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At least 955 records · Page 53Linked to original sources
PubMed2004

Results of the use of the Ex-PRESS miniature glaucoma implant in technically challenging, advanced glaucoma cases: a clinical pilot study.

PURPOSE: To report results of implantation of the Ex-PRESS Miniature Glaucoma Implant (Optonol, Neve Ilan, Israel) shunt directly under the conjunctiva in advanced glaucoma. DESIGN: Noncomparative case series. METHODS: Chart review of eleven cases of Ex-PRESS implantation. Outcome measures included intraocular pressure (IOP), complications, visual acuity, and additional interventions. Failure was defined as unacceptably high IOP requiring revision or explantation. RESULTS: Four patients (36%) failed. Ten (91%) experienced hypotony during postoperative week one. In the seven nonfailures, mean pre and postoperative IOPs were 30.3 +/- 9.3 mm Hg and 13.6 +/- 4.4 mm Hg, respectively (P = .006). The logMAR visual acuity did not change significantly from baseline to follow up (logMAR 1.1 +/- 0.9 and 1.4 +/- 0.9, respectively, P = .13). There were no intraoperative complications. Postoperative complications in the 11 eyes included choroidal detachment in 3 (27%) and suprachoroidal hemorrhage in 2 (18%). Of the 7 successful cases, additional interventions were required in 4 (57%). CONCLUSIONS: Despite significant IOP reduction, the incidence of complications following Ex-PRESS implantation directly under the conjunctiva was unacceptably high in this group of patients.

Conjunctiva↗
PubMed1999

Analysis of debris from brushing the femoral canal with a plastic brush--a potential cause of loosening in total hip replacement.

The generation of submicrometre sized polyethylene particles has been shown to be one of the major causes of osteolysis, loosening and failure of total replacement joints. It has been reported that intramedullary brushing of the femoral canal with polymer brushes prior to total hip arthroplasty results in the release of polymer particles into the femoral canal. The aim of this study was to isolate and characterize these particles on the basis of morphology and size and to determine whether these particles may play a role in osteolysis and loosening of the total hip prostheses. It was found that the majority of the particles shed by the polymer brushes were submicrometre in size and were similar in morphology to UHMWPE wear particles isolated from periprosthetic tissues. In addition, the majority of the particles released by the brushes were in the biologically active size range (0.1-10 microns), and may contribute to osteolysis and loosening of hip prostheses.

Arthroplasty, Replacement, Hip↗
PubMed2006

Aseptic loosening is uncommon with uncemented proximal tibia tumor prostheses.

UNLABELLED: Aseptic loosening is a frequent cause of failure of cemented proximal tibia tumor endoprostheses. Uncemented prostheses may lessen this risk. We identified complications including aseptic loosening that affected prosthetic survival, limb survival and functional outcome for 44 consecutive patients after sarcoma resection from the proximal tibia and uncemented endoprosthetic reconstruction. At a mean final followup of 60 months (range, 9-152 months), there were no cases of aseptic loosening. Twelve (27%) patients suffered 14 complications leading to prosthetic failure due to infection (n = 7), stem fracture (n = 2), rotational instability (n = 1), vascular compromise (n = 2) and local tumor relapse (n = 2). However, limb salvage was successful in 37 of 44 (84%) patients. Functional assessment for 35 patients revealed a mean Toronto Extremity Salvage Score of 77/100 (range, 33-98) and Musculoskeletal Tumor Society 1987 and 1993 scores of 25/35 (range, 13-31) and 75/100 (range, 33-97), respectively. Mean knee joint flexion was 91 degrees (range, 0-110 degrees ) and knee extension lag was 6 degrees (range, 0-30 degrees ). Three patients with knee extensor complications had inferior functional outcomes. Aseptic loosening is uncommon with uncemented proximal tibia reconstruction, but decreasing other complications at this location remains challenging. LEVEL OF EVIDENCE: Therapeutic study, level IV-1 (case series).

Adolescent↗
PubMed2003

Obtaining rigidity in total phalloplasty: experience with 35 patients.

PURPOSE: The combination of a neourethra and erection prosthesis in a single neophallus in the female-to-male transsexual remains a challenge. The outcome reported in the literature is disappointing. We report our experience with 35 patients. MATERIALS AND METHODS: Between August 1996 and December 2001, 35 patients underwent implantation surgery. A 1-piece hydraulic Dynaflex prosthesis (American Medical Systems, Minnetonka, Minnesota) was used in 10 patients, while a 3-piece hydraulic CXM and CX (American Medical Systems) prosthesis was placed in 9 and 16, respectively. The 1-piece model was withdrawn from the market in 1997. Thereafter a 3-piece prosthesis was implanted. RESULTS: Of 10 patients in the 1-piece group prosthesis implantation was uneventful in 8. In 2 patients with technical failure the prosthesis was replaced, including 1 in whom the new prosthesis was removed due to infection and successfully replaced by a 3-piece prosthesis. To date at a mean followup of 3.5 years 9 patients have a 1-piece hydraulic prosthesis in place. In the 3-piece prosthesis group of 25 patients implantation was uneventful in 20. In 1 patient infection and partial necrosis of the neophallus developed, 2 had infection, in 1 a cylinder perforated the tip of the phallus and in 1 technical failure occurred. Of the latter 4 patients the prosthesis was replaced successfully in 2 patients, while the other 2 are on the waiting list. The patient with partial necrosis of the phallus is no longer a candidate for an erection prosthesis. To date at a mean followup of 1.8 years 23 patients have a 3-piece hydraulic prosthesis in place. A single patient in the 1-piece group has a 3-piece CX prosthesis. CONCLUSIONS: Good results were observed after implantation of the Dynaflex prosthesis in patients who underwent total phalloplasty. This model is no longer available today. For the more complex 3-piece CX and CXM prostheses implantation results are comparable to those of the 1-piece model.

Device Removal↗
PubMed2005

Outcomes following revisions and secondary implantation of the artificial urinary sphincter.

PURPOSE: Durable success with the artificial urinary sphincter (AUS) is common but device revision and replacement are often needed for various reasons. We examined indications and outcomes following these secondary procedures with comparisons to outcomes after primary procedures. MATERIALS AND METHODS: The medical records of all patients undergoing primary and secondary bulbar urethral AUS implantation and revision from January 1990 to September 2002 were reviewed for various demographic and surgical variables. Female patients and males with bladder neck cuffs were excluded from study. RESULTS: Of 554 men undergoing AUS implantation or revision 119 (21.4%) underwent a total of 159 secondary procedures. Reasons for revision were mechanical failure in 31 cases (25.2%) and nonmechanical failure in 88 (73.9%). The latter included recurrent incontinence due to urethral atrophy in 63 cases (52.9%) and erosion in 21 (17.6%). Total device replacement was performed in 75 cases (47.2%). Of 119 patients undergoing secondary implantation 91 (76.5%) needed no additional surgical intervention, while 28 (23.5%) required a total of 40 surgical revisions for new mechanical (15 or 37.5%) and nonmechanical (25 or 62.5%) problems. Five-year durability outcomes for primary and secondary AUS implantation were comparable at 80% and 88%, respectively. Similarly excellent continence outcomes (0 to 1 pad daily) were noted in 90% and 82% of patients undergoing primary and secondary AUS implantation, respectively. Secondary and tertiary AUS revisions resulted in the restoration of baseline continence in 106 cases (89%). CONCLUSIONS: Our study suggests that outcomes for secondary AUS reimplantation are comparable to those of primary AUS implantation and salvage of a good outcome is always probable, even following multiple prior revisions and cuff erosion.

Adult↗
PubMed2001

Intermediate-term outcomes of 350-mm(2) Baerveldt glaucoma implants.

OBJECTIVE: To determine the intermediate-term outcome of 350-mm(2) Baerveldt glaucoma implants. DESIGN: Retrospective, noncomparative case series. PARTICIPANTS: Sixty-five patients (65 eyes). INTERVENTION: Implantation of 350-mm(2) Baerveldt glaucoma drainage device. MAIN OUTCOME MEASURES: Intraocular pressure, number of glaucoma medications, best-corrected Snellen visual acuity, length of follow-up, risk factors for failure, and complications. RESULTS: Mean intraocular pressure was reduced from a preoperative value of 32 mmHg to a 2-year postoperative value of 14 mmHg (56% reduction, P < 0.001). Success rates at 2-year follow-up were 71%, 81%, 78%, 60%, and 47% for the overall group, primary open-angle glaucoma group, neovascular group, uveitic group, and other group, respectively. After accounting for the effect of diagnosis group, significant risk factors in the overall group for failure at 2 years included younger age, high preoperative intraocular pressure, and more prior incisional surgeries. Glaucoma medication use in our overall study population was reduced from 2.5 mean preoperative medications to 0.8 postoperative medications (68%). Median change in Snellen visual acuity between preoperative and 2-year postoperative visits was not significant in the overall group. Postoperative complications included choroidal effusion in 15 patients (23%), tube obstruction by blood or vitreous in five patients (8%), phthisis in four patients (6%), aqueous misdirection in two patients (3%), strabismus in two patients (3%), tube-cornea touch in two patients (3%), endophthalmitis in two patients (3%), and retinal detachment in two patients (3%). No patients had suprachoroidal hemorrhage. CONCLUSIONS: The 350-mm(2) Baerveldt glaucoma implants are a safe and effective treatment for intermediate-term intraocular pressure control in patients with refractory glaucoma.

Adult↗
PubMed1997

[Failure of total uncemented trapeziometacarpal prosthesis. A multicenter study].

The total trapeziometacarpal prosthesis that we have designed has been used clinically for five years. We thought it would be useful to revise failures of these prostheses in a multicentre study in order to identify the causes of the problems and to provide necessary modifications for improvement of the results. Eleven surgeons participated in this study, allowing the review of 24 failures out of a total of 188 implanted prosthesis (12.7%). One case of sepsis and three prosthesis dislocations were observed. In ten cases, we found that the cup was not correctly oriented, leading to a progressive loosening of the cup. In five cases, the shaft had sunk into the metacarpal which was associated with modification of the axis of the shaft in relation to the metacarpal in two cases. In three of these cases, the size of the shaft was too small. Twenty-three failures were reoperated. Metallosis of periprosthetic tissues was observed in 6 cases. This disadvantage has disappeared since treating the heads with ionic nitrogen implantation. A larger size of the same type of prosthesis was able to be implanted in 5 cases. A silicone prosthesis was used in 2 cases and a trapezectomy with or without ligamentoplasty was performed in 16 cases. The high failure rate related to a poor orientation of the cup has led us to increase the range of motion of the prosthesis in order to compensate for the possibly poor orientation of the cup during implantation.

Adult↗
PubMed2004

Five year follow up of biocolonisable microporous fluorocarbon haptic (BIOKOP) keratoprosthesis implantation in patients with high risk of corneal graft failure.

AIM: To study the anatomical and visual performance following implantation of a model of artificial cornea and to evaluate the postoperative long term complications. METHODS: 11 eyes of 11 patients with bilateral corneal blindness considered as potentially having high risk of failure of penetrating corneal keratoplasty were implanted with biocolonisable Kpro keratoprosthesis (BIOKOP I, FCI, Rantigny, France) in the period between January 1996 and May 1998. Only one eye was implanted in all patients and followed up for a period of 60 months. The visual outcome, anatomical and functional stability, complications, and the general performance of the keratoprosthesis were evaluated. RESULTS: The keratoprosthesis (BIOKOP I) only 36.3% remained in position to date. In the patients' last visit five eyes (45.4%) were blind and one (9.0%) showed a slight improvement in the best corrected visual acuity (BCVA) in comparison to preoperative tests. Six eyes (54.5%) showed improved BCVA before having postoperative complications. Four eyes underwent replacement of a BIOKOP I Kpro with a BIOKOP II as a result of extrusion. The keratoprostheses remained anatomically in situ for a mean of 25.5 months and their functional performance period was limited to a mean of 22 months. CONCLUSION: Corneal keratoprosthesis (BIOKOP I, II) does not provide a stable anatomical relation with the surrounding ocular structures. Its ability to restore vision is limited to a short postoperative period in eyes implanted with severe ocular surface disease.

Adolescent↗
PubMed2005

The combined use of hydroxyapatite and bioresorbable plates to repair cranial defects in children.

OBJECT: Hydroxyapatite cement (HAC) is used with increasing frequency by craniofacial surgeons for building facial and skull base structures and by neurosurgeons for cranioplasty. Failures of HAC in cranioplasty have been attributed to breakage due to subjacent cerebrospinal fluid (CSF) pulsations through the dura mater. The authors describe a technique that involves inserting a resorbable MacroPore perforated plate to dampen CSF pulsations and then pouring HAC over the plate to fill a cranial defect and complete skull contouring. METHODS: Fifteen children ranging in age from 2 to 9.5 years were included in the study; the size of the skull defects in these patients ranged from 6.25 to 42.5 cm2, with a mean of 20.65 cm2. Patients in whom the combined MacroPore--HAC devices were implanted underwent follow-up examinations that included serial skull radiography and computerized tomography scans. No fractures of the implants were demonstrated. At 6 months postsurgery, small fingerlings of new bone growth appeared in the underside of the HAC plate, probably spanning from the dura through perforations in the MacroPore plate. At intervals ranging from 18 months to 20 years after implantation, the gaps between cranial bone edges and that the HAC began to blur, culminating in the complete bonding of host bone with the margin of the HAC plate. All implants remained radiopaque and maintained size, thickness, and shape. CONCLUSIONS: The findings of this study are promising and indicate that the combined use of HAC and a bioresorbable undercarriage that is osteoconductive, such as the MacroPore perforated plate, may produce a versatile and lasting cranioplasty in children.

Biocompatible Materials↗
PubMedDate not supplied

Implantation of second glaucoma drainage devices after failure of primary devices.

BACKGROUND AND OBJECTIVE: To evaluate the efficacy and safety of implantation of a second glaucoma drainage device for eyes that have failed a primary device. PATIENTS AND METHODS: Medical records of patients receiving a primary glaucoma drainage device at Bascom Palmer Eye Institute from January 1987 to October 1998 were reviewed, of which 18 eyes of 18 patients were studied. Patients failing a primary glaucoma drainage procedure and receiving a second glaucoma drainage device were included in this study. The second eye in the same patient was excluded if a second drainage implant was required. All patients received a second device in a standardized fashion with the drainage tube inserted in the anterior chamber. Main outcome measures included: visual acuity, intraocular pressure (IOP), antiglaucomatous medication, length of follow up, and surface area of glaucoma drainage device. Success was defined as an IOP less than or equal to 21 mm Hg with or without medications, and at least a 20% reduction in IOP, without the need for additional glaucoma procedures. RESULTS: The mean postoperative IOP (19.6 +/- 9.4 mm Hg; range, 8-50 mm Hg) was significantly (P = 0.006) lower than the mean preoperative IOP (29.5 +/- 8.1 mm Hg; range, 20-52 mm Hg) at last follow up (mean 19.6 +/- 13.6 months; range, 6-47 months). The mean number of postoperative antiglaucomatous medications (2.2 +/- 1.2; range 0-4) was statistically similar (P = 0.2) to mean preoperative number of antiglaucomatous medications (2.6 +/- 1.2, range 1-4). Using Kaplan-Meier estimates, successful IOP reduction was observed in 89%, 83%, 63%, and 37% of eyes at 6 months, 1, 2, and 3 years, respectively. Four patients (21%) had a decline in visual acuity. CONCLUSIONS: Implantation of secondary glaucoma drainage devices may be useful in eyes that have failed primary devices.

Adult↗
PubMed1999

Mechanisms of bioprosthetic heart valve failure: fatigue causes collagen denaturation and glycosaminoglycan loss.

Bioprosthetic heart valve (BPHV) degeneration, characterized by extracellular matrix deterioration, remodeling, and calcification, is an important clinical problem accounting for thousands of surgeries annually. Here we report for the first time, in a series of in vitro accelerated fatigue studies (5-500 million cycles) with glutaraldehyde fixed porcine aortic valve bioprostheses, that the mechanical function of cardiac valve cusps caused progressive damage to the molecular structure of type I collagen as assessed by Fourier transform IR spectroscopy (FTIR). The cyclic fatigue caused a progressive loss of helicity of the bioprosthetic cuspal collagen, which was evident from FTIR spectral changes in the amide I carbonyl stretching region. Furthermore, cardiac valve fatigue in these studies also led to loss of glycosaminoglycans (GAGs) from the cuspal extracellular matrix. The GAG levels in glutaraldehyde crosslinked porcine aortic valve cusps were 65.2 +/- 8.66 microg uronic acid/10 mg of dry weight for control and 7.91 +/- 1.1 microg uronic acid/10 mg of dry weight for 10-300 million cycled cusps. Together, these molecular changes contribute to a significant gradual decrease in cuspal bending strength as documented in a biomechanical bending assay measuring three point deformation. We conclude that fatigue-induced damage to type I collagen and loss of GAGs are major contributing factors to material degeneration in bioprosthetic cardiac valve deterioration.

Animals↗
PubMed2002

Standardized analysis of UHMWPE wear particles from failed total joint arthroplasties.

Periprosthetic tissue obtained at revision surgery from eight total hip replacement cases was hydrolyzed, and polyethylene debris particles were isolated from each case. Individual particles were analyzed by scanning electron microscopy (SEM) and computerized image analysis in accordance with ASTM F1877-98, a standard for quantitative description of wear debris. For comparison, periprosthetic tissues from eight total knee revision and four total shoulder revision cases were processed and analyzed with identical methods. A total of 2599 hip, 4345 knee, and 1200 shoulder particles were analyzed. The morphologies of the isolated polyethylene particles from the total hip specimens were distinctly different from the total knee and total shoulder particles. The mean equivalent circle diameter (ECD) for hip particles was 0.694 microm +/- 0.005; knee particles measured 1.190 microm +/-0.009; and shoulder particles 1.183 microm +/- 0.017. The ECD was significantly different between hip particles and those from the shoulder and knee. The mean aspect ratio (AR) for the hip particles was 1.626 +/- 0.015, compared to the knee particles at 1.935 +/- 0.015 and shoulder particles at 2.082 +/- 0.033. The AR was statistically different among all three groups. Other descriptors from the ASTM standard, elongation (E), form factor (FF), and roundness (R) were all significantly different among the three groups of joints. This study demonstrates the utility of ASTM F1877-98 in differentiating wear debris particles from different sources.

Adult↗
PubMed2003

Failure analysis of two Ti-alloy total hip arthroplasty femoral stems fractured in vivo.

Failure of total hip arthroplasty femoral stems is a serious clinical complication. Even modern metal alloys and designs sometimes suffer such incidents. The reported study aimed at the investigation of the reasons leading the in vivo fracture of two Ti6Al4V femoral stems. Stems were retrieved during revision surgery approximately 2 years postoperatively. Examination and analysis included XRF spectrometry for identification of chemical composition, macroscopic examination and topographical measurements, SEM study of fracture surfaces, study of alloy microstructure by optical microscopy, and finally measurement of mechanical properties by means of tensile testing conducted on alloy samples machined from the stems themselves. Macroscopic examination and measurements showed close topographical similarity between the two fractures. XRF spectrometry, tensile testing, and microstructure analysis identified the alloy as a typical Ti6Al4V surgical titanium alloy. During SEM analysis the fracture surfaces exhibited characteristic fatigue striations tidally running on the cross sections, which were considered as the weakest ones regarding toward geometry and stress concentration. Fracture in both stems occurred due to fatigue along these cross sections.

Adult↗
PubMed2003

Surface composition analysis of failed cementless CoCr- and Ti-base-alloy total hip implants.

The surfaces of retrieved failed cementless total hip implants made of cobalt-chromium-molybdenum casting alloy and of wrought titanium 6-aluminum 4-vanadium alloy were studied with the use of scanning-electron microscopy (SEM), energy-dispersive X-ray analysis (EDX) and X-ray photoelectron spectroscopy (XPS). New implants of the same make served as controls. The XPS scans revealed a dense carbon layer on the entire analyzed specimen. The relative composition of the titanium alloy implants showed an overall agreement with the international standards for implants for surgery, and the overall surface composition did not change over the period of the implantation. However, an inhomogeneous distribution of the constituents could be demonstrated in the retrieved as well as in the new MEC-screw rings made of TiAl6V4 alloy, an implant that has been linked to a high early failure rate. In the CoCr-alloy components (Lord-screw rings) a high percentage of aluminum, mainly organized in aluminum inclusions, was found in the retrieved as well as in the new implants.

Adult↗
PubMed2004

Long-term strength of ceramics for biomedical applications.

The influence of slow crack growth on the initiation of radial cracks at the lower surfaces of ceramic layers bonded to polymeric substrates is studied, with particular relevance to biomechanical systems, e.g., dental crowns and hip replacement prostheses. Critical loads are measured as a function of loading rate (dynamic fatigue) for model bilayers fabricated by epoxy-bonding selected clinical ceramics to polycarbonate bases. Radial crack initiation is observed in situ by viewing from below the transparent base during loading. Declines in the critical loads with diminishing load rate are consistent with slow crack growth of intrinsic flaws prior to radial crack pop in. A simple fracture mechanics relation incorporating a crack velocity function is used to analyze the data. Extrapolation beyond the data range enables long-lifetime (10 yr) estimates of sustainable loads. The procedure provides a basis for ranking ceramic types, and in particular for eliminating vulnerable candidate materials, for use in biomechanical systems. While slow crack growth is an important factor in failure, other mechanisms could operate in concert and even dominate under severe testing conditions, especially under cyclic loading.

Biocompatible Materials↗
PubMed2002

The influence of biomaterial on patterns of failure after cemented total hip replacement.

We examined aseptic loosening and osteolysis in 77 revised McKee-Arden total hip arthroplasties (THAs) using polyethylene cups and identical femoral stems made from either cobalt chrome alloy or titanium alloy. Time to failure was significantly shorter in the titanium group. Loosening and peri-prosthetic osteolysis occurred with significantly higher frequency in the titanium group compared to the cobalt chrome group.

Adult↗
PubMed2003

Increased volumetric wear of polyethylene liners with more than 3 years of shelf-life time.

We analyzed 20 retrieved gamma-sterilized polyethylene liners (Biomet Hexloc). The long-term durability varied significantly depending on shelf-life time before implantation. Liners with a shelf-life time of 3 years or more evinced significantly ( P 0.002) higher volumetric wear than those with a shelf life time less than 3 years. Infrared spectroscopy and scanning calorimetry showed that all explanted implants underwent substantial in vivo oxidation and crystallization. The oxidative ageing of polyethylene renders the polyethylene liner susceptible to severe wear. Scanning electron microscopy of the bearing surface of the liner revealed abrasive wear as a dominant mechanism. Moreover, poor acetabular design produces excessively thin liners, substandard locking mechanism, and backside wear of the liner. The primary reason for severe wear in the Hexloc liner was poor modular design and oxidative degradation of the polyethylene.

Adult↗
PubMed2003

Wear mode and wear mechanism of retrieved acetabular cups.

Nineteen ultra-high-molecular-weighted polyethylene (UHMWPE) cups were retrieved at revision surgery. The implant period was on average 9.9 (0.25-20.7) years. The cups were classified into the high-wear group (wear rate above 140 mm(3)/year), intermediate-wear group (wear rate 80-140 mm(3)/year) and low-wear group (wear rate below 80 mm(3)/year). The wear rate was measured by a fluid displacement method. The cups were studied using scanning electron microscopy. Ripples mainly appeared on the cups in the low-wear group, and nodules and fibrils mainly appeared in the high-wear group. Folding was observed in all cups, but folding with numerous fibrils was conspicuous in the high-wear group. The cup retrieved at 3 months already exhibited folding. From these results, the wear response appeared to be a three-step process: (1) foldings are generated, (2) ripples are formed on the surface, and (3) fibrils are produced from the surface and delaminated, leading to the formation of wear debris.

Adult↗