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PubMedDate not supplied

Failure of osseointegrated dental implants after diphosphonate therapy for osteoporosis: a case report.

Late loss of initially integrated endosseous implants has generally been attributed to implant overload often the result of inappropriate prosthesis design. Implant placement is rarely contraindicated by preexisting systemic diseases, and no instances of medication-induced implant failure have been reported in the literature. This paper reports a case in which a patient lost five endosseous implants that had successfully osseointegrated and had been restored with a lower hybrid prosthesis approximately 6 months after diphosphonate therapy for osteoporosis was started.

Aged↗
PubMed2005

Dermatologic conditions associated with use of a lower-extremity prosthesis.

OBJECTIVES: To document the frequency of skin problems among lower-limb prosthesis users and to assess for factors associated with skin problems among patients using a prosthesis. DESIGN: Six-year retrospective chart review. SETTING: An outpatient amputee clinic at a regional, referral rehabilitation hospital in Canada. PARTICIPANTS: Seven hundred forty-five subjects with a total of 828 lower-extremity amputations participated. Subjects were included if they had a lower-extremity amputation and used a prosthesis for ambulation or transfers. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The presence or absence of a skin problem. Descriptive and nonparametric statistics were used to analyze data. RESULTS: Three hundred thirty-seven residual limbs (40.7%) had at least 1 skin problem. Adjusted odds ratios showed that amputation level, being employed, type of walking aid, and absence of peripheral vascular disease (as a comorbidity) were independently associated with the presence of at least 1 skin problem ( P <.05). CONCLUSIONS; Dermatologic conditions are a frequent complication for the lower-extremity amputee who uses a prosthesis. The results suggest that more active amputees have an increased risk for developing skin problems. Further study in this area is warranted.

Aged↗
PubMed1992

Joint replacement components made of hot-forged and surface-treated Ti-6Al-7Nb alloy.

We have developed a titanium-aluminium alloy with the inert alloying element niobium. The optimal composition was found to be Ti-6Al-7Nb (Protasul-100). This custom-made alloy designed for implants shows the same alpha/beta structure as Ti-6Al-4V and exhibits equally good mechanical properties. The corrosion resistance of Ti-6Al-7Nb in sodium chloride solution is equivalent to that of pure titanium and Ti-6Al-4V. This is due to a very dense and stable passive layer. Highly stressed anchorage stems of different hip prosthesis designs have been made from hot-forged Ti-6Al-7Nb. The polished surfaces of hip, knee and wrist joints made of Ti-6Al-7Nb and articulating against polyethylene are surface-treated by means of a very hard and 3-5 microns thick titanium nitride coating (Tribosul-TiN) or by oxygen diffusion hardening (Tribosul-ODH) to a depth of 30 microns.

Humans↗
PubMed1996

An analysis of crack propagation paths at implant/bone-cement interfaces.

Clinical follow-up studies of joint replacements indicate that debonding of the implant from the bone-cement is the first mechanical event of loosening. Debonding can occur due to unsustainable interface stresses, usually initiated from defects along the interface. Such defects, or flaws, are inevitably introduced during the surgical procedure and from polymerisation shrinkage. Debonding leads to increased stresses within the cement mantle. This study is concerned with modelling the propagation of a crack from the debonded region on the cement/implant interface under physiological loading conditions for different implant materials and prosthesis designs. Using the theory of linear fracture mechanics for bimaterial interfaces, the behaviour of a crack along an interface between implant materials, under various states of stress, is studied. Specifically, a model is developed to determine the conditions under which a debonded region, along an otherwise bonded interface, will either propagate along the interface or will "kink" into the cement mantle. The relationship between the stress state and the crack propagation direction at the interface is then predicted for different interface materials, and it is shown that different crack directions exist for different materials, even when the stress state is the same. Furthermore, the crack behavior is shown to be dependent on the ratio of normal stress to shear stress at the interface and this may be important for the design optimisation of load-bearing cemented prostheses. Finally, the likelihood that an interface crack will propagate into the cement mantle is explored using a suitable fracture criterion.

Alloys↗
PubMed2006

The new 4DDome prosthesis: an original light and partially absorbable composite mesh for hernia repair.

INTRODUCTION: The use of non-absorbable meshes for the repair of inguinal hernias has become standard; however, these meshes have been associated with complications including long-term postoperative pain. To this end, a new partially absorbable composite mesh has been developed, and the aim of this study was to investigate its efficacy in animal and human trials. MATERIALS AND METHODS: Sixty male Wistar rats were used to evaluate the behavior of the newly designed composite mesh. Composite meshes were implanted in the extra-peritoneal plane for 2, 4 and 8 weeks and compared to a standard polypropylene mesh. Forty patients with symptomatic inguinal hernias were treated using a new 4DDome designed prosthesis. Follow-up was by clinical and ultrasound examination at 1, 6 and 12 months. RESULTS: The animal study demonstrated that the inflammatory reaction associated with the new composite mesh was significantly lower than a standard polypropylene mesh, characterized by a lower macrophage infiltrate (P < 0.001). The mesh did not shrink over the 8-week period, unlike the polypropylene mesh (P < 0.05). The human study showed that there were three minor postoperative complications, no recurrences and the mesh was well tolerated. Follow-up with serial ultrasound showed that at 10 days and 1 month the dome was clearly visible in position; however, by 6 months it had flattened out, been partially absorbed and become incorporated into the repair. CONCLUSION: These experimental and clinical studies have validated the concept of the new 4DDome composite mesh. It was well tolerated and was associated with good short-term results. The combination of the dome shape and the new composite mesh means that less polypropylene is required and represents a significant advance in anterior hernia repair.

Animals↗
PubMed1999

[The evolution of ankle arthroplasty].

The results of ankle arthroplasty have generally been disappointing compared to other forms of arthroplasty. The present survey of results of ankle arthroplasty deals with the anatomical, the kinemasiological the biomechanical and the biological features of the ankle joint. These features all seem important prerequisites for a successful total ankle prosthesis design. From the study of the results displayed in the literature and those of my own series it can be stated that a modern ankle arthroplasty should respect the normal anatomy and kinemasiology. Biomechanically it should work as a normal ankle joint i. e. cylindrical mobility, congruency and a possibility for normal torque within the ankle mortise. The prosthesis components should only be fixed in solid subchondral bone, and preferably without cement. Only compressible forces should act at the bone-prosthesis interface. The axis of the ankle joint as well as of that of the hindfoot should be aligned to normal. Meticulous surgery and special guide instruments are absolute necessities. Restoration of muscle power and gait postoperatively are essential for a good and lasting result. The indication for ankle arthroplasty is mainly cases of osteoarthritis (primary or traumatic) and rheumatoid arthritis. Contraindications are talus necrosis, Charcot joints, extreme osteoporosis, severe arteriosclerosis, and very aggressive arthritis. Mental disorders and neurological disorders may also be contraindications. Furthermore, the patients should agree not to perform sports involving jumping and running or other ankle demanding activities. The average annual failure rate should not exceed 1 % if these recommendations are followed.

Ankle Joint↗
PubMed1987

Effect of a maxillary glossectomy prosthesis on articulation and swallowing.

Swallowing was found to be substantially improved with the prosthesis. Less aspiration, less time necessary to complete the swallow, and greater variation in food consistency tolerated were all positive results of the prosthesis. In addition, videofluoroscopic studies of tongue movements during speech revealed that tip-alveolar /t-d/ and back-velar /k-g/ productions were more normal with the prosthesis. With the prosthesis, the understandibility of /t/ and /d/ was improved 20% and that of /k/ and /g/, 33%. It is clear that compromises must be effected in prosthesis design to facilitate improvement in both speech and swallowing. A large prosthetic mass in the oral cavity can also negatively change speech resonance. These issues are being investigated, as are acoustic and perceptual studies of speech articulation. Future research should address whether a combination of maxillary and mandibular prostheses would result in better speech and swallowing function. A mandibular prosthesis could replace missing teeth and alveolar contour that might influence speech and swallowing. A mandibular prosthesis might also allow construction of a smaller maxillary glossectomy prosthesis to interact with the mandibular prosthesis.

Articulation Disorders↗
PubMed1990

Koenig total great toe implant. Preliminary report.

A new first metatarsophalangeal joint implant arthroplasty is described. The two-component, titanium alloy and polyethylene prosthesis designed for weightbearing is noncemented and press-fit. Sixteen cases involving 18 implants were evaluated over 18 months with evidence that good correction and pain free motion can be obtained.

Adult↗
PubMed1988

The Ring total knee replacement.

A prospective study of the Ring Total Knee Replacement is presented. The senior author (P.A. Ring) designed this prosthesis and began to apply it clinically in 1974. The Ring prosthesis is a resurfacing, unconstrained type of knee prosthesis and is designed for use without cement. It comprises two components, femoral and tibial, both made of titanium. A polyethylene liner is attached to the tibial component. The method was used for treatment of osteoarthritis and rheumatoid arthritis of the knee on 149 patients (178 knees) in the period from 1974 to 1985. Seventeen patients were lost to follow-up, leaving 132 patients (161 knees) for review. During the last review, 75.2% of the knees were pain free and 72% had full correction of the deformity. The average follow-up period was 5.1 years and the survival rate of the prosthesis during the same period was 94.4%. To evaluate the method we used computer analysis of preoperative and postoperative assessment cards with 153 observations. The result was excellent in 92 (57.2%) knees, good in 38 (23.6%) knees, and poor in 31 (19.2%) knees. Loosening of the components occurred in 3.7% knees, and the total revision rate was 5%. One knee was arthrodesed.

Adult↗
PubMed1990

Stress analysis of the proximo-medial femur after total hip replacement.

Stress-induced bone loss in the proximo-medial femur has been identified as a factor leading to loosening in the artificial hip joint. In an effort to develop a quantitative understanding of the stress distribution that causes bone loss, axial and hoop stresses in the medial calcar of the femur have been determined after total hip replacement, using finite element stress analysis. Stress distributions for a high and a low Young's modulus prosthesis material are compared for both collared and uncollared prosthesis designs. The use of a low-modulus material, and of a collar, are predicted to be advantageous, giving rise to proximo-medial stress patterns similar to those of the normal, intact femur.

Biomechanical Phenomena↗
PubMed2000

Equilibrium and movement control strategies in trans-tibial amputees.

This study was aimed at identifying changes in equilibrium and movement control strategies in trans-tibial amputees (TTA) related to both the biomechanical changes and the loss of afferent inflow. The coordinations between equilibrium and movement were studied in traumatical TTA and in controls during transition from bipedal to monopodal stance. TTA failed to perform the task in a high percentage of trials both when the sound and the prosthetic limb were supporting. Significant differences were also found between TTA and controls in the duration of the weight transfer phase, in the length of the initial centre of pressure (CP) displacement and in the electromyographic (EMG) patterns. Despite adaptive posturomotor control strategies, transition from bipedal to monopodal stance remains a difficult task to perform for TTA, both when the supporting limb is the affected one and when the sound one is. The results of this study are discussed with respect to the rehabilitation programme and the prosthesis design for transtibial amputees.

Adult↗
PubMed2003

Tracheal replacement in rabbits with a new composite silicone-metallic prosthesis.

A new composite silicone-metallic prosthesis was tested, studying the potential for respiratory epithelial covering over the biocompatible inner lining, in a rabbit survival model. Seven New Zealand White rabbits underwent near-total excision of their trachea and implantation of a sterile prosthesis. After 2 months, they were sacrificed and the prostheses were retrieved. Specimens were fixed and histologically examined for tissue reaction around the prosthesis, at the anastomotic lines, and particularly for the presence or absence of epithelialization of the inner lumen over the biocompatible surface. All rabbits survived the operation. At 2 months, the outer layer of the prosthesis was consistently covered with fibrosis and neutrophils. The inner layer showed necrotic cells and scant re-epithelialization over the biocompatible lining, up to 5 mm beyond the anastomosis, with no evidence of organized respiratory epithelium in the middle sections. The new prosthesis is a viable temporary solution for airway replacement in rabbits. Granulation tissue was not observed at the anastomosis, and re-epithelialization did occur, but failed to achieve full-length luminal covering. The potential for granulation tissue does not yet make this an ideal long-term solution. Improvements in prosthesis design or biocompatibility are required, and need to be re-evaluated before applicability for chronic use.

Animals↗
PubMed1999

Osseointegrated implant failures.

This article discusses the criteria used for implant success and failure, the classification of implant failures, the causative factors, and diagnosis of the failing and failed implant. In spite of the impressive success rates of osseointegrated dental implants, failures occur and in some studies the incidence of failure is high. Many studies do not use objective criteria to define success and confuse survival with success. The criteria used affect reported success rates. Implant failures may occur early (primary) after implant placement or after the implant is loaded (secondary). There is no single aetiological factor and failures have been attributed to poor surgical technique, host factors that impair healing, poor bone quality, peri-implant infections, poor prosthesis design and traumatic loading conditions. Early diagnosis of problems is critical and every effort should be made to treat the problem while the damage can still be managed or even reversed.

Biomechanical Phenomena↗
PubMed2003

Twenty year comparison of a Bjork-Shiley mechanical heart valve with porcine bioprostheses.

OBJECTIVE: To compare survival and outcome in patients receiving a mechanical or bioprosthetic heart valve prosthesis. DESIGN: Randomised prospective trial. SETTING: Tertiary cardiac centre. PATIENTS: Between 1975 and 1979, patients were randomised to receive either a Bjork-Shiley or a porcine prostheses. The mitral valve was replaced in 261 patients, the aortic in 211, and both valves in 61 patients. Follow up now averages 20 years. MAIN OUTCOME MEASURES: Death, reoperation, bleeding, embolism, and endocarditis. RESULTS: After 20 years there was no difference in survival (Bjork-Shiley v porcine prosthesis (mean (SEM)): 25.0 (2.7)% v 22.6 (2.7)%, log rank test p = 0.39). Reoperation for valve failure was undertaken in 91 patients with porcine prostheses and in 22 with Bjork-Shiley prostheses. An analysis combining death and reoperation as end points confirmed that Bjork-Shiley patients had improved survival with the original prosthesis intact (23.5 (2.6)% v 6.7 (1.6)%, log rank test p < 0.0001); this difference became apparent after 8-10 years in patients undergoing mitral valve replacement, and after 12-14 years in those undergoing aortic valve replacement. Major bleeding was more common in Bjork-Shiley patients (40.7 (5.4)% v 27.9 (8.4)% after 20 years, p = 0.008), but there was no significant difference in major embolism or endocarditis. CONCLUSIONS: Survival with an intact valve is better among patients with the Bjork-Shiley spherical tilting disc prosthesis than with a porcine prosthesis but there is an attendant increased risk of bleeding.

Animals↗
PubMed2005

Effects of compliance mismatch on blood flow in an artery with endovascular prosthesis.

The objective of this paper is to study the mechanical effects caused by the local stiffening of an artery (due to the vascular prosthesis, for instance). At the junction of the host artery and the more rigid implantant, the abrupt change in compliance creates an abnormal stress concentration that initiates an adaptive response in the vascular tissue. The roles of both fluid and solid mechanical phenomena must be considered in the prosthesis design optimization. In this context, even the simple models could provide helpful tools for designing process. We present here a model of blood flow in compliant vessel. The artery is supposed to be an orthotropical thin elastic shell. We obtain the solution by matched asymptotic expansions. The results prove the high flexure concentration close to the compliance jump. It is shown that the use of orthotropical graft may reduce the peak value of these shear forces to a remarkable extent. Waves reflected from the suture and pressure increase in the prosthesis are discussed. Compliance mismatch is shown to reduce the peak value of maximal wall shear stress.

Arteries↗
PubMed2000

Cemented Lubinus and Furlog total hip endoprosthesis: a 12-year follow-up study of 175 hips comparing the cementing technique.

We analyzed 175 total hip replacements with cemented Lubinus and Furlong arthroplasties in 164 patients with a median age of 65 (32-80) years and followed them for 12 years to evaluate and compare the efficacy of total hip prosthesis designs. Survival analysis was combined with an analysis of radiological findings and a study of functional outcome of the patients. The 12-year survival of Furlong arthroplasty in patients of 60 years of age and older was O.85 (95% CI 1.00-0.52). The survival of Lubinus arthroplasty in patients younger than 60 years of age was 0.70 (0.91-0.48), while the survival in older patients was 0.75 (0.89-0.61). The 12-year survival of well-cemented Lubinus prosthesis was 0.91 (1.00-0.79), indicating the importance of the cementing technique. The survival of the cups was marginally better than that of the stems. In the 12-year follow-up study, the clinical state and function varied from hips ready for revision to hips where a continuously long survival could be predicted. Harris hip score did not differentiate between patients who had intact and loose components. We conclude that cemented arthroplasty affords a notable alternative with satisfactory long-term survival and function. The better survival of cemented cup than the stem may be utilized as a basis for "reverse" hybrid arthroplasty. Adequate long-term follow-up of all arthroplasties as a quality maintenance and to prevent difficult revisions is a major challenge.

Adult↗
PubMed1997

Primary uncemented Osteonics total hip arthroplasty: preliminary results of 2-6 year follow-up.

BACKGROUND: Cemented total hip arthroplasty (THA) bears the inherent disadvantages of cement complications. A research toward the improvement of uncemented prosthesis design continues to evolve. The purpose of this report is to present the preliminary results and to identify common problems in uncemented THA. METHODS: The results of 402 primary Osteonics total hip prostheses were reviewed with an average follow-up period of 3.1 years. The postoperative rating according to the modified D' Aubigne & Postel hip score included functional and radiographic analysis. RESULTS: The results were rated as good or excellent in 95% of hips. Stable fixation of the prosthesis was shown in 97% of radiographs. The most common zone of focal osteolysis was in the periarticular area. CONCLUSION: The clinical results in a 2 to 6 year follow-up was encouraging. A relatively high incidence of thigh pain did not correlate with femoral canal filling of prosthesis. Periarticular osteolysis is still an unsettled problem in uncemented prostheses and needs further investigation.

Adolescent↗