearing groups showed abnormal electromyography patterns in both descending and ascending. CONCLUSIONS: During stair climbing, the mobile bearing design demonstrates a different kinematic pattern to the fixed bearing total knee replacement. Lower limb compensatory mechanisms seemed to be adopted particularly by the mobile bearing patients during ascending stairs. RELEVANCE: Total knee replacement patient with mobile bearing design can feel excessive femoro-tibial motion during daily living activities such as stair climbing and descending. Proprioceptive control of this tibio-femoral translation is needed as demonstrated by the lower limb compensatory mechanism. This data suggest that antero-posterior constraint structures (ligamentous or mechanical) are important to obtain reproducible knee kinematics.

Aged↗

PubMed1992

Functional evaluation of patients fitted with total knee prostheses.

Degenerative or inflammatory diseases of the knee joint account for a large proportion of diseases affecting the elderly. Treatment aims to eliminate pain, correct the deformity and maintain complete joint mobility. In cases of total joint degeneration, fitting of a joint prosthesis is the technique currently favoured since elimination of pain and correction of the deformity, accompanied by recovery of joint mobility (the fundamental requirements for normal everyday life) can only be obtained if the knee joint is completely replaced. With the discovery of new materials and increasingly sophisticated knowledge about articular mechanics, the knee prosthesis, although more recent than the hip prosthesis, has become ever more widespread to the point that it now represents an irreplaceable aid in the treatment of this common disease. The clinical results obtained are already stable and particularly encouraging and prosthesis design is sophisticated and accurate. There is, however, still the suspicion that current prostheses can be considered "rudimentary" in comparison with the physiological and biomechanical behaviour of the human joint. We therefore wanted to begin an evaluation using a gait analysis system to assess patients fitted with knee prostheses. The first impressions gained in this study are the subject of this article.

Activities of Daily Living↗

PubMed2000

Survivorship of AGC knee replacement in juvenile chronic arthritis: 13-year follow-up of 77 knees.

This study analyzed the survivorship and results of 77 knee replacements in 52 patients with juvenile chronic arthritis using the nonconstrained Anatomically Graduated Components (AGC; Biomet, Warsaw, IN) prosthesis design. Patients were operated on between the years 1985 and 1995. The mean duration of the general disease was 24 years (range, 10-56 years), and the mean age of the patients at the time of surgery was 33 years (range, 16-64 years). Bone-grafts were installed into 15 knees, custom-made components were used in 5 knees, and cemented fixation in 4 knees. The patella was resurfaced in 23 knees. Clinical follow-up examinations were conducted 3 months, 1 year, 4 years, and 8 years postoperatively. An interview was arranged at the end of 1998, 3 to 13 years after surgery; 2 patients were not reached, and 2 died during the follow-up. Fifty-five of 73 (75%) knees were subjectively excellent, 18 (25%) were fair, and none was poor. Radiolucent lines of 1.0 to 1.5 mm were found under 14 tibial trays but not adjacent to femoral components. No deep infections were detected. One knee was revised 4 years after the implantation. The overall survival was 99% (95% confidence interval, 92-100) at 5 years. We consider these results excellent in this demanding patient material. The nonconstrained AGC prosthesis with cementless fixation proved to be feasible in knee replacement in patients with juvenile chronic arthritis.

Adult↗

PubMedDate not supplied

A new woven double velour vascular prosthesis.

A new woven double velour vascular prosthesis designed to minimize intraoperative blood loss was implanted in 24 animals. Grafts were examined at 3 to 12 month intervals for healing and were compared to woven non-velour grafts implanted in 13 control animals. At 12 months, the velour grafts were 93 to 98% covered with neointima while the control grafts were only 86% covered with neointima. The neointima on the velour grafts was thinner (60 mu) and more vascular than that on the control grafts. Woven double velour grafts were implanted in 20 patients. Minimal bleeding occurred through the grafts which did not require preclotting, were easy to sew, and did not fray.

Aged↗