Bioprosthetic valve failure.
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Bioprosthesis↗
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Success rates and failure rates, and causes of failure for common arterial reconstructive procedures.
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Angioplasty, Balloon↗
[Vascularized fibular transplant for avascular necrosis of the femoral head: 16 cases].
PURPOSE OF THE STUDY: We report our experience with vascularized fibular transplant using the technique described by Urbaniak for the treatment of avascular necrosis of the femoral head. MATERIAL AND METHODS: Sixteen patients, mean age 39 years 4 months at surgery, were evaluated at mean 3 years 6 months follow-up (minimum 15 months). Mean pain score (analog visual scale) was 6.25/10. Mean Postel-Merle-d'Aubigné (PMA) function score was 12. The Ficat classification was grade 2A (n=9) or grade 2B (n=7). RESULTS: There were no cases of infection or migration of the fibula. The only complication at the donor site was one case of paresia of the long extensor of the hallux which resolved spontaneously. There were five failures which required a hip prosthesis (31%). Three failures occurred early during the first 18 months. Two were late. These patients had grade 2B (n=4) or grade 2A (n=1) necrosis. At last follow-up, eleven hips had not required prosthetic revision (69%). The pain score improved in 81% of patients: mean score=2.3. Nine patients were satisfied or very satisfied (81%). Among these eleven hips, function was good or excellent in eight (72%). Walking distance was improved in nine patients, unchanged in one and worse in one. Joint motion improved in nine patients, was unchanged in one and decreased in one. Nine patients resumed their full-time job. Mean sick leave was 13.3 months. Radiographically, only two of the initial Ficat grade 2A hips remained at this stage. Likewise only one of the three hips initially rated grade 2B remained at this stage. Overall radiographic results were: failure (n=5), worsening (n=9), stabilization and no improvement (n=2). Among the nine 2A hips, one was converted to a total hip prosthesis and five femoral heads remained spheric. Among the seven 2B hips, four were converted to a total hip prosthesis and two femoral heads collapsed. DISCUSSION: At mean follow-up (3.5 years), 69% of the hips had not required total hip arthroplasty. The grade 2A hips did better but the small sample size did not allow statistical comparison. There was a clear discordance between the clinical presentation and the radiographic findings among the hips which were not treated with a prosthesis: good function score, maintained occupational and daily life activities contrasting with unfavorable radiographic evolution. Results could be improved by detailed quantification of the lesion using 3D imaging and by associating intraoperative navigation.
Adult↗
De la Caffinière arthroplasty for basal thumb joint osteoarthritis.
We performed 20 de la Caffinière trapeziometacarpal arthroplasties for osteoarthritis occurring only at this joint and reviewed all patients after periods of up to ten years. Eighteen arthroplasties were satisfactory postoperatively, although all 20 patients had a satisfactory range of motion and only one experienced pain after surgery such that it impeded normal function. Failure occurred in two patients and was due to overreaming of the trapezium during surgery and a traumatic dislocation. A radiolucency between the prosthesis and bone was observed in one arthroplasty, although this patient was asymptomatic. We recommend arthroplasty using the de la Caffinière prosthesis as a satisfactory method of treatment for the osteoarthritic trapeziometacarpal joint.
Female↗
Composite fixation of salvage prostheses for the hip and knee.
A composite fixation method for a porous-coated modular segmental bone/joint prosthetic system was developed to improve fixation at revision surgery of the hip and knee after failure of the original implant with resulting massive bone loss. The porous coating is limited only to the segmental shoulder region of the prosthesis, while bone cement is used to provide initial implant stability. Autogenous bone grafts are applied over the porous-coated region to achieve extracortical bone bridging and ingrowth for long-term biologic fixation. Bench tests, theoretical analysis, and animal experiments were performed to validate this fixation concept. Clinical, roentgenographic, and functional results of revision patients using these prostheses and the underlying fixation principle are very encouraging. A number of limiting factors were identified and further improvements are being investigated to foster this concept as a viable salvage alternative.
Bone Regeneration↗
The microscopic anatomy of the bone-cement interface in failed total hip arthroplasties.
Thirty specimens were removed from the bone-cement interface in 25 hips revised for aseptic loosening of total hip arthroplasty. Histologic examination of the membranous tissues revealed that histiocytosis, fibrosis, and necrosis were present in every specimen. Other prominent features included particles of acrylic cement, polyethylene debris, and fragments of necrotic bone. Mechanical failure was characterized by cement fractures, and microfracture of bone. The presence of cement debris and bone detritus in the membranes, and smooth appearance of the removed cement mantles substantiated the presence of mechanical failure. The process of loosening was characterized by the recruitment of histiocytes into the interface and the subsequent resorption of bone around the prosthesis. This may be a manifestation of the rate of cement wear and tear, particle size, and the immunologic predispositions of the host. These observations on interfaces of loosened prostheses are reexamined and reinterpreted in the light of radiologic observations on interface radiolucent zones and well-functioning prostheses.
Acetabulum↗
Factors affecting sagittal malalignment due to cage subsidence in standalone cage assisted anterior cervical fusion.
Fusion of cervical spine in kyphotic alignment has been proven to produce an acceleration of degenerative changes at adjacent levels. Stand-alone cages are reported to have a relatively high incidence of implant subsidence with secondary kyphotic deformity. This malalignment may theoretically lead to adjacent segment disease in the long term. The prospective study analysed possible risk factors leading to cage subsidence with resulting sagittal malalignment of cervical spine. Radiographic data of 100 consecutive patients with compressive radiculo-/myelopathy due to degenerative disc prolapse or osteophyte formation were prospectively collected in those who were treated by anterior cervical discectomy and implantation of single type interbody fusion cage. One hundred and forty four implants were inserted altogether at one or two levels as stand-alone cervical spacers without any bone graft or graft substitute. All patients underwent standard anterior cervical discectomy and the interbody implants were placed under fluoroscopy guidance. Plain radiographs were obtained on postoperative days one and three to verify position of the implant. Clinical and radiographic follow-up data were obtained at 6 weeks, 3 and 6 months and than annually in outpatient clinic. Radiographs were evaluated with respect to existing subsidence of implants. Subsidence was defined as more than 2 mm reduction in segmental height due to implant migration into the adjacent end-plates. Groups of subsided and non-subsided implants were statistically compared with respect to spacer distance to the anterior rim of vertebral body, spacer versus end-plate surface ratio, amount of bone removed from adjacent vertebral bodies during decompression and pre- versus immediate postoperative intervertebral space height ratio. There were 18 (18%) patients with 19 (13.2%) subsided cages in total. No patients experienced any symptoms. At 2 years, there was no radiographic evidence of accelerated adjacent segment degeneration. All cases of subsidence occurred at the anterior portion of the implant: 17 cases into the inferior vertebra, 1 into the superior and 1 into both vertebral bodies. In most cases, the process of implant settling started during the perioperative period and its progression did not exceed three postoperative months. There was an 8.7 degrees average loss of segmental lordosis (measured by Cobb angle). Average distance of subsided intervertebral implants from anterior vertebral rim was found to be 2.59 mm, while that of non-subsided was only 0.82 mm (P < 0.001). Spacer versus end-plate surface ratio was significantly smaller in subsided implants (P < 0.001). Ratio of pre- and immediate postoperative height of the intervertebral space did not show significant difference between the two groups (i.e. subsided cages were not in overdistracted segments). Similarly, comparison of pre- and postoperative amount of bone mass in both adjacent vertebral bodies did not show a significant difference. Appropriate implant selection and placement appear to be the key factors influencing cage subsidence and secondary kyphotisation of box-shaped, stand-alone cages in anterior cervical discectomy and fusion. Mechanical support of the implant by cortical bone of the anterior osteophyte and maximal cage to end-plate surface ratio seem to be crucial in the prevention of postoperative loss of lordosis. Our results were not able to reflect the importance of end-plate integrity maintenance; the authors would, however, caution against mechanical end-plate damage. Intraoperative overdistraction was not shown to be a significant risk factor in this study. The significance of implant subsidence in acceleration of degenerative changes in adjacent segments remains to be evaluated during a longer follow-up.
Adult↗
The biologic responses to orthopedic implants and their wear debris.
The use of artificial materials in the treatment of orthopaedic conditions, most notably arthritis, over the past few decades has been increasing dramatically. Such use makes an understanding of the tissue responses to the various materials necessary to determine their effectiveness and acceptability. This review concentrates on the studies of the biological responses to the materials that are used mainly in joint replacements and fixation of fractures. In-vivo and in-vitro experimental studies of various metals, polymers and ceramics and their constituents are first presented with discussions regarding their clinical importance. Studies of clinically successful implants are then presented to illustrate the expected morphological features of incorporation and acceptance by the host tissues. The local and systemic effects complicating the use of the implanted materials as well as the failure of the implant are then presented.
Ceramics↗
Left ventricular assist device performance with long-term circulatory support: lessons from the REMATCH trial.
BACKGROUND: Left ventricular assist device (LVAD) failure and malfunction rates are critical gauges for establishing LVADs as a long-term therapy for end-stage heart failure patients. These device performance measures, however, have been inadequately characterized in the bridge-to-transplantation literature. METHODS: REMATCH is a randomized trial that compares optimal medical management with LVAD implantation for patients with end-stage heart failure. An independent committee adjudicated patient outcomes. The primary endpoint--survival--was analyzed by intention to treat using the log-rank statistic. Frequency of event occurrence was analyzed by Poisson regression. The time to first event was analyzed by the product limit method. Device performance was disaggregated into confirmed malfunctions and system failures. The latter were events in which patients could not be rescued with backup circulatory support measures. RESULTS: The 1-year survival rate was 52% (95% confidence limit [CL]; 40%-63%) for LVAD patients versus 28% (95% CL; 17%-39%) for medical patients and the 2-year survival rate was 29% (95% CL; 19%-40%) for LVAD patients versus 13% (95% CL; 5%-22%) for medical patients. System failure was 0.13 per patient per year and the confirmed LVAD malfunction rate was 0.90. Freedom from device replacement was 87% at 1 year and 37% at 2 years. CONCLUSIONS: Despite the observed rates of device malfunction and replacement, LVAD implantation confers clinically significant improvement with regard to survival as compared with medical management. Device modifications and innovations for infection management exhibit great promise of improving device performance in the near future.
Aged↗
Failure of humeral fracture fixation plate in a young patient using the Philos system: case report.
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Adult↗
Failure analysis of broken pedicle screws on spinal instrumentation.
Revised spinal surgery is needed when there is a broken pedicle screw in the patient. This study investigated the pedicle screw breakage by conducting retrieval analyses of broken pedicle screws from 16 patients clinically and by performing stress analyses in the posterolateral fusion computationally using finite element (FE) models. Fracture surface of screws was studied by scanning electron microscope (SEM). The FE model of the posterolateral fusion with the screw showed that screws on the caudal side had larger axial stress than those on the cephalic side, supporting the clinical findings that 75% of the patients had the screw breakage on the caudal side. SEM fractography showed that all broken screws exhibited beach marks or striations on the fractured surface, indicating fatigue failure. Screws of patients with spinal fracture showed fatigue striations and final ductile fracture around the edge. Among the 16 patients who had broken pedicle screws 69% of them achieved bone union in the bone graft, showing that bone union in the bone graft did not warrant the prevention of screw breakage.
Adult↗
Clinical correlation of femoral component migration in hip resurfacing arthroplasty analyzed by Einzel-Bild-Röntgen-analyze-femoral component analysis.
Hip resurfacing arthroplasty using metal-on-metal bearings has become increasingly popular. Wear of these bearings has been imperceptible on plain radiographs. Migration analysis studies may represent the opportunity to detect early failures and evaluate long-term prosthetic survival. The authors retrospectively reviewed 29 hips in a consecutive series of metal-on-metal hip resurfacing arthroplasties with a long-term clinical follow-up (average 8.7 years) to analyze the femoral component migration pattern by means of Einzel-Bild-Röntgen-Analyze-femoral component analysis (EBRA-FCA). Femoral component migrations at 2 years and latest follow-up were compared with the known clinical outcomes. The authors' findings add validity to EBRA-FCA as a means to monitor femoral component migration and the clinical outcome of metal-on-metal hip resurfacing arthroplasty.
Arthroplasty, Replacement, Hip↗
Slide track analysis of eight contemporary hip simulator designs.
In an earlier paper, the authors presented a new method of computation of slide tracks in the relative motion between femoral head and acetabular cup of total hip prostheses. For the first time, computed tracks were verified experimentally and with an alternative method of computation. Besides being an efficient way to illustrate hip kinematics, the shapes of the slide tracks are known to be of fundamental importance regarding the wear behaviour of prostheses. The verified method was now applied to eight contemporary hip simulator designs. The use of correct motion waveforms and an Euler sequence of rotations in each case was again found to be essential. Considerable differences were found between the simulators. For instance, the shapes of the tracks drawn by the resultant contact force included a circle, ellipse, irregular oval, leaf, twig, and straight line. Computation of tracks correctly for the most widely used hip simulator, known as biaxial, was made possible by the insight that the device is actually three-axial. Slide track patterns have now been computed for virtually all contemporary hip simulators, and both for the heads and for the cups. This comparative analysis forms a valuable basis for studies on the relationship between the type of multidirectional motion and wear. These studies can produce useful information for the design of joint simulators, and improve the understanding of wear phenomena in prosthetic joints.
Acetabulum↗
[Deflation of breast implants, pre-filled with saline or hydrogel. Results and analysis of 650 treated patients].
SUBJECT: The main mechanical side effect of saline or hydrogel filled implants is deflation. The aim of this study was to analyse the prosthetic deflation rate in the last 7 years in the plastic surgery unit of Toulouse. PATIENTS AND METHODS: We tracked 650 patients operated on between july 1993 and july 2000 (representing 1117 primary implants) which we separated in two groups: the first group contained patients in need of breast reconstruction; the second group contained all the patients with implants placed for aesthetic or breast asymMetry reasons. For each of the two groups we determined the number and the type of implants, as well as the rate and the mean delay after which deflation occurred. RESULTS: During this period, we've determined that: rate of deflation of group 1 (reconstruction) is highest than group 2 (aesthetic), despite sort of implant; rates of deflation of pre-filled hydrogel implants are highest than rates of deflation of pre-filled saline implants. DISCUSSION: Only a few series concerning implants deflation have been described in the literature. We can find a large difference in results which vary from 2 to 76%. We were surprised by the result of our series with a rate of deflation up to 15% with a medium follow-up 5 years in both groups and a mean delay before the fourth year. Deflation's factors are numerous: type of sterilisation, rippling, texture, valve's incompetence, prosthetic patch, guarantee control and iatrogenic causes. Because the silicone gel implants (the one uncomplicated by deflation) were taken off the french market, the saline implants tried to supplant them but without satisfactory results. CONCLUSIONS: With the unacceptable rate deflation of implants in our study, the return in the french market of silicone gel implants seems us an acceptable alternative.
Adolescent↗
[Medical-legal aspects in fractured ceramic liners after implantation of a hip endoprosthesis].
We report the case of a male patient after implantation of a thrust plate endoprosthesis to discuss reliable questions concerning the insurance and liability fields. The indication for implantation of this type of endoprosthesis should be decided critically. To prevent an early implant failure, both articulating ceramic partners - the liner and the femoral head - should be exchanged in any case of doubt during a hip revision surgery. In case of an implant failure, a surface analysis of the broken fragments can show signs of material insufficiencies. A detailed preoperative consent of the patient combined with an exact documentation is necessary to prevent potential medical claims by the patient, and also increases the compliance and reduces the costs for the health system.
Adult↗
Biochemical pathways of tissue degeneration in bioprosthetic cardiac valves. The role of matrix metalloproteinases.
Degeneration processes that affect bioprosthetic heart valves made from glutaraldehyde treated bovine pericardium are poorly understood. The present study undertook the identification and characterization of matrix metalloproteinases (MMPs) in extracts obtained from 28 pericardial derived bioprosthetic heart valves explanted at surgery. A lysosomal marker was used to assess the incidence of infiltrating extracellular matrix degrading cells. The major biochemical features that were associated with tissue degeneration and bioprosthetic heart valve failure were increased levels of MMP 9, high levels of beta-glucuronidase, and constant levels of active collagenase and MMP 2. The MMPs extracted from ruptured bioprostheses were inhibited by calcium chelators and zinc binding compounds. These data suggest that tissue failure, in addition to known mechanical and calcification related factors, may be contributed to by the intervention of proteolytic enzymes. A schematic working model was proposed that described the major biochemical pathways underlying tissue degeneration, starting from bioprostheses preparation and ending with clinical failure.
Animals↗
A finite element analysis of factors influencing total hip dislocation.
A previously validated three-dimensional finite element model was used to study how several total hip component design and surgical placement variables contribute to resisting the propensity for posterior dislocation in the case of leg crossing in an erectly seated position. The computational formulation incorporated treatments of polyethylene material nonlinearity and large displacement sliding contact. The primary outcome measures were the peak intrinsic moment developed to resist dislocation, and the ranges of motion before neck on lip impingement and before frank dislocation. Modifications of the acetabular linear design (chamfer bevel angle, lip breadth, head center inset) involved trading off improved peak resisting moment for compromised range of motion and vice versa. Increases of head size led to substantial improvements in peak resisting moment, but if the head to neck diameter ratio was held constant, had almost no influence on the component range of motion. For the leg crossing event studied, increased component anteversion, and even more so increased tilt (less net abduction), achieved improvements in range of motion and in peak resisting moment, but these changes imply diminished resistance to anterior dislocation from extension and adduction motion inputs.
Arthroplasty, Replacement, Hip↗
Femoral arterial graft failure caused by the secondary abdominal compartment syndrome.
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Adult↗